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Duong M, Golzi A, Peytavin G, Piroth L, Froidure M, Grappin M, Buisson M, Kohli E, Chavanet P, Portier H. Usefulness of Therapeutic Drug Monitoring of Antiretrovirals in Routine Clinical Practice. HIV CLINICAL TRIALS 2015; 5:216-23. [PMID: 15472796 DOI: 10.1310/nxju-9erq-adww-uc5x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Clinical trials have shown that therapeutic drug monitoring (TDM) of antiretrovirals (ARV) improves patient care. However, little is known about the usefulness of TDM in routine practice. METHOD We reviewed all the trough concentrations of protease inhibitors and nonnucleoside reverse transcriptase inhibitors that were performed for therapeutic failure, suspected drug toxicity, or routine purposes. RESULTS Between 1998 and 2001, 146 TDMs were done in 109 HIV patients. Of the 48 patients with therapeutic failure, 62% had resistance to ARV with adequate ARV concentrations, 16% had insufficient drug exposure without any ARV resistance mutations, and 16% combined both resistance and suboptimal drug concentrations. Subsequent therapeutic interventions (increasing adherence and/or changing HAART) resulted in an undetectable viral load in 37.5% of the patients (14/48). Five (24%) of 21 patients with suspected drug toxicity had high drug concentrations associated with side effects. In all the cases, adverse events regressed after reduction of drug dosage. Of the 77 TDMs done for routine purposes, 26% were outside the therapeutic range. CONCLUSION The data show that TDM of ARVs in the clinical setting provides important information that can be used to improve the management of HIV patients receiving antiretroviral therapy.
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Affiliation(s)
- Michel Duong
- Division of Infectious Diseases, University Hospital, Dijon, France.
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Factors affecting antiretroviral pharmacokinetics in HIV-infected women with virologic suppression on combination antiretroviral therapy: a cross-sectional study. BMC Infect Dis 2013; 13:256. [PMID: 23732043 PMCID: PMC3679788 DOI: 10.1186/1471-2334-13-256] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 05/16/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Although some studies show higher antiretroviral concentrations in women compared to men, data are limited. We conducted a cross-sectional study of HIV-positive women to determine if protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) C(min) and Cmax values were significantly different than historical general population (predominantly male) averages and to evaluate correlates of higher concentrations. METHODS HIV-positive women with virologic suppression (viral load < 50copies/mL) on their first antiretroviral regimen were enrolled. Timed blood samples for C(min) and Cmax were drawn weekly for 3 weeks. The ratio of each individual's median C(min) and Cmax to the published population mean values for their PI or NNRTI was calculated and assessed using Wilcoxon sign-rank. Intra- and inter-patient variability of antiretroviral drug levels was assessed using coefficient of variation and intra-class correlation. Linear regression was used to identify correlates of the square root-transformed C(min) and Cmax ratios. RESULTS Data from 82 women were analyzed. Their median age was 41 years (IQR=36-48) and duration of antiretrovirals was 20 months (IQR=9-45). Median antiretroviral C(min) and Cmax ratios were 1.21 (IQR=0.72-1.89, p=0.003) (highest ratios for nevirapine and lopinavir) and 0.82 (IQR=0.59-1.14, p=0.004), respectively. Nevirapine and efavirenz showed the least and unboosted atazanavir showed the most intra- and inter-patient variability. Higher CD4+ count correlated with higher C(min). No significant correlates for Cmax were found. CONCLUSIONS Compared to historical control data, C(min) in the women enrolled was significantly higher whereas Cmax was significantly lower. Antiretroviral C(min) ratios were highly variable within and between participants. There were no clinically relevant correlates of drug concentrations. TRIAL REGISTRATION NCT00433979.
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Abstract
PURPOSE OF REVIEW Although the past 20 years have seen many advances in HIV pharmacotherapy, host variability has only been more recently recognized as an important driver of both treatment response and toxicity. This review will focus on the importance of variability in drug metabolizing enzymes and the potential research and clinical applications of these findings in HIV care. RECENT FINDINGS The treatment of HIV is complex and involves chronic treatment with multiple drugs and drug classes. Recent research has been important in uncovering genetic differences in drug metabolizing and drug transporter genes, which underpin dose-dependent toxicity and efficacy, but also in genes defining differences in immune response and human leukocyte antigen genes, which restrict processes that are less dependent on the drug dose. SUMMARY The advancement of pharmacogenetics will continue to further our knowledge of disease-drug interactions and pathogenesis. Ultimately, the goals of pharmacogenetics and pharmacogenomics in HIV medicine will be the development of the right drugs for the right patient or population. The strong association between HLA-B5701 and abacavir hypersensitivity reaction shows promise for a genetic screening test to be feasibly incorporated into clinical practice. The clinical applicability of many findings demonstrating associations between single nucleotide polymorphisms, particularly in drug metabolism and transporter genes and drug efficacy and toxicity, are currently uncertain.
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Michaud V, Bar-Magen T, Turgeon J, Flockhart D, Desta Z, Wainberg MA. The Dual Role of Pharmacogenetics in HIV Treatment: Mutations and Polymorphisms Regulating Antiretroviral Drug Resistance and Disposition. Pharmacol Rev 2012; 64:803-33. [DOI: 10.1124/pr.111.005553] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Sheehan NL, van Heeswijk RPG, Foster BC, Akhtar H, Singhal N, Seguin I, DelBalso L, Bourbeau M, Chauhan BM, Boulassel MR, Burger DM, Lalonde RG, Cameron DW. The effect of β-carotene supplementation on the pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1-infected patients. Molecules 2012; 17:688-702. [PMID: 22241465 PMCID: PMC6268962 DOI: 10.3390/molecules17010688] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 01/11/2023] Open
Abstract
β-Carotene supplements are often taken by individuals living with HIV-1. Contradictory results from in vitro studies suggest that β-carotene may inhibit or induce cytochrome P450 enzymes and transporters. The study objective was to investigate the effect of β-carotene on the steady-state pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1 infected individuals. Twelve hour nelfinavir pharmacokinetic analysis was conducted at baseline and after 28 days of β-carotene supplementation (25,000 IU twice daily). Nelfinavir and M8 concentrations were measured with validated assays. Non-compartmental methods were used to calculate the pharmacokinetic parameters. Geometric mean ratios comparing day 28 to day 1 area under the plasma concentration-time curve (AUC(0-12 h)), maximum (C(max)) and minimum (C(min)) concentrations of nelfinavir and M8 are presented with 90% confidence intervals. Eleven subjects completed the study and were included in the analysis. There were no significant differences in nelfinavir AUC(0-12 h) and C(min) (-10%, +4%) after β-carotene supplementation. The M8 C(min) was increased by 31% while the M8 AUC(0-12 h) and C(max) were unchanged. During the 28 day period, mean CD4+ % and CD4+:CD8+ ratio increased significantly (p < 0.01). β-carotene supplementation increased serum carotene levels but did not cause any clinically significant difference in the nelfinavir and M8 exposure.
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Affiliation(s)
- Nancy L. Sheehan
- Faculty of Pharmacy, Universite de Montreal, C.P. 6128, succursale Centre-Ville, Montreal, H3C 3J7, Canada
- Immunodeficiency Service, McGill University Health Centre, 3650 St. Urbain, Montreal, H2X 2P4, Canada; (L.D.); (M.-R.B.); (R.G.L.)
- Authors to whom correspondence should be addressed; (N.L.S.); (D.W.C.); Tel.: +1-514-934-1934, ext 32169 (N.L.S.); Fax: +1-514-843-2828 (N.L.S.); Tel.: +1-613-737-8923 (D.W.C.); +1-613-737-8925 (D.W.C.)
| | - Rolf P. G. van Heeswijk
- Division of Infectious Diseases, University of Ottawa at the The Ottawa Hospital/Research Institute, 501 Smyth Road, Ottawa, K1H 8L6, Canada; (R.P.G.H.); (N.S.); (I.S.)
| | - Brian C. Foster
- Office of Science Laboratory, Therapeutics Products Program, Health Canada, 0900C2, Ottawa, K1A 0K9, Canada; (B.C.F.); (B.M.C.)
- Faculty of Medicine, Cellular and Molecular Medicine Department, University of Ottawa, 451 Smyth Road, Room 3206, Ottawa, K1H 8M5, Canada
| | - Humayoun Akhtar
- Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, N1G 5C9, Canada;
| | - Neera Singhal
- Division of Infectious Diseases, University of Ottawa at the The Ottawa Hospital/Research Institute, 501 Smyth Road, Ottawa, K1H 8L6, Canada; (R.P.G.H.); (N.S.); (I.S.)
| | - Isabelle Seguin
- Division of Infectious Diseases, University of Ottawa at the The Ottawa Hospital/Research Institute, 501 Smyth Road, Ottawa, K1H 8L6, Canada; (R.P.G.H.); (N.S.); (I.S.)
| | - Lina DelBalso
- Immunodeficiency Service, McGill University Health Centre, 3650 St. Urbain, Montreal, H2X 2P4, Canada; (L.D.); (M.-R.B.); (R.G.L.)
| | - Marc Bourbeau
- The University of Ottawa at the Ottawa Hospital/Research Institute, 501 Smyth Road, Ottawa, K1H 8L6, Canada;
| | - Bobby M. Chauhan
- Office of Science Laboratory, Therapeutics Products Program, Health Canada, 0900C2, Ottawa, K1A 0K9, Canada; (B.C.F.); (B.M.C.)
- Faculty of Medicine, Cellular and Molecular Medicine Department, University of Ottawa, 451 Smyth Road, Room 3206, Ottawa, K1H 8M5, Canada
| | - Mohammed-Rachid Boulassel
- Immunodeficiency Service, McGill University Health Centre, 3650 St. Urbain, Montreal, H2X 2P4, Canada; (L.D.); (M.-R.B.); (R.G.L.)
| | - David M. Burger
- Department of Pharmacy & Nijmegen Institute for Infection, Inflammation and Immunity (N4i), Radboud University Nijmegen Medical Center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands;
| | - Richard G. Lalonde
- Immunodeficiency Service, McGill University Health Centre, 3650 St. Urbain, Montreal, H2X 2P4, Canada; (L.D.); (M.-R.B.); (R.G.L.)
| | - Donald William Cameron
- Division of Infectious Diseases, University of Ottawa at the The Ottawa Hospital/Research Institute, 501 Smyth Road, Ottawa, K1H 8L6, Canada; (R.P.G.H.); (N.S.); (I.S.)
- Authors to whom correspondence should be addressed; (N.L.S.); (D.W.C.); Tel.: +1-514-934-1934, ext 32169 (N.L.S.); Fax: +1-514-843-2828 (N.L.S.); Tel.: +1-613-737-8923 (D.W.C.); +1-613-737-8925 (D.W.C.)
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Brandmann M, Tulpule K, Schmidt MM, Dringen R. The antiretroviral protease inhibitors indinavir and nelfinavir stimulate Mrp1-mediated GSH export from cultured brain astrocytes. J Neurochem 2011; 120:78-92. [DOI: 10.1111/j.1471-4159.2011.07544.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Saberi P, Ranatunga DK, Quesenberry CP, Silverberg MJ. Clinical implications of the nelfinavir-proton pump inhibitor drug interaction in patients with human immunodeficiency virus. Pharmacotherapy 2011; 31:253-61. [PMID: 21361735 DOI: 10.1592/phco.31.3.253] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
STUDY OBJECTIVE To determine if the concomitant use of nelfinavir and proton pump inhibitors (PPIs) in patients with human immunodeficiency virus (HIV) infection results in the loss of virologic control. DESIGN Retrospective cohort study. DATA SOURCE Pharmacy, laboratory, and administrative databases of a large integrated health care system in northern California. PATIENTS A total of 1147 HIV-positive adults who started nelfinavir therapy between November 1, 1998, and June 20, 2003; within this cohort, 141 patients (12.3%) were also prescribed PPIs. MEASUREMENTS AND MAIN RESULTS The effects on two virologic outcomes--achievement of undetectable HIV viral load and subsequent virologic rebound--were compared between patients receiving nelfinavir alone and those receiving nelfinavir with PPIs. Cox proportional hazards models were used, with adjustments for age, sex, race, HIV risk factors, hepatitis B or C coinfection, and other concurrent drugs known to affect the metabolism of nelfinavir. The use of PPIs had little effect on the ability to achieve an undetectable HIV viral load (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.58-1.19, p=0.29), but there was an approximate 50% increased risk of virologic rebound with the concurrent use of PPIs (adjusted HR 1.53, 95% CI 1.06-2.19, p=0.02). Short-term use of PPIs (defined as within 30 days of initial PPI dispensation) was not associated with increased risk of virologic rebound (HR 1.07, 95% CI 0.26-4.41, p=0.93) compared with no use of PPIs. CONCLUSION Use of PPIs should be minimized or avoided in patients who have attained an undetectable HIV viral load while taking a nelfinavir-based antiretroviral regimen. However, concomitant use of these drugs may be acceptable for indications where PPIs are required for fewer than 30 days.
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Affiliation(s)
- Parya Saberi
- Department of Medicine, University of California-San Francisco, San Francisco, California 94105, USA.
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Genetically Polymorphic Cytochrome P450s and Transporters and Personalized Antimicrobial Chemotherapy. Mol Microbiol 2011. [DOI: 10.1128/9781555816834.ch52] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Zhou SF, Liu JP, Chowbay B. Polymorphism of human cytochrome P450 enzymes and its clinical impact. Drug Metab Rev 2009; 41:89-295. [PMID: 19514967 DOI: 10.1080/03602530902843483] [Citation(s) in RCA: 502] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.
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Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Bundoora, Victoria, Australia.
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Bryson YJ, Mirochnick M, Stek A, Mofenson LM, Connor J, Capparelli E, Watts DH, Huang S, Hughes MD, Kaiser K, Purdue L, Asfaw Y, Keller M, Smith E. Pharmacokinetics and safety of nelfinavir when used in combination with zidovudine and lamivudine in HIV-infected pregnant women: Pediatric AIDS Clinical Trials Group (PACTG) Protocol 353. HIV CLINICAL TRIALS 2008; 9:115-25. [PMID: 18474496 DOI: 10.1310/hct0902-115] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Combination antiretroviral regimens including nelfinavir (NFV) are commonly used in pregnancy. We studied the safety, antiviral effect, and pharmacokinetics of NFV and its M8 metabolite with two dosing regimens in combination with zidovudine (ZDV) and lamivudine (3TC) in HIV-infected pregnant women. METHOD HIV-infected pregnant women between 14 and 34 weeks gestation received NFV (Cohort 1: 750 mg tid, n = 10; Cohort 2: 1250 mg bid, n = 23) with ZDV and 3TC. Serial blood sampling for NFV concentrations was performed antepartum (AP) and 6 weeks postpartum (PP). Maternal and cord blood samples were also obtained at delivery. NFV and M8 levels were determined by high-performance liquid chromatography. The pharmacokinetic (PK) target was an extrapolated NFV AUC0-24 > 30 mug . h/mL. Mothers were followed frequently for potential clinical and laboratory toxicity. RESULTS Overall, NFV in combination with ZDV and 3TC was well tolerated. The PK target was met in 3/8 AP and 5/7 PP in Cohort 1 and 17/21 AP and 16/17 PP in Cohort 2. When Cohort 2 NFV PK parameters AP and PP were compared, median Cmax (3.90 microg/mL vs. 5.01 microg/mL, p < .05) and AUC0-24 (56.6 vs. 86.8 microg . h/mL, p < .05) were increased PP and oral clearance (Cl/F; 44.2 vs. 28.8 L/h, p < .05) was decreased PP. The average M8/NFV ratio was increased PP compared to AP (0.085 vs. 0.29, p < .001). Placental transfer of NFV was low with a median cord blood:maternal plasma ratio at delivery of 0.05. Maternal mean CD4+ T cell counts increased significantly and plasma HIV-1 RNA levels decreased from entry to delivery and 6 to 12 weeks postpartum. CONCLUSION NFV used in combination with ZDV and 3TC was well tolerated in pregnant HIV-infected women and produced a significant improvement in HIV disease parameters. NFV drug exposure is inadequate in most pregnant women receiving 750 mg tid but is much improved with 1250 mg bid. NFV crosses the placenta poorly. The AP increase in NFV oral clearance and decrease in M8/NFV ratio suggest that CYP3A activity increases relative to CYP2C19 activity during pregnancy.
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Affiliation(s)
- Y J Bryson
- David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1752, USA.
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Abstract
Pharmacogenetics holds promise in HIV treatment because of the complexity and potential toxicity of multidrug therapies that are prescribed for long periods. Thus far, few candidate genes have been examined for a limited number of allelic variants, but a number of confirmed associations have already emerged. A change in paradigm emerges from the availability of the HapMap, the wealth of data on less-common genetic polymorphisms, and new genotyping technology. This review presents a comprehensive analysis of the existing literature on pharmacogenetic determinants of antiretroviral drug exposure, drug toxicity, as well as genetic markers associated with the rate of disease progression. It is expected that larger-scale comprehensive genome approaches will profoundly change the landscape of knowledge in the future.
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Affiliation(s)
- A Telenti
- Institute of Microbiology, University of Lausanne, Lausanne, Switzerland.
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Estes KE, Busse KH, Penzak SR. Pharmacogenetic Considerations in the Management of HIV Infection. J Pharm Pract 2007. [DOI: 10.1177/0897190007304819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Potent combination antiretroviral drug therapy has now been available to HIV-infected patients for more than a decade, resulting in a significant decline in disease-related morbidity and mortality. Nonetheless, a number of HIV-infected individuals fail to experience the full benefit of their antiretroviral medications; some lack a robust virologic response, while others experience treatment-limiting toxicities. A number of factors may contribute to variable drug response in patients with HIV infection. Virologic, immunologic, pharmacologic, and pharmacokinetic differences between HIV-infected patients have all been noted to contribute to interpatient variability in drug response. Recent data suggest that pharmacogenetic differences among HIV-infected individuals may also be an important variable that contributes to antiretroviral drug response. Pharmacogenetic studies of antiretroviral drug therapy have explored the influence of single nucleotide polymorphisms in genes responsible for key proteins involved in antiretroviral drug metabolism (cytochrome P50 enzymes) and drug transport (P-glycoprotein). In addition, the human leukocyte antigen genotype (HLA-B*57) has been found to predict abacavir-associated hypersensitivity reactions. Antiretroviral pharmacogenetics offers the possibility of optimizing virologic response and minimizing drug toxicity by individualizing anti-HIV pharmacotherapy. The authors review those genetic polymorphisms that have been shown, or are strongly suspected, to influence antiretroviral drug metabolism, transport, and toxicity.
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Affiliation(s)
- Kristina E. Estes
- National Institutes of Health, Clinical Center, Pharmacy, Bethesda, Maryland
| | - Kristin H. Busse
- National Institutes of Health, Clinical Center, Pharmacy, Bethesda, Maryland
| | - Scott R. Penzak
- Clinical Pharmacokinetics Research Laboratory, National Institutes of Health, Clinical Center Pharmacy Department, Bethesda, Maryland,
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Panhard X, Goujard C, Legrand M, Taburet AM, Diquet B, Mentré F. Population pharmacokinetic analysis for nelfinavir and its metabolite M8 in virologically controlled HIV-infected patients on HAART. Br J Clin Pharmacol 2006; 60:390-403. [PMID: 16187971 PMCID: PMC1884828 DOI: 10.1111/j.1365-2125.2005.02456.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
AIMS To describe the pharmacokinetics of nelfinavir and its main metabolite M8 in HIV-infected patients with a sustained virological response, to characterize the effect of covariates and to estimate inter- and intra-individual variability in the pharmacokinetics. METHODS Three hundred and twenty concentrations of both nelfinavir and M8 were measured in 46 patients enrolled in the COPHAR 1-ANRS 102 study. Blood samples were taken at a first visit (one sample before drug administration and four samples at fixed times after) and at a second visit 1 to 3 months later (one before and one 3 h after drug administration). The data from both visits on nelfinavir and M8 were modelled jointly in all patients using a population approach. RESULTS A one-compartment model with first-order absorption and elimination best described nelfinavir data, with an additional compartment incorporating a first order rate-constant describing the metabolism of the drug to M8. For nelfinavir, the apparent volume of distribution (V/F ) (95% confidence interval for the mean), was 309 l (185, 516), the absorption rate constant (k(a)) was 0.4 h(-1) (0.2, 0.8), and the apparent clearance (CL/F ) was 37.3 l h(-1) (32, 44). For M8, V(m) /(Fk(m)) and CL(m)/(Fk(m)) were 866 l h(-1) (351, 2161) and 1670 l (965, 2894), respectively. The interindividual variabilities were 34.9%, 34.3% and 62.2% for V/F, CL/F and CL(m)/(Fk(m)), respectively. The interoccasion variability was 27.8% for CL/F. The mean half-lives were 05.38 h and 00.44 h for nelfinavir and M8, respectively. Significant but opposite effects of comedication with zidovudine were found on nelfinavir CL/F and M8 CL(m)/(Fk(m)), but they were not considered to be clinically relevant. CONCLUSIONS A joint model was found to describe adequately nelfinavir and M8 concentrations and was used to estimate pharmacokinetic parameters for M8. The model can be used to build reference pharmacokinetic profiles for therapeutic drug monitoring of the drug.
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Affiliation(s)
- X Panhard
- INSERM U738, Department of Epidemiology, Biostatistics and Clinical research, AP-HP, Bichat University Hospital, Paris, France.
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Hirt D, Treluyer JM, Jullien V, Firtion G, Chappuy H, Rey E, Pons G, Mandelbrot L, Urien S. Pregnancy-related effects on nelfinavir-M8 pharmacokinetics: a population study with 133 women. Antimicrob Agents Chemother 2006; 50:2079-86. [PMID: 16723569 PMCID: PMC1479099 DOI: 10.1128/aac.01596-05] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A relationship between nelfinavir antiretroviral efficacy and plasma concentrations has been previously established. As physiological changes associated with pregnancy have a large impact on the pharmacokinetics of many drugs, a nelfinavir population study with women was developed, and the large intersubject variability was analyzed in order to optimize individual treatment schedules for this drug during pregnancy. A population pharmacokinetic model was developed in order to describe the concentration time course of nelfinavir and its metabolite M8 in pregnant and nonpregnant women. Individual characteristics, such as age, body weight, and weeks of gestation or delivery, which may influence nelfinavir-M8 pharmacokinetics were investigated. Data from therapeutic drug monitoring in 133 women treated with nelfinavir were retrospectively analyzed with NONMEM. Nelfinavir pharmacokinetics was described by a one-compartment model with linear absorption and elimination and M8 produced from the nelfinavir central compartment. Mean pharmacokinetic estimates and the corresponding intersubject percent variabilities for a nonpregnant woman were the following: absorption rate, 0.83 h(-1); absorption lag time, 0.85 h; apparent nelfinavir elimination clearance (CL(10)/F), 35.5 liters/h (50%); apparent volume of distribution (V/F), 596 liters (118%); apparent formation clearance to M8 (CL(1M)/F), 0.65 liters/h (69%); and M8 elimination rate constant (k(M0)), 3.3 h(-1) (59%). During pregnancy, we observed significant increases in nelfinavir (44.4 liters/h) and M8 (5 h(-1)) elimination but unchanged nelfinavir transformation clearance to M8, suggesting an induction of CYP3A4 but no effect on CYP2C19. Apparent nelfinavir clearance and volume showed a twofold increase on the day of delivery, suggesting a decrease in bioavailability on this day. The M8 elimination rate was increased by concomitant administration of nonnucleoside reverse transcriptase inhibitors. A trough nelfinavir plasma concentration above 1 mg/liter was previously shown to improve the antiretroviral response. The Bayesian individual pharmacokinetic estimates suggested that the dosage should not be changed in pregnant women but may be doubled on the day of delivery.
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Affiliation(s)
- Déborah Hirt
- Pharmacologie Clinique, Hôpital Saint Vincent de Paul, Paris, France.
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Bruce RD, Altice FL, Gourevitch MN, Friedland GH. Pharmacokinetic drug interactions between opioid agonist therapy and antiretroviral medications: implications and management for clinical practice. J Acquir Immune Defic Syndr 2006; 41:563-72. [PMID: 16652030 DOI: 10.1097/01.qai.0000219769.89679.ec] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Opioid dependence and HIV/AIDS are 2 of the most serious yet treatable diseases worldwide. Global access to opioid agonist therapy and HIV treatment is expanding but when concurrently used, problematic pharmacokinetic drug interactions can occur. METHODS We reviewed English, Spanish, French, and Italian language articles from 1966 to 2005 in Medline using the following keywords: HIV, AIDS, HIV therapy, antiretroviral therapy, HAART, drug interactions, methadone, and buprenorphine. Additionally, we reviewed abstracts from national and international meetings and conference proceedings. Selected references from these articles were reviewed as well. RESULTS Clinical case series and carefully controlled pharmacokinetic interaction studies have been conducted between methadone and most approved antiretroviral therapies. Important pharmacokinetic drug interactions have been demonstrated within each class of agents, affecting either methadone or antiretroviral agents. Few studies, however, have been conducted with buprenorphine. The metabolism of both therapies, description of the known interactions, and clinical implications and management of these interactions are reviewed. CONCLUSIONS Certain interactions between methadone and antiretroviral medications are known and may have important clinical consequences. To optimize care, clinicians must be alert to these interactions and have a basic knowledge regarding their management.
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Affiliation(s)
- R Douglas Bruce
- Yale University AIDS Program, 135 College Street, New Haven, CT 06511, USA.
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16
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Hirt D, Urien S, Jullien V, Firtion G, Rey E, Pons G, Blanche S, Treluyer JM. Age-related effects on nelfinavir and M8 pharmacokinetics: a population study with 182 children. Antimicrob Agents Chemother 2006; 50:910-6. [PMID: 16495250 PMCID: PMC1426418 DOI: 10.1128/aac.50.3.910-916.2006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As a relationship between nelfinavir antiretroviral efficacy and plasma concentrations has been previously established, nelfinavir pharmacokinetics was investigated in order to optimize the individual treatment schedule in a pediatric population. A population pharmacokinetic model was developed to describe the concentration-time course of nelfinavir and its active metabolite M8. Individual characteristics were used to explain the large interindividual variability in children. Data from therapeutic drug monitoring in 182 children treated with nelfinavir were analyzed with NONMEM. Then Food and Drug Administration (FDA) current recommendations were evaluated estimating the percentage of children who reached the target minimum plasma concentration (0.8 mg/liter) by using Bayesian estimates. Nelfinavir pharmacokinetics was described by a one- compartment model with linear absorption and elimination. Pharmacokinetic estimates and the corresponding intersubject variabilities for the model were as follows: nelfinavir total clearance, 0.93 liters/h/kg (39%); volume of distribution, 6.9 liters/kg (109%); absorption rate, 0.5 h(-1); formation clearance fraction to hydroxy-tert-butylamide (M8), 0.025; M8 elimination rate, 1.88 h(-1) (49%). Apparent nelfinavir total clearance and volume of distribution decreased as a function of age. M8 elimination rate was increased by concomitant administration of nevirapine or efavirenz. Our data confirm that the FDA recommendations for children from 2 to 13 years are optimal and that the dose recommended for children younger than 2 years is adequate for the children from 2 months to 2 years old. However, in children younger than 2 months, the proposed nelfinavir newborn dose of 40 mg/kg of body weight twice daily is inadequate and we suggest increasing the dose to 50 to 60 mg/kg administered thrice daily. This assumption should be further evaluated.
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Affiliation(s)
- Déborah Hirt
- Pharmacologie Clinique, Assistance Publique--Hôpitaux Paris, France.
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17
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Justesen US. Therapeutic Drug Monitoring and Human Immunodeficiency Virus (HIV) Antiretroviral Therapy. Basic Clin Pharmacol Toxicol 2006; 98:20-31. [PMID: 16433887 DOI: 10.1111/j.1742-7843.2006.pto_246.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Treatment with antiretroviral drugs such as the HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors have contributed to the improvement of life of many HIV-infected patients in recent years, but antiretroviral therapy is not without problems. In some patients, treatment is not effective and suppression of viral replication is not achieved. Other patients experience toxicity and have to stop treatment or change to a less effective treatment. Several studies have demonstrated a relationship between plasma concentrations of the protease inhibitors and non-nucleoside reverse transcriptase inhibitors and viral suppression and toxicity. Therapeutic drug monitoring uses drug concentrations to individualize and optimise therapy by dosage adjustments and many clinicians have advocated for the use of therapeutic drug monitoring in HIV antiretroviral therapy. Evidence from a number of randomized clinical trials supports the use of therapeutic drug monitoring, but the studies have limitations and might not apply to all the antiretroviral drugs. However, the consensus is that certain patients are very likely to benefit from therapeutic drug monitoring. Additionally, the combination of therapeutic drug monitoring and genotypic or phenotypic resistance testing might further improve antiretroviral therapy.
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Affiliation(s)
- Ulrik Stenz Justesen
- Institute of Public Health, Clinical Pharmacology, University of Southern Denmark and Department of Infectious Diseases, Odense University Hospital, Odense, Denmark.
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18
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Smith PF, Robbins GK, Shafer RW, Wu H, Yu S, Hirsch MS, Merigan TC, Park JG, Forrest A, Fischl MA, Morse GD. Pharmacokinetics of nelfinavir and efavirenz in antiretroviral-naive, human immunodeficiency virus-infected subjects when administered alone or in combination with nucleoside analog reverse transcriptase inhibitors. Antimicrob Agents Chemother 2005; 49:3558-61. [PMID: 16048984 PMCID: PMC1196281 DOI: 10.1128/aac.49.8.3558-3561.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pharmacokinetic studies were conducted with human immunodeficiency virus-infected patients receiving efavirenz, nelfinavir, or both agents at weeks 4 and 32. Reductions of 25% and 45% were observed in the mean nelfinavir area under the concentration-time curve and minimum concentration of the drug in serum, and there was a 31% more rapid half-life for patients receiving both drugs compared to patients receiving nelfinavir alone. There were no significant differences in efavirenz pharmacokinetics.
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Affiliation(s)
- Patrick F Smith
- Adult ACTG Pharmacology Support Laboratory, Laboratory for Antiviral Research, Department of Pharmacy Practice, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 12460, USA.
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19
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Justesen US, Hansen IM, Andersen AB, Klitgaard NA, Black FT, Gerstoft J, Mathiesen LR, Pedersen C. The long-term pharmacokinetics and safety of adding low-dose ritonavir to a nelfinavir 1250 mg twice-daily regimen in HIV-infected patients. HIV Med 2005; 6:334-40. [PMID: 16156881 DOI: 10.1111/j.1468-1293.2005.00317.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To evaluate the long-term pharmacokinetics and safety of adding ritonavir 100 mg twice-daily to a nelfinavir 1250 mg twice-daily regimen in HIV-infected patients. METHODS This was a prospective, randomized, open-label, controlled 24-week study. Sixteen patients receiving a nelfinavir 1250 mg twice-daily regimen with plasma viral load <1000 HIV-1 RNA copies/mL were randomized to continue treatment or to have ritonavir 100 mg twice-daily added. Safety, including fasting lipid levels, was evaluated at weeks 4, 12 and 24. Patients who were randomized to have ritonavir added (n=9) participated in three 12-h pharmacokinetic evaluations at baseline, week 4 and week 24. RESULTS Increases in median nelfinavir steady-state plasma concentrations at 12 h (C(12)) from 512 to 773 ng/mL [median difference 450 ng/mL; 95% confidence interval (CI) 116--1510 ng/mL] and in median active nelfinavir metabolite M 8 C(12) from 107 to 603 ng/mL (median difference 545 ng/mL; 95% CI 370--891) were seen after the addition of low-dose ritonavir (baseline to week 24). There were no differences between the nelfinavir or M 8 pharmacokinetic parameters at weeks 4 and 24. No significant changes or differences in the concentration of fasting total cholesterol, low-density lipoprotein (LDL) cholesterol or total triglycerides or in the occurrence of adverse events were observed within or between the two groups. CONCLUSIONS Nelfinavir and especially M 8 concentrations are increased when low-dose ritonavir is added to a nelfinavir-containing regimen. The combination seems to be safe and the nelfinavir/ritonavir regimen could be an option in patients with low nelfinavir+M 8 concentrations.
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Affiliation(s)
- U S Justesen
- Department of Infectious Diseases, Odense University Hospital, Odense, Denmark.
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20
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Robertson SM, Scarsi KK, Postelnick MJ, Lynch P. Elevated Plasma Concentrations of Protease Inhibitors and Nonnucleoside Reverse Transcriptase Inhibitors in Patients Coinfected with Human Immunodeficiency Virus and Hepatitis B or C: Case Series and Literature Review. Pharmacotherapy 2005; 25:1068-72. [PMID: 16207097 DOI: 10.1592/phco.2005.25.8.1068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
STUDY OBJECTIVE To evaluate antiretroviral pharmacokinetics in patients who are coinfected with human immunodeficiency virus (HIV) and hepatitis B and/or C virus. Specifically, we sought to determine whether coinfection results in higher than expected concentrations of protease inhibitors and nonnucleoside reverse transcriptase inhibitors (NNRTIs). DESIGN Case series. SETTING Human immunodeficiency virus clinic. PATIENTS Twenty-six patients infected with HIV and hepatitis B and/or C virus. MEASUREMENTS AND MAIN RESULTS Patients' plasma trough concentrations (Cmeasured) of protease inhibitors and NNRTIs were compared with population average trough concentrations reported in the literature (Cpredicted). Trough concentrations were obtained irrespective of the patients' liver function. A concentration ratio of Cmeasured: Cpredicted was determined for each patient. The mean concentration ratio of the 26 patients was 1.43 (95% confidence interval 1.08-1.78). For the six patients taking nelfinavir, the ratio of nelfinavir's active metabolite (M8): parent drug was calculated. The median M8:nelfinavir ratio for these six patients was 69% lower than what has been reported in a general HIV population. CONCLUSION These preliminary findings suggest that trough concentrations of protease inhibitors and NNRTIs may be elevated in patients with HIV infection who are coinfected with hepatitis B and/or C, compared with a general population of patients with HIV infection. Until further investigation defines the relationship between coinfection, metabolic dysfunction, and increased antiretroviral exposure, therapeutic drug monitoring may be helpful to identify coinfected patients at risk for antiretroviral toxicity secondary to elevated plasma drug concentrations.
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Affiliation(s)
- Sarah M Robertson
- Clinical Pharmacokinetics Research Laboratory, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA.
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21
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Droste JAH, Koopmans PP, Hekster YA, Burger DM. TDM: Therapeutic Drug Measuring or Therapeutic Drug Monitoring? Ther Drug Monit 2005; 27:412-6. [PMID: 16044095 DOI: 10.1097/01.ftd.0000162521.16060.13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The third round of the International Interlaboratory Quality Control Program for Therapeutic Drug Monitoring in HIV infection (QC-program) consisted of the analysis not only of plasma samples but also of patient cases. The case was composed of different topics related to the therapeutic drug monitoring of antiretroviral drugs. The participants were asked to give recommendations concerning dose adjustments, changes to the regimen, and drug-drug interactions to observe whether the expert recommendations were comparable. Of the 30 participants of the QC-program, 16 returned their comments and recommendations with regard to the patient case. The drug level was easy to judge: approximately 90% were able to correctly do so. Almost half of the recommendations (44%) given were satisfactory. Levels of knowledge regarding HIV treatment appeared to be variable among the respondents and for this reason were partly incomparable.
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Affiliation(s)
- Jacqueline A H Droste
- Department of Clinical Pharmacy, University Medical Centre, Nijmegen, The Netherlands.
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22
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Slish JC, Catanzaro LM, Okusanya O, Demeter LM, Albrecht M, Difrancesco R, Morse GD. Therapeutic Drug Monitoring: Role for a Pharmacist in Multidisciplinary Antiretroviral Management. J Pharm Pract 2005. [DOI: 10.1177/0897190005278501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The current treatment guidelines for HIV pharmacotherapy recommend combinations of antiretrovirals (ARVs) to achieve optimal suppression of HIV replication. However, the initiation and long-term management of ARV therapy in a patient is often complicated by variable medication adherence, complex medication use with multiple drug interactions, the occurrence of drug toxicity, and drug therapy for comorbid conditions that require additional patient education and laboratory monitoring. For these reasons, the inclusion of a well-trained pharmacist in multidisciplinary health system management strategies has been increasing. Furthermore, the use of fixed-dose ARVs is accompanied by considerable interpatient variation in pharmacokinetics yielding a range of drug exposures from any given ARV dose. One approach to overcoming this variable drug exposure is to use plasma concentration monitoring (eg, therapeutic drug monitoring [TDM]) as a clinical tool to adjust doses to achieve targeted concentration ranges, often in conjunction with HIV resistance tests. While data in support of TDM are emerging, the development of programs that include an HIV pharmaceutical care specialist and an adherence program with an integrated clinical pharmacology resource that can provide reliable TDM assays has been reported and provides the rationale for including pharmacists in the implementation of ARV TDM programs.
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Affiliation(s)
- Judianne C. Slish
- University at Buffalo, School of Pharmacy and Pharmaceutical Sciences, Erie County Medical Center, Department of Medicine, Division of Infectious Diseases; 315 Cooke Hall, Buffalo, NY 14260
| | - Linda M. Catanzaro
- University at Buffalo, School of Pharmacy and Pharmaceutical Sciences; Erie County Medical Center, Buffalo, New York
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Ribera E, Fernando López-Cortés L, Soriano V, Luis Casado J, Mallolas J. Therapeutic drug monitoring and the inhibitory quotient of antiretroviral drugs: can they be applied to the current situation? Enferm Infecc Microbiol Clin 2005. [DOI: 10.1016/s0213-005x(05)75161-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Ribera E, Fernando López-Cortés L, Soriano V, Luis Casado J, Mallolas J. Monitorización terapéutica y cociente inhibitorio de los fármacos antirretrovirales: ¿son aplicables a nuestra realidad? Enferm Infecc Microbiol Clin 2005. [DOI: 10.1016/s0213-005x(05)75160-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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la Porte CJL, de Graaff-Teulen MJA, Colbers EPH, Voncken DS, Ibanez SM, Koopmans PP, Hekster YA, Burger DM. Effect of efavirenz treatment on the pharmacokinetics of nelfinavir boosted by ritonavir in healthy volunteers. Br J Clin Pharmacol 2005; 58:632-40. [PMID: 15563361 DOI: 10.1111/j.1365-2125.2004.02214.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
AIMS A once-daily (q.d.) nucleoside-sparing regimen can prevent mitochondrial toxicity, overcome viral resistance and improve compliance. In the present study the effect of efavirenz on the pharmacokinetics and tolerability of once-daily nelfinavir/ritonavir was evaluated in healthy subjects. METHODS This was a multiple-dose, open-label, single-group, two-period study in 24 healthy subjects. Each received from days 1-10 (period 1): 1875 mg nelfinavir plus 200 mg ritonavir q.d. with a 300-kcal snack. During days 11-20 (period 2) efavirenz 600 mg q.d. was added to the regimen. Blood samples were collected up to 24 h after dosing on days 10 (period 1) and 20 (period 2). High-performance liquid chromatography methods were used for the determination of the concentrations of all compounds. The main pharmacokinetic parameters were calculated using noncompartmental methods. RESULTS All subjects completed the study. After the first period mean nelfinavir AUC(0-24 h), C(max) and C(24) were 49.6 mg h(-1) l(-1), 5.0 mg l(-1) and 0.37 mg l(-1), and the sum of nelfinavir plus its active metabolite M8 C(24) was 0.83 mg l(-1). The relative bioavailability, expressed as a geometric mean ratio (90% confidence interval) for nelfinavir AUC(0-24 h), C(max) and C(24) of period 2 compared with period 1 was: 1.30 (1.21, 1.40), 1.29 (1.19, 1.40) and 1.48 (1.32, 1.66). The sum of nelfinavir and M8 C(24) in period 2 was 0.99 mg l(-1), an increase of 19%. No serious adverse events occurred. CONCLUSIONS The studied regimens were well tolerated. Nelfinavir/ritonavir given together with efavirenz resulted in a 48% higher mean C(24) concentration for nelfinavir, and the sum of nelfinavir and M8 C(24) concentrations was 0.99 mg l(-1). Efavirenz exposure in this study was similar to that reported previously, and therefore can be used effectively in combination with ritonavir and nelfinavir.
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Affiliation(s)
- C J L la Porte
- Department of Clinical Pharmacy, University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, the Netherlands.
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Kappelhoff BS, Crommentuyn KML, de Maat MMR, Mulder JW, Huitema ADR, Beijnen JH. Practical guidelines to interpret plasma concentrations of antiretroviral drugs. Clin Pharmacokinet 2005; 43:845-53. [PMID: 15509183 DOI: 10.2165/00003088-200443130-00002] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Several relationships have been reported between antiretroviral drug concentrations and the efficacy of treatment, and toxicity. Therefore, therapeutic drug monitoring (TDM) may be a valuable tool in improving the treatment of HIV-1-infected patients in daily practice. In this regard, several measures of exposure have been studied, e.g. trough and maximum concentrations, concentration ratios and the inhibitory quotient. However, it has not been unambiguously established which pharmacokinetic parameter should be monitored to maintain optimal viral suppression. Each pharmacokinetic parameter has its pros and cons. Many factors can affect the pharmacokinetics of antiretroviral agents, resulting in variability in plasma concentrations between and within patients. Therefore, plasma concentrations should be considered on several occasions. In addition, the interpretation of the drug concentration of a patient should be performed on an individual basis, taking into account the clinical condition of the patient. Important factors herewith are viral load, immunology, occurrence of adverse events, resistance pattern and comedication. In spite of the described constraints, the aim of this review is to provide a practical guide for TDM of antiretroviral agents. This article outlines pharmacokinetic target values for the HIV protease inhibitors amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir, and the non-nucleoside reverse transcriptase inhibitors efavirenz and nevirapine. Detailed advice is provided on how to interpret the results of TDM of these drugs.
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Affiliation(s)
- Bregt S Kappelhoff
- Department of Pharmacy and Pharmacology, Slotervaart Hospital, Amsterdam, The Netherlands.
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Fellay J, Marzolini C, Decosterd L, Golay KP, Baumann P, Buclin T, Telenti A, Eap CB. Variations of CYP3A activity induced by antiretroviral treatment in HIV-1 infected patients. Eur J Clin Pharmacol 2005; 60:865-73. [PMID: 15657782 DOI: 10.1007/s00228-004-0855-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 10/08/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To measure the in vivo variations of CYP3A activity induced by anti-HIV drugs in human immunodeficiency virus (HIV)1-positive patients. METHODS A low oral dose of midazolam (MID) (0.075 mg) was given to the patients and the 30-min total 1-OH midazolam (1-OHMID)/MID ratio was determined. Patients were phenotyped either before the introduction of antiretroviral treatments (control group, 90 patients) or after a variable period of antiretroviral treatment (56 patients). Twenty-one subjects underwent multiple phenotyping tests (before and during the course of the treatment). RESULTS The median MID ratio was 3.51 in the control group (range 0.20-14.6). It was 5-fold higher in the group with efavirenz (28 patients; median, range: 16.0, 3.81-367; P < 0.0001), 13-fold lower with nelfinavir (18 patients; 0.27, 0.06-36.3; P < 0.0001), 17-fold lower with efavirenz + ritonavir (three patients; 0.21, 0.05-0.47; P = 0.006), 50-fold lower with ritonavir (four patients; 0.07, 0.06-0.17; P = 0.0007), and 7-fold lower with nevirapine + (ritonavir or nelfinavir or grapefruit juice) (three patients; 0.48, 0.03-1.83; P = 0.03). CYP3A activity was lower in the efavirenz + ritonavir group (P = 0.01) and in the ritonavir group (P = 0.04) than in the nelfinavir group, although already strongly inhibited in the latter. CONCLUSION The low-dose MID phenotyping test was successfully used to measure the in vivo variations of CYP3A activity induced by antiretroviral drugs. Efavirenz strongly induces CYP3A activity, while ritonavir almost completely inhibits it. Nelfinavir strongly decreases CYP3A activity, but to a lesser extent than ritonavir. The inhibition of CYP3A by ritonavir or nelfinavir offsets the inductive effects of efavirenz or nevirapine administered concomitantly. Finally, no induction of CYP3A activity was noticeable after long-term administration of ritonavir at low dosages (200 mg/day b.i.d.) or of nelfinavir at standard dosages (2,500 mg/day b.i.d.).
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Affiliation(s)
- Jacques Fellay
- Division of Infectious Diseases, University Hospital of Lausanne, Switzerland
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28
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Ribera E, Lopez RM, Diaz M, Pou L, Ruiz L, Falcó V, Crespo M, Azuaje C, Ruiz I, Ocaña I, Clotet B, Pahissa A. Steady-state pharmacokinetics of a double-boosting regimen of saquinavir soft gel plus lopinavir plus minidose ritonavir in human immunodeficiency virus-infected adults. Antimicrob Agents Chemother 2004; 48:4256-62. [PMID: 15504850 PMCID: PMC525389 DOI: 10.1128/aac.48.11.4256-4262.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Management of treatment-experienced human immunodeficiency virus patients has become complex, and therapy may need to include two protease inhibitors at therapeutic doses. The objective of this study was to characterize the pharmacokinetics in serum of saquinavir (1,000 mg twice daily [b.i.d.]), lopinavir (400 mg b.i.d.), and ritonavir (100 mg b.i.d.) in a multidrug rescue therapy study and to investigate whether steady-state pharmacokinetics of lopinavir-ritonavir are affected by coadministration of saquinavir. Forty patients were included (25 given ritonavir, lopinavir, and saquinavir and 15 given ritonavir and lopinavir). The median pharmacokinetic parameters of lopinavir were as follows: area under the concentration-time curve from 0 to 12 h (AUC(0-12)), 85.1 microg/ml . h; maximum concentration of drug in serum (C(max)), 10.0 microg/ml; trough concentration of drug in serum (C(trough)), 7.3 microg/ml; and minimum concentration of drug in serum (C(min)), 5.5 microg/ml. Lopinavir concentrations were similar in patients with and without saquinavir. The median pharmacokinetic parameters for saquinavir were as follows: AUC(0-12), 22.9 microg/ml . h; C(max), 2.9 microg/ml; C(trough), 1.6 microg/ml; and C(min), 1.4 microg/ml. There was a strong linear correlation between lopinavir and ritonavir and between saquinavir and ritonavir concentrations in plasma. The correlation between lopinavir and saquinavir levels was weaker. We found higher saquinavir concentrations in women than in men, with no difference in lopinavir levels. Only patients with very high body weight presented lopinavir and saquinavir concentrations lower than the overall group. Ritonavir has a double-boosting function for both lopinavir and saquinavir, and in terms of pharmacokinetics, the drug doses selected seemed appropriate for combining these agents in a dual protease inhibitor-based antiretroviral regimen for patients with several prior virologic failures.
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Affiliation(s)
- Esteban Ribera
- Servicio de Enfermedades Infecciosas, Hospital Universitari Vall d'Hebron, Paseo Vall Hebron 119-129, 08035 Barcelona, Spain.
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Hirani VN, Raucy JL, Lasker JM. Conversion of the HIV protease inhibitor nelfinavir to a bioactive metabolite by human liver CYP2C19. Drug Metab Dispos 2004; 32:1462-7. [PMID: 15448116 DOI: 10.1124/dmd.104.001743] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Antiretroviral therapy for human immunodeficiency virus (HIV) infection includes treatment with both reverse transcriptase inhibitors and protease inhibitors, which markedly suppress viral replication and circulating HIV RNA levels. Cytochrome P450 (P450) enzymes in human liver, chiefly CYP3A4, play a pivotal role in protease inhibitor biotransformation, converting these agents to largely inactive metabolites. However, the protease inhibitor nelfinavir (Viracept) is metabolized mainly to nelfinavir hydroxy-t-butylamide (M8), which exhibits potent antiviral activity, and to other minor products (termed M1 and M3) that are inactive. Since indirect evidence suggests that CYP2C19 underlies M8 formation, we examined the role of this inducible, polymorphic P450 enzyme in nelfinavir t-butylamide hydroxylation by human liver. Rates of microsomal M8 formation were 50.6 +/- 28.3 pmol of product formed/min/nmol P450 (n = 5 subjects), whereas kinetic analysis of the reaction revealed a KM of 21.6 microM and a Vmax of 24.6 pmol/min/nmol P450. In reconstituted systems, CYP2C19 catalyzed nelfinavir t-butylamide hydroxylation at a turnover rate of 2.2 min(-1), whereas CYP2C9, CYP2C8, and CYP3A4 were inactive toward nelfinavir. Polyclonal anti-CYP2C9 (cross-reactive with CYP2C19) and monoclonal anti-CYP2C19 completely inhibited microsomal M8 production, whereas monoclonal CYP2C9 and polyclonal CYP3A4 antibodies were without effect. Similarly, the CYP2C19 substrate omeprazole strongly inhibited (75%) hepatic nelfinavir t-butylamide hydroxylation at a concentration of only 12.5 microM. Our study shows that CYP2C19 underlies formation in human liver of M8, a bioactive nelfinavir metabolite. The inducibility of CYP2C19 by agents (e.g., rifampicin) often taken concurrently with nelfinavir, together with this P450's known polymorphic nature, may thus be important determinants of nelfinavir's antiviral potency.
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Affiliation(s)
- Vandana N Hirani
- Institute for Biomedical Research, Hackensack University Medical Center, 30 Prospect Avenue, Hackensack, NJ 07601, USA
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Martin AM, Nolan D, Gaudieri S, Phillips E, Mallal S. Pharmacogenetics of antiretroviral therapy: genetic variation of response and toxicity. Pharmacogenomics 2004; 5:643-55. [PMID: 15335286 DOI: 10.1517/14622416.5.6.643] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The application of a pharmacogenetic approach to antiretroviral drug therapy represents a significant challenge, as treatment involves multiple drugs and drug classes with the potential for significant variability in drug–host, as well as drug–drug, interactions. However, despite this inherent complexity, considerable gains have been made in understanding how genetic factors influence the efficacy and toxicity of HIV therapy. In this review the available evidence regarding genetic variation in drug disposition will be examined, including the potential for relatively polymorphic drug-metabolizing enzymes (e.g., cytochrome P450 isoforms) and drug transporters (e.g., P-glycoprotein) to influence the disposition of HIV protease inhibitor and non-nucleoside reverse transcriptase inhibitor drugs. In addition, the role of genetic variation in determining the immune response to drug-specific antigens will be considered as a potentially significant determinant of susceptibility to idiosyncratic drug reactions (e.g., major histocompatibility complex alleles associated with abacavir hypersensitivity). The current and potential clinical utility of pharmacogenetic testing in HIV management will also be emphasized.
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Affiliation(s)
- Annalise M Martin
- Centre for Clinical Immunology and Biomedical Statistics, Royal Perth Hospital and Murdoch University, Perth, Western Australia
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Nellen JFJB, Schillevoort I, Wit FWNM, Bergshoeff AS, Godfried MH, Boer K, Lange JMA, Burger DM, Prins JM. Nelfinavir plasma concentrations are low during pregnancy. Clin Infect Dis 2004; 39:736-40. [PMID: 15356791 DOI: 10.1086/422719] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2003] [Accepted: 03/27/2004] [Indexed: 11/03/2022] Open
Abstract
Plasma nelfinavir concentration ratios (CRs) were calculated for all pregnant (n=27) and nonpregnant (n=48) human immunodeficiency virus type 1-infected women receiving the drug who visited our outpatient clinic. In pregnant women, mean and median nelfinavir CRs were significantly lower (P=.02 and P=.04, respectively), and 51% of the CRs were below the clinically relevant threshold of 0.90, compared with 35% of the CRs in nonpregnant women. After we adjusted for confounders, we found that the mean nelfinavir CR was 34% lower in pregnant women (P=.02). With targeted interventions, subsequent CRs in pregnant women showed a significant increase (median increase, 0.31; P=.01).
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MESH Headings
- Adult
- Confounding Factors, Epidemiologic
- Drug Administration Schedule
- Female
- HIV Infections/blood
- HIV Infections/drug therapy
- HIV Protease Inhibitors/blood
- HIV Protease Inhibitors/therapeutic use
- HIV-1/drug effects
- Humans
- Infectious Disease Transmission, Vertical/prevention & control
- Nelfinavir/administration & dosage
- Nelfinavir/blood
- Nelfinavir/therapeutic use
- Pregnancy
- Pregnancy Complications, Infectious/blood
- Pregnancy Complications, Infectious/drug therapy
- Pregnancy Complications, Infectious/virology
- Pregnancy Trimester, First/blood
- Pregnancy Trimester, First/drug effects
- Pregnancy Trimester, Second/blood
- Pregnancy Trimester, Second/drug effects
- Pregnancy Trimester, Third/blood
- Pregnancy Trimester, Third/drug effects
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Affiliation(s)
- Jeannine F J B Nellen
- Academic Medical Center, Department of Internal Medicine, Division of Infectious Diseases, Tropical Medicine, and AIDS, Amsterdam, The Netherlands
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Skowron G, Leoung G, Hall DB, Robinson P, Lewis R, Grosso R, Jacobs M, Kerr B, MacGregor T, Stevens M, Fisher A, Odgen R, Yen-Lieberman B. Pharmacokinetic Evaluation and Short-Term Activity of Stavudine, Nevirapine, and Nelfinavir Therapy in HIV-1???Infected Adults. J Acquir Immune Defic Syndr 2004; 35:351-8. [PMID: 15097151 DOI: 10.1097/00126334-200404010-00004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Evaluate pharmacokinetic interaction, short-term safety, and antiretroviral activity of stavudine (d4T), nevirapine (NVP), and nelfinavir (NFV) as combination HIV-1 therapy. DESIGN Prospective, open-label study investigating the pharmacokinetic interactions between d4T, NVP, and NFV and documenting short-term tolerability and virologic and immunologic activity. METHODS Twenty-five HIV-1-infected adults, naive to nonnucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs), < or = 6 months of d4T treatment, CD4 > or = 100 cells/mm, and viral load > = 5,000 copies/mL enrolled. All received NFV 750 mg 3 times daily and d4T 30-40 mg twice daily for 1 week, then added NVP at 200 mg once daily for 2 weeks and 200 mg twice daily thereafter. Steady-state pharmacokinetic parameters of NFV, AG1402 (metabolite of NFV), and d4T were compared before and after the addition of NVP. RESULTS No statistically significant changes in NFV or d4T pharmacokinetics were observed following the addition of NVP. Levels of AG1402 were suppressed 60-70%. Drug-related adverse events were seen at expected rates. At day 36, median viral load suppression was 2.0 log10 and absolute CD4 count increased by 111 cells/mm. CONCLUSIONS NVP administration did not significantly affect the steady-state pharmacokinetic parameters of NFV or d4T. The combination of d4T, NVP, and NFV induced rapid suppression of HIV-1 viral load and rises in CD4 cell count.
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Affiliation(s)
- Gail Skowron
- Division of Infectious Diseases, Roger Williams Medical Center, Providence, RI 02908, USA.
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DiCenzo R, Forrest A, Fischl MA, Collier A, Feinberg J, Ribaudo H, DiFrancecso R, Morse GD. Pharmacokinetics of indinavir and nelfinavir in treatment-naive, human immunodeficiency virus-infected subjects. Antimicrob Agents Chemother 2004; 48:918-23. [PMID: 14982784 PMCID: PMC353135 DOI: 10.1128/aac.48.3.918-923.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 09/23/2003] [Accepted: 11/04/2003] [Indexed: 01/11/2023] Open
Abstract
AIDS Clinical Trials Group protocol 388 was designed to compare a three-drug regimen (indinavir with dual nucleosides) to a four-drug regimen (indinavir plus nelfinavir or indinavir plus efavirenz with dual nucleosides). Blood samples from patients taking indinavir and nelfinavir were collected over 8 to 12 h following a specified dose and were analyzed with high-performance liquid chromatography. Pharmacokinetic data were derived by using noncompartmental analysis. Following administration of indinavir every 8 h in the absence of nelfinavir (n = 8), the median predose indinavir concentration (C(0)) was 369 ng/ml (range, <10 to 949 ng/ml; one subject had a concentration of <10 ng/ml), and the concentration 8 h after administration of the study dose was 159 ng/ml (range, 85 to 506 ng/ml). In the group receiving 1000 mg of indinavir every 12 h with nelfinavir (n = 10), the median indinavir C(0) was <10 ng/ml (range, <10 to 3740 ng/ml; six subjects had a value of <10 ng/ml), and the C(12 h) was 44 ng/ml (range, <10 to 4236 ng/ml; five subjects had a value of <10 ng/ml), while the subjects who received 1200 mg of indinavir every 12 h with nelfinavir (n = 7) had a C(0) of 146 ng/ml (range, 58 to 5215 ng/ml) and a C(12 h) of 95 ng/ml (range, 12 to 954 ng/ml). Indinavir clearance was significantly lower in the presence of nelfinavir (median [interquartile range], 34.1 liters/h [range, 22.6 to 45.8 liters/h] versus 47.9 liters/h [range, 42.7 to 70.3 liters/h]; P < 0.017). For subjects receiving 1,000 mg of indinavir every 12 h, the median C(0) value for nelfinavir (n = 9) was 1,779 ng/ml (range, <187.5 to 4579 ng/ml), and the C(12 h) was 1554 ng/ml (range, <187.5 to 5,540 ng/ml). Due to the unacceptable number of undetectable indinavir trough concentrations, 1200 mg of indinavir appears to be the preferred dose in a twice-daily regimen that includes nelfinavir.
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Ford J, Cornforth D, Hoggard PG, Cuthbertson Z, Meaden ER, Williams I, Johnson M, Daniels E, Hsyu P, Back DJ, Khoo SH. Intracellular and Plasma Pharmacokinetics of Nelfinavir and M8 in HIV-Infected Patients: Relationship with P-Glycoprotein Expression. Antivir Ther 2004. [DOI: 10.1177/135965350400900101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
One of the targets of antiretroviral therapy is within cells infected with HIV. In order to improve therapeutic efficacy, it is therefore important that the intracellular pharmacokinetics of drugs, such as nelfinavir mesylate and its active metabolite M8, are studied in addition to plasma pharmacokinetics. Previously, the intracellular accumulation of protease inhibitors has been reported in vivo, displaying the following hierarchy: nelfinavir > saquinavir > ritonavir > indinavir. Multidrug resistance transporters, such as P-glycoprotein (P-gp), may result in a lower intracellular concentration of drug via an efflux mechanism, thus contributing to sanctuary site formation. The objective of this study was to determine concentrations of nelfinavir and M8 in plasma and peripheral blood mononuclear cells from HIV-infected patients, and to ascertain the relationship between intracellular accumulation and lymphocyte P-gp expression. Venous blood samples from 12 HIV-infected patients (viral load <50 copies/ml) receiving nelfinavir (1250 mg twice daily) and dual nucleoside reverse transcriptase inhibitor therapy were collected over a full dosage interval (0, 2, 4, 8 and 12 h). Plasma and intracellular (cell-associated) drug concentrations were measured by HPLC-MS/MS. Drug exposure in plasma and cells was expressed as the area under the concentration–time curve (AUC0-12h), derived from non-compartmental modelling. The ratio of intracellular AUC0-12h/total plasma AUC0-12h was calculated to determine cellular drug accumulation. P-gp expression on lymphocytes was determined by flow cytometry. The median (range) AUC0-12h of nelfinavir in plasma and cellular compartments was 21.8 mg.h.l-1 (5.64–50.8) and 104.6 mg.h.l-1 (23.1–265.7), respectively. Corresponding values for M8 in plasma and cells were 6.60 mg.h.l–1 (2.16–17.3) and 19.6 mg.h.l–1 (5.14–60.8). A ratio of plasma M8/plasma nelfinavir (AUC0–12h) and intracellular M8/intracellular nelfinavir (AUC0–12h) gave median values of 0.32 and 0.17, respectively. The cellular accumulations [median; (range)] of nelfinavir and M8 were 5.30 (2.28–16.2) and 2.32 (1.01–10.7), respectively. A significant correlation between plasma and intracellular nelfinavir minimum concentration (Cmin) (r2=0.34; P=0.049), but not between plasma and intracellular M8 Cmin was observed. C0h concentrations were higher than C12h for both nelfinavir and M8. No relationship was observed between nelfinavir or M8 accumulation and lymphocyte cell surface expression of P-gp. This study illustrates that intracellular concentrations were higher than plasma concentrations for both nelfinavir and M8, suggesting lymphocyte accumulation. The mechanism of differential intracellular accumulation of nelfinavir and M8 remains to be elucidated. It may be that affinities for influx transporters or fundamental drug characteristics play a major role in the greater accumulation of nelfinavir than M8.
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Affiliation(s)
- Jennifer Ford
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
| | - David Cornforth
- Department of Sexually Transmitted Diseases, Royal Free and University College Medical School, University College London, London, UK
| | - Patrick G Hoggard
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
| | - Zoe Cuthbertson
- Department of Thoracic Medicine, Royal Free Hospital, London, UK
| | - E Rhiannon Meaden
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
| | - Ian Williams
- Department of Sexually Transmitted Diseases, Royal Free and University College Medical School, University College London, London, UK
| | - Margaret Johnson
- Department of Thoracic Medicine, Royal Free Hospital, London, UK
| | | | - Poe Hsyu
- Agouron Pharmaceuticals, Inc., San Diego, Calif., USA
| | - David J Back
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
| | - Saye H Khoo
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
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Hoody DW, Fletcher CV. Pharmacology considerations for antiretroviral therapy in human immunodeficiency virus (HIV)-infected children. ACTA ACUST UNITED AC 2003; 14:286-94. [PMID: 14724793 DOI: 10.1053/j.spid.2003.09.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The contemporary treatment of the child infected with human immunodeficiency virus (HIV) unavoidably requires combination therapy with antiretroviral agents and may include additional drugs for the prevention and treatment of opportunistic infections or other disease states. The current guidelines for the treatment of the HIV-infected child recommend that the same principles of treatment for adults should apply to children. However, the pharmacokinetic and pharmacodynamic characteristics of many agents and regimens used in adults have not been defined adequately in children, and large-scale clinical trials to establish safety and show efficacy have not been completed. Therefore, the clinician will be required to use agents with incomplete knowledge about their pharmacologic properties. The purpose of this article is to provide an overview of the pediatric pharmacologic principles, a review of the pharmacologic characteristics of selected antiretroviral agents in children, and a prospectus on the design of drug dosing regimens in children.
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Affiliation(s)
- Dorie W Hoody
- Antiviral Pharmacology Laboratory, School of Pharmacy, University of Colorado Health Sciences Center, Denver, 80206, USA
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Rendón AL, Núñez M, González-Requena D, Jiménez-Nácher I, González-Lahoz J, Soriano V. Diarrhea Related to Lopinavir Is Most Often Mild and Not Related to Plasma Drug Levels. J Acquir Immune Defic Syndr 2003; 34:247. [PMID: 14526217 DOI: 10.1097/00126334-200310010-00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Aarnoutse RE, Schapiro JM, Boucher CAB, Hekster YA, Burger DM. Therapeutic drug monitoring: an aid to optimising response to antiretroviral drugs? Drugs 2003; 63:741-53. [PMID: 12662123 DOI: 10.2165/00003495-200363080-00002] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Therapeutic drug monitoring (TDM) has been proposed as a means to optimise response to highly active antiretroviral therapy (HAART) in HIV infection. Protease inhibitors (PIs) and the non-nucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz and nevirapine satisfy many criteria for TDM. Nucleoside reverse transcriptase inhibitors (NRTIs) are not suitable candidates for TDM, since no clear plasma concentration-effect relationships have been established for these drugs. Several important limitations to the application of TDM for antiretroviral drugs should be recognised, including uncertainty about the best pharmacokinetic predictor of response and insufficient validation of target concentrations for individual PIs and NNRTIs. Data from two clinical trials support the use of TDM in treatment-naive HIV-infected patients who start with an indinavir- or nelfinavir-based regimen. TDM either prevented virological failures (presumably by preventing the development of resistance) or treatment discontinuations due to concentration-related toxicity. Application of routine TDM in other patient groups (treatment-experienced patients) or for drugs other than indinavir or nelfinavir (NNRTIs, other PIs, combination of PIs) is speculative at this moment. However, TDM can be used in selected patient groups (children, pregnant women, patients with renal or hepatic dysfunction) to confirm adequate drug concentrations, and for management of drug-drug interactions.TDM in treatment-experienced patients may be optimally used in conjunction with resistance testing. The integration of pharmacological and virological measures in the inhibitory quotient (IQ) needs to be standardised and elaborated further. TDM should be accompanied by careful assessment of adherence and can itself help identify non-adherence, although a drug concentration only reflects the last few drug doses taken by a patient. Additional clinical trials are needed before routine TDM can be adopted as standard of care in the treatment of HIV infection.
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Affiliation(s)
- Rob E Aarnoutse
- Department of Clinical Pharmacy, University Medical Center Nijmegen, Nijmegen, The Netherlands.
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Abstract
The use of therapeutic drug monitoring (TDM) in the treatment of HIV-infection is gaining momentum in resource-rich countries. However, data justifying its use is still in short supply. In this manuscript we review the necessary components of TDM before it should be implemented in widespread clinical use. In addition, we provide specific examples of clinical situations where TDM is likely to useful. The overall conclusion of this review is that TDM is a promising therapeutic modality for improving antiretroviral efficacy and reducing toxicity. However, more prospective clinical trials are necessary in order to validate the therapeutic concentrations of antiretroviral drugs suggested by various investigators. In addition, both the clinical utility and cost effectiveness of TDM will need to be demonstrated by well-designed and adequately powered clinical trials in both antiretroviral nai;ve and experienced subjects. At this point in time we consider TDM in the treatment of HIV-infection as experimental with significant promise for the future.
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Affiliation(s)
- John G Gerber
- Divisions of Clinical Pharmacology and Infectious Diseases, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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Gatti G, Castelli-Gattinara G, Cruciani M, Bernardi S, De Pascalis CR, Pontali E, Papa L, Miletich F, Bassetti D. Pharmacokinetics and pharmacodynamics of nelfinavir administered twice or thrice daily to human immunodeficiency virus type 1-infected children. Clin Infect Dis 2003; 36:1476-82. [PMID: 12766843 DOI: 10.1086/375062] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2002] [Accepted: 02/10/2003] [Indexed: 11/03/2022] Open
Abstract
We studied the pharmacokinetics and pharmacodynamics of nelfinavir administered 2 or 3 times per day to human immunodeficiency virus type 1 (HIV-1)-infected children receiving highly active antiretroviral therapy containing nelfinavir. The geometric mean trough concentrations of nelfinavir for the thrice- and twice-daily regimens were 1.55 mg/L and 1.11 mg/L, respectively (P=not significant). Nelfinavir concentrations did not correlate with total daily dose, dose per kilogram of weight, age, weight, previous protease inhibitor (PI) experience, or CD4(+) cell percentage. In the 25 PI-naive children, the virus load reductions at 24 weeks of treatment with the twice- and thrice-daily regimens were comparable. A significantly higher percentage of children in the twice-daily group had a trough concentration of nelfinavir of less than the inhibitory concentration of 95% (P=.042). The decrease in the virus load at 24 weeks of treatment was not correlated with the trough concentration of nelfinavir. The variability of trough concentrations was extremely high, particularly among recipients of the twice-daily regimen, resulting in a higher number of patients with subinhibitory concentrations of nelfinavir in this group.
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Affiliation(s)
- G Gatti
- Gaslini Childrens Hospital, Genoa, Italy.
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Rentsch KM. Sensitive and specific determination of eight antiretroviral agents in plasma by high-performance liquid chromatography-mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 788:339-50. [PMID: 12705974 DOI: 10.1016/s1570-0232(03)00039-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Therapeutic drug monitoring of antiretroviral drugs has become more and more important. Therefore, a highly specific method is presented, which is capable of quantifying the different proteinase inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir) and non-nucleoside reverse transcriptase inhibitors (efavirenz, nelfinavir). The antiretroviral agents were separated and detected using LC-MS and atmospheric pressure chemical ionization. After solid-phase extraction, the antiretrovirals were separated within 21 min using gradient elution. The calibration range of each drug was linear including the expected minimum and maximum concentrations measured in plasma after the administration of the different drugs. All within-day and between-day coefficients of variation were below 10% and the recovery rates were between 34.8 and 124%. The respective quantification limits were 1 microg/l (indinavir), 10 microg/l (amprenavir, efavirenz), 50 microg/l (saquinavir), 90 microg/l (nelfinavir), 200 microg/l (nevirapine, ritonavir) and 250 microg/l (lopinavir).
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Affiliation(s)
- Katharina M Rentsch
- Institute of Clinical Chemistry, University Hospital Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland.
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Burger D, Hugen P, Reiss P, Gyssens I, Schneider M, Kroon F, Schreij G, Brinkman K, Richter C, Prins J, Aarnoutse R, Lange J. Therapeutic drug monitoring of nelfinavir and indinavir in treatment-naive HIV-1-infected individuals. AIDS 2003; 17:1157-65. [PMID: 12819517 DOI: 10.1097/00002030-200305230-00007] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Both virological failure and the toxicity of HIV protease inhibitors have been related to interindividual variability of plasma drug concentrations. Therapeutic drug monitoring (TDM) offers the possibility to detect patients with drug concentrations outside therapeutic ranges, who can subsequently benefit from dose modifications. METHODS ATHENA was a randomized controlled clinical trial. Subjects were randomly assigned to either a TDM group, in which the results of drug concentration measurements plus advice were reported to their treating physician, or to a control group for whom TDM results were not reported. This analysis refers to treatment-naive patients who started a regimen containing indinavir or nelfinavir before November 1999. FINDINGS A total of 147 patients were randomly assigned: 92 to nelfinavir, 55 to indinavir. After one year of follow-up significantly fewer patients in the TDM group had discontinued nelfinavir or indinavir than in the control group: 17.4 versus 39.7%. This was mainly driven by a significantly lower rate of discontinuation because of virological failure in nelfinavir patients: 2.4% in the TDM group versus 17.6% in the control group, and by a non-significant difference in the rate of discontinuation because of toxicity in indinavir patients: 14.3% in the TDM group versus 29.6% in the control group. In a non-completer equals failure analysis of all randomized patients, the TDM group showed a significantly higher proportion of patients with a viral load below 500 copies after 12 months of treatment (78.2 versus 55.1%). INTERPRETATION TDM of nelfinavir and indinavir in treatment-naive patients improves treatment response.
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Affiliation(s)
- David Burger
- Department of Clinical Pharmacy, University Medical Centre, Nijmegen, the Netherlands.
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Bergshoeff AS, Wolfs TFW, Geelen SPM, Burger DM. Ritonavir-enhanced pharmacokinetics of nelfinavir/M8 during rifampin use. Ann Pharmacother 2003; 37:521-5. [PMID: 12659608 DOI: 10.1345/aph.1c335] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To describe a case of successful protease inhibitor-based highly active antiretroviral therapy (HAART) concomitant with rifampin. CASE SUMMARY In a 7-month-old male infant with tuberculosis and HIV-1 infection, tuberculosis therapy including rifampin and HAART containing the protease inhibitor nelfinavir 40 mg/kg every 8 hours was started. Intensive steady-state pharmacokinetic sampling from baseline to 8 hours revealed very low plasma concentrations of nelfinavir: area under the plasma concentration-time curve (AUC(0-24)) <10% of adult population values for 750 mg every 8 hours and nonquantifiable concentrations of nelfinavir's principal metabolite (M8). Nelfinavir 40 mg/kg every 8 hours was then substituted with nelfinavir 30 mg/kg twice daily plus ritonavir 400 mg/m(2) twice daily. Intensive steady-state (0-12 h) pharmacokinetic sampling was repeated. Nelfinavir concentrations had improved, but remained low when compared with adult population values of 1250 mg every 12 hours: AUC(0-24) 21.9 versus 47.6 mg/L*h (46%) and 12-hour trough level (C(12)) 0.25 versus 0.85 mg/L (29%). However, concentrations of M8 considerably exceeded population values: AUC(0-24) 57.5 versus 13.6 mg/L*h (443%) and C(12) 1.35 versus 0.28 mg/L (482%). Since M8 concentrations were highly elevated, pharmacokinetic parameters for (nelfinavir + M8) were used rather than those for nelfinavir alone. Thus, AUC(0-24) (nelfinavir + M8) and C(12) (nelfinavir + M8) comprised 130% and 142%, respectively of the adult population values. This, in addition to good clinical response and tolerability, favored continuation of the regimen. CONCLUSIONS In an infant, nelfinavir-containing HAART was successfully used with rifampin after the addition of ritonavir. Ritonavir resolved the pharmacokinetic interaction between rifampin and nelfinavir by boosting nelfinavir and, especially, M8 concentrations. More research is needed to confirm these results.
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Affiliation(s)
- Alina S Bergshoeff
- Department of Clinical Pharmacy, University Medical Center, Nijmegen, The Netherlands.
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Guiard-Schmid JB, Poirier JM, Meynard JL, Bonnard P, Gbadoe AH, Amiel C, Calligaris F, Abraham B, Pialoux G, Girard PM, Jaillon P, Rozenbaum W. High variability of plasma drug concentrations in dual protease inhibitor regimens. Antimicrob Agents Chemother 2003; 47:986-90. [PMID: 12604531 PMCID: PMC149294 DOI: 10.1128/aac.47.3.986-990.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ritonavir (RTV) strongly increases the concentrations of protease inhibitors (PIs) in plasma in patients given a combination of RTV and another PI. This pharmacological interaction is complex and poorly characterized and shows marked inter- and intraindividual variations. In addition, RTV interacts differently with saquinavir (SQV), indinavir (IDV), amprenavir (APV), and lopinavir (LPV). In this retrospective study on 542 human immunodeficiency virus-infected patients, we compared inter- and intraindividual variability of plasma PI concentrations and correlations between the C(min) (minimum concentration of drug in plasma) values for RTV and the coadministered PI C(min) values. Mean RTV C(min)s are significantly lower in patients receiving combinations containing APV or LPV than in combinations with SQV or IDV. With the most common PI dose regimens (600 mg of IDV twice a day [BID], 800 mg of SQV BID, and 400 mg of LPV BID), the interindividual C(min) variability of patients treated with a PI and RTV seemed to be lower with APV and LPV than with IDV and SQV. As regards intraindividual variability, APV also differed from the other PIs, exhibiting lower C(min) variability than with the other combinations. Significant positive correlations between RTV C(min) and boosted PI C(min) were observed with IDV, SQV, and LPV, but not with APV. Individual dose adjustments must take into account the specificity the pharmacological interaction of each RTV/PI combination and the large inter- and intraindividual variability of plasma PI levels to avoid suboptimal plasma drug concentrations which may lead to treatment failure and too high concentrations which may induce toxicity and therefore reduce patient compliance.
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Aarnoutse RE, Droste JAH, van Oosterhout JJG, Koopmans PP, Popescu M, Reiss P, Hekster YA, Burger DM. Pharmacokinetics, food intake requirements and tolerability of once-daily combinations of nelfinavir and low-dose ritonavir in healthy volunteers. Br J Clin Pharmacol 2003; 55:115-25. [PMID: 12580982 PMCID: PMC1894733 DOI: 10.1046/j.1365-2125.2003.01756.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
AIMS This study was performed to evaluate the steady-state pharmacokinetics, food intake requirements and short-term tolerability of once-daily combinations of nelfinavir and low-dose ritonavir. METHODS Twenty-seven healthy volunteers were randomized over three groups to receive a once-daily regimen of nelfinavir/ritonavir 2,000/200 mg (group 1), 2,000/400 mg (group 2) or 2,500/200 mg (group 3) with food for 14 days. Pharmacokinetic parameters for nelfinavir and its active metabolite M8 were assessed on study days 15 and 16, after administration of the regimens with a full (610 kcal) or light (271 kcal) breakfast, respectively. RESULTS Pharmacokinetic data were evaluable for eight volunteers in group 1, eight in group 2 and four in group 3. Administration of nelfinavir/ritonavir with a full breakfast resulted in geometric mean (GM) nelfinavir AUC(24h) values of 76.8, 51.3, and 61.9 h*mg/l in group 1, 2 and 3, respectively. GM 24-h Cmin concentrations of nelfinavir were 0.76 mg l(-1), 0.43 mg l(-1) and 0.47 mg l(-1), respectively. Co-administration of ritonavir increased M8 concentrations more than nelfinavir concentrations, resulting in GM AUC(24h) and Cmin values for nelfinavir plus M8 that were higher than or comparable to reference values for the approved regimen of nelfinavir (1,250 mg BID without ritonavir). In the 2,000/200 mg group, seven out of eight subjects had a Cmin value of nelfinavir plus M8 above a threshold of 1.0 mg l-1. Administration of the combinations with a light breakfast resulted in significant decreases in the AUC(24h) and Cmin of nelfinavir and nelfinavir plus M8, compared with intake with a full breakfast. For the Cmin of nelfinavir plus M8, the GM ratio (light/full breakfast) was 0.76 (90% confidence interval 0.67-0.86, participants from all groups combined). Short-term tolerability was satisfactory, apart from a higher than expected incidence of mild rash (12%). CONCLUSIONS Administration of nelfinavir in a once-daily regimen appears feasible. A nelfinavir/ritonavir 2,000/200 mg combination appears appropriate for further evaluation. Once-daily nelfinavir/ritonavir should be taken with a meal containing at least 600 kcal.
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Affiliation(s)
- R E Aarnoutse
- Department of Clinical Pharmacy, University Medical Centre Nijmegen, Nijmegen, The Netherlands.
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Justesen US, Pedersen C, Klitgaard NA. Simultaneous quantitative determination of the HIV protease inhibitors indinavir, amprenavir, ritonavir, lopinavir, saquinavir, nelfinavir and the nelfinavir active metabolite M8 in plasma by liquid chromatography. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 783:491-500. [PMID: 12482492 DOI: 10.1016/s1570-0232(02)00728-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A simple HPLC method that quantitates all six currently available protease inhibitors and the nelfinavir active metabolite M8 in one assay is presented. A 500-microliter plasma sample was treated by liquid-liquid extraction with a mixture of heptane and ethyl acetate. After evaporation, the residue was redissolved in sodium dihydrogenphosphate and acetonitrile and washed twice with heptane. Chromatography was performed with an analytical C(18) column. Ultraviolet detection at 210 and 239 nm was used. The present method is associated with high accuracy and low imprecision in the concentration range of 25-5000 ng/ml of all six protease inhibitors and M8. This makes it suitable for monitoring purposes.
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Affiliation(s)
- U S Justesen
- Institute of Public Health, Clinical Pharmacology, University of Southern Denmark, Winsloewparken 19, DK-5000 C, Odense, Denmark.
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Treluyer JM, Burgard M, Cazali N, Quartier P, Veber F, Rey E, Alkaer G, Rouzioux C, Pons G, Blanche S. Relationship between antiretroviral drug plasma concentrations and viral load in children. J Acquir Immune Defic Syndr 2003; 32:112-5. [PMID: 12514422 DOI: 10.1097/00126334-200301010-00016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pfister M, Labbé L, Hammer SM, Mellors J, Bennett KK, Rosenkranz S, Sheiner LB. Population pharmacokinetics and pharmacodynamics of efavirenz, nelfinavir, and indinavir: Adult AIDS Clinical Trial Group Study 398. Antimicrob Agents Chemother 2003; 47:130-7. [PMID: 12499180 PMCID: PMC148981 DOI: 10.1128/aac.47.1.130-137.2003] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The present population pharmacokinetic (PK) and pharmacodynamic (PD) study modeled the effects of covariates including drug adherence and the coadministration of protease inhibitors (PIs) on the pharmacokinetics of efavirenz (EFV) and the relationship between EFV exposure and virological failure in patients who failed initial PI treatment in Adult AIDS Clinical Trial Group (AACTG) study 398. We also report on the population PKs of the PIs nelfinavir (NFV) and indinavir (IDV). AACTG study 398 patients received EFV, amprenavir, adefovir dipivoxil, and abacavir and were randomized to take, in addition, one of the following: NFV, IDV, saquinavir (SQV), or placebo. The PK databases consisted of 531 EFV concentrations (139 patients), 219 NFV concentrations (75 patients), and 66 IDV concentrations (11 patients). Time to virological failure was ascertained for all patients in the PK databases. PK data were fit with a population PK model that assumed exclusive hepatic elimination (the well-stirred model). Notable findings with respect to EFV PK and PD are as follows. (i) The hepatic clearance of EFV is unaltered by NFV, IDV, or SQV coadministration. (ii) The hepatic clearance of EFV appears to be 28% higher in white non-Hispanics than in African Americans and Hispanics (P = 0.03). (iii) Higher adherence scores (as measured with the Medication Event Monitoring System) are associated with marginally increased levels of exposure to EFV. (iv) In patients with no prior experience with nonnucleoside reverse transcriptase inhibitors (NNRTIs), a given percent increase in the oral clearance (CL/F) of EFV is associated with a greater percent increase in the hazard of virological failure (P < 0.0003). Among NNRTI-experienced patients, however, hazard is relatively uncorrelated with EFV CL/F.
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Affiliation(s)
- Marc Pfister
- Department of Laboratory Medicine and Biopharmaceutical Sciences, University of California, San Francisco, San Francisco, California 94143, USA
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Affiliation(s)
- Ulrik S Justesen
- Institute of Public Health, Clinical Pharmacology, University of Southern Denmark, Odense, Denmark
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Desta Z, Zhao X, Shin JG, Flockhart DA. Clinical significance of the cytochrome P450 2C19 genetic polymorphism. Clin Pharmacokinet 2002; 41:913-58. [PMID: 12222994 DOI: 10.2165/00003088-200241120-00002] [Citation(s) in RCA: 584] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cytochrome P450 2C19 (CYP2C19) is the main (or partial) cause for large differences in the pharmacokinetics of a number of clinically important drugs. On the basis of their ability to metabolise (S)-mephenytoin or other CYP2C19 substrates, individuals can be classified as extensive metabolisers (EMs) or poor metabolisers (PMs). Eight variant alleles (CYP2C19*2 to CYP2C19*8) that predict PMs have been identified. The distribution of EM and PM genotypes and phenotypes shows wide interethnic differences. Nongenetic factors such as enzyme inhibition and induction, old age and liver cirrhosis can also modulate CYP2C19 activity. In EMs, approximately 80% of doses of the proton pump inhibitors (PPIs) omeprazole, lansoprazole and pantoprazole seem to be cleared by CYP2C19, whereas CYP3A is more important in PMs. Five-fold higher exposure to these drugs is observed in PMs than in EMs of CYP2C19, and further increases occur during inhibition of CYP3A-catalysed alternative metabolic pathways in PMs. As a result, PMs of CYP2C19 experience more effective acid suppression and better healing of duodenal and gastric ulcers during treatment with omeprazole and lansoprazole compared with EMs. The pharmacoeconomic value of CYP2C19 genotyping remains unclear. Our calculations suggest that genotyping for CYP2C19 could save approximately 5000 US dollars for every 100 Asians tested, but none for Caucasian patients. Nevertheless, genotyping for the common alleles of CYP2C19 before initiating PPIs for the treatment of reflux disease and H. pylori infection is a cost effective tool to determine appropriate duration of treatment and dosage regimens. Altered CYP2C19 activity does not seem to increase the risk for adverse drug reactions/interactions of PPIs. Phenytoin plasma concentrations and toxicity have been shown to increase in patients taking inhibitors of CYP2C19 or who have variant alleles and, because of its narrow therapeutic range, genotyping of CYP2C19 in addition to CYP2C9 may be needed to optimise the dosage of phenytoin. Increased risk of toxicity of tricyclic antidepressants is likely in patients whose CYP2C19 and/or CYP2D6 activities are diminished. CYP2C19 is a major enzyme in proguanil activation to cycloguanil, but there are no clinical data that suggest that PMs of CYP2C19 are at a greater risk for failure of malaria prophylaxis or treatment. Diazepam clearance is clearly diminished in PMs or when inhibitors of CYP2C19 are coprescribed, but the clinical consequences are generally minimal. Finally, many studies have attempted to identify relationships between CYP2C19 genotype and phenotype and susceptibility to xenobiotic-induced disease, but none of these are compelling.
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Affiliation(s)
- Zeruesenay Desta
- Division of Clinical Pharmacology, Indiana University School of Medicine, Wishard Hospital, Indianapolis 46202, USA
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Abstract
The interest in therapeutic drug monitoring (TDM) of antiretroviral drugs is growing rapidly. For the protease inhibitors, and to a lesser extent for the non-nucleoside reverse transcriptase inhibitors, relationships between plasma drug concentrations and their efficacy and toxicity have been identified. Furthermore, the pharmacokinetics of especially the protease inhibitors vary widely between patients, suggesting a role for TDM to individualize antiretroviral therapy. Recently, randomized, prospective clinical trials evaluating the role of TDM in the management of HIV-1-infected patients showed promising results. However, there are still many questions to be answered before large-scale introduction of TDM can be justified (e.g., which pharmacokinetic parameter should be optimized, and what is the minimal effective concentration). This review summarizes the basis for TDM of antiretroviral drugs and discusses the problems and prospects of this potential tool in the care for HIV-1-infected individuals.
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Affiliation(s)
- Rolf P G Van Heeswijk
- International Antiviral Therapy Evaluation Center, Academic Medical Center, Amsterdam, The Netherlands.
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