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Abstract
OBJECTIVE: To review the chemistry, intracellular metabolism, pharmacokinetics, and clinical experience with didanosine (2',3'-dideoxyinosine [ddI]). DATA SOURCES: English-language articles and conference proceedings (indexing terms were didanosine, 2′,3′-dideoxyinosine, and ddI). STUDY SELECTION: Available Phase I studies and abstracts determined to have clinical significance were included. DATA EXTRACTION: Clinical experience with ddI is limited to uncontrolled Phase I studies and a large “expanded-access” program. The primary outcome parameters used to evaluate ddI were the HIV surrogate markers: CD4+ lymphocytes and p24 antigen. Thus, the clinical data reviewed here must be evaluated critically and be considered preliminary until the results of studies comparing ddI with zidovudine (ZDV) and combination studies are available. DATA SYNTHESIS: Didanosine has been approved for the treatment of HIV infection in patients who are unable to tolerate ZDV because of adverse effects (e.g., anemia and neutropenia) or who experience clinical or immunologic deterioration while receiving ZDV. Compared with ZDV, ddI has a long intracellular half-life and negligible bone-marrow toxicity. It also has in vitro activity against ZDV-resistant strains of HIV. Phase I studies indicate that ddI has a beneficial effect on the CD4+ cell counts and HIV p24 antigen concentrations. As a result of the acid-labile nature of ddI, oral formulations are buffered or must be mixed with antacid to neutralize gastric pH. Bioavailability then averages 20–40 percent, depending on the dose and formulation given. The plasma half-life, total body clearance, and volume of distribution of ddI are one to two hours, 0.7–1 L/kg/h, and 0.8–1 L/kg, respectively. Painful peripheral neuropathy and pancreatitis (dose-limiting toxicities of ddI) occurred in 34 and 9 percent of patients in Phase I studies, respectively. CONCLUSIONS: Didanosine has demonstrated preliminary efficacy in the treatment of late-stage HIV infection; however, its effect on patient survival, its efficacy relative to ZDV, and its utility in combination with other agents are still under evaluation.
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Affiliation(s)
- M J Shelton
- Center for Clinical Pharmacy Research, State University of New York, Buffalo
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2
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Severino P, Da Silva CF, Dalla Costa TCT, Silva H, Chaud MV, Santana MHA, Souto EB. In vivo absorption of didanosine formulated in pellets composed of chitosan microspheres. In Vivo 2014; 28:1045-1050. [PMID: 25398797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The in vivo absorption of didanosine was studied, focusing on the performance of a novel pharmaceutical formulation for didanosine, composed of chitosan granules containing didanosine incorporated in chitosan microspheres. This novel formulation is aimed at oral administration in AIDS therapy. The experimental results in male adult dogs showed controlled delivery of didanosine along 36 h, with a 2-fold increase in the absorption time of didanosine compared to the commercial granules, gastro-resistant didanosine and tablets. The higher absorption is due to adhesion to the intestinal membrane, improving absorption through increase of residence time, permeation and release. Furthermore, the novel formulation facilitates handling and deglutition, especially in the elderly and children, as well as enhances the taste and reduces the frequency of doses and collateral effects associated with a high concentration of the buffer agents usually used in other formulations.
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Affiliation(s)
- Patrícia Severino
- School of Chemical Engineering, University of Campinas, Campinas, Sao Paulo, Brazil University of Tiradentes, Aracaju, Brazil Institute of Technology and Research, Aracaju, Brazil
| | | | | | - Heloisa Silva
- Federal University of Bahia, Salvador, Bahia, Brazil Federal University of Sao Paulo, Salvador, Bahia, Brazil
| | - Marco V Chaud
- Laboratory of Biomaterials and Nanotechnology, University of Sorocaba, Sorocaba, Sao Paulo, Brazil
| | | | - Eliana B Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, Azinhaga de Santa Comba, Coimbra, Portugal
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Hien H, Meda N, Diagbouga S, Zoure E, Yaméogo S, Tamboura H, Somé J, Ouiminga A, Rouet F, Drabo A, Hien A, Nicolas J, Chappuy H, Van de Perre P, Msellati P, Nacro B. 24-Month adherence, tolerance and efficacy of once-a-day antiretroviral therapy with didanosine, lamivudine, and efavirenz in African HIV-1 infected children: ANRS 12103/12167. Afr Health Sci 2013; 13:287-94. [PMID: 24235926 DOI: 10.4314/ahs.v13i2.13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND There is no data on long-term benefit of once-a-day antiretroviral therapy (ART) with combination of DDI, 3TC and EFV to allow its use in future therapeutic strategies. OBJECTIVES To assess 24-month immuno-virological, adherence, tolerance, and effectiveness of a once-a-day ART with DDI, 3TC and EFV. METHODS A phase 2 open trial including 51 children aged from 30 months to 15 years, monitored a once-a-day regimen for 24 months from 2006 to 2008 in the Departement de Pediatrie du CHUSS, at Bobo-Dioulasso in Burkina Faso. We tested immunological and virological response, adherence, tolerance and resistance of the treatment. RESULTS Children with CD4 >25% at 24 months were 67.4% (33/49) CI 95% [54%, 80%]. The proportion of children with viral plasma RNA <300 cp / ml at 24 months of treatment was 81.6 % (40/49) CI [68.0% 91.2%]. Good adherence was obtained with more than 88% adherence > 95% over the 24 months. Drugs were well tolerated. CONCLUSIONS Given the limited number of antiretroviral drugs available in Africa and the inadequacy of laboratory monitoring in support program, once-a-day treatment and especially the DDI-based combination strategies could be an attractive operational option.
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Affiliation(s)
- H Hien
- Unité de recherche Santé de la Reproduction VIH et Maladies Associées, Centre MURAZ, Bobo-Dioulasso, Burkina Faso ; Institut de recherche en sciences de la santé, Bobo-Dioulasso, Burkina Faso
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Kearney BP, Sayre JR, Flaherty JF, Chen SS, Kaul S, Cheng AK. Drug-Drug and Drug-Food Interactions Between Tenofovir Disoproxil Fumarate and Didanosine. J Clin Pharmacol 2013; 45:1360-7. [PMID: 16291710 DOI: 10.1177/0091270005281351] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The drug-drug and drug-food interactions between tenofovir DF and didanosine EC were evaluated in 2 pharmacokinetic studies in healthy adult subjects. When 400 mg was dosed with tenofovir DF, mean didanosine AUC was increased by 44% to 60% following fasted or fed administration. Staggered coadministration (2 hour, fasted) of a reduced didanosine dose of 250 mg resulted in equivalent didanosine exposure, while simultaneous administration with tenofovir DF in the fasted and fed state resulted in didanosine AUCs similar to that of the reference treatment of 400 mg alone in the fasted state. These data indicate that a dose reduction of didanosine is warranted when it is used with tenofovir DF. The drug-drug-food interaction of didanosine may offer more flexible dosing of didanosine EC when it is used with tenofovir DF. Patients receiving tenofovir DF and didanosine together should be carefully monitored for safety and efficacy.
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Affiliation(s)
- Brian P Kearney
- Gilead Sciences, Inc, 333 Lakeside Drive, Foster City, CA 94404, USA
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5
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la Porte C, Verweij-van Wissen C, van Ewijk N, Aarnoutse R, Koopmans P, Reiss P, Stek M, Hekster Y, Burger D. Pharmacokinetic Interaction Study of Indinavir/Ritonavir and the Enteric-Coated Capsule Formulation of Didanosine in Healthy Volunteers. J Clin Pharmacol 2013; 45:211-8. [PMID: 15647414 DOI: 10.1177/0091270004271063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Didanosine enteric-coated should be taken on an empty stomach, but the once-daily combination of indinavir/ritonavir can be taken with food. Because these drugs are frequently included in 1 regimen, the food effects on the pharmacokinetics were evaluated. This was a randomized, 4-way crossover study of single doses of didanosine enteric-coated 400 mg and indinavir/ritonavir 1200/400 mg in 8 healthy subjects. The following regimens were given: didanosine enteric-coated 2 hours after breakfast (reference regimen A), indinavir/ritonavir with breakfast (reference regimen B), didanosine enteric-coated + indinavir/ritonavir 2 hours after breakfast (test regimen C), and didanosine enteric-coated + indinavir/ritonavir with breakfast (test regimen D). Breakfast was 550 kcal, 28% fat. Blood samples were drawn before and up to 24 hours after ingestion. Statistical comparisons of test regimens C and D with reference regimens A and B were made using the equivalence approach for indinavir and didanosine area under the curve and C(max) (0.80-1.25). Eight subjects (5 men, 3 women) were enrolled and completed the study. Indinavir area under the curves were bioequivalent in test regimens C and D compared to reference regimen B. A 14% increased C(max) was observed in test regimen C. Didanosine area under the curve in test regimen D was 4% lower and suggestive of bioequivalence compared to reference regimen A. However, test regimen C didanosine area under the curve was 23% lower and bioinequivalent compared to reference regimen A. Didanosine C(max) decreased 42% and 46% in test regimens C and D, respectively, in comparison to reference regimen A. In this study, dosing didanosine enteric-coated 400 mg once daily + indinavir/ritonavir 1200/400 mg once daily with breakfast indicated no decrease in the amount of absorption for either didanosine and indinavir and that this regimen could be administered with food.
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Affiliation(s)
- C la Porte
- Department of Clinical Pharmacy, University Medical Centre Nijmegen, PO Box 9101, 533 KF, 6500 HB, Nijmegen, the Netherlands
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Ojewole E, Mackraj I, Akhundov K, Hamman J, Viljoen A, Olivier E, Wesley-Smith J, Govender T. Investigating the effect of Aloe vera gel on the buccal permeability of didanosine. Planta Med 2012; 78:354-361. [PMID: 22161764 DOI: 10.1055/s-0031-1280431] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The buccal mucosal route offers several advantages but the delivery of certain drugs can be limited by low membrane permeability. This study investigated the buccal permeability properties of didanosine (ddI) and assessed the potential of Aloe vera gel (AVgel) as a novel buccal permeation enhancer. Permeation studies were performed using Franz diffusion cells, and the drug was quantified by UV spectroscopy. Histomorphological evaluations were undertaken using light and transmission electron microscopy. The permeability of ddI was concentration-dependent, and it did not have any adverse effects on the buccal mucosae. A linear relationship (R² = 0.9557) between the concentrations and flux indicated passive diffusion as the mechanism of drug transport. AVgel at concentrations of 0.25 to 2 %w/v enhanced ddI permeability with enhancement ratios from 5.09 (0.25 %w/v) to 11.78 (2 %w/v) but decreased permeability at 4 and 6 %w/v. Ultrastructural analysis of the buccal mucosae treated with phosphate buffer saline pH 7.4 (PBS), ddI/PBS, and ddI/PBS/AVgel 0.5 %w/v showed cells with normal plasmalemma, well-developed cristae, and nuclei with regular nuclear envelopes. However, cells from 1, 2, and 6 %w/v AVgel-treated mucosae showed irregular nuclear outlines, increased intercellular spacing, and plasmalemma crenulations. This study demonstrates the potential of AVgel as a buccal permeation enhancer for ddI to improve anti-HIV and AIDS therapy.
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Affiliation(s)
- Elizabeth Ojewole
- School of Pharmacy and Pharmacology, University of KwaZulu-Natal, Durban, South Africa
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Hirt D, Bardin C, Diagbouga S, Nacro B, Hien H, Zoure E, Rouet F, Ouiminga A, Urien S, Foulongne V, Van De Perre P, Tréluyer JM, Msellati P. Didanosine population pharmacokinetics in West African human immunodeficiency virus-infected children administered once-daily tablets in relation to efficacy after one year of treatment. Antimicrob Agents Chemother 2009; 53:4399-406. [PMID: 19581461 PMCID: PMC2764159 DOI: 10.1128/aac.01187-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 01/08/2009] [Accepted: 06/25/2009] [Indexed: 11/20/2022] Open
Abstract
Our objective was to study didanosine pharmacokinetics in children after the administration of tablets, the only formulation available in Burkina Faso for which data are missing, and to establish relationships between doses, plasma drug concentrations, and treatment effects (efficacy/toxicity). Didanosine concentrations were measured for 40 children after 2 weeks and for 9 children after 2 to 5 months of treatment with a didanosine-lamivudine-efavirenz combination. A population pharmacokinetic model was developed with NONMEM. The link between the maximal concentration of the drug in plasma (Cmax), the area under the concentration-time curve (AUC), and the decrease in human immunodeficiency virus (HIV) type 1 RNA levels after 12 months of treatment was evaluated. The threshold AUC that improved efficacy was determined by the use of a Wilcoxon test for HIV RNA, and an optimized dosing schedule was simulated. Didanosine pharmacokinetics was best described by a one-compartment model with first-order absorption and elimination. The apparent clearance and volume of distribution were higher for tablets, probably due to a lower bioavailability with tablets than with pediatric powder. The decrease in the viral load after 12 months of treatment was significantly correlated with the didanosine AUC and Cmax (P < or = 0.02) during the first weeks of treatment. An AUC of >0.60 mg/liter x h was significantly linked to a greater decrease in the viral load (a decrease of 3 log10 versus 2.4 log10 copies/ml; P = 0.03) than that with a lower AUC. A didanosine dose of 360 mg/m2 administered as tablets should be a more appropriate dose than 240 mg/m2 to improve efficacy for these children. However, data on adverse events with this dosage are missing.
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Affiliation(s)
- Déborah Hirt
- EA3620, Université Paris-Descartes, Paris, France.
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8
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Pediatric efficacy supplement for Videx EC. AIDS Patient Care STDS 2008; 22:919. [PMID: 19043843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
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9
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FDA notifications. FDA approves pediatric efficacy supplement for didanosine capsules. AIDS Alert 2008; 23:129. [PMID: 19043871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Ramanathan S, Shen G, Hinkle J, Enejosa J, Kearney BP. Pharmacokinetics of coadministered ritonavir-boosted elvitegravir and zidovudine, didanosine, stavudine, or abacavir. J Acquir Immune Defic Syndr 2007; 46:160-6. [PMID: 17693892 DOI: 10.1097/qai.0b013e318151fd9a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the potential for clinically relevant drug interactions between ritonavir-boosted elvitegravir (EVG/r) and the nucleoside reverse transcriptase inhibitors (NRTIs) zidovudine (ZDV), didanosine (ddI), stavudine (d4T), or abacavir (ABC) upon coadministration. METHODS In 3 studies, healthy subjects were administered a single dose of ddI, d4T, or ABC, or multiple doses of ZDV, followed by multiple doses of EVG/r alone and together with an NRTI; pharmacokinetics (PK) of EVG and NRTIs were evaluated after individual administration and coadministration. Lack of PK alteration bounds (90% confidence intervals [CI]) for the NRTIs were based on the lack of PK-based dose adjustments per prescribing information. RESULTS Twenty-four of 28, 32/32, and 24/26 subjects completed the ZDV-EVG/r, ddI/d4T-EVG/r, and ABC-EVG/r studies, respectively. All study drugs were well tolerated and no serious adverse events were noted. The PK of ZDV, its glucuronide (G-ZDV), d4T, ABC, and EVG were within the lack of PK alteration 90% CI bounds upon coadministration. Exposures of ddI were modestly (approximately 15%) lower, but these changes are unlikely to be clinically meaningful. CONCLUSIONS There are no clinically relevant drug interactions between EVG/r and the NRTIs zidovudine, didanosine, stavudine, or abacavir. These agents can be coadministered without dose adjustment.
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Velasque LS, Estrela RCE, Suarez-Kurtz G, Struchiner CJ. A new model for the population pharmacokinetics of didanosine in healthy subjects. ACTA ACUST UNITED AC 2007; 40:97-104. [PMID: 17225002 DOI: 10.1590/s0100-879x2007000100013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Accepted: 03/09/2006] [Indexed: 11/22/2022]
Abstract
Didanosine (ddI) is a component of highly active antiretroviral therapy drug combinations, used especially in resource-limited settings and in zidovudine-resistant patients. The population pharmacokinetics of ddI was evaluated in 48 healthy volunteers enrolled in two bioequivalence studies. These data, along with a set of co-variates, were the subject of a nonlinear mixed-effect modeling analysis using the NONMEM program. A two-compartment model with first order absorption (ADVAN3 TRANS3) was fitted to the serum ddI concentration data. Final pharmacokinetic parameters, expressed as functions of the co-variates gender and creatinine clearance (CL CR), were: oral clearance (CL = 55.1 + 240 x CL CR + 16.6 L/h for males and CL = 55.1 + 240 x CL CR for females), central volume (V2 = 9.8 L), intercompartmental clearance (Q = 40.9 L/h), peripheral volume (V3 = 62.7 + 22.9 L for males and V3 = 62.7 L for females), absorption rate constant (Ka = 1.51/h), and dissolution time of the tablet (D = 0.43 h). The intraindividual (residual) variability expressed as coefficient of variation was 13.0%, whereas the interindividual variability of CL, Q, V3, Ka, and D was 20.1, 75.8, 20.6, 18.9, and 38.2%, respectively. The relatively high (>30%) interindividual variability for some of these parameters, observed under the controlled experimental settings of bioequivalence trials in healthy volunteers, may result from genetic variability of the processes involved in ddI absorption and disposition.
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Affiliation(s)
- L S Velasque
- Programa de Computação Científica, Fundação Oswaldo Cruz, Brasil.
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Lowe SH, van Leeuwen E, Droste JAH, van der Veen F, Reiss P, Lange JMA, Burger DM, Repping S, Prins JM. Semen Quality and Drug Concentrations in Seminal Plasma of Patients Using a Didanosine or Didanosine Plus Tenofovir Containing Antiretroviral Regimen. Ther Drug Monit 2007; 29:566-70. [PMID: 17898645 DOI: 10.1097/ftd.0b013e31811fef29] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Data on the concentrations of didanosine (ddI) and tenofovir (TFV) in seminal plasma are sparse. Subtherapeutic drug concentrations within the lumen of the male genital tract may have implications for selection and transmission of drug-resistant HIV strains. On the other hand, sufficient penetration of these drugs into the male genital tract has potential toxic effects on the spermatozoa and their precursors. In the current study, the authors obtained paired semen and blood samples at variable time points after drug intake from 30 HIV-1-infected patients using a ddI (n = 15) or ddI + TFV (n = 15) containing an antiretroviral regimen. Didanosine and TFV concentrations were measured in seminal and blood plasma and semen quality was assessed. Both ddI and TFV penetrated well into seminal plasma. Whereas blood plasma ddI concentrations dropped to near or below the lower limit of quantification of 0.017 microg/mL 9 hours after drug intake, the ddI concentration in seminal plasma remained detectable during the whole dosing interval with a median of 0.20 and 0.21 microg/mL in the ddI and ddI + TFV groups, respectively. Tenofovir was detectable during the whole dosing interval in both blood and seminal plasma with a median concentration of 0.12 and 0.25 microg/mL, respectively, and a median seminal-to-blood-plasma ratio of 3.3. Semen quality was within the normal range according to the criteria of the World Health Organization, except for the percentage of progressively motile sperm, which was low in both groups of patients. The authors conclude that ddI and TFV penetrate well into seminal plasma and that the reduced sperm motility deserves further study.
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Affiliation(s)
- Selwyn H Lowe
- Department of Internal Medicine, Division of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Abstract
Didanosine, which is a synthetic nucleoside analogue intracellularly phosphorylated to the active metabolite, inhibits the activity of HIV-1 reverse transcriptase by competing with the natural substrate. Currently, didanosine is mainly provided as an enteric-coated capsule. In vitro, the molecule is active against laboratory strains and clinical isolates of HIV-1 in resting and activated T cells and monocyte/macrophages. Didanosine may select for resistance mutations that may render the drug inactive against the virus; L74V and K65R remain as the main didanosine-related mutations. In vitro, phenotypic susceptibility to didanosine was decreased beyond a defined fold change clinical cut-off (1.7), and it is considered that genotypic resistance exists when five thymidine-associated mutations or four plus M184V are present. In vivo, clinical studies have shown that didanosine retains significant antiviral activity in patients who have up to five nucleoside analogue mutations at baseline. Didanosine is useful in patients with no previous therapy, as well as in experienced patients in whom one or more antiretroviral regimens has failed.Enteric-coated didanosine is taken once daily, its co-administration with food has been recently evaluated and a reduction of the efficacy of the antiretroviral treatment was not observed. Administered with lamivudine (or emtricitabine), it can be considered a good alternative for use in the nucleoside analogue backbone included in combination therapies for antiretroviral-naive patients. Didanosine could be used in initial treatments for patients intolerant of zidovudine, abacavir or tenofovir. It can be included in once-daily combination regimens, which are more convenient and patient friendly.Prospective, observational and open-label studies, as well as clinical trials (with durations between 24 and 96 weeks), have demonstrated the safety and efficacy of didanosine plus lamivudine (or emtricitabine) plus efavirenz (or nevirapine) in previously untreated HIV-1-infected patients. The administration of didanosine to treatment-experienced patients has been evaluated in two different contexts: patients in whom previous therapies have failed (rescue therapy) and those with controlled viraemia who are switched to a didanosine-containing regimen for simplification.Adverse events associated with the administration of didanosine have been well known since the initial clinical trials with the drug. Gastrointestinal intolerance, peripheral neuropathy and hyperamylasaemia/pancreatitis were the most frequently reported. In the highly active antiretroviral therapy (HAART) era, the rate of adverse events has decreased. The tolerability of didanosine has been clearly improved with the development of the enteric-coated capsule. Severe manifestations of mitochondrial toxicity, including lactic acidosis and abnormal fat distribution, are rare complications, and occur most frequently when didanosine is used in combination with stavudine.
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Affiliation(s)
- Santiago Moreno
- Department of Infectious Diseases, Ramón y Cajal Hospital, Alcalá University, Madrid, Spain.
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Lalanne M, Paci A, Andrieux K, Dereuddre-Bosquet N, Clayette P, Deroussent A, Ré M, Vassal G, Couvreur P, Desmaële D. Synthesis and biological evaluation of two glycerolipidic prodrugs of didanosine for direct lymphatic delivery against HIV. Bioorg Med Chem Lett 2007; 17:2237-40. [PMID: 17276686 DOI: 10.1016/j.bmcl.2007.01.062] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 01/18/2007] [Accepted: 01/19/2007] [Indexed: 11/29/2022]
Abstract
Novel glycerolipidic prodrugs of didanosine and didanosine monophosphate designed to by-pass the hepatic first pass metabolism were synthesized and tested for their cytotoxicity and anti-HIV-1 activity. Formulation as liposomes of dipalmitoylphosphatidylcholine was elaborated. A simple quantitative HPLC-UV method was developed and validated, and ESI-MS was used for qualitative purpose. These two prodrugs exhibited promising biological activities against HIV-1 in in vitro infected cell culture.
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Affiliation(s)
- Muriel Lalanne
- Université Paris-Sud, UMR CNRS 8612, IFR 141, F-92296 Châtenay-Malabry, France
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Cruciani M, Liuzzi G, Chirianni A, Audagnotto S, Bonora S, Di Biagio A, Sinicco A, Bassetti M, Gatti G. Penetration of didanosine in semen of HIV-1-infected men. J Antimicrob Chemother 2006; 57:1244-7. [PMID: 16556633 DOI: 10.1093/jac/dkl111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The disposition of antiretroviral agents into genital tissue and fluids is one of the factors implicated in the control of viral replication within the male genital tract and should be an objective of highly active antiretroviral therapy. We have investigated didanosine penetration in seminal plasma of 16 HIV-infected patients. PATIENTS AND METHODS A total of 16 patients on didanosine (200 mg every 12 h or 400 mg once daily) participated in the pharmacokinetic study. After the didanosine morning dose, peripheral blood plasma and semen plasma were collected within the intervals 0-4, 4-8 and 8-12 h in the twice-daily regimen and 0-4, 4-12 and 12-24 h in the once-daily regimen. RESULTS Within each sampling time interval didanosine concentrations in seminal plasma were higher than in blood. The interquartile range of concentrations in seminal plasma was 292-1217 ng/mL, compared with 50-150 ng/mL in blood plasma. Didanosine could be detected in 14 of the 16 semen samples analysed and in 8 of the 16 blood samples. CONCLUSIONS We have demonstrated that didanosine penetrates into the seminal plasma in higher concentrations than in blood plasma.
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Affiliation(s)
- M Cruciani
- Centre of Preventive Medicine & HIV Outpatient Clinic, Via Germania 20, 37135 Verona, Italy.
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Schramm Andrade S, Kano EK, de Lima Souza Brioschi TM, Koono EEM, dos Reis Serra CH, Porta V. Bioavailability study of two oral formulations of didanosine in healthy volunteers. Arzneimittelforschung 2006; 56:359-64. [PMID: 16821647 DOI: 10.1055/s-0031-1296734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
An open-label, randomised, crossover single dose study, using 2 periods, 2 sequences, with a minimum washout period of 7 days, was conducted in order to assess the comparative bioavailability of two formulations of didanosine (CAS 69655-05-6) 100 mg tablets. Didanosine plasma concentrations were determined by means of a validated HPLC method [DAD detector, stavudine (CAS 3056-17-5) as an internal standard]. The limit of detection was 30 ng/ml. The results showed that overall classical 90 % confidence intervals (CI) were 92.4-111.2 % for AUC0-inf, 91.8-109.9 %f for AUC0-t, and 87.0-110.0 % for Cmax. Since the 90 % CI for both, AUC and Cmax ratios were within the 80-125 % interval proposed by the European Agency for the Evalution of Medicinal Products (EMEA) and Food and Drug Administration (FDA), it is concluded that the new didanosine formulation is equivalent to the conventional formulation for both, the extent and the rate of absorption after single dose administration in healthy volunteers.
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King JR, Nachman S, Yogev R, Hodge J, Aldrovandi G, Hughes MD, Chen J, Wiznia A, Damle B, Acosta EP. Efficacy, tolerability and pharmacokinetics of two nelfinavir-based regimens in human immunodeficiency virus-infected children and adolescents: pediatric AIDS clinical trials group protocol 403. Pediatr Infect Dis J 2005; 24:880-5. [PMID: 16220085 DOI: 10.1097/01.inf.0000180508.21918.8a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Few combinations of highly active antiretrovirals have been studied in nucleoside reverse transcription inhibitor (NRTI)-experienced, human immunodeficiency virus (HIV)-infected children. We tested the efficacy, tolerability and pharmacokinetics of 2 combination therapies containing an NRTI, protease inhibitors +/- a nonnucleoside reverse transcription inhibitor (NNRTI). METHODS This was a phase II, randomized, multicenter study. Forty-one children and youths between 5 months and 21 years with prior NRTI and no prior NNRTI or protease inhibitor experience received either nelfinavir (NFV) 30 mg/kg twice daily (bid), ritonavir (RTV) 400 mg/m bid and buffered didanosine (ddI) 240 mg/m daily (arm A) or NFV 50-55 mg/kg bid, nevirapine (NVP) 120 mg/m bid and stavudine (d4T) 1 mg/kg bid (arm B). Patients were evaluated clinically for 48 weeks after initiation of therapy. Intensive pharmacokinetic sampling occurred after 4 weeks of therapy. RESULTS : The proportion of children with HIV-1 RNA < or =400 copies/mL and on randomized treatment at 48 weeks was 65% among children assigned NFV + RTV + ddI versus 28% among those assigned NFV + NVP + d4T (P = 0.039). No significant difference in median CD4% change from baseline to week 48 was found (3% versus 1%). No significant differences in safety or tolerability between children randomized to NFV + RTV + ddI versus NFV + NVP + d4T were identified. However, a trend toward a higher rate of permanent discontinuation of study treatment was noted among children assigned to NFV + NVP + d4T compared with NFV + RTV + ddI [7 of 20 (35%) versus 2 of 21 (10%); P = 0.12]. NFV pharmacokinetic measurements were not statistically different between the treatment groups, yet exposure to the NFV metabolite, M8, was significantly higher in subjects receiving RTV. The pharmacokinetics for NVP, RTV and d4T were similar to those of previously reported data. CONCLUSION : Combination therapy containing NFV + RTV + ddI appears more efficacious in NRTI-experienced children than a regimen containing NFV + NVP + d4T. Differences in tolerability between the 2 treatment groups were not identified. Systemic exposure of these drugs was similar to that reported in other HIV-infected children and adults.
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Pruvost A, Negredo E, Benech H, Theodoro F, Puig J, Grau E, García E, Moltó J, Grassi J, Clotet B. Measurement of intracellular didanosine and tenofovir phosphorylated metabolites and possible interaction of the two drugs in human immunodeficiency virus-infected patients. Antimicrob Agents Chemother 2005; 49:1907-14. [PMID: 15855513 PMCID: PMC1087635 DOI: 10.1128/aac.49.5.1907-1914.2005] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent work has demonstrated the existence of a systemic interaction between didanosine (ddI) and tenofovir disoproxyl fumarate (TDF) that leads to a significant increase in plasma ddI levels when coadministered with TDF (40 to 50% increase). These two drugs are, respectively, nucleoside and nucleotide analogues of adenosine and efficiently inhibit the human immunodeficiency virus (HIV) reverse transcriptase when transformed to their triphosphate moieties in the intracellular (IC) medium (ddA-TP and TFV-DP, respectively). Since ddI and TDF partly share the same IC metabolic pathway leading to the active triphosphates, we investigated a putative IC interaction. We used high-performance liquid chromatography-tandem mass spectrometry techniques to determine ddA-TP and TFV-DP IC levels in HIV-infected patients cotreated with both drugs, in comparison with patients treated with just one of the two drugs. These measurements revealed no significant differences in IC levels of the corresponding triphosphates when ddI (250 mg, once a day [QD]) was coadministered with TDF (300 mg, QD) compared to ddI 400 mg (QD) administered without TDF, thus supporting the dose adaptation proposed for this combination. However, we observed that both ddA-TP and TFV-DP have very long IC half-lives, resulting in unusual IC pharmacokinetic profiles with no significant changes in triphosphate concentrations between two dosings. In the case of TFV-DP, this t(1/2) of elimination was roughly estimated to be 180 h (7.5 days). This characteristic is certainly interesting in terms of efficacy but could have some drawbacks in terms of virus resistance for patients discontinuing these drugs.
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Affiliation(s)
- Alain Pruvost
- CEA, Service de Pharmacologie et d'Immunologie, DSV/DRM, CEA/Saclay, 91191 Gif sur Yvette cedex, France
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20
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Kovacs A, Cowles MK, Britto P, Capparelli E, Fowler MG, Moye J, McIntosh K, Rathore MH, Pitt J, Husson RN. Pharmacokinetics of didanosine and drug resistance mutations in infants exposed to zidovudine during gestation or postnatally and treated with didanosine or zidovudine in the first three months of life. Pediatr Infect Dis J 2005; 24:503-9. [PMID: 15933559 DOI: 10.1097/01.inf.0000164787.63237.0b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND There are limited numbers of drugs that are available in formulations that are appropriate for neonates and few studies assessing resistance among infants born to human immunodeficiency virus (HIV)-infected women. METHODS Pharmacokinetics and tolerance of didanosine (ddI) were determined for infants < or =120 days of age. Infants received at least 24 hours of zidovudine (ZDV) treatment, followed by a single ddI dose and pharmacokinetic sampling. The target area under the concentration-time curve (AUC) was between 2.5 and 5.0 microM . hour. Toxicity and drug resistance mutations were assessed at baseline and follow-up times. RESULTS The initial ddI pharmacokinetic dosing of 50 mg/m for infants >28 days of age achieved a median AUC0-infinity of 2.8 microM . hour. For infants < or =28 days of age, the target AUC was achieved after dose escalation from 25 mg/m (median AUC0-infinity, 1.4 microM . hour) to 50 mg/m (median AUC0-infinity, 5.40 microM . hour). At baseline, 25% of infected infants had drug resistance mutations (9 of 44 to ZDV and 2 of 44 to ddI). Resistance mutations were present for 29% of infants (5 of 17 infants) with in utero ZDV exposure and 25% (8 of 32 infants) with prior ZDV treatment. The most common ZDV mutation noted at baseline was the T215Y/F (n = 7) mutation; 2 of these infants also had the M41L mutation, which is associated with high level ZDV resistance. No prior exposure was noted for the 2 infants with ddI resistance, which indicates possible perinatal transmission of ddI-resistant virus to these infants. CONCLUSIONS A dose of 50 mg/m is the appropriate ddI dose for infants <120 days of age and is a safe treatment for newborns when used in combination with ZDV. Genotypic resistance occurs frequently among infected infants exposed to ZDV during gestation or postnatally, which suggests that resistance testing should be considered for infants with newly diagnosed HIV infection.
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Affiliation(s)
- Andrea Kovacs
- Maternal, Child and Adolescent Center for Infectious Diseases and Virology, University of Southern California, Keck School of Medicine, Los Angeles, 90033, USA.
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Payen S, Faye A, Compagnucci A, Giaquinto C, Gibbs D, Gomeni R, Bressolle F, Jacqz-Aigrain E. Bayesian parameter estimates of nelfinavir and its active metabolite, hydroxy-tert-butylamide, in infants perinatally infected with human immunodeficiency virus type 1. Antimicrob Agents Chemother 2005; 49:525-35. [PMID: 15673728 PMCID: PMC547202 DOI: 10.1128/aac.49.2.525-535.2005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 05/24/2004] [Accepted: 10/14/2004] [Indexed: 12/11/2022] Open
Abstract
The objective of the present study was to develop a population pharmacokinetic model for nelfinavir mesylate (NFV) and nelfinavir hydroxy-tert-butylamide (M8), the most abundant metabolite of NFV, in infants vertically infected with human immunodeficiency virus type 1 and participating in the Paediatric European Network for Treatment of AIDS 7 study. Plasma NFV concentrations were determined during repeated NFV administrations (two to three times a day). Eighteen infants younger that age 2 years participated in this study. The doses administered ranged from 71 to 203 mg/kg of body weight/day. Pharmacokinetic parameter estimates were obtained by a compartmental approach by using a kinetic model to simultaneously fit NFV and M8 (active metabolite) concentrations. M8 was shown to be formation rate limited and was characterized by first-order rate constants of formation and elimination. Body weight was found to be a more appropriate predictor than age of the changes in (i) the rate of metabolism, (ii) the elimination rate constant of NFV, and (iii) NFV clearance. Population parameters were computed to account for the relationship between the rate of metabolism and body weight. The estimated NFV and M8 elimination half-lives were 4.3 and 2.04 h, respectively. The estimated NFV clearance was 2.13 liters/h/kg. The M8 concentration-to-NFV concentration ratio was 0.64 +/- 0.44. In conclusion, the population pharmacokinetic model describing the dispositions of NFV and M8 should facilitate the design of future studies to elucidate the relative contributions of the parent compound and M8 to the pharmacological and toxic effects of NFV therapy.
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Affiliation(s)
- Salomé Payen
- Laboratoire de Pharmacocinétique Clinique, Faculté de Pharmacie, BP 14491, 34093 Montpellier Cedex 5, France
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22
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Abstract
OBJECTIVE To report a case of pancreatitis associated with the combined use of didanosine and tenofovir. CASE SUMMARY A 51-year-old white man with HIV was initiated on antiretroviral therapy with didanosine 250 mg/day, tenofovir 300 mg/day, lamivudine 300 mg/day, stavudine 60 mg/day, and efavirenz 600 mg/day. Didanosine was prescribed at a reduced dosage due to the known interaction with tenofovir. Despite this dosage adjustment, the patient developed acute pancreatitis 10 weeks after antiretrovirals were initiated. Pancreatitis resolved spontaneously after antiretroviral discontinuation. DISCUSSION Our report of didanosine-induced pancreatitis secondary to concurrent use with tenofovir is the third reported case that utilized a reduced didanosine dosage. Five previous pancreatitis reports have been described using full-strength didanosine with tenofovir. The exact mechanism of action for this interaction is unknown. Utilizing the Naranjo probability scale to assess causality, a possible adverse drug reaction was determined. CONCLUSIONS Tenofovir and didanosine may be used cautiously in antiretroviral combination therapy. Reduced didanosine dosage (250 mg) should be used to reduce serum didanosine concentrations and subsequent toxicities. Practitioners should be aware that a significant drug interaction with resulting pancreatitis may occur even when a reduced dosage is prescribed.
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Affiliation(s)
- Margaret A Kirian
- Department of Pharmacy, Cleveland Clinic Foundation, Cleveland, OH, USA
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Abstract
Lactic acidosis is an uncommon but potentially life-threatening adverse effect of didanosine. When given concomitantly with tenofovir disoproxil fumarate (DF), the area under the concentration-time curve of didanosine is increased by 48-60%. A 63-year-old man with human immunodeficiency virus (HIV) infection tolerated several didanosine-containing antiretroviral regimens. He developed generalized weakness, loss of appetite, weight loss, nausea, and vomiting 1.5 years after tenofovir DF was added to his didanosine-containing regimen. He was diagnosed with lactic acidosis and died after a 13-day hospital stay, when his lactate level increased to 189.7 mg/dl and his arterial blood gas pH value fell to 6.75. Health care providers should maintain a high index of suspicion for lactic acidosis in patients with HIV infection who receive didanosine and tenofovir DF concurrently. For patients receiving antiretroviral regimens containing this drug combination, it would be prudent to monitor lactate levels periodically. This is especially important when patients experience symptoms suggestive of lactic acidosis, such as weakness, abdominal pain, weight loss, nausea and vomiting, and shortness of breath.
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Affiliation(s)
- Yi Guo
- Department of Pharmacy, Montefiore Medical Center, Bronx, New York, USA
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Molina JM, Peytavin G, Perusat S, Lascoux-Combes C, Sereni D, Rozenbaum W, Chene G. Pharmacokinetics of emtricitabine, didanosine and efavirenz administered once-daily for the treatment of HIV-infected adults (pharmacokinetic substudy of the ANRS 091 trial). HIV Med 2004; 5:99-104. [PMID: 15012649 DOI: 10.1111/j.1468-1293.2004.00194.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE This study was conducted to investigate the pharmacokinetics of emtricitabine (FTC), didanosine (ddI), and efavirenz (EFV) when administered in a once-daily combination. METHODS Nine antiretroviral-naïve HIV-infected adults who received FTC [200 mg once a day (q.d.)], ddI (400 mg q.d. if > or =60 kg; 250 mg q.d. if <60 kg) and EFV (600 mg q.d.) were studied. The following pharmacokinetic (PK) parameters were determined over 24 h at steady-state after 4 weeks of treatment: area under the plasma concentration vs. time curve (AUC(0-24 h)), maximum (Cmax) and minimum (Cmin) plasma concentrations, time to reach Cmax (Tmax), and the elimination half-life (t(1/2)). EFV plasma concentrations were also measured during follow-up. RESULTS Median PK parameters for FTC, ddI and EFV, respectively, were as follows. AUC(0-24 h): 7.2, 7.0 and 36.4 h x mg/L; Cmax: 1.8, 2.6 and 2.5 mg/L; Cmin: 0.04, <0.01 and 1.0 mg/L; Tmax: 1.8, 1.1 and 2.5 h; t(1/2): 7.4, 2.3, and 23.7 h. EFV plasma concentrations measured 10-13 h postdosing were higher during follow-up than during the PK study (2.57 vs. 1.19 mg/L, P<0.01). CONCLUSION The simultaneous administration of FTC, ddI and EFV did not affect the PK parameters of FTC when compared to historical controls. EFV Cmax and Cmin were lower than expected, but the data may have been slightly underestimated in this study. High ddI AUC and Cmax were measured in these patients, and further studies are warranted to confirm this finding.
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Affiliation(s)
- J-M Molina
- Department of Infectious Diseases, Hôpital Saint-Louis, Paris, France.
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Ray AS, Olson L, Fridland A. Role of purine nucleoside phosphorylase in interactions between 2',3'-dideoxyinosine and allopurinol, ganciclovir, or tenofovir. Antimicrob Agents Chemother 2004; 48:1089-95. [PMID: 15047506 PMCID: PMC375307 DOI: 10.1128/aac.48.4.1089-1095.2004] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The level of systemic exposure to 2',3'-dideoxyinosine (ddI) is increased 40 to 300% when it is coadministered with allopurinol (Allo), ganciclovir (GCV), or tenofovir. However, the mechanism for these drug interactions remains undefined. A metabolic route for ddI clearance is its breakdown by purine nucleoside phosphorylase (PNP). Consistent with previous reports, enzymatic inhibition assays showed that acyclic nucleotide analogs can inhibit the phosphorolysis of inosine. It was further established that the mono- and diphosphate forms of tenofovir were inhibitors of PNP-dependent degradation of ddI (K(i)s, 38 nM and 1.3 microM, respectively). Allo and its metabolites were found to be relatively weak inhibitors of PNP (K(i)s, >100 microM). Coadministration of tenofovir, GCV, or Allo decreased the amounts of intracellular ddI breakdown products in CEM cells, while they increased the ddI concentrations (twofold increase with each drug at approximately 20 microM). While inhibition of the physiological function of PNP is unlikely due to the ubiquitous presence of high levels of enzymatic activity, phosphorylated metabolites of GCV and tenofovir may cause the increased level of exposure to ddI by direct inhibition of its phosphorolysis by PNP. The discrepancy between the cellular activity of Allo and the weak enzyme inhibition by Allo and its metabolites may be explained by an indirect mechanism of PNP inhibition. This mechanism may be facilitated by the unfavorable equilibrium of PNP and the buildup of one of its products (hypoxanthine) through the inhibition of xanthine oxidase by Allo. These findings support the inhibition of PNP-dependent ddI degradation as the molecular mechanism of these drug interactions.
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Affiliation(s)
- Adrian S Ray
- Gilead Sciences, Inc., Foster City, California 94404, USA.
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Le Saint C, Terreux R, Duval D, Durant J, Ettesse H, Dellamonica P, Guedj R, Vincent JP, Cupo A. Determination of ddATP levels in human immunodeficiency virus-infected patients treated with dideoxyinosine. Antimicrob Agents Chemother 2004; 48:589-95. [PMID: 14742213 PMCID: PMC321518 DOI: 10.1128/aac.48.2.589-595.2004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clinical failures of the highly active antiretroviral therapy could result from inefficient intracellular concentrations of antiviral drugs. The determination of drug contents in target cells of each patient would be useful in clinical investigations and trials. The purpose of this work was to quantify the intracellular concentration of ddATP, the active metabolite of dideoxyinosine (ddI), in peripheral blood mononuclear cells (PBMCs) of human immunodeficiency virus (HIV)-infected patients treated with ddI. We have raised antibodies against ddA-citrate, a stable isostere of ddATP selected on the basis of its structural and electronic analogies with ddATP. The anti-ddA-citrate antibodies recognized ddATP and ddA with nanomolar affinities and cross-reacted neither with any of the nucleotide reverse transcriptase inhibitors used in HIV therapy nor with their phosphorylated metabolites. The three phosphorylated metabolites of ddI (ddAMP, ddADP, and ddATP) were purified by anion exchange chromatography and the amount of each metabolite was determined by radioimmunoassay with or without prior phosphatase treatment. The intracellular levels of the three ddI metabolites were measured both in an in vitro model and in PBMCs of HIV-infected patients under ddI treatment. The possibility to measure intracellular levels of ddATP from small blood samples of HIV-infected patients treated with ddI could be exploited to develop individual therapeutic monitoring.
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Affiliation(s)
- Cecile Le Saint
- Institut de Pharmacologie Moleculaire et Cellulaire, Unite Mixte de Recherche CNRS 6097, Sophia Antipolis, France
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Abstract
PURPOSE Previous attempts to ascertain the role of uptake and efflux transporters in the oral absorption of anti-HIV dideoxypurine nucleosides have been inconclusive. A novel in situ intestinal perfusion technique with complete mesenteric arterial/venous cannulation was used to examine the asymmetry of ileal dideoxynucleoside permeability under near in vivo conditions. METHODS Intestinal perfusions were performed in the rat ileum, with cannulation of the artery and vein immediately entering and leaving the segment. Urea and mannitol were used as passive permeability markers, and the directional transport of 2',3'-dideoxyinosine (ddI), 2'-beta-fluoro-2',3'-dideoxyinosine (F-ddI), and 2'-beta-fluoro-2',3'-dideoxyadenosine (F-ddA) were examined. RESULTS Urea and mannitol exhibited symmetric permeability (PLtoB = PBtoL), whereas F-ddI and ddI showed significantly higher permeability in blood-to-lumen transport (PBtoL > PLtoB). PBtoL for F-ddA exceeded PLtoB, but the difference did not reach significance at p < 0.05. PBtoL for ddI was demonstrated to be saturable with increasing ddI concentrations, but PLtoB was independent of ddI concentration. PBtoL for ddI was shown to be dependent on sodium concentration and inhibited by probenecid. CONCLUSIONS Symmetric transport was demonstrated for urea and mannitol as expected for these passive permeability markers. F-ddI and ddI were shown to be preferentially transported from blood to lumen. The basolateral to luminal transport of ddI is saturable, inhibited by probenecid, and sodium ion dependent. These results are consistent with carrier-mediated uptake on the basolateral membrane.
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Affiliation(s)
- R Tyler DeGraw
- Division of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40506, USA
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Becher F, Landman R, Mboup S, Kane CNT, Canestri A, Liegeois F, Vray M, Prevot MH, Leleu G, Benech H. Monitoring of didanosine and stavudine intracellular trisphosphorylated anabolite concentrations in HIV-infected patients. AIDS 2004; 18:181-7. [PMID: 15075534 DOI: 10.1097/00002030-200401230-00006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE To determine the concentrations of intracellular active anabolites of stavudine (d4T) and didanosine (DDI) and their interpatient variability in HIV-infected patients and to explore relationships between plasma and intracellular forms. METHODS This pilot study included 28 antiretroviral-naive HIV-infected patients who received d4T (40/30 mg twice daily), ddI (400/250 mg daily) and efavirenz (600 mg daily). After 6 months of therapy, 7 ml of blood was collected between 0.5 and 16.2 h and 2.5 and 28.5 h after the last dose of d4T and ddI, respectively. Plasma samples were obtained for the determination of d4T and ddI concentrations. Peripheral blood mononuclear cells were prepared for measuring intracellular d4T and ddI triphosphates (d4T-TP and ddA-TP, respectively). RESULTS d4T-TP and ddA-TP concentrations were above the limit of quantification in 25 of 26 compliant patients: median d4T-TP was 31 fmol/10(6) cells (range, 0-99) and median ddA-TP was 8 fmol/10(6) cells (range, 0-23). The half-life of d4T-TP was calculated as 7 h. Interpatient variability in d4T-TP and ddA-TP concentrations was 48% and 58%, respectively. A significant relationship was observed between plasma d4T and intracellular d4T-TP. No relation was found between ddI and ddA-TP. A linear relation was observed between the intracellular concentrations of d4T-TP and ddA-TP. CONCLUSION This is the first time that data have been obtained on intracellular concentrations of d4T-TP and ddA-TP, their intracellular pharmacokinetics and interpatient variability. Other similar studies with more patients are needed to enhance knowledge of the intracellular pharmacology of the nucleoside reverse transcriptase inhibitors.
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Affiliation(s)
- François Becher
- CEA, Pharmacology and Immunology Unit, DSV/DRM, Gif-Sur-Yvette, France
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Huang Y, Zurlinden E, Lin E, Li X, Tokumoto J, Golden J, Murr A, Engstrom J, Conte J. Liquid chromatographic–tandem mass spectrometric assay for the simultaneous determination of didanosine and stavudine in human plasma, bronchoalveolar lavage fluid, alveolar cells, peripheral blood mononuclear cells, seminal plasma, cerebrospinal fluid and tonsil tissue. J Chromatogr B Analyt Technol Biomed Life Sci 2004; 799:51-61. [PMID: 14659435 DOI: 10.1016/j.jchromb.2003.10.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have developed a sensitive, high-pressure liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method for the simultaneous determination of didanosine (ddI) and stavudine (d4T) in human plasma, bronchoalveolar lavage fluid (BALF), alveolar cells (AC), peripheral blood mononuclear cells (PBMC), seminal plasma, cerebrospinal fluid (CSF), and tonsil tissue. Plasma, AC, PBMC and CSF were run with an isocratic HPLC method, while BALF supernatant, semen, and tonsil tissue utilized a gradient elution. Samples were prepared by solid phase extraction. Detection was by electrospray positive ionization with multiple reaction monitoring mode. The lower limits of quantitation for both ddI and d4T were 2.0 ng/ml in plasma; 0.5 ng/ml in CSF; 0.4 ng/ml in AC, PBMC, and BALF; 1.0 ng/ml in seminal plasma; and 0.01 ng/mg in tonsil tissue.
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Affiliation(s)
- Yong Huang
- Department of Biopharmaceutical Sciences, University of California San Francisco, 94117, San Francisco, CA, USA
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Abstract
OBJECTIVE To evaluate the pharmacokinetic interaction between tenofovir and didanosine when used in combination as a highly active antiretroviral therapy regimen. DATA SOURCES Literature retrieval was accessed through MEDLINE (1966-January 2003) using the terms tenofovir and didanosine. Abstracts from recent meetings, including the International AIDS Society, Interscience Conference on Antimicrobial Agents and Chemotherapy, and the Infectious Diseases Society of America, were reviewed for relevant abstracts and poster presentations. DATA SYNTHESIS Pharmacokinetic studies evaluating the concurrent use of tenofovir and didanosine have been performed in healthy volunteers. Tenofovir 300 mg administered concurrently with 400 mg didanosine results in a 48-64% increase in the didanosine maximum plasma concentration and AUC with no significant alterations in the tenofovir pharmacokinetic parameters. Tenofovir 300 mg and didanosine 250 mg has been compared with didanosine 400 mg alone. The results demonstrated equivalent didanosine AUCs. CONCLUSIONS When used concurrently, tenofovir significantly increases the maximum plasma concentration and the AUC of didanosine. Additional data in HIV-infected patients are needed to determine the long-term toxicities of this combination therapy. Didanosine dose reduction should be considered when these 2 agents are used concurrently.
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Affiliation(s)
- Patricia Pecora Fulco
- Virginia Commonwealth University Health System, Department of Pharmacy Services, Medical College of Virginia Hospitals and Physicians, Richmond, VA 23298-0042, USA.
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Becher F, Pruvost A, Gale J, Couerbe P, Goujard C, Boutet V, Ezan E, Grassi J, Benech H. A strategy for liquid chromatography/tandem mass spectrometric assays of intracellular drugs: application to the validation of the triphosphorylated anabolite of antiretrovirals in peripheral blood mononuclear cells. J Mass Spectrom 2003; 38:879-890. [PMID: 12938109 DOI: 10.1002/jms.500] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The pharmacokinetics of intracellular drugs have recently aroused new interest because monitoring a drug's behaviour near the site of action can enhance knowledge of its efficacy and toxicity. Liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) is particularly attractive for intracellular analytes. Very few papers deal precisely with special features encountered in intracellular drug assay or with how closely the assay matches the actual recommendations. Particular problems are encountered mainly because the analytes are located intracellularly. This mainly concerns the handling of biological media, including provision of blank samples using Ficoll gradient separation, cell counts, optimisation of cell lysis, sample extraction, plotting standard curves using either fmol/10(6) cells or fmol/ml of extract or fmol/sample, the matrix effect as a function of the number of cells, stability before and during cell separation, as well as in storage conditions using clinical samples, biological matrix replacement and interference by endogenous compounds. This paper describes a strategy for the full validation and routine use of an LC/MS/MS assay applied to the simultaneous intracellular determination of the triphosphorylated anabolites of didanosine (2',3'-dideoxyadenosine triphosphate or ddA-TP) and stavudine (2',3'-didehydro-3'-deoxythymidine triphosphate or d4T-TP), two nucleoside reverse transcriptase inhibitors of HIV, in human peripheral blood mononuclear cells (PBMCs), as a guide for further LC/MS/MS assay of intracellular drugs.
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Affiliation(s)
- François Becher
- CEA, Service de Pharmacologie et d'Immunologie, DSV/DRM, CEA/Saclay, 91191 Gif-sur-Yvette cedex, France
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Estrela RDCE, Salvadori MC, Raices RSL, Suarez-Kurtz G. Determination of didanosine in human serum by on-line solid-phase extraction coupled to high-performance liquid chromatography with electrospray ionization tandem mass spectrometric detection: application to a bioequivalence study. J Mass Spectrom 2003; 38:378-385. [PMID: 12717749 DOI: 10.1002/jms.449] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A method based on solid-phase extraction coupled to liquid chromatography with positive ion electrospray ionization and tandem mass spectrometric detection was developed for the determination of didanosine in human serum, using lamivudine as internal standard. The acquisition was performed in the multiple reaction monitoring mode, monitoring the transitions m/z 237 --> 136.7 for didanosine and m/z 230 --> 111.7 for lamivudine. The method was linear over the range studied (10-1500 ng ml(-1)), with r(2) > 0.98, and the run time was 5 min. The intra- and inter-assay precisions were < or =10% and the intra- and inter-assay accuracies were >95%. The absolute recoveries were 99.8% (10 ng ml(-1)), 98.4% (30 ng ml(-1)), 91.5% (700 ng ml(-1)) and 94.7% (1200 ng ml(-1)). The limits of detection and quantitation were 5 and 10 ng ml(-1), respectively. The method was applied to a bioequivalence study, in which 24 healthy adult volunteers (12 men) received single oral doses (200 mg) of reference and test didanosine formulations (buffered powder for oral solutions), in an open, two-way, randomized, crossover protocol. The 90% confidence interval of the individual ratios (test formulation/reference formulation) for C(max) (peak serum concentration) and AUC(0-inf) (area under the serum concentration versus time curve from time zero to infinity) were within the range 80-125%, which supports the conclusion that the two formulations are bioequivalent regarding the rate and extent of didanosine absorption.
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Affiliation(s)
- Rita de Cassia E Estrela
- Coordenação de Pesquisa, Instituto Nacional de Câncer, Praça Cruz Vermelha 23, Rio de Janeiro, Brazil
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Abstract
The influence of transport mechanisms at the blood-brain barrier (BBB) and blood-CSF barrier (choroid plexus) on the CNS distribution of anti-human immunodeficiency virus (HIV) drugs was examined using guinea-pig brain perfusion and incubated choroid plexus models. 2',3'-dideoxyinosine (ddI) passage across the BBB was demonstrated to be via non-saturable (Kd = 0.22 +/- 0.3 microL/min/g) and saturable (Km = 20.1 +/- 15.0 microm, Vmax = 6.5 +/- 2.1 pmol/min/g) processes. Cross competition studies implicated an equilibrative nucleoside transporter in this influx. The brain distribution of ddI was unchanged in the presence of additional nucleoside reverse transcriptase inhibitors (NRTIs). ddI transport from blood into choroid plexus was demonstrated to involve an organic anion transporting polypeptide 2-like transporter. The NRTIs, abacavir, 3'-azido 3'-deoxythymidine and (-)-beta-L-2',3'-dideoxy-3'-thiacytidine, competed with ddI for transporter binding sites at the choroid plexus, altering the tissue concentration of ddI. This has clinical implications as the choroid plexus is a site of HIV replication, and suboptimal CNS concentrations of anti-HIV drugs could result in neurological complications. Furthermore, this may promote the selection of drug resistant variants of HIV within the CNS, which could re-infect the periphery and lead to HIV therapy failure. This study indicates that understanding drug interactions at the transporter level could prove valuable when selecting drug combinations to treat HIV within the CNS.
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Affiliation(s)
- J E Gibbs
- Centre for Neuroscience, Guy's King's and St Thomas' School of Biomedical Science, King's College London, Guy's Hospital Campus, London Bridge, London SE1 1UL, UK
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Abstract
The aim of our study is to assess the release characteristics, in vitro permeation, and stability of an enteric-coated, bioadhesive, sustained-release formulation of didanosine (ddI). Enteric-coated tablets of ddI, containing Polyox WSRN-303 and Methocel K4M, were prepared using hydroxypropylmethylcellulose phthalate (HPMCP 5.5). The enteric-coated formulation was resistant to dissolution in 0.1 N HCl solution but dissolved within 10 min (+/-2 min) in pH 7.4 phosphate buffered saline. The release profiles were linear with square root time. Stability studies indicate that the formulations were stable at 4 degrees C, room temperature, and 40 degrees C upon storage for 6 months. Polyox WSRN-303 tablets exhibited a higher ddI permeation ratio across live intestinal tissue compared with conventional tablets. Enteric-coated, sustained-release, bioadhesive tablets deliver ddI in small doses and at the same time prevent acid-induced degradation and hence hold a potential to improve ddI's oral bioavailability.
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Affiliation(s)
- Deepali Deshmukh
- Department of Pharmacal Sciences, School of Pharmacy, Auburn University, Auburn, Alabama, USA
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35
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King JR, Nachman S, Yogev R, Hodge J, Aldrovandi G, Damle B, Smith E, Wiznia A, Acosta EP. Single-dose pharmacokinetics of enteric-coated didanosine in HIV-infected children. Antivir Ther 2002; 7:267-70. [PMID: 12553481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Didanosine remains a cornerstone nucleoside analogue for the treatment of HIV infection. A potential problem with the buffered formulations of didanosine is the likelihood of interactions with other drugs that require an acidic pH for absorption or can be chelated by cations in the buffer. An encapsulated enteric-coated (EC) bead formulation of didanosine has been approved and is routinely used as an alternative to the chewable/dispersible buffered tablet formulation. The objective of this study was to evaluate the single-dose pharmacokinetics of didanosine EC at 240 mg/m2 in 10 HIV-infected children. Didanosine EC was administered at time 0 on an empty stomach with no other concomitant medications. Blood samples were collected at pre-dose, 0.5, 1, 2, 4, 8 and 12 h post-dose. Didanosine was measured in plasma using radioimmunoassay. Ten subjects completed the intensive pharmacokinetic evaluation; data are available for eight participants. Plasma concentrations of didanosine following EC administration were analysed using non-compartmental methods. Median (range) AUCinfinity, Cmax, Tmax and CL/F for didanosine following EC administration were 2385 (1291, 3966) ng x h/ml, 854 (300, 1799) ng/ml, 3.0 (1.0, 8.1) h and 3.3 (2.7-6.4) l/h/kg, respectively. Results from this study indicate that the didanosine Cmax is decreased and Tmax is prolonged, but total exposure of didanosine in plasma following didanosine EC administration appears similar to previous data collected in HIV-infected children following buffered didanosine administration.
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Affiliation(s)
- Jennifer R King
- The University of Alabama at Birmingham, Birmingham, Ala., USA
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Affiliation(s)
- Johan R Boelaert
- Department of Internal Medicine and Infectious Diseases, Algemeen Ziekenhuis St Jan, Brugge, Belgium
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37
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Yao SY, Ng AM, Loewen SK, Cass CE, Baldwin SA, Young JD. An ancient prevertebrate Na+-nucleoside cotransporter (hfCNT) from the Pacific hagfish (Eptatretus stouti). Am J Physiol Cell Physiol 2002; 283:C155-68. [PMID: 12055084 DOI: 10.1152/ajpcell.00587.2001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The human concentrative (Na+-linked) plasma membrane transport proteins hCNT1, hCNT2, and hCNT3 are pyrimidine nucleoside-selective (system cit), purine nucleoside-selective (system cif), or broadly selective for both pyrimidine and purine nucleosides (system cib), respectively. All have orthologs in other mammalian species and belong to a gene family (CNT) that has members in insects, nematodes, pathogenic yeast, and bacteria. Here, we report the cDNA cloning and functional characterization of a CNT family member from an ancient marine prevertebrate, the Pacific hagfish (Eptatretus stouti). This Na+-nucleoside symporter, designated hfCNT, is the first transport protein to be characterized in detail in hagfish and is a 683-amino acid residue protein with 13 predicted transmembrane helical segments (TMs). hfCNT was 52, 50, and 57% identical in sequence to hCNT1, hCNT2, and hCNT3, respectively. Similarity to hCNT3 was particularly marked in the TM 4-13 region. When produced in Xenopus oocytes, hfCNT exhibited the transport properties of system cib, with uridine, thymidine, and inosine apparent K(m) values of 10-45 microM. The antiviral nucleoside drugs 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, and 2',3'-dideoxyinosine were also transported. Simultaneous measurement of uridine-evoked currents and radiolabeled uridine uptake under voltage-clamp conditions gave a Na+-to-uridine coupling ratio of 2:1 (cf. 2:1 for hCNT3 and 1:1 for hCNT1/2). The apparent K50 value for Na+ activation was >100 mM. A 50:50 chimera between hfCNT and hCNT1 (TMs 7-13 of hfCNT replaced by those of hCNT1) exhibited hCNT1-like cation interactions, establishing that the structural determinants of cation stoichiometry and binding affinity were located within the carboxy-terminal half of the protein. The high degree of sequence similarity between hfCNT and hCNT3 may indicate functional constraints on the primary structure of the transporter and suggests that cib-type CNTs fulfill important physiological functions.
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Affiliation(s)
- Sylvia Y Yao
- Department of Physiology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada T6G 2H7
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38
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Sánchez-Lafuente C, Furlanetto S, Fernández-Arévalo M, Alvarez-Fuentes J, Rabasco AM, Faucci MT, Pinzauti S, Mura P. Didanosine extended-release matrix tablets: optimization of formulation variables using statistical experimental design. Int J Pharm 2002; 237:107-18. [PMID: 11955809 DOI: 10.1016/s0378-5173(02)00028-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Statistical experimental design was applied to evaluate the influence of some process and formulation variables and possible interactions among such variables, on didanosine release from directly-compressed matrix tablets based on blends of two insoluble polymers, Eudragit RS-PM and Ethocel 100, with the final goal of drug release behavior optimization. The considered responses were the percent of drug released at three determined times, the dissolution efficiency at 6 h and the time to dissolve 10% of drug. Four independent variables were considered: tablet compression force, ratio between the polymers and their particle size, and drug content. The preliminary screening step, carried out by means of a 12-run asymmetric screening matrix according to a D-optimal design strategy, allowed evaluation of the effects of different levels of each variable. The drug content and the polymers ratio had the most important effect on drug release, which, moreover, was favored by greater polymers particle size; on the contrary the compression force did not have a significant effect. The Doehlert design was then applied for a response-surface study, in order to study in depth the effects of the most important variables. The desirability function was used to simultaneously optimize the five considered responses, each having a different target. This procedure allowed selection, in the studied experimental domain, of the best formulation conditions to optimize drug release rate. The experimental values obtained from the optimized formulation highly agreed with the predicted values. The results demonstrated the reliability of the model in the preparation of extended-release matrix tablets with predictable drug release profiles.
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Affiliation(s)
- Carla Sánchez-Lafuente
- Departamento de Farmacia y Tecnología Farmacéutica, c/Prof. García González s/n, 41012 Sevilla, Spain
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39
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Damle B, Hess H, Kaul S, Knupp C. Absence of clinically relevant drug interactions following simultaneous administration of didanosine-encapsulated, enteric-coated bead formulation with either itraconazole or fluconazole. Biopharm Drug Dispos 2002; 23:59-66. [PMID: 11932960 DOI: 10.1002/bdd.296] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This open-label, two-way crossover study was undertaken to determine whether the enteric formulation of didanosine influences the pharmacokinetics of itraconazole or fluconazole, two agents frequently used to treat fungal infections that occur with HIV infection, and whose bioavailability may be influenced by changes in gastric pH. Healthy subjects were randomized to Treatment A (200-mg itraconazole or 200-mg fluconazole) or Treatment B (same dose of itraconazole or fluconazole with 400 mg of didanosine as an encapsulated, enteric-coated bead formulation). In the itraconazole study, a lack of interaction was concluded if the 90% confidence interval (CI) of the ratio of the geometric means of log-transformed C(max) and AUC(0-T) values of itraconazole and hydroxyitraconazole, the active metabolite of itraconazole, were contained entirely between 0.75 and 1.33. In the fluconazole study, the equivalence interval for C(max) and AUC(0-T) was 0.80-1.25. The data showed that for itraconazole the point estimate and 90% CI of the ratios of C(max) and AUC(0-T) values were 0.98 (0.79, 1.20) and 0.88 (0.71, 1.09), respectively; for hydroxyitraconazole the respective values were 0.91 (0.76, 1.08) and 0.85 (0.68, 1.06). In the fluconazole study, the point estimate and 90% CI of the ratios of C(max) and AUC(0-T) values were 0.98 (0.93, 1.03) and 1.01 (0.99, 1.03), respectively. The T(max) for itraconazole, hydroxyitraconazole, and fluconazole were similar between treatments. Both studies indicated a lack of clinically significant interactions of the didanosine formulation with itraconazole or fluconazole. These results showed that the encapsulated, enteric-coated bead formulation of didanosine can be concomitantly administered with drugs, such as the azole antifungal agents, whose bioavailability may be influenced by interaction with antacids.
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Affiliation(s)
- B Damle
- Clinical Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543, USA.
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Johnson MD, Chen J, Anderson BD. Investigation of the mechanism of enhancement of central nervous system delivery of 2'-beta-fluoro-2',3'-dideoxyinosine via a blood-brain barrier adenosine deaminase-activated prodrug. Drug Metab Dispos 2002; 30:191-8. [PMID: 11792690 DOI: 10.1124/dmd.30.2.191] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Enhanced central nervous system (CNS) delivery of certain poorly penetrating 2',3'-dideoxynucleosides has been achieved by designing prodrugs that are substrates for enzymes, such as adenosine deaminase (ADA), that are present at high activities in brain tissue. In this study, the potential role of adenosine deaminase localized within the endothelial cells of the blood-brain barrier (BBB) in providing enhanced intracellular and CNS delivery of an ADA-activated prodrug is assessed in vitro using cell culture models of the BBB. The kinetics of uptake and bioconversion of 2'-beta-fluoro-2',3'-dideoxyadenosine (F-ddA), a model ADA-activated prodrug of 2'-beta-fluoro-2',3'-dideoxyinosine, were determined in primary cultured bovine brain microvascular endothelial cells. Model-based simulations of CNS availability derived from in vitro estimates of parameters for simple passive diffusion and ADA-catalyzed deamination suggest that ADA that is localized within the BBB plays an important role in the conversion of F-ddA to 2'-beta-fluoro-2',3'-dideoxyinosine during its passage across the BBB. Consistent with in vivo observations, these simulations demonstrate that elevated levels of certain enzymes, such as ADA, in the brain microvascular endothelial cells of the BBB may be exploited in the design of brain-targeted prodrugs or drug-carrier conjugates, which brain tissue selectively converts.
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Affiliation(s)
- Mark D Johnson
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah, USA
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Rongkavilit C, Thaithumyanon P, Chuenyam T, Damle BD, Limpongsanurak S, Boonrod C, Srigritsanapol A, Hassink EA, Hoetelmans RM, Cooper DA, Lange JM, Ruxrungtham K, Phanuphak P. Pharmacokinetics of stavudine and didanosine coadministered with nelfinavir in human immunodeficiency virus-exposed neonates. Antimicrob Agents Chemother 2001; 45:3585-90. [PMID: 11709344 PMCID: PMC90873 DOI: 10.1128/aac.45.12.3585-3590.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We evaluated the pharmacokinetics of stavudine (d4T) and didanosine (ddI) in neonates. Eight neonates born to human immunodeficiency virus-infected mothers were enrolled to receive 1 mg of d4T per kg of body weight twice daily and 100 mg of ddI per m(2) once daily in combination with nelfinavir for 4 weeks after birth. Pharmacokinetic evaluations were performed at 14 and 28 days of age. For d4T, on days 14 and 28, the median areas under the concentration-time curves from 0 to 12 h (AUC(0-12)s) were 1,866 and 1,603, ng x h/ml, respectively, and the median peak concentrations (C(max)s) were 463 and 507 ng/ml, respectively. For ddI, on days 14 and 28, the median AUC(0-10)s were 1,573 and 1,562 h x ng/ml, respectively, and the median C(max)s were 627 and 687 ng/ml, respectively. Systemic levels of exposure to d4T were comparable to those seen in children, suggesting that the pediatric dose of 1 mg/kg twice daily is appropriate for neonates at 2 to 4 weeks of age. Levels of exposure to ddI were modestly higher than those seen in children. Whether this observation warrants a reduction of the ddI dose in neonates is unclear.
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Affiliation(s)
- C Rongkavilit
- HIV Netherlands-Australia-Thailand Research Collaboration, Thai Red Cross AIDS Research Centre, Bangkok, Thailand.
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Mole L, Schmidgall D, Holodniy M. A pilot trial of indinavir, ritonavir, didanosine, and lamivudine in a once-daily four-drug regimen for HIV infection. J Acquir Immune Defic Syndr 2001; 27:260-5. [PMID: 11464145 DOI: 10.1097/00126334-200107010-00007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the tolerance, pharmacokinetics, and virologic and immunologic outcomes of once-daily indinavir, ritonavir, didanosine, and lamivudine in HIV-seropositive individuals. DESIGN Open-label 24-week pilot study. PATIENTS Ten HIV-seropositive subjects who were either antiretroviral-naive or minimally experienced with short-term single-or dual-nucleoside therapy provided informed consent and were enrolled. All subjects received didanosine (400 mg) 30 to 60 minutes before a meal followed by indinavir (1200 mg), ritonavir (400 mg), and lamivudine (300 mg) concurrent with the aforementioned meal. METHODS Safety laboratory tests, including a complete blood cell count and amylase, lipase, liver transaminase, and nonfasting lipid monitoring as well as plasma HIV viral load and CD4+ lymphocyte count, were carried out at monthly intervals. Genotyping was performed at baseline. Pharmacokinetic studies for indinavir and ritonavir were performed at week 8. RESULTS Nine of 10 subjects completed 24 weeks of therapy. No subject demonstrated primary protease inhibitor mutations at baseline. Toxicities experienced by subjects were typically mild and consistent with those commonly reported for each of the medications, including two cases of hematuria. By week 24, median nonfasting cholesterol and triglyceride levels increased by 49% and 108%, respectively. Median baseline plasma HIV viral load and CD4+ lymphocyte count were 29,292 (4.47 log10) copies/ml and 224 cells/mm3, respectively. Eight of 10 subjects had a plasma HIV viral load of <50 copies/ml by week 12. The 2 subjects with a detectable HIV viral load reached <50 copies/ml by week 28. Median CD4+ lymphocyte counts increased by 193 cells/mm3 at week 24. Indinavir and ritonavir plasma concentrations remained above respective inhibitory and effective concentrations (IC95 and EC50) (uncorrected for protein binding) throughout the 24-hour dosing interval for 6 of 10 and 8 of 10 subjects, respectively. CONCLUSIONS Our pilot study demonstrates excellent virologic suppression despite low minimum protease inhibitor concentrations during a dosing interval in some patients and is supportive of further study.
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Affiliation(s)
- L Mole
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304, USA.
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Sanne I, Smego RA, Mendelow BV. Systematic review of combination antiretroviral therapy with didanosine plus hydroxyurea: a partial solution to Africa's HIV/AIDS problem? Int J Infect Dis 2001; 5:43-8. [PMID: 11285159 DOI: 10.1016/s1201-9712(01)90048-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Effective antiretroviral therapy remains beyond the reach of most human immunodeficiency virus (HIV)-infected persons living in the third world because of its tremendous cost. The cancer drug, hydroxyurea, inhibits HIV-1 replication in vitro and, when combined with didanosine (ddI), results in significant antiretroviral synergy. In vivo, hydroxyurea specifically targets quiescent lymphocytes and macrophages, important cellular reservoirs for HIV-1, and the combination of ddI plus hydroxyurea effectively reduces plasma HIV-1 RNA levels. Combination ddI-hydroxyurea costs about one-eighth as much as currently recommended triple drug combinations, and several countries in Africa are exploring the feasibility of widescale use of ddI-hydroxyurea for their HIV-infected populations. Intrigued by its potential relevance for Africa, the authors reviewed the literature on the in vitro and clinical efficacy of ddI plus hydroxyurea against HIV. The combination of ddI plus hydroxyurea is an effective and potentially more affordable regimen for HIV-infected persons living in poorer countries.
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Affiliation(s)
- I Sanne
- Department of Infectious Diseases and Clinical Microbiology, University of Witwaterswand, Johannesburg, Republic of South Africa
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45
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Abstract
Two studies were conducted in HIV-infected subjects to assess the potential for azithromycin to interact with zidovudine and dideoxyinosine. Both studies used 12 subjects. The zidovudine study dosed subjects with 1200 mg/day of azithromycin (n = 7) (later changed to 600 mg/day [n = 5]) for Days 8 to 21 of a 21-day course of 100 mg, five times/day of zidovudine. Subjects treated with 200 mg of dideoxyinosine twice daily for 21 days received 1200 mg of azithromycin or an equivalent amount of placebo/day for Days 8 to 21. Antiretroviral plasma and urine sampling were conducted on Days 1, 7, and 21 for zidovudine and on Days 7 and 21 for dideoxyinosine. Peripheral mononuclear cells were also collected for quantitation of phosphorylated zidovudine. Azithromycin had no significant impact on the Cmax and AUC of zidovudine, although it significantly decreased the zidovudine tmax by 44% and increased the intracellular exposure to phosphorylated zidovudine by 110%. Azithromycin had no significant effect on dideoxyinosine pharmacokinetics. Based on the results of these studies, it is concluded that azithromycin may be safely coadministered with both zidovudine and dideoxyinosine.
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Affiliation(s)
- G Amsden
- Clinical Pharmacology Research Center, Bassett Healthcare, One Atwell Road, Cooperstown, NY 13326, USA
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Abstract
Factors affecting patient adherence to therapy, such as frequent daily dosing and complex dosing schedules, are widely understood to be key obstacles to the durability of effective anti-HIV therapy. Didanosine, a nucleoside analogue reverse transcriptase inhibitor (NRTI) that is a core component of combination antiretroviral regimens, is currently indicated for twice-daily dosing. However, the active metabolite of didanosine (2',3'-dideoxyadenosine-5'-triphosphate) has a long intracellular half-life that supports the use of didanosine in a more patient-friendly, once-daily dosing schedule. Clinical studies in which didanosine was administered either once or twice daily, as monotherapy or in combination with another NRTI, have demonstrated the equivalence of both dosing schedules, with respect to safety and tolerability, virologic and immunologic endpoints, and short-term clinical effects (e.g., weight gain). Preliminary results from recent studies support the clinical efficacy and utility of once-daily didanosine in combination antiretroviral regimens that provide maximal drug exposure, while allowing for once- or twice-daily dosing of all component drugs.
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van Heeswijk RP, Veldkamp AI, Mulder JW, Meenhorst PL, Wit FW, Reiss P, Lange JM, Kwakkelstein MO, Beijnen JH, Hoetelmans RM. Nevirapine plus didanosine: once or twice daily combination? J Acquir Immune Defic Syndr 2000; 25:93-5. [PMID: 11064511 DOI: 10.1097/00042560-200009010-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abreu T, Plaisance K, Rexroad V, Nogueira S, Oliveira RH, Evangelista LA, Rangel R, Silva IS, Knupp C, Lambert JS. Bioavailability of once- and twice-daily regimens of didanosine in human immunodeficiency virus-infected children. Antimicrob Agents Chemother 2000; 44:1375-6. [PMID: 10770783 PMCID: PMC89876 DOI: 10.1128/aac.44.5.1375-1376.2000] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bioavailability of didanosine at 180 mg/m(2) once daily was compared to that at 90 mg/m(2) twice daily in 24 children with advanced human immunodeficiency virus infection. Children were studied at steady state using optimal sampling and prior pharmacokinetic parameter estimates. Relative bioavailability was 0. 95 +/- 0.49, supporting the potential clinical adequacy of once-daily dosing.
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Affiliation(s)
- T Abreu
- Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Fletcher CV, Brundage RC, Remmel RP, Page LM, Weller D, Calles NR, Simon C, Kline MW. Pharmacologic characteristics of indinavir, didanosine, and stavudine in human immunodeficiency virus-infected children receiving combination therapy. Antimicrob Agents Chemother 2000; 44:1029-34. [PMID: 10722507 PMCID: PMC89808 DOI: 10.1128/aac.44.4.1029-1034.2000] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The use of human immunodeficiency virus (HIV) protease inhibitors in children has lagged behind that in adults because of the lack of suitable pediatric formulations and information on safe and effective dosing regimens. This study was designed to obtain pharmacokinetic information on indinavir, administered to HIV-infected children also receiving therapy with two nucleoside agents, and to explore relationships between pharmacokinetic parameters and anti-HIV effect. Indinavir was initiated at a dose of 500 mg/m(2) every 8 h. Plasma indinavir concentrations were measured every 4 weeks; the dose or dosing interval was adjusted to maintain trough concentrations of > or =0.1 mg/liter. All children were evaluated clinically at baseline and every 4 weeks. Plasma HIV RNA was quantitated at baseline and at weeks 4, 12, and 24. Eighteen children participated in this study. The average daily dose of indinavir was 2,043 mg/m(2); nine children received indinavir at 6-h intervals. Pharmacokinetic characteristics of indinavir (mean +/- standard deviation) were the following: oral clearance, 1.4 +/- 0.5 liters/h/kg; half-life, 1.1 +/- 0.43 h; and trough concentration, 0. 29 +/- 0.32 mg/liter. In nine children that completed 24 weeks of therapy, the baseline-to-week-24 change in HIV RNA level was related to indinavir trough concentration and didanosine area under the curve. This study illustrates the ability to obtain pharmacokinetic information from children during routine clinic visits and to use this information to provide a safeguard against underdosing. The incorporation of pharmacologic knowledge with virologic, immunologic, and behavioral considerations should result in improved clinical outcomes for children infected with HIV.
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Affiliation(s)
- C V Fletcher
- University of Minnesota Health Sciences Center, Minneapolis, MN 55455, USA. fletc0012tc.umn.edu
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Youle M. Didanosine once daily: an overview. Antivir Ther 2000; 3 Suppl 4:35-7. [PMID: 10723507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The current focus on simplifying treatment regimens for patients with human immunodeficiency virus (HIV) infection has contributed to the interest in once-daily therapy. The triphosphate of didanosine (2',3'-dideoxyinosine or DDI) has a long intracellular half-life, which supports the use of didanosine in a once-daily dosing schedule. Early clinical studies found that changes in surrogate markers were similar whether didanosine was dosed once or twice daily, while toxic effects occurred less frequently with once-daily dosing. Didanosine once-a-day used in combination with other drugs has also been studied, and results of some of these trials are summarized in this paper.
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Affiliation(s)
- M Youle
- Royal Free Centre for HIV Medicine, Royal Free Hospital, Hampstead, London, UK.
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