Nevirapine Plasma Research Articles

Methadone Reduced Nevirapine Pharmacokinetic Parameters in People Living With HIV in Malaysia

Introduction: The HIV epidemic in Malaysia predominantly affects males (90% of total HIV cases) mostly intravenous drugs users. Nevirapine-based of highly active antiretroviral therapy (HAART) once- or twice-daily dosage improve accessibility and effectiveness of antiretroviral treatment for HIV positive intravenous drug users (IDUs) receiving methadone maintenance treatment. Studies reported that concomitant administration of nevirapine with methadone reduced methadone plasma concentration. Since methadone and nevirapine were both known to be the substrate for cytochrome 2B6 (CYP 2B6), concomitant use of both drugs may affect nevirapine concentration too. However, methadone effect on nevirapine concentration is still unclear. This is a cross sectional study which reports how methadone co-administration affects the pharmacokinetic parameters of nevirapine in people living with HIV (PLHIV). Methods: 112 patients receiving nevirapine-based antiretroviral drugs were recruited. Seventeen were maintained with methadone without withdrawal symptoms. High-performance liquid chromatography was used to measure plasma nevirapine concentrations. Nevirapine population pharmacokinetics was modelled with a non-parametric approach using Pmetrics software. Result: According to univariate analysis, concurrent methadone administration increased the clearance of nevirapine by 25.3% (p = 0.046). Multivariate analysis showed that methadone medication was independently linked with lower nevirapine concentrations and area-under-curve (Cmin was reduced by 15.2%, p = 0.011, Cmax 19.5%; p = 0.003, AUC12 16.2%; p = 0.021 respectively). Conclusion: This study provides in-vivo evidence of methadone co-administration reducing nevirapine exposure. Since a low concentration of nevirapine will lead to treatment failure, monitoring is essential for PLHIV using both medications at the same time.

Nevirapine plasma concentration is associated with virologic failure and the emergence of drug-resistant mutations among HIV patients in Kenya: A cross sectional study

This study aimed to determine the association between the plasma concentration of nevirapine (NVP) and clinical outcomes. In this cross-sectional study, sociodemographic and clinical data were collected from 233 HIV patients receiving NVP-based first-line antiretroviral therapy (ART) regimens in Nairobi, Kenya. The mean age was 41.2 (SD ± 11.9) years. Fifty-four (23.2%) patients had virological failure (>1000 copies/mL), whereas 23 (9.9%) were infected with drug-resistant HIV strains. Eleven patients had nucleoside reverse transcriptase inhibitor resistance mutations, including M184V and T215Y, whereas 22 had non-nucleoside reverse transcriptase inhibitor resistance mutations, including G190A, K103N, V106A, Y181C, A98G, and Y188L. The median NVP plasma concentration was 6180 ng/mL (IQR 4444-8843 ng/mL), with 38 (16.3%) patients having suboptimal NVP plasma levels of <3400 ng/mL. The majority 23 of the 38 (60.5%) patients with NVP Cmin < 3400 ng/mL were significantly infected with drug-resistant HIV virus (P = .001). In the multivariate analysis, the time taken to arrive at the ART clinic (β -11.1, 95% CI -21.2 to -1.1; P = .031), higher HIV viral load (β -2008, 95% CI -3370.7 to -645.3; P = .004), and the presence of HIV drug resistance mutation (β 3559, 95% CI 2580.8-4537.2; P = .0001) were associated with NVP plasma concentration. A significant proportion of patients receiving the NVP-based regimen had supra- and sub-therapeutic plasma concentrations. Higher HIV viral load and the presence of HIV drug-resistant mutations are important factors associated with NVP plasma concentrations.

Determination of lamivudine and nevirapine in human plasma by Lc-Ms/Ms method

A sensitive and selective LC-MS/MS method to quantify Lamivudine and Nevirapine in K3EDTA human plasma over the concentration range of 25.0240 to 3997.1740 ng/mL and 37.5080 to 5991.0460 ng/mL, respectively were developed and validated. Lamivudine and Nevirapine and its internal standard (Lamivudine 13C 15N2 and Nevirapine D5) were selectively extracted from 300 µL plasma by direct elution using solid phase extraction technique. Elution was achieved by reverse phase liquid chromatography on Hypurity C18 (100 mm × 4.6 mm, 5.0 µm) column was done. LLOQ of 25.0240 ng/mL and 37.5080 ng/mL were resolute for this technique for Lamivudine and Nevirapine respectively. Accuracy and precision values for Lamivudine were 99.55 &amp; 1.50 and for Nevirapine the accuracy and precision values are 99.33 &amp; 1.03%, respectively.

Trough plasma nevirapine levels, immunologic and virologic responses in composite CYP2B6*6/*18 HIV-infected adult Nigerian patients.

The influence of composite CYP2B6*6/*18 genotype on trough plasma nevirapine levels, HIV RNA levels (virologic response) and CD4+ T lymphocyte and absolute lymphocyte counts (immunologic response) of HIV-infected patients were evaluated. Patients with records of trough plasma nevirapine levels, CD4+ T lymphocyte, absolute lymphocyte and viral load counts at baseline and months 6 and 12 after initiation of nevirapine-based antiretroviral therapy combinations were retrospectively analysed. Participants were from a cohort of 150 patients previously genotyped and with measured plasma nevirapine levels. Relationship between genotype and nevirapine levels, absolute lymphocyte and CD4+ T lymphocyte counts and viral load were explored. Composite CYP2B6*6/*18 genotype was significantly associated with trough plasma nevirapine levels (geometric mean [standard deviation]: 4482 ng/ml [1349] of normal metabolizers vs. 4632 ng/ml [1793] of intermediate metabolizers vs. 6229 ng/ml [2549] of poor metabolizers; P < 0.001), but not the plasma HIV RNA levels, absolute lymphocyte and CD4+ T lymphocyte counts. Overall, immunologic response showed improvement with approximately 61.3% and 70.4% of patients with CD4+ T lymphocyte count >350 cells/mm3 at months 6 and 12 therapy duration respectively compared to 23.1% at baseline. Composite CYP2B6*6/*18 genotype correlated with plasma nevirapine levels but not immunologic and virologic responses.

Association between social psychological status and efavirenz and nevirapine plasma concentration among HIV patients in Kenya

HIV-related stigma, lack of disclosure and social support are still hindrances to HIV testing, care, and prevention. We assessed the association of these social-psychological statuses with nevirapine (NVP) and efavirenz (EFV) plasma concentrations among HIV patients in Kenya. Blood samples were obtained from 254 and 312 consenting HIV patients on NVP- and EFV-based first-line antiretroviral therapy (ART), respectively, and a detailed structured questionnaire was administered. The ARV plasma concentration was measured by liquid chromatography-tandem mass spectrometry (LC–MS/MS). There were 68.1% and 65.4% of the patients on NVP and EFV, respectively, who did not feel guilty for being HIV positive. The disclosure rates were approximately 96.1% and 94.6% of patients on NVP and EFV, respectively. Approximately 85% and 78.2% of patients on NVP and EFV, respectively, received social support as much as needed. There were 54.3% and 14.2% compared to 31.7% and 4.5% patients on NVP and EFV, respectively, with supratherapeutic and suboptimal plasma concentrations. Multivariate quantile regression analysis showed that feeling guilty for being HIV positive was associated with increased 954 ng/mL NVP plasma concentrations (95% CI 192.7 to 2156.6; p = 0.014) but not associated with EFV plasma concentrations (adjusted β = 347.7, 95% CI = − 153.4 to 848.7; p = 0.173). Feeling worthless for being HIV positive was associated with increased NVP plasma concentrations (adjusted β = 852, 95% CI = 64.3 to 1639.7; p = 0.034) and not with EFV plasma concentrations (adjusted β = − 143.3, 95% CI = − 759.2 to 472.5; p = 0.647). Being certain of telling the primary sexual partner about HIV-positive status was associated with increased EFV plasma concentrations (adjusted β 363, 95% CI, 97.9 to 628.1; p = 0.007) but not with NVP plasma concentrations (adjusted β = 341.5, 95% CI = − 1357 to 2040; p = 0.692). Disclosing HIV status to neighbors was associated with increased NVP plasma concentrations (adjusted β = 1731, 95% CI = 376 to 3086; p = 0.012) but not with EFV plasma concentrations (adjusted β = − 251, 95% CI = − 1714.1 to 1212.1; p = 0.736). Obtaining transportation to the hospital whenever needed was associated with a reduction in NVP plasma concentrations (adjusted β = − 1143.3, 95% CI = − 1914.3 to − 372.4; p = 0.004) but not with EFV plasma concentrations (adjusted β = − 6.6, 95% CI = − 377.8 to 364.7; p = 0.972). HIV stigma, lack disclosure and inadequate social support are still experienced by HIV-infected patients in Kenya. A significant proportion of patients receiving the NVP-based regimen had supra- and subtherapeutic plasma concentrations compared to EFV. Social-psychological factors negatively impact adherence and are associated with increased NVP plasma concentration compared to EFV.

Pharmacokinetics and safety of early nevirapine-based antiretroviral therapy for neonates at high risk for perinatal HIV infection: a phase 1/2 proof of concept study

With increasing intention to treat HIV as early as possible, evidence to confirm the safety and therapeutic drug concentrations of a nevirapine-based antiretroviral regimen in the early neonatal period is needed. This study aims to establish dosing of nevirapine for very early treatment of HIV-exposed neonates at high risk of HIV acquisition. IMPAACT P1115 is a multinational phase 1/2 proof-of-concept study in which presumptive treatment for in-utero HIV infection is initiated within 48 h of birth in HIV-exposed neonates at high risk of HIV acquisition. Participants were neonates who were at least 34 weeks gestational age at birth and enrolled within 48 h of birth, born to women with presumed or confirmed HIV infection who had not received antiretrovirals during this pregnancy. The regimen consisted of two nucleoside reverse transcriptase inhibitors plus nevirapine dosed at 6 mg/kg twice daily for term neonates (≥37 weeks gestational age) or 4 mg/kg twice daily for 1 week and 6 mg/kg twice daily thereafter for preterm neonates (34 to <37 weeks gestational age). Here, we report the secondary outcomes of the study: nevirapine exposures in study weeks 1 and 2 and treatment-associated grade 3 or 4 adverse events at least possibly related to study treatment up to study week 4. A population pharmacokinetic model to assess nevirapine exposure was developed from dried blood spot and plasma nevirapine concentrations at study weeks 1 and 2. Nevirapine exposure was assessed in all patients with available blood samples and safety was assessed in all participants. This trial is registered at ClinicalTrials.gov (NCT02140255). Between Jan 23, 2015, and Sept 4, 2017, 438 neonates were enrolled and included in analyses; 36 had in-utero HIV infection and 389 (89%) were born at term. Neonates without confirmed in-utero HIV infection received nevirapine for a median of 13 days (IQR 7-14). Measured dried blood spot nevirapine concentrations were higher than the minimum HIV treatment target (3 μg/mL) in 314 (90%, 95% CI 86-93) of 349 neonates at week 1 and 174 (87%, 81-91) of 201 at week 2. In Monte-Carlo simulations, week 1 nevirapine concentrations exceeded 3 μg/mL in 80% of term neonates and 82% of preterm neonates. DAIDS grade 3 or 4 adverse events at least possibly related to antiretrovirals occurred in 30 (7%, 95% CI 5-10) of 438 infants but did not lead to nevirapine cessation in any neonates; neutropenia (25 [6%] neonates) and anaemia (six [1%]) were most common. Nevirapine at the dose studied was confirmed to be safe and provides therapeutic exposure concentrations. These data support nevirapine as a component of presumptive HIV treatment in high-risk neonates. National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute of Mental Health.

Effects of CYP2B6 polymorphisms on plasma nevirapine concentrations: a systematic review and meta-analysis

Cytochrome P450 (CYP) is involved in the metabolism of nevirapine (NVP); especially, CYP2B6 has been known to be one of the main enzymes involved in NVP metabolism. The objective of this study was to investigate the effects of CYP2B6 variants on plasma concentrations of NVP by a systematic review and meta-analysis. A search for qualifying studies published until April 2020 was conducted using the EMBASE, PubMed, and Web of Science databases. The mean difference (MD) and 95% confidence intervals (CIs) were calculated. Data analysis was performed using R Studio (version 3.6) and Review Manager (version 5.3). In total, data from six studies involving 634 patients were analyzed in the systematic review and five studies in the meta-analysis. We found that carriers of the CYP2B6 516TT genotype had a 2.18 µg/mL higher NVP concentration than did the GG or GT (95% CI 1.28–3.08). In the respective comparisons of the three genotypes, it was found that the MD was 1.87 µg/mL between the TT and GT groups, 2.53 µg/mL between TT and GG, and 0.60 µg/mL between GT and GG. This meta-analysis confirmed that CYP2B6 polymorphisms was associated with plasma NVP concentrations. Therefore, CYP2B6 genotyping may be useful to predict the responses to NVP.

Role of pharmacogenetics and clinical parameters on nevirapine plasma concertation among HIV-1 patients receiving Antiretroviral Therapy in Kenya

Background:Patients’ clinical outcomes and pharmacogenetic factors are important predictors of nevirapine (NVP) plasma concentration. This study evaluated the association of socio-demographic factors and Cytochrome P450 2B6 (CYP2B6) polymorphisms with NVP plasma concentrations among patients receiving antiretroviral therapy (ART) treatment in western and coastal Kenya.Methods:Blood samples were collected from 377 consenting HIV adult patients receiving an NVP-based first-line ART regimen. A detailed sociodemographic questionnaire was administered. NVP plasma concentration was measured by liquid chromatography - tandem mass spectrometry (LC-MS/MS). CYP2B6 c.516 G&gt;T rs3745274 and c.983T&gt;C genotypes were evaluated using real-time polymerase chain reaction. HIV drug resistance mutations were detected using an in-house genotypic assay.Results:The patients’ mean age was 41.6 (SD ± 11.5) years and the majority (59.2%) were female. The mean duration of ART was 5.1 (SD ± 4.8) years. Overall NVP plasma levels ranged from 4-44207 ng/mL (median 6213 ng/mL, IQR 3097–8606.5 ng/mL). There were 105 (25.5%) participants with NVP levels of &lt;3100 ng/mL, associated with poor viral suppression. Multivariate linear regression analysis showed CYP2B6 516 G&gt;T polymorphism (β 0.71, 95% CI 0.4–0.98; p&lt;0.0001), male gender (β 0.45, 95% CI 0.01–0.9; p=0.047) and presence of HIV drug-resistant virus (β 1.98, 95% CI 1.24–2.72; p&lt;0.001) were the independent factors influencing NVP plasma concentration.Conclusions:The majority of patients receiving an NVP-based ART regimen had plasma concentrations within the therapeutic range. CYP2B6 516 G&gt;T polymorphism, gender and presence of a HIV drug-resistant mutation significantly influences NVP plasma concentration. Routine pharmacogenetic testing and measurement of NVP plasma concentrations, considering gender and presence of HIV drug-resistant mutations are key to ensuring optimal ART treatment outcomes in Kenya.

Investigating time dependent brain distribution of nevirapine via mass spectrometric imaging.

Central nervous system (CNS) HIV infection causes brain tissue inflammation and tissue deficit that contributes to neuroAIDS. This complication is escalated by the blood-brain barrier (BBB), which prevents easy access to antiretroviral drugs entering the CNS. In this study the aims were to investigate the BBB membrane penetration and brain localization patterns of Nevirapine (NVP) using Imaging Mass Spectrometry (MSI). Sprague-Dawley rats received an intraperitoneal dose of NVP (50mgkg-1). Plasma and brain samples were harvested, and mass spectrometric methods were then applied to determine the pharmacokinetic properties and localization patterns of NVP in the brain. The pharmacokinetic parameters demonstrated a rapid bio-distribution of NVP in plasma and brain. The plasma Cmax was 6320ngmL-1 and the brain Cmax was 1923ngmL-1, both at a Tmax of 0.25h. MSI of coronal brain sections showed that NVP penetrated and localized in the brain regions implicated with the development of HIV associated neurodegeneration. NVP has great potential to combat neuroAIDS.

Adherence to combination antiretroviral therapy among orphaned children in Dar es Salaam, Tanzania.

BackgroundAdherence to combination antiretroviral therapy (cART) among HIV-infected children is often complicated by various factors including medication formulation, dosing frequency, drug toxicities, age and developmental stage, psychosocial and behavioural characteristics of both children and caregivers and can additionally be complicated by being an orphan.ObjectivesThis study was aimed at determining the factors and the extent of their influence on cART adherence among HIV-infected orphaned children attending Care and Treatment Centres (CTCs) in Dar es Salaam, Tanzania.MethodsA cross-sectional study was performed, which assessed adherence in HIV-positive orphaned children aged 2–14 years receiving nevirapine (NVP) based cART for at least 6 months. Data was collected using questionnaires administered to primary caregivers of HIV-infected orphaned children, the review of medical files, and the laboratory measurement of NVP plasma concentrations and CD4 counts. Adherence to cART was determined based on caregivers’ self-report, consistency of clinic attendance and NVP plasma concentrations.ResultsAmong the 216 enrolled orphaned children, adherence to cART was found to be 79.6%, 82.9% and 72.2% respectively based on caregivers’ self-report, clinic attendance and NVP plasma levels. Significant reductions in NVP concentrations (< 3 µg/mL) were seen among children with poor immunological outcomes, poor clinic attendance (p < 0.05) and were suggested by caregivers’ self-reported adherence (p = 0.06). Adherence challenges identified by caregivers included financial constraints (87.5%), lengthy waiting times at clinics (75.5% spent > 2 h at the clinic) and low HIV knowledge among caregivers.ConclusionSignificant numbers of HIV-infected orphans have poor adherence to cART ranging between 17% and 28% based on different assessment methods. Inadequate caregiver knowledge of HIV/AIDS, long clinic waiting times and forgetfulness were identified as barriers to cART adherence in these orphans.

Non-nucleoside reverse transcriptase inhibitor levels among HIV-exposed uninfected infants at the time of HIV PCR testing - findings from a tertiary healthcare facility in Pretoria, South Africa.

IntroductionTo date, very little programmatic data has been published regarding serial antiretroviral (ARV) levels in infants exposed to maternal treatment and/or infant prophylaxis during the first months of life. Such data provide the opportunity to describe the proportion of infants exposed to virologically suppressive levels of ARVs and to gauge adherence to the prevention of mother‐to‐child transmission of HIV (PMTCT) programme.MethodsFrom August 2014 to January 2016, HIV‐exposed infants born at Kalafong Provincial Tertiary Hospital in Pretoria, South Africa were enrolled as part of an observational cohort study. Plasma samples from HIV‐exposed uninfected infants were obtained at birth, 6‐weeks, 10‐weeks and 14‐weeks of age and quantitative efavirenz (EFV) and nevirapine (NVP) drug level testing performed using liquid chromatography‐mass spectrometry, irrespective of maternal ARV regimen. Descriptive analysis of EFV and NVP levels in relation to self‐reported maternal and infant ARV exposure was performed. EFV levels >500 ng/mL and NVP levels >100 ng/mL were reported based on studies suggesting that trough levels above these thresholds are associated with virological suppression and PMTCT respectively.ResultsAmong 66 infants exposed to maternal EFV in utero, 29 (44%) had virologically suppressive plasma EFV levels at birth, with a median level of 1665 ng/mL (IQR: 1094 to 3673). Among infants who were exclusively breastfed at 6‐, 10‐ and 14 weeks, 13/48 (27%), 5/25 (25%) and 0/21 (0%) had virologically suppressive EFV levels. Among 64 infants whose mothers reported administering daily infant NVP at time of their 6‐week HIV PCR test, only 45 (70%) had NVP levels above the minimum prophylactic trough level.ConclusionsDuring the first 10‐weeks after delivery, a quarter of breastfed infants born to women on an EFV‐containing treatment regimen maintained virologically suppressive EFV plasma levels. This finding highlights the importance of both careful monitoring of ARV side effects and repeat HIV PCR after the first few months of life among HIV‐exposed uninfected infants. As 30% of infants had inadequate NVP plasma levels at 6‐weeks of age, adherence counselling to caregivers regarding infant prophylaxis needs to be enhanced to further reduce mother‐to‐child transmission of HIV.

The relationship between zidovudine, lamivudine and nevirapine plasma drug levels and antiretroviral treatment outcomes in Nigeria children living with HIV

Plasma concentrations of antiretrovirals are significant and important determinants of treatment failure and toxicity. The relationship between antiretroviral pharmacokinetic exposures and immunovirological outcomes has not been extensively studied in our setting. The aim of this study was to investigate the relationship between antiretroviral plasma concentrations and virological and immunological treatment outcomes in children living with human immunodeficiency virus (HIV) A retrospective collection of demographic, clinical , laboratory data and a prospective determination of plasma drug concentrations in 120 children aged 2-14 years after two years of receiving fixed dose zidovudine, lamivudine and nevirapine tablets using a simple, rapid, sensitive and validated method of high performance liquid chromatography with UV detection for simultaneous quantification of zidovudine, lamivudine and nevirapine in human plasma. All analyses were performed using graph pad prism version 5.0. A perfect agreement (p 100 cells/mm3). At 2 years zidovudine, lamivudine and nevirapine therapeutic levels, zidovudine supra therapeutic levels ,and nevirapine subtherapeutic levels were respectively significantly associated with immunologic success (CD4%>15 %). Low nevirapine levels can be used to identify those that require adherence counseling. Despite good virological and immunological outcomes, plasma concentrations of zidovudine, lamivudine and nevirapine were not significantly associated with virological and immunological outcomes (Absolute CD4 counts) but was significantly associated with immunological outcomes (CD4%). Plasma drug levels may be good surrogates of adherence but not of treatment outcomes. Monitoring CD4% remains important to optimize paediatric HIV treatment.Keywords: Antiretroviral treatment, children, therapeutic drug monitoring, treatment outcomes, immune-virological outcomes, plasma concentrations, zidovudine, lamivudine and nevirapine

Development and validation of a high performance liquid chromatography method to determine nevirapine in plasma in a resource-limited setting.

BackgroundThere are several instances where nevirapine pharmacokinetic monitoring may be useful, such as in special populations or pharmacokinetic drug interaction studies that require the ascertainment of nevirapine pharmacokinetics in the sub-Saharan region.ObjectivesThe main aim of this study was to produce a validated, sustainable and relevant nevirapine assay method that meets bio-analytical regulatory requirements.MethodsThe developed method utilised a Waters 2795 Alliance high performance liquid chromatography system with a 2996 photo diode array detector, an Atlantis dC18 5 micron, 3.9 mm × 150 mm analytical column and a gradient flow rate of 1 mL/min. Ultraviolet detection data were collected from 210 nm to 400 nm, extracted at 260 nm, and processed for nevirapine and internal standard peak height responses.ResultsThe method proved to be linear (R2 0.995), precise (+1.92% – +9.69%) and accurate (-9.70% – 12.0%). Recovery for the analyte and internal standard was between 98.8% and 114%. The method showed good specificity as no interferences were caused by common African traditional medicines, anti-tuberculosis medications or other concomitant antiretrovirals nor endogenous components.ConclusionThe method is reproducible, relevant to our setting and uses considerably low plasma volumes with preservation of some consumables, a desirable key factor in a resource-limited setting.

Solid-phase extraction combined with dispersive liquid-liquid microextraction/HPLC-UV as a sensitive and efficient method for extraction, pre-concentration and simultaneous determination of antiretroviral drugs nevirapine, efavirenz and nelfinavir in pharmaceutical formulations and biological samples

Therapeutic drug monitoring (TDM) of antiretroviral drugs requires accurate and precise analysis of their trace amounts in plasma samples. Solid-phase extraction (SPE) coupled with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) was introduced as a simple and sensitive method for extraction, pre-concentration and simultaneous determination of efavirenz (EFV), nelfinavir (NFV) and nevirapine (NVP) in human plasma and pharmaceutical formulations by using high performance liquid chromatography (HPLC) with UV detection. A response surface methodology (RSM) based on central composite design (CCD) was used for optimizing the main variables in the extraction procedure. Under the optimum experimental conditions, the calibration curves were linear in the range of 0.1–400 ng mL−1 with correlation coefficients from 0.9982 to 0.9997 and limits of detection (at S/N = 3) of 0.03 to 0.07 ng mL−1. Moreover the intra-day and inter-day precision (RSD%) were in the range of 2.2–4.2% and 3.1–5.2%, respectively. The enrichment factors and relative recoveries of the anti-HIV drugs were 459–1507 and 93.7–105.4%. The method was successfully applied to the simultaneous determination of the trace amounts of the antiretroviral drugs in blood plasma and pharmaceutical formulations.

Effect of ATP-Binding cassette, Sub-Family B polymorphism on plasma nevirapine and efavirenz levels in human immunodeficiency virus with tuberculosis-infected cases: A molecular structure analysis

Background: Tuberculosis (TB) is an important infection that is usually seen in the patient with underlying human immunodeficiency virus (HIV) infection. An important concern on the cases with HIV/TB is the management of HIV by antiretroviral drug treatment (antiretroviral therapy). The effect of underlying genetic factor is interesting. The effect of adenosine triphosphate-binding cassette, sub-family B (ABCB-1) polymorphism on plasma nevirapine and efavirenz levels is inconclusive. Methods: The authors perform standard molecular structure analysis to assess the effect of C and T alleles of ABCB-1 C3435T polymorphism. The phenotype expressions, reflected by nevirapine and efavirenz levels, are comparatively studied. Results: With focus on 3435 position, the ratio of derived molecular weight after quantum assessment, comparing CC to CT and TT genotypes, is equal to 1:1.068:1.135. Conclusion: The authors can identify the effect of ABCB-1 on the plasma nevirapine and efavirenz levels in HIV/TB patients.

Short Communication: Reduced Nevirapine Concentrations Among HIV-Positive Women Receiving Mefloquine for Intermittent Preventive Treatment for Malaria Control During Pregnancy.

Clinical trials demonstrated intermittent preventive treatment in pregnancy with mefloquine (MQ) reduced malaria rates among pregnant women, yet an unexpected higher risk of mother-to-child transmission (MTCT) of HIV among HIV-positive women receiving MQ has also been observed. To determine if interactions between antiretroviral drugs (ARVs) and MQ could contribute to the increased MTCT observed in women receiving MQ, we performed a retrospective cross-sectional analysis of ARV plasma concentrations in peripheral blood (maternal plasma) and cord blood (cord plasma) collected at delivery from 186 mothers participating in a randomized clinical trial of MQ (n = 102) compared with placebo (n = 84) in Kenya. Plasma zidovudine (AZT), lamivudine (3TC), and nevirapine (NVP) concentrations were measured by high-performance liquid chromatography–tandem mass spectrometry. Although only 4% (7/186) reported not using these ARVs, AZT, 3TC, and NVP were all below the limit of detection in 44% of maternal plasma and 42% of cord plasma samples, and proportions were similar between the two study arms. Median concentrations of AZT and 3TC were not significantly lower in the MQ arm compared with the placebo arm for maternal plasma and cord plasma (p > .05). However, median NVP concentrations were significantly lower in the MQ study arm compared with the placebo study arm in both maternal plasma (1,597 ng/mL vs. 2,353 ng/mL, Mann–Whitney Rank Sum, p = .023) and cord plasma (2,038 ng/mL vs. 2,434 ng/mL, p = .048). Reduced NVP concentrations in maternal and cord plasma of women receiving MQ suggest MQ may affect NVP metabolism for both mother and infant. These results highlight the need to evaluate potential drug–drug interactions between candidate antimalarials and ARVs for use in pregnant women.

Sex-dependent metabolism of nevirapine in rats: impact on plasma levels, pharmacokinetics and interaction with nortriptyline

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) widely used in the treatment of human immunodeficiency virus type 1 (HIV-1) and is the first-choice NNRTI during pregnancy. NVP shows a sex dimorphic profile in humans with sex differences in bioavailability, biotransformation and toxicity. In this study, sex differences in NVP metabolism and inhibition of NVP metabolism by the antidepressant nortriptyline (NT) were evaluated using rats as experimental animals. NVP was administered orally to male and female rats and sex differences in plasma levels and pharmacokinetic parameters were analysed. NVP plasma levels were higher in female compared with male rats, and pharmacokinetic parameters such as maximum plasma concentration (Cmax), time to Cmax (Tmax), half-life (t1/2) and area under the plasma concentration–time curve from the time of dosing to the last measurable concentration (AUClast) showed ca. 4-, 5-, 7- and 22-fold higher values in female rats. In vitro experiments carried out with hepatic microsomes confirmed slower NVP metabolism in female rats, with a maximum velocity (Vmax) 2-fold lower than in male hepatic microsomes. The major metabolite in both sexes was 12-hydroxynevirapine (12-OH-NVP), with the Vmax for this metabolite being 15-fold lower in female compared with male rat hepatic microsomes. Inhibition of NVP metabolism by NT was similar in both sexes, with statistically non-significant differences in 50% inhibitory concentration (IC50) values. In summary, NVP is metabolised more slowly in female compared with male rats, but the inhibitory effect of NT is similar in both sexes.

Evaluation of Zidovudine, Lamivudine and Nevirapine Plasma Concentrations and Factors influencing their Plasma Drug Exposure in Children Aged 2–14 Years Living with HIV at the Lagos University Teaching Hospital

Background: Plasma concentrations of antiretroviral drugs have become important determinants of treatment success, treatment failure and toxicity. There is a paucity of antiretroviral plasma concentration data in our local paediatric human immunodeficiency virus (HIV) literature in Nigeria. Objective: To evaluate plasma concentrations of zidovudine, lamivudine, and nevirapine after 2 years of combination therapyand to determine factors that influence plasma drug exposure in children aged 2–14 years living with HIV. Subjects and Methods: This was a cross-sectional prospective study in which plasma concentrations of zidovudine, lamivudine and nevirapine were simultaneously determined using a simple, rapid and sensitive high performance liquid chromatographic method with UV detection. Plasma concentrations obtained were compared to published data (Cmin and Cmax ) and regulatory reference data (C max only). Results: The median plasma concentrations were 0.062, 1.435 and 4.450 μg/mL for zidovudine, lamivudine and nevirapine respectively. Supratherapeutic plasma zidovudine, lamivudine and nevirapine levels occurred in 33%, 22% and 26% of patients respectively. Supratherapeutic levels were however not significantly associated with adverse events (p&gt;0.05).At 2 years,age (p=0.018) was significantly associated with zidovudine concentrations, with older children having higher levels. There was a perfect agreement between adherence and plasma concentrations of nevirapine (p=0.020). Conclusion: Plasma concentrations were similar to levels previously reported in children with therapeutic, supratherapeutic and nevirapine supratherapeutic levels. There were no observed significant associations between plasma drug concentrations and toxicity. The clinical relevance of observed significant higher levels of plasma zidovudine with increasing age, and supratherapeutic plasma exposures of zidovudine, lamivudine and nevirapine needs further investigations.

Sub-therapeutic nevirapine concentration during antiretroviral treatment initiation among children living with HIV: Implications for therapeutic drug monitoring.

Nevirapine, a component of antiretroviral therapy (ART) in resource-limited settings, known for auto-induction of metabolism, is initiated at half therapeutic dose until day 14 (‘lead-in period’), and subsequently escalated to full dose. However, studies have shown that this dosing strategy based on adult studies may not be appropriate in children, given that younger children have higher drug clearance rates. In this prospective cohort study, we studied trough plasma nevirapine levels by high performance liquid chromatography (HPLC) at days 7, 14 (lead-in period) and 28 (full dose period) after ART initiation amongst HIV-1 infected children initiating nevirapine-based ART in southern India. Among the 20 children (50% male, median age 9 years) included in the study, sub-therapeutic trough plasma nevirapine concentration (<4μg/ml) was seen in 65% (13/20) of children during the lead-in period within two weeks of ART initiation and among 10% of children at 4 weeks during full-dose nevirapine. Adherence was documented as ≥95% in all children by both caregiver self-report and pill count. Median nevirapine concentrations achieved at week 1 was 4.8 μg/ml, significantly lower than 8 μg/ml, the concentration achieved at week 4 (p = 0.034). Virological failure at one year of ART was observed in six children, and was not associated with median nevirapine concentration achieved during week 1, 2 or 4. We conclude that the dose escalation strategy currently practiced among young children living with HIV-1 resulted in significant subtherapeutic nevirapine concentration (≤4μg/ml) during the lead-in period. We call for a closer look at pediatric-focused dosing strategies for nevirapine initiation in young children. Further studies to establish age-appropriate threshold nevirapine concentration are warranted in young children to corroborate the role of therapeutic drug monitoring in predicting virological outcome.

Prevention of TB using rifampicin plus isoniazid reduces nevirapine concentrations in HIV-exposed infants.

Newborns of HIV-infected mothers are given daily doses of nevirapine to prevent HIV-1 acquisition. Infants born to mothers with TB should also receive TB preventive therapy. TB preventive regimens include isoniazid for 6 months or rifampicin plus isoniazid for 3 months (RH preventive therapy). The effect of concomitant RH preventive therapy on nevirapine concentrations in infants is unknown. Tshepiso was a prospective case-control cohort study of pregnant HIV-infected women with and without TB whose newborn infants received standard doses of nevirapine for HIV prophylaxis. Infants born to mothers with TB also received RH preventive therapy. Infant plasma nevirapine concentrations were measured at 1 and 6 weeks. The effects of RH preventive therapy on nevirapine disposition were investigated in a population pharmacokinetic model. Of 164 infants undergoing pharmacokinetic sampling, 46 received RH preventive therapy. After adjusting for weight using allometric scaling, the model estimated a 33% reduction in nevirapine trough concentrations with RH preventive therapy compared with TB-unexposed infants not receiving concomitant rifampicin and a 30% decline in trough concentrations in a typical infant between day 7 and 35 post-partum. Rifampicin-based TB preventative treatment reduces nevirapine concentrations significantly in HIV-exposed infants. Although the nevirapine exposures required to prevent HIV acquisition in breastfeeding infants are undefined, given the potential risks associated with underdosing nevirapine in this setting, it is prudent to avoid rifampicin-based preventive therapy in HIV-exposed children receiving prophylactic nevirapine.