Synthesis and biological activities of potential metabolites of the non-nucleoside reverse transcriptase inhibitor efavirenz

Impact of efavirenz pharmacokinetics and pharmacogenomics on neuropsychological performance in older HIV-infected patients

BACKGROUND

Pharmacokinetics (PK) and pharmacodynamics of efavirenz and its 8-hydroxy metabolite (8-OH-efavirenz) have not been robustly evaluated in older HIV-infected persons.

OBJECTIVES

We investigated relationships between neuropsychological (NP) performance and efavirenz and 8-OH-efavirenz PK in HIV-infected individuals >50 years of age.

METHODS

A cross-sectional study of HIV-infected adults on an efavirenz-containing regimen. The 12 and 18 h post-dose plasma efavirenz and 8-OH-efavirenz were quantified. CYP2B6 polymorphisms were investigated. Participants underwent neuropsychological tests; surveys were used for depression, sleep quality and anxiety. We investigated potential correlations of efavirenz and 8-OH-efavirenz plasma concentrations with NP performance, sleep, depression, anxiety and CYP2B6 polymorphisms.

RESULTS

Thirty participants (24 men and 6 women) with mean age 57 years (range 50-68). Plasma efavirenz concentrations did not correlate with NP performance; however, higher plasma 8-OH-efavirenz correlated with better learning (P = 0.002), language (P = 0.002) and total NP z-scores (P = 0.003). No correlation was seen for efavirenz or 8-OH-efavirenz with sleep, anxiety or depression. Median 12 and 18 h efavirenz plasma concentrations were 1967 ng/mL (IQR 1476-2394) and 1676 ng/mL (IQR 1120-2062), respectively. Median 12 and 18 h 8-OH-efavirenz plasma concentrations were 378 ng/mL (IQR 223-589) and 384 ng/mL (IQR 216-621), respectively. CYP2B6 G516T was associated with significantly higher plasma efavirenz at 12 and 18 h (P = 0.02) but not worse NP function.

CONCLUSIONS

Better neurocognitive functioning was associated with higher 8-OH-efavirenz but not efavirenz plasma concentrations. No correlation was observed with sleep or depression. These findings point to a need for greater understanding of the metabolic profile of efavirenz and 8-OH-efavirenz in plasma and the CNS and relationships with antiviral effect and neurotoxicity.

Antiretroviral drug toxicity in relation to pharmacokinetics, metabolic profile and pharmacogenetics

INTRODUCTION

Besides therapeutic effectiveness, drug tolerability is a key issue for treatments that must be taken indefinitely. Given the high prevalence of toxicity in HIV therapy, the factors implicated in drug-induced morbidities should be identified in order to improve the safety, tolerability and adherence to the treatments. Current approaches have focused almost exclusively on parent drug concentrations; whereas recent evidence suggests that drug metabolites resulting from complex genetic and environmental influences can also contribute to treatment outcome. Pharmacogenetic variations have shown to play a relevant role in the variability observed in antiretroviral drug exposure, clinical response and sometimes toxicity. The integration of pharmacokinetic, pharmacogenetic and metabolic determinants will more probably address current therapeutic needs in patients.

AREAS COVERED

This review offers a concise description of three classes of antiretroviral drugs. The review looks at the metabolic profile of these drugs and gives a comprehensive summary of the existing literature on the influence of pharmacogenetics on their pharmacokinetics and metabolic pathways, and the associated drug or metabolite toxicity.

EXPERT OPINION

Due to the high prevalence of toxicity and the related risk of low adherence to the treatments, association of kinetic, genetic and metabolic markers predictive of therapeutic or toxicity outcomes could represent a more complete approach for optimizing antiretroviral therapy.

Development of a competitive immunoassay for efavirenz: Hapten design and validation studies

The reverse transcriptase inhibitor efavirenz (EFV) is widely used in human immunodeficiency virus (HIV) therapy. Knowledge of the plasma and intracellular concentrations of the drug is of prime importance to get further insight into EFV action in vivo and would be useful for therapeutic drug monitoring (TDM). The aim of this study was to develop a sensitive and specific competitive enzyme immunoassay (EIA) for EFV in biological fluids. Two haptens that differed by the position of the linker were synthesized using two different ways and coupled to BSA. Anti-EFV polyclonal antibodies (pAb) were raised in rabbits using the corresponding immunogens. By comparing results obtained with EIA study with those observed with high-performance liquid chromatography (HPLC) we have shown that the position of the linker appears to be crucial for the specificity of the pAb. EIA was then developed in microtitration plates using the most specific pAb. The assay was performed on a minimum of 30 microL of plasma. It showed good precision and efficiency as well as good cross-validation with HPLC. The lowest limit of quantification (LLOQ) was 150 pg mL(-1), i.e., a value at least 10 times lower than those currently achieved using previously described techniques. This EIA should be useful in the clinical laboratory for monitoring patients during antiretroviral therapy especially young children as well as for measuring EFV in intracellular studies requiring lower amounts of biological material.

Towards discovering dual functional inhibitors against both wild type and K103N mutant HIV-1 reverse transcriptases: molecular docking and QSAR studies on 4,1-benzoxazepinone analogues

To find useful information for discovering dual functional inhibitors against both wild type (WT) and K103N mutant reverse transcriptases (RTs) of HIV-1, molecular docking and 3D-QSAR approaches were applied to a set of twenty-five 4,1-benzoxazepinone analogues of efavirenz (SUSTIVA), some of them are active against the two RTs. 3D-QSAR models were constructed, based on their binding conformations determined by molecular docking, with r(2)(cv) values ranging from 0.656 to 0.834 for CoMFA and CoMSIA, respectively. The models were then validated to be highly predictive and extrapolative by inhibitors in two test sets with different molecular skeletons. Furthermore, CoMFA models were found to be well matched with the binding sites of both WT and K103N RTs. Finally, a reasonable pharmacophore model of 4,1-benzoxazepinones were established. The application of the model not only successfully differentiated the experimentally determined inhibitors from non-inhibitors, but also discovered two potent inhibitors from the compound database SPECS. On the basis of both the 3D-QSAR and pharmacophore models, new clues for discovering and designing potent dual functional drug leads against HIV-1 were proposed: (i) adopting positively charged aliphatic group at the cis-substituent of C3; (ii) reducing the electronic density at the position of O4; (iii) positioning a small branched aliphatic group at position of C5; (iv) using the negatively charged bulky substituents at position of C7.