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Houff SA, Major EO. Neuropharmacology of HIV/AIDS. HANDBOOK OF CLINICAL NEUROLOGY 2007; 85:319-364. [PMID: 18808990 DOI: 10.1016/s0072-9752(07)85019-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Vyas TK, Shah L, Amiji MM. Nanoparticulate drug carriers for delivery of HIV/AIDS therapy to viral reservoir sites. Expert Opin Drug Deliv 2006; 3:613-28. [PMID: 16948557 DOI: 10.1517/17425247.3.5.613] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Providing the optimum treatment of AIDS is a major challenge in the 21st Century. HIV is localised and harboured in certain inaccessible compartments of the body, such as the CNS, the cerebrospinal fluid, the lymphatic system and in the macrophages, where it cannot be reached by the majority of therapeutic agents in adequate concentrations or in which the therapeutic agents cannot reside for the necessary duration. Progression in HIV/AIDS treatment suggests that available therapy can lower the systemic viral load below the detection limit. However, on discontinuation of treatment, there is relapse of the infection from the reservoir sites and a potential for resistance development. This review discusses the aetiology and pathology of HIV, with emphasis on the viral reservoirs, current therapy of AIDS, and the opportunity for nanotechnology-based drug delivery systems to facilitate complete eradication of viral load from the reservoir sites. Literature-cited examples of drug delivery systems that are under investigation for the treatment of AIDS are discussed. The article also focuses on the future outlook and strategies for investigational drug formulations that use nanotherapeutic strategy for HIV/AIDS.
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Affiliation(s)
- Tushar K Vyas
- Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, 110 Mugar Life Sciences Building, Boston, MA 02115, USA
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McGee B, Smith N, Aweeka F. HIV pharmacology: barriers to the eradication of HIV from the CNS. HIV CLINICAL TRIALS 2006; 7:142-53. [PMID: 16880170 DOI: 10.1310/aw2h-tp5c-np43-k6by] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Total eradication of HIV-1 is not yet achievable, in part because reservoirs of latent HIV-1 can develop within lymphoid tissue, the testes, and the central nervous system (CNS). The presence of HIV-1 in the CNS is clinically significant because of its association with the development of HIV dementia, which occurs in up to one fifth of untreated patients. This review summarizes current theory regarding HIV-1 infection within the CNS, describes physiologic and pharmacologic factors limiting CNS penetration of antiretroviral drugs used to treat HIV-1 infection, and reviews current treatment of CNS HIV-1 infection and HIV encephalopathy.
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Affiliation(s)
- Bryan McGee
- Drug Research Unit, University of California-San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143, USA
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Hayashi K, Pu H, Andras IE, Eum SY, Yamauchi A, Hennig B, Toborek M. HIV-TAT protein upregulates expression of multidrug resistance protein 1 in the blood-brain barrier. J Cereb Blood Flow Metab 2006; 26:1052-65. [PMID: 16395283 DOI: 10.1038/sj.jcbfm.9600254] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Central nervous system (CNS) complications of human immunodeficiency virus (HIV) infection remain a serious health risk in HIV/acquired immunodeficiency syndrome despite significant advances in highly active antiretroviral therapy (HAART). Specific drugs used for HAART are substrates for the efflux transport systems, such as the multidrug resistance-associated proteins (MRPs), which are present on brain microvascular endothelial cells (BMEC) and astrocytes, that is, the main cell types that form the blood-brain barrier (BBB). Thus, drugs employed in HAART are actively removed from the CNS and do not efficiently inhibit HIV replication in the brain. To study the potential mechanisms of this process, the aim of the present research was to address the hypothesis that HIV Tat protein can contribute to upregulation of MRP expression at the BBB level. Tat is a protein produced and released by HIV-infected cells, which may play an important role in brain vascular pathology in the course of HIV infection. Among the family of MRPs, exposure to Tat specifically induced MRP1 messenger ribonucleic acid and protein expression both in BMEC and astrocytes. These alterations were accompanied by enhanced MRP1-mediated efflux functions. Furthermore, activation of the mitogen-activated protein kinase signaling cascade was identified as the mechanism involved in Tat-mediated overexpression of MRP1. These results indicate that Tat exposure can lead to alterations of the BBB functions and decrease HAART efficacy in the CNS through overexpression of drug efflux transporters.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/biosynthesis
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- Acquired Immunodeficiency Syndrome/complications
- Acquired Immunodeficiency Syndrome/drug therapy
- Acquired Immunodeficiency Syndrome/genetics
- Acquired Immunodeficiency Syndrome/metabolism
- Animals
- Antiretroviral Therapy, Highly Active
- Astrocytes/cytology
- Astrocytes/metabolism
- Astrocytes/virology
- Blood-Brain Barrier/metabolism
- Blood-Brain Barrier/virology
- Cells, Cultured
- Central Nervous System Viral Diseases/drug therapy
- Central Nervous System Viral Diseases/etiology
- Central Nervous System Viral Diseases/genetics
- Central Nervous System Viral Diseases/metabolism
- Endothelial Cells/metabolism
- Endothelial Cells/virology
- Gene Products, tat/genetics
- Gene Products, tat/metabolism
- HIV-1/genetics
- HIV-1/metabolism
- Humans
- Male
- Mice
- Protein Biosynthesis/drug effects
- Protein Biosynthesis/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Up-Regulation/drug effects
- Up-Regulation/genetics
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Kentaro Hayashi
- Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA
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55
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Pettersen JA, Jones G, Worthington C, Krentz HB, Keppler OT, Hoke A, Gill MJ, Power C. Sensory neuropathy in human immunodeficiency virus/acquired immunodeficiency syndrome patients: protease inhibitor-mediated neurotoxicity. Ann Neurol 2006; 59:816-24. [PMID: 16634006 DOI: 10.1002/ana.20816] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Human immunodeficiency virus-associated sensory neuropathy (HIV-SN) is a common and disabling disorder, often associated with antiretroviral therapy (ART) use. We investigated the clinical features and associated pathogenic determinants of HIV-SN in a neurological cohort of HIV-infected patients, together with a novel model of HIV-SN. METHODS HIV-infected patients with neurological disease were investigated in terms of clinical and laboratory aspects together with ART exposure focusing on symptomatic HIV-SN. Rat-derived dorsal root ganglion (DRG) cultures, transgenic for human CD4 and CCR5 treated with ARTs or HIV infected, or both, were studied with respect to quantitative neuronal injury. RESULTS Among 221 patients assessed from 1998 to 2004, 120 had no sensory neuropathy, whereas 101 displayed HIV-SN, including 64 with distal sensory neuropathy and 37 with antiretroviral toxic neuropathy. HIV-SN patients exhibited significantly greater mean age, peak plasma viral loads, and exposure to neurotoxic dideoxynucleosides and protease inhibitors, including indinavir, saquinavir, or ritonavir. HIV-infected DRG cultures exposed to indinavir or didanosine showed significant neuronal atrophy, neurite retraction, and process loss, compared with controls. Indinavir was selectively cytotoxic to DRG macrophages compared with other ARTs. INTERPRETATION Protease inhibitor exposure is an unrecognized risk factor for the development of HIV-SN, which may potentiate neuronal damage in HIV-infected DRGs, possibly through the loss of macrophage-derived trophic factors.
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Martin TM, Morse GD, Kurpewski J, Difrancesco R, Caliendo AM, Flanigan TP, Tashima KT. Plasma and cerebrospinal pharmacokinetics and pharmacodynamics in subjects taking lopinavir/ritonavir. AIDS 2006; 20:1085-7. [PMID: 16603871 DOI: 10.1097/01.aids.0000222091.59658.6d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Giancola ML, Lorenzini P, Balestra P, Larussa D, Baldini F, Corpolongo A, Narciso P, Bellagamba R, Tozzi V, Antinori A. Neuroactive antiretroviral drugs do not influence neurocognitive performance in less advanced HIV-infected patients responding to highly active antiretroviral therapy. J Acquir Immune Defic Syndr 2006; 41:332-7. [PMID: 16540934 DOI: 10.1097/01.qai.0000197077.64021.07] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To analyze the effect of antiretroviral therapy, including drugs that have good penetration in cerebrospinal fluid (CSF), on neuropsychologic performance. METHODS One hundred sixty-five HIV-1-infected patients exposed to a stable highly active antiretroviral therapy (HAART) regimen were studied. Neuropsychologic examinations were performed for all patients. RESULTS A total of 50.3% of patients were impaired. In multivariate analysis, older age (for 10-year increase, odds ratio [OR] = 4.8, 95% confidence interval [CI]: 2.2 to 10.4; P< 0.0001) and higher plasma HIV-1 RNA levels (OR = 1.90, 95% CI: 1.1 to 3.2; P = 0.021) at testing were independently associated with an increased probability of impaired neurocognitive performance, whereas higher educational level was a protective factor (OR = 0.76, 95% CI: 0.65 to 0.90; P=0.001). A significant linear correlation was observed between the neuropsychologic z score for 8 tests (NPZ8) score, a quantitative parameter of neurocognitive impairment, and CD4 cell count at neuropsychologic testing (R = 0.273, P = 0.001) and between the NPZ8 score and the patient's age (R = 0.288, P = 0.001). CONCLUSIONS Our study indicates that the use of stable HAART, including multiple drugs that have good CSF penetration, was not associated with neuropsychologic performance. To prevent independent replication of HIV in CSF with better control of a relevant reservoir of HIV is one of the crucial aims of therapeutic strategy.
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Affiliation(s)
- Maria Letizia Giancola
- Clinical Department, Lazzaro Spallanzani National Institute for Infectious Diseases, Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Via Portuense 292, 00149 Rome, Italy.
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Raines C, Radcliffe O, Treisman GJ. Neurologic and psychiatric complications of antiretroviral agents. J Assoc Nurses AIDS Care 2006; 16:35-48. [PMID: 16433108 DOI: 10.1016/j.jana.2005.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Advances in highly active antiretroviral therapy (HAART) aim to improve the efficacy of HIV drugs as well as the quality of life in HIV-infected patients. Neurologic and psychologic disturbances that occur because of HIV disease and therapy are of great concern, and because they can overlap and are often difficult to distinguish, their pathogenesis is not clearly understood. Furthermore, these complications can lead to decreased adherence, thereby interfering with treatment outcomes. Antiretrovirals, including nonnucleoside reverse transcriptase inhibitors, can penetrate the central nervous system (CNS) and suppress viral replication, but they can also exacerbate CNS side effects and neuropsychiatric symptoms. When deciding which HAART drug combination is most appropriate for a patient, clinicians must consider the individual's risk of CNS complications together with the efficacy of the specific HAART regimen.
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Affiliation(s)
- Charles Raines
- Division of Infectious Disease, Department of Medicine, Johns Hopkins University School of Medicine, USA
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59
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Christo PP, Greco DB, Aleixo AW, Livramento JA. HIV-1 RNA levels in cerebrospinal fluid and plasma and their correlation with opportunistic neurological diseases in a Brazilian AIDS reference hospital. ARQUIVOS DE NEURO-PSIQUIATRIA 2005; 63:907-13. [PMID: 16400403 DOI: 10.1590/s0004-282x2005000600001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND: Plasma HIV RNA levels reflect systemic viral replication but in CNS it may occur relatively independent of systemic infection, yet clinical application of CSF HIV-1 RNA levels is less clear. OBJECTIVE: to compare CSF and plasma HIV-1 RNA levels of patients with different opportunistic neurological diseases to those without neurological disease, as well as to correlate these levels with the outcome of the disease and use of HAART. METHOD: 97 patients who had lumbar puncture for routine work up of suspected neurological diseases, were divided in 2 groups: without neurological disease (23) and with neurological disease (74). NASBA was used for plasma and CSF HIV RNA. RESULTS: Median CSF viral load was higher in toxoplasmic encephalitis, cryptococcal meningitis, HIV dementia and neurological diseases without a defined etiology when compared to patients without neurological disease. There was no difference between plasma viral load in patients with and without neurological diseases. Median viral load was higher in plasma and CSF among patients who died when compared to those successfully treated. CSF and plasma viral load were lower in patients with opportunistic diseases on HAART than without HAART. CONCLUSION: CSF viral load was higher in patients with any neurological disease, but this difference was not present in plasma viral load, suggesting that neurological disease influences more the CSF than plasma compartments. Notwithstanding different neurological diseases were not possible to be diferentiated by the levels of CSF HIV-1.
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Affiliation(s)
- Paulo P Christo
- Eduardo de Menezes Hospital, FHEMIG, Belo Horizonte, MG, Brazil.
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Evers S, Rahmann A, Schwaag S, Frese A, Reichelt D, Husstedt IW. Prevention of AIDS dementia by HAART does not depend on cerebrospinal fluid drug penetrance. AIDS Res Hum Retroviruses 2004; 20:483-91. [PMID: 15186522 DOI: 10.1089/088922204323087723] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The impact of the cerebrospinal fluid (CSF) penetrance properties of different highly active antiretroviral therapy (HAART) regimes on cognitive processing in AIDS dementia is still undetermined. We therefore designed a retrospective cross-sectional and prospective longitudinal analysis of event-related potentials in HIV-infected patients with different combinations of HAART or without antiretroviral treatment. A total of 353 consecutive patients without secondary CNS manifestation of HIV infection were enrolled in the cross-sectional study and 135 consecutive patients without secondary CNS manifestations of HIV infection were enrolled in the longitudinal study. HAART in different combinations (n = 306) or no antiretroviral treatment (n = 47) was given for at least 6 months in the retrospective cross-sectional study. HAART in different combinations (n = 110) or no antiretroviral treatment (n = 25) was given for 1 year in the prospective longitudinal study. We evaluated the latency and amplitude of the P3 component of visually evoked event-related potentials and mean choice reaction time as measures of cognitive processing. Patients receiving HAART had decreased P3 latencies as compared to those patients not receiving HAART but P3 latency and P3 amplitude were not correlated with the amount of CSF penetrance of the different HAART combinations in either statistical analysis. However, mean choice reaction time was significantly correlated with the amount of CSF penetrance. In HIV-infected patients, the CSF penetrance properties of HAART do not have any significant influence on cognitive processing as measured by event-related potentials.
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Affiliation(s)
- Stefan Evers
- Department of Neurology, University of Münster, 48129 Münster, Germany.
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Letendre SL, McCutchan JA, Childers ME, Woods SP, Lazzaretto D, Heaton RK, Grant I, Ellis RJ. Enhancing antiretroviral therapy for human immunodeficiency virus cognitive disorders. Ann Neurol 2004; 56:416-23. [PMID: 15349869 DOI: 10.1002/ana.20198] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The benefits of combination antiretroviral therapy (ART) for HIV cognitive disorders vary substantially between individuals. This study evaluated whether cerebrospinal fluid (CSF) drug penetration and CSF virological suppression influence the extent of neuropsychological (NP) improvement during ART. Overall performance on a battery of NP tests administered at baseline and follow-up (median 15 weeks) was computed by using the global deficit score (GDS) methods in 31 cognitively impaired, HIV-infected individuals who began new ART regimens. Virological suppression (attaining undetectable viral load by RT-PCR at follow-up) was assessed separately for plasma and CSF. Subjects on regimens containing greater numbers of CSF-penetrating drugs showed significantly greater reduction in CSF viral load. Subjects attaining CSF virological suppression demonstrated greater GDS improvement than those who did not (median GDS change, 0.62 vs 0.23; p = 0.01). A similar trend for plasma did not reach statistical significance (p = 0.053). NP improvement was greater in ART-naive versus treatment-experienced subjects. In a multivariate model (overall p = 0.0008), significant, independent predictors of GDS reduction were CSF HIV RNA suppression, baseline antiretroviral history, and their interaction. Including CSF-penetrating drugs in the ART regimen and monitoring CSF viral load may be indicated for individuals with HIV-associated cognitive impairment.
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Affiliation(s)
- Scott L Letendre
- HIV Neurobehavioral Research Center, University of California at San Diego, San Diego, CA 92103, USA
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Fliers E, Sauerwein HP, Romijn JA, Reiss P, van der Valk M, Kalsbeek A, Kreier F, Buijs RM. HIV-associated adipose redistribution syndrome as a selective autonomic neuropathy. Lancet 2003; 362:1758-60. [PMID: 14643128 DOI: 10.1016/s0140-6736(03)14858-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abnormal body-fat distribution in HIV-1-associated adipose redistribution syndrome (HARS) remains unexplained at present. White adipose tissue is controlled by humoral factors and by neural regulation. Sympathetic innervation stimulates lipolysis, whereas parasympathetic innervation has an anabolic influence on white adipose tissue. Results of neuroanatomical studies showed a clear somatotopy with respect to autonomic control of white adipose tissue by both the sympathetic and parasympathetic branch, with separate sets of autonomic neurons innervating either the subcutaneous or the visceral fat compartment. Thus, the CNS is likely to be a key player in regulation of body-fat distribution. We propose that HARS is mediated by effects of antiretroviral treatment on the CNS and could indicate a change in autonomic balance resulting in redistribution of adipose tissue.
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Affiliation(s)
- E Fliers
- Department of Endocrinology and Metabolism,Academic Medical Centre of the University of Amsterdam, 1105 AZ, Amsterdam, Netherlands.
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Fliers E, Kreier F, Voshol PJ, Havekes LM, Sauerwein HP, Kalsbeek A, Buijs RM, Romijn JA. White adipose tissue: getting nervous. J Neuroendocrinol 2003; 15:1005-10. [PMID: 14622429 DOI: 10.1046/j.1365-2826.2003.01096.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuroendocrine research has altered the traditional perspective of white adipose tissue (WAT) as a passive store of triglycerides. In addition to fatty acids, WAT produces many hormones and can therefore be designated as a traditional endocrine gland actively participating in the integrative physiology of fuel and energy metabolism, eating behaviour and the regulation of hormone secretion and sensitivity. WAT is controlled by humoral factors, para- and intracrine factors and by neural regulation. Sympathetic nerve fibres innervate WAT and stimulate lipolysis, leading to the release of glycerol and free fatty acids. In addition, recent research in rats has clearly shown a functional parasympathetic innervation of WAT. There appears to be a distinct somatotopy within the parasympathetic nuclei: separate sets of autonomic neurones in the brain stem innervate either the visceral or the subcutaneous fat compartment. We therefore propose that the central nervous system (CNS) plays a major role in the hitherto unexplained regulation of body fat distribution. Parasympathectomy induces insulin resistance with respect to glucose and fatty acid uptake in the innervated fat depot and has selective effects on local hormone synthesis. Thus, the CNS is involved not only in the regulation of hormone production by WAT, but also in its hormone sensitivity. The developments in this research area are likely to increase our insights in the pathogenesis of metabolic disorders such as hypertriglyceridemia, diabetes mellitus type 2 and lipodystrophy syndromes.
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Affiliation(s)
- E Fliers
- Academic Medical Center of the University of Amsterdam, Department of Endocrinology and Metabolism, Amsterdam, The Netherlands.
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Ward BA, Gorski JC, Jones DR, Hall SD, Flockhart DA, Desta Z. The cytochrome P450 2B6 (CYP2B6) is the main catalyst of efavirenz primary and secondary metabolism: implication for HIV/AIDS therapy and utility of efavirenz as a substrate marker of CYP2B6 catalytic activity. J Pharmacol Exp Ther 2003; 306:287-300. [PMID: 12676886 DOI: 10.1124/jpet.103.049601] [Citation(s) in RCA: 454] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used human liver microsomes (HLMs) and recombinant cytochromes P450 (P450s) to identify the routes of efavirenz metabolism and the P450s involved. In HLMs, efavirenz undergoes primary oxidative hydroxylation to 8-hydroxyefavirenz (major) and 7-hydroxyefavirenz (minor) and secondary metabolism to 8,14-dihydroxyefavirenz. The formation of 8-hydroxyefavirenz in two HLMs showed sigmoidal kinetics (average apparent Km, 20.2 micro M; Vmax, 140 pmol/min/mg protein; and Hill coefficient, 1.5), whereas that of 7-hydroxyefavirenz formation was characterized by hyperbolic kinetics (Km, 40.1 micro M and Vmax, 20.5 pmol/min/mg protein). In a panel of 10 P450s, CYP2B6 formed 8-hydroxyefavirenz and 8,14-dihydroxyefavirenz from efavirenz (10 micro M) at the highest rate. The Km value for the formation of 8-hydroxyefavirenz in CYP2B6 derived from hyperbolic Eq. 12.4 micro M) was close to that obtained in HLMs (Km, 20.2 micro M). None of the P450s tested showed activity toward 7-hydroxylation of efavirenz. When 8-hydroxyefavirenz (2.5 micro M) was used as a substrate, 8,14-dihydroxyefavirenz was formed by CYP2B6 at the highest rate, and its kinetics showed substrate inhibition (Ksi, approximately 94 micro M in HLMs and approximately 234 micro M in CYP2B6). In a panel of 11 HLMs, 8-hydroxyefavirenz and 8,14-dihydroxyefavirenz formation rates from efavirenz (10 micro M) correlated significantly with the activity of CYP2B6 and CYP3A. N,N',N"-Triethylenethiophosphoramide (thioTEPA; 50 micro M) inhibited the formation rates of 8-hydroxyefavirenz and 8,14-dihydroxyefavirenz from efavirenz (10 micro M) by > or = 60% in HLMs) and CYP2B6, with Ki values < 4 micro M. In conclusion, CYP2B6 is the principal catalyst of efavirenz sequential hydroxylation. Efavirenz systemic exposure is likely to be subject to interindividual variability in CYP2B6 activity and to drug interactions involving this isoform. Efavirenz may be a valuable phenotyping tool to study the role of CYP2B6 in human drug metabolism.
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Affiliation(s)
- Bryan A Ward
- Department of Medicine, Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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