Nevirapine in the treatment of HIV

Synthesis, Characterization, and antiviral evaluation of New Chalcone-Based Imidazo[1,2-a]pyridine Derivatives: Insights from in vitro and in silico Anti-HIV studies

Given the ease of synthetic accessibility and the promising biological profile demonstrated by both imidazo[1,2-a]pyridine and Chalcone derivatives, a series of Chalcone-based imidazo[1,2-a]pyridine derivatives were synthesized and characterized using 1H NMR, 13C NMR, Mass Spectrometry and FTIR techniques. Density functional theory (DFT) was employed to investigate the structural and electronic properties, providing insights into potential reactive sites. The synthesized compounds were evaluated in vitro for their antiviral properties against human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) in MT-4 cells. Furthermore, Molecular docking studies show strong binding affinities with HIV-1 reverse transcriptase and HIV-2 protease. To further understand the dynamic behavior and stability of these interactions, molecular dynamics (MD) simulations were conducted. The MD results indicated stable binding conformations of the ligands within the active sites, with low RMSD and RMSF values throughout the simulation, confirming the robustness of these interactions. ADME predictions suggested acceptable pharmacokinetic profiles, though solubility remains a limitation for these compounds. Although the in vitro antiviral activity was limited, the combination of in vitro and in silico approaches provided valuable insights, guiding further structural optimization to improve bioavailability and enhance the therapeutic potential of these derivatives.

Ringing medicinal chemistry: The importance of 3-membered rings in drug discovery

Scaffold-based drug design has become increasingly prominent in the pharmaceutical field due to the systematic and effective approach through which it facilitates the development of novel drugs. The identification of key scaffolds provides medicinal chemists with a fundamental framework for subsequent research. With mounting evidence suggesting that increased aromaticity could impede the chances of developmental success for oral drug candidates, there is an imperative need for a more thorough exploration of alternative ring systems to mitigate attrition risks. The unique characteristics exhibited by three-membered rings have led to their application in medicinal chemistry. This review explores the use of cyclopropane-, aziridine-, thiirane-, and epoxide-containing compounds in drug discovery, focusing on their roles in approved medicines and drug candidates. Specifically, the importance of the three-membered ring systems in rending biological activity for each drug molecule was highlighted. The undeniable therapeutic value and intriguing features presented by these compounds suggest significant pharmacological potential, providing justification for their incorporation into the design of novel drug candidates.

Synthesis, crystal structure, and antiviral evaluation of new imidazopyridine-schiff base derivatives: in vitro and in silico anti-HIV studies

A series of Imidazo[1,2-a]pyridine-Schiff base derivatives were synthesized and characterized using 1H NMR, 13C NMR, Mass Spectrometry and FTIR techniques, and the structure of 4a was further confirmed through single-crystal X-ray diffraction analysis. Density Functional Theory (DFT) has been used to investigate the structural and electronic properties. The synthesized compounds were evaluated in vitro for their antiviral activity against human immunodeficiency virus type-1 (HIV-1) and human immunodeficiency virus type-2 (HIV-2) in MT-4 cells. Compound 4a displayed EC50 values of 82,02 and 47,72 μg ml-1 against HIV-1 and HIV-2, respectively. Molecular docking studies were conducted to gain insights into the interaction mechanism of the synthesized compounds with HIV-1 reverse transcriptase. ADME analysis suggested acceptable pharmacokinetic profiles, though solubility remains a limitation for these compounds, highlighting the need for further structural modifications to enhance bioavailability and therapeutic potential.

Water-assisted cascade synthesis of trifluoromethylated dipyridodiazepinone analogues: in vitro and in silico antibacterial studies

A base-promoted palladium-catalyzed cascade reaction is described to access trifluoromethylated dipyridodiazepinone derivatives in an aqueous system (1,4-dioxane-H2O). This methodology uses simple chemicals, has a broad substrate scope, is waste minimized (E-factor = 0.3-0.9) and produces 11-CF3-tethered dipyridiodiazepinone derivatives in good to excellent yields. All the synthesized analogues were preliminarily examined for antibacterial activity against E. coli and S. aureus and compared to the reference drugs. Furthermore, inhibition of the peptide deformylase enzyme and antibiofilm studies were performed and compound 5i exhibited the best inhibitory effect among the other analogues. Furthermore, these analogues were in silico analysed via molecular docking, molecular simulation, drug-likeness, physicochemical and ADMET studies. Results from biological evaluation and computational studies revealed that compound 5i could be used as a lead molecular structure for the development of novel antibacterial agents. In conclusion, the green metrics evaluation of the defined protocol provides advantages in the synthesis of biologically active compounds.

On Integral INICS Aromaticity of Pyridodiazepine Constitutional Isomers and Tautomers

The structure, energetics, and aromaticity of c.a. 100 constitutional isomers and tautomers of pyrido[m,n]diazepines (m = 1, 2; n = 2, 3, 4, 5; m ≠ n) were studied at the B3LYP/cc-pVTZ level. The pyrido[1,3]diazepines appear the most, while pyrido[2,4]diazepines are the least stable (ca. 26 kcal/mol). In the pyrido[1,n]diazepine group (n = 2-5), the [1,5] isomers are higher in energy by ca. 4.5 kcal/mol and the [1,4] ones by ca. 7 kcal/mol, and the pyrido[1,2]diazepines are the least stable (ca. 20 kcal/mol). All the most stable pyrido[1,n]diazepines have N-atoms near the ring's junction bond but on opposite sites. The most stable [2,n]-forms are also those with the pyridine ring N6-atom near the junction bond. Surprisingly, for the [1,2]-, [1,3]-, and [1,4]-isomer condensation types of pyridine and diazepine rings, the same N9 > N7 > N6 > N8 stability pattern obeys. The stability remains similar in a water medium simulated with the Polarizable Continuum Model of the solvent and is conserved when calculated using the CAM-B3LYP or BHandHlyp functionals. The ring's aromaticity in the pyridine[m,n]diazepines was established based on the integral INICS index resulting from the NICSzz-scan curves' integration. The integral INICS index is physically justified through its relation to the ringcurrent as demonstrated by Berger, R.J.F., et al. Phys. Chem. Chem. Phys. 2022, 24, 624. The six-membered pyrido rings have negative INICSZZ indices and can be aromatic only if they are not protonated at the N-atom. All protonated pyrido and seven-membered rings exhibit meaningful positive INICSZZ values and can be assigned as antiaromatic. However, some non-protonated pyrido rings also have substantial positive INICSZZ indices and are antiaromatic. A weak linear correlation (R2 = 0.72) between the INICSZZ values of the pyridine I(6) and diazepine I(7) rings exists and is a consequence of the communication between the π-electron systems of the two rings. The juxtaposition of the INICS descriptor of the six- and seven-membered rings and diverse electron density parameters at the Ring Critical Points (RCP) revealed good correlations only with the Electrostatic Potentials from the electrons and nuclei (ESPe and ESPn). The relationships with other RCP parameters like electron density and its Laplacian, total energy, and the Hamiltonian form of kinetic energy density were split into two parts: one nearly constant for the six-membered rings and one linearly correlating for the seven-membered rings. Thus, most of the electron density parameters at the RCP of the six-membered rings of pyridodiazepines practically do not change with the diazepine type and the labile proton position. In contrast, those of the seven-membered rings display aromaticity changes in the antiaromatic diazepine with its ring structural modifications.

A sensitive sensor based on molecularly imprinted polypyrrole on reduced graphene oxide modified glassy carbon electrode for nevirapine analysis

A molecularly imprinted polymer (MIP) sensor was offered for nevirapine (NVP) analysis based on the electropolymerization of pyrrole (Py) on electrochemically reduced graphene oxide (ErGO) immobilized on a glassy carbon electrode (GCE). Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and atomic force microscope (AFM) were applied to characterize the proposed sensor (MIP/ErGO/GCE). The electrochemical operation of this sensor for NVP analysis was tested using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) methods in an alkaline medium. The prepared MIP/ErGO/GCE exhibited better analytical performance than other modified electrodes toward NVP detection. The offered sensor depicted a linearity range between 0.005 µM and 400 µM with a limit of detection (LOD) of 2 nM under optimal conditions. Notably, the offered sensor illustrated excellent selectivity, good reproducibility, acceptable repeatability, and reliable long-term performance. These experiments depicted the constructed sensor as a favorable and good sensing element towards NVP monitoring in pharmaceutical and serum samples.

Clinical and genetic factors associated with increased risk of severe liver toxicity in a monocentric cohort of HIV positive patients receiving nevirapine-based antiretroviral therapy

Background

Nevirapine has been used as antiretroviral agent since early ‘90. Although nevirapine is not currently recommended in initial anti-HIV regimens, its use remains consistent in a certain number of HIV-1-positive subjects. Thus, our aim was to determine clinical and genetic factors involved in the development of severe nevirapine induced liver toxicity.

Methods

We retrospectively analyzed all HIV positive patients who were followed at the Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan from May 2011 to December 2015. All patients treated with nevirapine who underwent a genotyping for the functional variants mapping into ABCB1, CYP2B6, CYP3A4 and CYP3A5 genes were included in the analysis. Severe hepatotoxicity was defined as ACTG grade 3–4 AST/ALT increase during the first three months of nevirapine treatment. The causality assessment between NVP exposure and drug-induced liver injury was performed by using the updated Roussel Uclaf Causality Assessment Methods. Hardy Weinberg equilibrium was tested by χ² test. A multivariable logistic regression model was constructed using a backward elimination method.

Results

Three hundred and sixty-two patients were included in the analysis, of which 8 (2.2%) experienced a severe liver toxicity. We observed no differences between patients with and without liver toxicity as regards gender, ethnicity, age and immune-virological status. A higher prevalence of HCV coinfection (75.0% vs 30.2%; p = .0013) and higher baseline AST (58 IU/L vs 26 IU/L; p = 0.041) and ALT (82 IU/L vs 27 IU/L; p = 0.047) median levels were observed in patients with liver toxicity vs those without toxicity. The genotypes CT/TT at ABCB1 rs1045642 single nucleotide polymorphism (SNP), showed a protective effect for liver toxicity when compared with genotype CC (OR = 0.18, 95%CI 0.04–0.76; p = 0.020) in univariate analysis. In the multivariate model, HCV coinfection was independently associated with higher risk of developing liver toxicity (aOR = 8.00, 95%CI 1.27–50.29; p = 0.027), whereas ABCB1 rs1045642 CT/TT genotypes (aOR = 0.10, 95%CI 0.02–0.47; p = 0.004) was associated with a lower risk.

Conclusions

According to our findings HCV coinfection and ABCB1 rs1045642 SNP represent independent determinants of severe liver toxicity related to nevirapine. This genetic evaluation could be included as toxicity assessment in HIV-1-positive subjects treated with nevirapine.

Clinical and genetic determinants of nevirapine plasma trough concentration

Background:

Only few data are available on the influence of CYP2B6 and CYP3A4/A5 polymorphisms on nevirapine plasma concentrations in the Caucasian population. Our aim was to assess the impact of CYP2B6 and CYP3A4/A5 polymorphisms on nevirapine plasma concentrations consecutively collected.

Methods:

We retrospectively analyzed clinical data of all HIV-positive patients who were followed at the Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan between January 2000 and December 2015. All patients with at least one nevirapine plasma trough concentration (NVP C_min) determination were tested for CYP2B6 c.516 G>T, CYP3A4*22C>T and CYP3A5*3 A>G polymorphisms. Univariate and multivariate regression analyses were carried out considering NVP C_min as the dependent variable and genetic polymorphisms and clinical characteristics as independent variables.

Results:

A total of 143 patients were evaluated. Most of them were males (61.5%) and Caucasian (92.3%). Overall, NVP C_min varied from 1571 to 14,189  ng/mL (median  =  5063  ng/mL, interquartile range  =  3915–6854). The median NVP C_min significantly differed in patients with different CYP2B6 genotypes, but did not vary in those with different CYP3A phenotypes. In the final general linear model, factors significantly associated with a higher NVP C_min were each extra unit of T alleles of CYP2B6 rs3745274 (β  =  0.328, 95% confidence interval  =  0.172–0.484; p  <  0.0001), older age (β  =  0.362, 95% confidence interval  =  0.193–0.532; p  <  0.0001) and hepatitis C virus coinfection (β  =  0.161, 95% confidence interval  =  0.006–0.315; p  <  0.041).

Conclusion:

Our study, conducted in a prevalent Caucasian population, highlighted the importance of CYP2B6 genetic variants in influencing nevirapine plasma trough concentration. Furthermore, older age and hepatitis C virus coinfection significantly increase exposure to nevirapine.

Effect of diurnal variation, CYP2B6 genotype and age on the pharmacokinetics of nevirapine in African children

OBJECTIVES

To characterize the effects of CYP2B6 polymorphisms, diurnal variation and demographic factors on nevirapine pharmacokinetics in African children.

METHODS

Non-linear mixed-effects modelling conducted in NONMEM 7.3 described nevirapine plasma concentration-time data from 414 children aged 0.3-15 years.

RESULTS

Nevirapine pharmacokinetics was best described using a one-compartment disposition model with elimination through a well-stirred liver model accounting for a first-pass effect and transit-compartment absorption. Intrinsic clearance was affected by diurnal variation (characterized using a cosine function with peak amplitude 29% at 12 noon) and CYP2B6 metabolizer status [extensive metabolizer (EM) 516GG|983TT, reference; intermediate metabolizer (IM) 516GT|983TT or 516GG|983TC, 17% lower; slow metabolizer (SM) 516TT|983TT or 516GT|983TC, 50% lower; ultra-slow metabolizer (USM) 516GG|983CC, 68% lower]. Age was found to affect pre-hepatic bioavailability: 31.7% lower at birth and increasing exponentially. Median (90% CI) evening Cmin values in the different metabolizer groups were 5.01 (3.01-7.47), 6.55 (3.65-13.32), 11.59 (5.44-22.71) and 12.32 (12.32-27.25) mg/L, respectively. Evening Cmin values were <3 mg/L in 43% of EM weighing <6 kg and 26% of IM weighing <6 kg, while 73% of SM and 88% of USM in all weight-bands had evening Cmin values >8 mg/L. Cmin was not markedly affected by administration time, but was altered by unequal splitting of the daily dose.

CONCLUSIONS

Diurnal variation does not greatly affect nevirapine exposure. However, when daily doses cannot be split equally, the larger dose should be given in the morning. To achieve homogeneous exposures, nevirapine doses for SM and USM should be reduced by 50%, and children weighing <6 kg with EM or IM metabolizer status should receive the same dose as children weighing 6-10 kg.

Antiviral Drugs

Viruses are major pathogenic agents causing a variety of serious diseases in humans, other animals, and plants.

Drugs that combat viral infections are called antiviral drugs. There are no effective antiviral drugs for many viral infections. However, there are several drugs for influenza, a couple of drugs for herpesviruses, and some new antiviral drugs for treatment of HIV and hepatitis C infections.

The arsenal of antivirals is complex. As of March 2014, it consists of approximately 50 drugs approved by the FDA, approximately half of which are directed against HIV. Antiviral drug creation strategies are focused on two different approaches: targeting the viruses themselves or targeting host cell factors.

Direct virus-targeting antiviral drugs include attachment inhibitors, entry inhibitors, uncoating inhibitors, protease inhibitors, polymerase inhibitors, nucleoside and nucleotide reverse transcriptase inhibitors, nonnucleoside reverse-transcriptase inhibitors, and integrase inhibitors.

Protease inhibitors (darunavir, atazanavir, and ritonavir), viral DNA polymerase inhibitors (acyclovir, valacyclovir, valganciclovir, and tenofovir), and an integrase inhibitor (raltegravir) are included in the list of Top 200 Drugs by sales for the 2010s.

The HEPT Analogue WPR-6 Is Active against a Broad Spectrum of Nonnucleoside Reverse Transcriptase Drug-Resistant HIV-1 Strains of Different Serotypes

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are important components of the highly active antiretroviral therapy (HAART) used to treat human immunodeficiency type 1 virus (HIV-1). However, because of the emergence of drug resistance and the adverse effects of current anti-HIV drugs, it is essential to develop novel NNRTIs with an excellent safety profile, improved activity against NNRTI-resistant viruses, and enhanced activity against clinical isolates of different subtypes. Here, we have identified 1-[(benzyloxy)methyl]-6-(3,5-dimethylbenzyl)-5-iodopyrimidine-2,4(1H,3H)-dione (WPR-6), a novel NNRTI with a 50% effective concentration (EC50) of 2 to 4 nM against laboratory-adapted HIV-1 strain SF33 and an EC50 of 7 to 14 nM against nucleoside reverse transcriptase inhibitor-resistant HIV-1 strain 7391 with a therapeutic index of >1 × 10(4). A panel of five representative clinical virus isolates of different subtypes circulating predominantly in China was highly sensitive to WPR-6, with EC50s ranging from 1 to 6 nM. In addition, WPR-6 showed excellent antiviral potency against the most prevalent NNRTI-resistant viruses containing the K103N and Y181C mutations. To determine whether WPR-6 selects for novel resistant mutants, in vitro resistance selection was conducted with laboratory-adapted HIV-1 strain SF33 on MT-4 cells. The results demonstrated that V106I and Y188L were the two dominant NNRTI-associated resistance mutations detected in the breakthrough viruses. Taken together, these in vitro data indicate that WPR-6 has greater efficacy than the reference HEPT analogue TNK651 and the marketed drug nevirapine against HIV-1. However, to develop it as a new NNRTI, further improvement of its pharmacological properties is warranted.

Prospective, Open-Label Comparative Study of Liver Toxicity in an Unselected Population of HIV-Infected Patients Treated for the First Time with Efavirenz or Nevirapine

OBJECTIVE

To compare the two nonnucleoside reverse transcriptase inhibitors (NNRTIs) when first introduced in an antiretroviral regimen, a prospective open-label assessment of the frequency, severity, risk factors, and outcome of hepatotoxicity was performed.

METHOD

Liver enzymes were followed-up during 18 months in patients who received efavirenz (EFV; 324 patients) or nevirapine (NVP; 299).

RESULTS

The two study groups were comparable, except for the lower baseline CD4+ count found in the EFV group. No differences were found when considering the type and duration of eventual prior anti-HIV therapy; frequency and length of protease inhibitors, methadone, or anti-tubercular drug use; HCV-HBV co-infection; other hepatobiliary disorders; and alcohol-drug abuse. The frequency of overall and first-month drug interruption proved similar in the two study groups. A hepatotoxicity characterized by at least a 2-fold increase of transaminases versus baseline was significantly linked with NVP, and the number of patients showing hepatotoxicity tended to a reduction in the EFV group. Also the time to peak transaminase alterations was shorter in the NVP group. All significant differences regarding liver-pancreatic toxicities were controlled per eventual baseline hepatobiliary-pancreatic diseases, HIV stage, and concurrent drug therapies.

DISCUSSION

Hepatotoxicity is a significant concern in the setting of antiretroviral-treated HIV disease. NVP-based HAART may be more hepatotoxic than EFV-based HAART, and a role is played by chronic liver disorders. Although concurrent hepatobiliary disorders and the possible hepatotoxicity of antiretrovirals do not represent contraindications to nonnucleoside inhibitor use, strict monitoring is recommended.

Nevirapine exposure with WHO pediatric weight band dosing: enhanced therapeutic concentrations predicted based on extensive international pharmacokinetic experience

Nevirapine (NVP) is a nonnucleoside reverse transcriptase inhibitor (NNRTI) used worldwide as part of combination antiretroviral therapy in infants and children to treat HIV infection. Dosing based on either weight or body surface area has been approved by the U.S. Food and Drug Administration (FDA) but can be difficult to implement in resource-limited settings. The World Health Organization (WHO) has developed simplified weight band dosing for NVP, but it has not been critically evaluated. NVP pharmacokinetic data were combined from eight pediatric clinical trials (Pediatric AIDS Clinical Trials Group [PACTG] studies 245, 356, 366, 377, 403, 1056, and 1069 and Children with HIV in Africa Pharmacokinetics and Adherence of Simple Antiretroviral Regimens [CHAPAS]) representing subjects from multiple continents and across the pediatric age continuum. A population pharmacokinetic model was developed to characterize developmental changes in NVP disposition, identify potential sources of NVP pharmacokinetic variability, and assess various pediatric dosing strategies and their impact on NVP exposure. Age, CYP2B6 genotype, and ritonavir were independent predictors of oral NVP clearance. The Triomune fixed-dose tablet was an independent predictor of bioavailability compared to the liquid and other tablet formulations. Monte Carlo simulations of the final model were used to assess WHO weight band dosing recommendations. The final pharmacokinetic model indicated that WHO weight band dosing is likely to result in a percentage of children with NVP exposure within the target range similar to that obtained with FDA dosing. Weight band dosing of NVP proposed by the WHO has the potential to provide a simple and effective dosing strategy for resource limited settings.

Morphological and metabolic components of lipodystrophy in various nevirapine-based highly active antiretroviral therapy (HAART) regimens: a cross-sectional, observational study

BACKGROUND

Morphological abnormalities (lipoatrophy and central fat accumulation) and metabolic changes (dyslipidaemia and glucose regulation impairment) have emerged as components of lipodystrophy and as major tolerability issues with long-term use of highly active antiretroviral therapy (HAART) in HIV-positive patients. Protease inhibitors (PIs) are recognized as having the greatest impact in terms of metabolic complications, followed by nucleoside reverse transcriptase inhibitors, while the non-nucleoside reverse transcriptase inhibitors (NNRTIs) have the least impact. In particular, regimens based on the NNRTI nevirapine have been shown to achieve significant metabolic benefits and may help to improve dyslipidaemia. Improvements in body shape changes associated with lipodystrophy have also been reported when nevirapine replaced a PI in long-term triple therapy.

OBJECTIVE

The objective of this cross-sectional observational ('real-world') study was to investigate the effect of three HAART regimens plus stable nevirapine therapy on morphological and metabolic components of lipodystrophy in HIV-infected patients.

METHODS

Consecutive patients (aged >18 years) with serologically documented HIV infection, who had received HAART for at least 2 years and who had been diagnosed with lipodystrophy, were followed up as outpatients at the metabolic clinic of the University of Modena and Reggio Emilia, Modena, Italy. Patients received stable nevirapine therapy plus fixed-dose combinations of tenofovir disoproxil fumarate plus emtricitabine (Truvada(®); TVD), zidovudine plus lamivudine (3TC) [Combivir(®); CBV], or abacavir plus lamivudine (Kivexa(®); KVX). Multivariate regression analyses were performed to analyse predictors of four components of lipodystrophy: lipoatrophy using leg fat mass measured by dual-emission x-ray absorptiometry (DXA), fat accumulation using waist circumference, dyslipidaemia using apolipoprotein (Apo)B/ApoA1 ratio, and glucose intolerance using the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Overall, 101 patients were enrolled (TVD group = 61, CBV group = 20, KVX group = 20); 191 observations were analysed. Male sex was associated with reduced leg fat mass, while age and body mass index (BMI) were associated with increased leg fat mass (all p < 0.05). Leg fat mass and male sex were associated with increased waist circumference (p < 0.001 for both). Leg fat mass predicted reduced ApoB/ApoA1 ratio, while age and BMI predicted increased ApoB/ApoA1 ratio (all p < 0.05). BMI predicted HOMA-IR increase (p = 0.0017). No differences in lipoatrophy, central fat accumulation, dyslipidaemia or glucose metabolism were observed among any of the three different nevirapine plus nucleoside backbone groups (TVD, CBV or KVX).

CONCLUSION

HAART including nevirapine has a limited impact on components of lipodystrophy in patients with HIV infection. Further studies are needed to verify if nevirapine overcomes the expected distinct lipodystrophy risk profile associated with different nucleoside backbone therapies.

Morphological and metabolic components of lipodystrophy in various nevirapine-based highly active antiretroviral therapy (HAART) regimens: a cross-sectional, observational study

BACKGROUND

Morphological abnormalities (lipoatrophy and central fat accumulation) and metabolic changes (dyslipidaemia and glucose regulation impairment) have emerged as components of lipodystrophy and as major tolerability issues with long-term use of highly active antiretroviral therapy (HAART) in HIV-positive patients. Protease inhibitors (PIs) are recognized as having the greatest impact in terms of metabolic complications, followed by nucleoside reverse transcriptase inhibitors, while the non-nucleoside reverse transcriptase inhibitors (NNRTIs) have the least impact. In particular, regimens based on the NNRTI nevirapine have been shown to achieve significant metabolic benefits and may help to improve dyslipidaemia. Improvements in body shape changes associated with lipodystrophy have also been reported when nevirapine replaced a PI in long-term triple therapy.

OBJECTIVE

The objective of this cross-sectional observational ('real-world') study was to investigate the effect of three HAART regimens plus stable nevirapine therapy on morphological and metabolic components of lipodystrophy in HIV-infected patients.

METHODS

Consecutive patients (aged >18 years) with serologically documented HIV infection, who had received HAART for at least 2 years and who had been diagnosed with lipodystrophy, were followed up as outpatients at the metabolic clinic of the University of Modena and Reggio Emilia, Modena, Italy. Patients received stable nevirapine therapy plus fixed-dose combinations of tenofovir disoproxil fumarate plus emtricitabine (Truvada(®); TVD), zidovudine plus lamivudine (3TC) [Combivir(®); CBV], or abacavir plus lamivudine (Kivexa(®); KVX). Multivariate regression analyses were performed to analyse predictors of four components of lipodystrophy: lipoatrophy using leg fat mass measured by dual-emission x-ray absorptiometry (DXA), fat accumulation using waist circumference, dyslipidaemia using apolipoprotein (Apo)B/ApoA1 ratio, and glucose intolerance using the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Overall, 101 patients were enrolled (TVD group = 61, CBV group = 20, KVX group = 20); 191 observations were analysed. Male sex was associated with reduced leg fat mass, while age and body mass index (BMI) were associated with increased leg fat mass (all p < 0.05). Leg fat mass and male sex were associated with increased waist circumference (p < 0.001 for both). Leg fat mass predicted reduced ApoB/ApoA1 ratio, while age and BMI predicted increased ApoB/ApoA1 ratio (all p < 0.05). BMI predicted HOMA-IR increase (p = 0.0017). No differences in lipoatrophy, central fat accumulation, dyslipidaemia or glucose metabolism were observed among any of the three different nevirapine plus nucleoside backbone groups (TVD, CBV or KVX).

CONCLUSION

HAART including nevirapine has a limited impact on components of lipodystrophy in patients with HIV infection. Further studies are needed to verify if nevirapine overcomes the expected distinct lipodystrophy risk profile associated with different nucleoside backbone therapies.

F18, a novel small-molecule nonnucleoside reverse transcriptase inhibitor, inhibits HIV-1 replication using distinct binding motifs as demonstrated by resistance selection and docking analysis

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are one of the key components of antiretroviral therapy drug regimen against human immunodeficiency virus type 1 (HIV-1) replication. We previously described a newly synthesized small molecule, 10-chloromethyl-11-demethyl-12-oxo-calanolide A (F18), a (+)-calanolide A analog, as a novel anti-HIV-1 NNRTI (H. Xue et al., J. Med. Chem. 53:1397-1401, 2010). Here, we further investigated its antiviral range, drug resistance profile, and underlying mechanism of action. F18 consistently displayed potent activity against primary HIV-1 isolates, including various subtypes of group M, circulating recombinant form (CRF) 01_AE, and laboratory-adapted drug-resistant viruses. Moreover, F18 displayed distinct profiles against 17 NNRTI-resistant pseudoviruses, with an excellent potency especially against one of the most prevalent strains with the Y181C mutation (50% effective concentration, 1.0 nM), which was in stark contrast to the extensively used NNRTIs nevirapine and efavirenz. Moreover, we induced F18-resistant viruses by in vitro serial passages and found that the mutation L100I appeared to be the dominant contributor to F18 resistance, further suggesting a binding motif different from that of nevirapine and efavirenz. F18 was nonantagonistic when used in combination with other antiretrovirals against both wild-type and drug-resistant viruses in infected peripheral blood mononuclear cells. Interestingly, F18 displayed a highly synergistic antiviral effect with nevirapine against nevirapine-resistant virus (Y181C). Furthermore, in silico docking analysis suggested that F18 may bind to the HIV-1 reverse transcriptase differently from other NNRTIs. This study presents F18 as a new potential drug for clinical use and also presents a new mechanism-based design for future NNRTI.

Lersivirine, a nonnucleoside reverse transcriptase inhibitor with activity against drug-resistant human immunodeficiency virus type 1

The nonnucleoside reverse transcriptase inhibitors (NNRTIs) are key components of highly active antiretroviral therapy (HAART) for the treatment of human immunodeficiency virus type 1 (HIV-1). A major problem with the first approved NNRTIs was the emergence of mutations in the HIV-1 reverse transcriptase (RT), in particular K103N and Y181C, which led to resistance to the entire class. We adopted an iterative strategy to synthesize and test small molecule inhibitors from a chemical series of pyrazoles against wild-type (wt) RT and the most prevalent NNRTI-resistant mutants. The emerging candidate, lersivirine (UK-453,061), binds the RT enzyme in a novel way (resulting in a unique resistance profile), inhibits over 60% of viruses bearing key RT mutations, with 50% effective concentrations (EC(50)s) within 10-fold of those for wt viruses, and has excellent selectivity against a range of human targets. Altogether lersivirine is a highly potent and selective NNRTI, with excellent efficacy against NNRTI-resistant viruses.

Polymorphism of human cytochrome P450 enzymes and its clinical impact

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

Discovery of novel non-cyclam polynitrogenated CXCR4 coreceptor inhibitors

HIV cell fusion and entry have been validated as targets for therapeutic intervention against infection. Bicyclams were the first low-molecular-weight compounds to show specific interaction with CXCR4. The most potent bicyclam was AMD3100, in which the two cyclam moieties are tethered by a 1,4-phenylenebis(methylene) bridge. It was withdrawn from clinical trials owing to its lack of oral bioavailability and cardiotoxicity. We have designed a combinatorial library of non-cyclam polynitrogenated compounds by preserving the main features of AMD3100. At least two nitrogen atoms on each side of the p-phenylene moiety, one in the benzylic position and the other(s) in the heterocyclic system were maintained, and the distances between them were similar to the nitrogen atom distances in cyclam. A selection of diverse compounds from this library were prepared, and their in vitro activity was tested in cell cultures against HIV strains. This led to the identification of novel potent CXCR4 coreceptor inhibitors without cytotoxicity at the tested concentrations.

Population pharmacokinetics of nevirapine in combination with rifampicin-based short course chemotherapy in HIV- and tuberculosis-infected South African patients

OBJECTIVE

The aim was to develop a model to describe the population pharmacokinetics of nevirapine in South African human immunodeficiency virus (HIV)-infected patients who were taking nevirapine-based antiretroviral therapy concomitantly or in the absence of rifampicin-based tuberculosis therapy.

METHODS

Patients were divided into two groups: (1) patients receiving nevirapine-containing antiretroviral regimen (200 mg twice daily) and continuation phase rifampicin-containing tuberculosis therapy (n = 27) in whom blood samples were obtained before and not less than 14 days after they completed tuberculosis therapy; (2) patients without tuberculosis who were receiving a nevirapine-containing antiretroviral regimen for at least 3 weeks (n = 26). The population pharmacokinetics of nevirapine was described using nonlinear mixed effects modelling with NONMEM software. Based on the developed model, plasma concentration profiles after 300, 400 and 500 mg of nevirapine twice daily were simulated.

RESULTS

Concomitant administration of rifampicin increased nevirapine oral clearance (CL/F) by 37.4% and reduced the absorption rate constant (k(a)) by almost sixfold. Rifampicin reduced the nevirapine average minimum concentration by 39%. Simulated doses of 300 mg twice daily elevated nevirapine concentrations above subtherapeutic levels in most patients, with minimum exposure above the recommended maximum concentration. The area under the concentration-time curve of 12-hydroxynevirapine was not different in the presence of rifampicin. 2-, 3- and 8-Hydroxynevirapine were not detectable (LLOQ = 0.025 mg/L).

CONCLUSION

The developed model adequately describes nevirapine population pharmacokinetics in a South African population when taken with/and in the absence of rifampicin treatment. The simulations suggest that an increased dose of 300 mg twice daily would achieve adequate nevirapine concentrations in most patients during rifampicin-containing treatment for tuberculosis.

Targeting protein–protein interactions for HIV therapeutics

The majority of current anti-HIV drugs target the viral reverse transcriptase or protease enzymes. However, enfuvirtide and maraviroc are drugs that have been US FDA approved recently and which function by inhibiting virus cell binding and entry which normally occurs through the interaction of the viral envelope protein with its cellular coreceptor. As HIV-1 utilizes many cellular cofactors during its replication cycle, there are a number of other protein–protein interactions that can serve as targets for anti-HIV drug development. In this review article we discuss the general method used to identify anti-HIV drugs that function through targeting protein–protein interactions. We also discuss the currently known cellular cofactors that may serve as targets in future drugs screens.

CYP2B6 983T>C polymorphism is prevalent in West Africa but absent in Papua New Guinea: implications for HIV/AIDS treatment

AIMS

To determine the prevalence of the novel CYP2B6 functional polymorphism 983T>C in Papua New Guinea where HIV/AIDS poses a significant health problem.

METHOD

We genotyped Papua New Guineans (PNG, n = 174), West Africans (WA, n = 170), and North Americans (NA, n = 361).

RESULTS

The polymorphism was absent in PNG, while its overall frequency was 4.7% in WA. Among NA, the polymorphism was present in African-Americans (7.5%) and Hispanic-Americans (1.1%) but not in Caucasian-Americans and Asian-Americans. Haplotype analysis indicated that 983T>C was present alone as the CYP2B6*18 allele in WA and African-Americans.

CONCLUSIONS

Significant interethnic differences occur at the CYP2B6 locus, which may influence treatment outcomes with efavirenz.

HIV-1 reverse transcriptase inhibitors

Reverse transcriptase (RT) is one of the three enzymes encoded by the human immunodeficiency virus type 1 (HIV-1), the etiological agent of AIDS. Together with protease inhibitors, drugs inhibiting the RNA- and DNA-dependant DNA polymerase activity of RT are the major components of highly active antiretroviral therapy (HAART), which has dramatically reduced mortality and morbidity of people living with HIV-1/AIDS in developed countries. In this study, we focus on RT inhibitors approved by the US Food and Drugs Administration (FDA) or in phases II and III clinical trials. RT inhibitors belong to two main classes acting by distinct mechanisms. Nucleoside RT inhibitors (NRTIs) lack a 3' hydroxyl group on their ribose or ribose mimic moiety and thus act as chain terminators. Non-NRTIs bind into a hydrophobic pocket close to the polymerase active site and inhibit the chemical step of the polymerization reaction. For each class of inhibitors, we review the mechanism of action, the resistance mechanisms selected by the virus, and the side effects of the drugs. We also discuss the main perspectives for the development of new RT inhibitors.

Plasma nevirapine levels, adverse events and efficacy of antiretroviral therapy among HIV-infected patients concurrently receiving nevirapine-based antiretroviral therapy and fluconazole

Background

The clinical data of plasma NVP level, safety and efficacy of antiretroviral therapy (ART) for the concurrent use of nevirapine (NVP)-based ART and fluconazole (FLU) is scanty.

Methods

A retrospective study was conducted in patients who were initiated NVP-based ART between October 2004 and November 2005. The objectives were to compare NVP levels, adverse events, and 36-week efficacy of NVP-based ART between patients who did not receive FLU (group A) and those who received FLU 200 mg/day or 400 mg/day (group B).

Results

There were 122 patients with mean ± SD age of 36 ± 9 years; 81 in group A and 41 in group B. Median (IQR) baseline CD4 cell count was 29 (8–79) cell/mm³ in group A and 19 (8–33) cell/mm³ in group B (P = 0.102). Baseline characteristics between the two groups were similar. Mean ± SD NVP levels were 6.5 ± 3.0 mg/L in group A and 11.4 ± 6.1 mg/L in group B(P < 0.001). One (2.4%) patient in group B developed clinical hepatitis (P = 0.336). Six (7.4%) patients in group A developed NVP-related skin rashes (P = 0.096). There were no differences in term of 36-week antiviral efficacy between the two groups (P > 0.05).

Conclusion

Co-administration of NVP and daily dosage of FLU (200 mg/day and 400 mg/day) results in markedly increased trough plasma NVP level when compared to the administration of NVP alone. The concurrent use of NVP and FLU in very advanced HIV-infected patients is well-tolerated. The immunological and virological responses are favorable.

Nevirapine versus efavirenz in 742 patients: no link of liver toxicity with female sex, and a baseline CD4 cell count greater than 250 cells/microl

Recent studies have reported increased nevirapine hepatotoxicity in female patients with CD4 lymphocyte counts greater than 250 cells/microl (especially pregnant women). However, our open-label comparison of 742 patients treated with either nevirapine or efavirenz-based HAART as naive patients, experienced subjects, or patients on salvage therapy, found no increased hepatotoxicity in nevirapine-treated subjects, in particular with regard to both sex (females versus males) and T-cell-mediated immunodeficiency (CD4 cell counts above versus below 250 cells/microl).

A comparison of the steady-state pharmacokinetics of nevirapine in men, nonpregnant women and women in late pregnancy

AIMS

To evaluate the pharmacokinetics of nevirapine and any possible influencing factors in pregnant women (n = 16), nonpregnant women (n = 13) and men (n = 14), who received nevirapine 200 mg twice daily together with nucleoside reverse transcriptase inhibitors.

METHODS

Blood samples were taken for 12 h at steady state. Nevirapine concentrations were measured by liquid chromatography-tandem mass spectrometry. The influence of gender, age, body weight and comedication on minimum and maximum concentrations (C(min), C(max)), area under the concentration-time curve (AUC), total clearance (CL(tot)), half-life (t(1/2)) and volume of distribution (V(d)) was analysed by multivariate techniques.

RESULTS

Mean [95% confidence interval (CI)]C(max), AUC(ss) and clearance were 5221 ng ml(-1) (4267, 6175), 50 789 ng (-1)h ml(-1) (43 453, 58 125) and 69.9 ml min(-1) for men, 5871 ng ml(-1) (4848, 6895), 57 045 ng h(-1) ml(-1) (45 997, 68 093) and 65.6 ml min(-1) for nonpregnant women and 4505 ng ml(-1) (3644, 5366), 44 579 ng h(-1) ml(-1) (36 564, 52 594) and 82.1 ml min(-1) for pregnant women. The differences between pregnant and nonpregnant women (% difference, 95% CI) in C(max) (-30.3; -28.5, -33.0), AUC(ss) (-28.0; - 25.8, - 29.5) and clearance (20.2; 26.6, 15.6) reached statistical significance (P = 0.010, P = 0.028 and P = 0.028, respectively). The multivariate analysis underscored the influence of bodyweight on the plasma exposure to nevirapine.

CONCLUSIONS

Pregnant women exhibited an increased nevirapine clearance and comparably low plasma concentrations, whereas women with a low bodyweight achieved high plasma nevirapine concentrations. The large variability in nevirapine concentrations in women may lead to loss of efficacy and viral resistance, or drug toxicity, and therefore these patients should be monitored frequently.

Characterization of drug-resistance mutations in HIV-1 isolates from non-HAART and HAART treated patients in Burkina Faso

Non-B HIV subtypes have been estimated to account for 88% of HIV infections in the world. These subtypes are particularly relevant in view of the availability of antiretroviral (ARV) drugs, since subtype-specific mutations are associated with drug-resistance in developing countries. Therefore, the pol gene sequences in HIV-1 isolates were examined from the three distinct groups of 39 infected patients from Ouagadougou in Burkina Faso: 17 patients who had not received any antiretroviral therapy (ART); 16 patients received ART, and 6 HIV-infected children, from infected mothers, received a single Nevirapine dose prophylaxis during birth. HIV-1 pol sequencing was successful for 29 samples. As expected, all patients presented the common (non-B subtype) M36I polymorphism and 26/29 (90%) the K20I mutation. Phylogenetic studies showed high predominance of recombinant HIV-1 strains: CRF06_cpx 16/29 (55.17%), CRF02_AG 9/29 (31.03%), A1 2/29 (6.89%), G 1/29 (3.44%), and CRF09_cpx 1/29 (3.44%). Two twins showed, 6 months after birth, a NNRTI-mutation (Y181C/Y). During the same period, the twin mother presented a different NNRTI-mutation (V106I), thus suggesting that the different blood drug concentration may determine a different drug-resistance pathway. Among 17 non-highly active antiretroviral therapy (HAART) patients, 3/17 (17.64%) presented virus with reverse transcriptase (RT) mutations [V118I: 1/17 patients (5.88%), V179E: 2/17 patients (11.76%)]. 10/17 (58.82%) presented virus with minor protease (PR) mutations [L63P: 5/17 patients (29.41%), V77I: 3/17 patients (17.64%), L10I: 2/17 patients (11.76%)]. 4/17 patients did not show any PR and RT mutations (23.52%). Among six HAART-treated patients, 6/6 and 3/6 had M36I and L63LP protease minor subtypes, respectively; and only two (33.33%) presented virus with K103N mutation. The low prevalence of drug-resistant associated mutations in Burkina Faso is encouraging. However, further studies with a larger cohort with a high non-B subtype prevalence are necessary to optimize ART in developing countries.

Safety and tolerability of nevirapine-based antiretroviral therapy in HIV-infected patients receiving fluconazole for cryptococcal prophylaxis: a retrospective cohort study

BACKGROUND

To compare the adverse events after initiation of NVP-based ART among HIV-infected patients who did not receive fluconazole (group A), received fluconazole 400 mg/week (group B), and received fluconazole 200 mg/day (group C).

METHODS

A retrospective cohort study was conducted among HIV-infected patients who began NVP-based ART between December 2003 and September 2004. Patients were followed up for 6 months. Clinical hepatitis, elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (> 3 times from baseline), and skin rashes were studied.

RESULTS

There were 686 patients; 225, 392, and 69 patients in group A, B, and C, respectively. Baseline characteristics including age, previous opportunistic infections, use of antituberculous drugs, and baseline aminotransferase levels among the three groups were similar. Group C had a higher proportion of men (p = 0.016). Baseline median (IQR) CD4 cell counts were 85 (21-159), 18 (7-48), and 16 (5-35) cell/mm3 in group A, B, and C, respectively (p < 0.001). Of 2/225 (0.9%), 4/392 (1.0%), and 0/69 (0%) patients in group A, B, and C developed clinical hepatitis (p = 0.705). There were no significant difference of elevated AST or ALT among the three groups (p > 0.05). By logistic regression, receiving fluconazole was not predictive of clinical hepatitis, elevated aminotransferase, or skin rashes. At 6 months after initiating NVP, 174 (77.3%) patients in group A, 309 (78.8%) patients in group B, and 58 (84.1%) patients in group C remained on NVP.

CONCLUSION

Initiation of NVP-based ART among Thais with advance HIV disease receiving fluconazole is safe and well-tolerated. NVP should not be contraindicated for patients receiving fluconazole for treatment or prophylaxis of cryptococcosis.