Safety profile of nevirapine, a nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus infection

Sulfation of 12-hydroxy-nevirapine by human SULTs and the effects of genetic polymorphisms of SULT1A1 and SULT2A1

Nevirapine (NVP) is an effective drug for the treatment of HIV infections, but its use is limited by a high incidence of severe skin rash and liver injury. 12-Hydroxynevirapine (12-OH-NVP) is the major metabolite of nevirapine. There is strong evidence that the sulfate of 12-OH-NVP is responsible for the skin rash. While several cytosolic sulfotransferases (SULTs) have been shown to be capable of sulfating 12-OH-NVP, the exact mechanism of sulfation in vivo is unclear. The current study aimed to clarify human SULT(s) and human organs that are capable of sulfating 12-OH-NVP and investigate the metabolic sulfation of 12-OH-NVP using cultured HepG2 human hepatoma cells. Enzymatic assays revealed that of the thirteen human SULTs, SULT1A1 and SULT2A1 displayed strong 12-OH-NVP-sulfating activity. 1-Phenyl-1-hexanol (PHHX), which applied topically prevents the skin rash in rats, inhibited 12-OH-NVP sulfation by SULT1A1 and SULT2A1, implying the involvement of these two enzymes in the sulfation of 12-OH-NVP in vivo. Among five human organ cytosols analyzed, liver cytosol displayed the strongest 12-OH-NVP-sulfating activity, while a low but significant activity was detected with skin cytosol. Cultured HepG2 cells were shown to be capable of sulfating 12-OH-NVP. The effects of genetic polymorphisms of SULT1A1 and SULT2A1 genes on the sulfation of 12-OH-NVP by SULT1A1 and SULT2A1 allozymes were investigated. Two SULT1A1 allozymes, Arg37Asp and Met223Val, showed no detectable 12-OH-NVP-sulfating activity, while a SULT2A1 allozyme, Met57Thr, displayed significantly higher 12-OH-NVP-sulfating activity compared with the wild-type enzyme. Collectively, these results contribute to a better understanding of the involvement of sulfation in NVP-induced skin rash and provide clues to the possible role of SULT genetic polymorphisms in the risk of this adverse reaction.

Class-Based Antiretroviral Exposure and Cognition Among Women Living with HIV

Neurologic complications of the human immunodeficiency virus (HIV) are common in treated individuals, and toxicity of certain antiretroviral therapies (ART) may contribute to cognitive impairment. We investigated exposures to specific ART and cognition among women living with HIV (WLWH). Virologically suppressed (viral load <200 copies/mL during at least two semi-annual visits) WLWH and age/race matched HIV-seronegative controls enrolled in the Women's Interagency HIV Study who completed at least two biennial cognitive assessments were included. Analysis of WLWH was restricted to those with exposure to the drug class of interest and a nucleoside reverse transcriptase inhibitor (NRTI) backbone. Generalized estimating equations were used to evaluate repeated measures of cognition over time in association with ART class exposure. Among 1,242 eligible WLWH, 20% (n = 247) had isolated drug exposure to non-nucleoside reverse transcriptase inhibitors (NNRTI), 18% (n = 219) to protease inhibitors (PIs), and 6% (n = 79) to integrase inhibitors with a NRTI backbone. Cognitive assessments were performed at a median of 3 biennial visits {IQR 2-4 visits}. At the index assessment, 21% of WLWH demonstrated global cognitive impairment versus 29% at their last cognitive assessment. In multivariable analyses adjusted for hypertension, depression, diabetes mellitus, history of AIDS-defining illness, alcohol use, number of medications, and time on ART, WLWH exposed to NNRTIs demonstrated verbal learning improvements (mean T-score change 1.3, p = .020) compared to other treated women. Compared to HIV-seronegative women, WLWH exposed to PIs had worse verbal learning (mean T-score difference -2.62, p = .002) and verbal memory performance (mean T-score difference -1.74, p = .032) at baseline. Compared to HIV-seronegative women, WLWH exposed to PIs had improvements in verbal learning (mean T-score slope difference 0.36, p = .025) and verbal memory (mean T-score slope difference 0.32, p = .042). The index T-score and slope of change in the T-score were similar among other treated groups and the HIV-seronegative group. We noted emerging trends in cognition in WLWH exposed to specific drug classes. Ongoing study of this relatively young group is important to characterize long-term cognitive outcomes and effect of antiretrovirals as treatment guidelines evolve.

Nanoparticle delivery system, highly active antiretroviral therapy, and testicular morphology: The role of stereology

The conjugation of nanoparticles (NPs) with antiretroviral drugs is a drug delivery approach with great potential for managing HIV infections. Despite their promise, recent studies have highlighted the toxic effects of nanoparticles on testicular tissue and their impact on sperm morphology. This review explores the role of stereological techniques in assessing the testicular morphology in highly active antiretroviral therapy (HAART) when a nanoparticle drug delivery system is used. Also, NPs penetration and pharmacokinetics concerning the testicular tissue and blood-testis barrier form the vital part of this review. More so, various classes of NPs employed in biomedical and clinical research to deliver antiretroviral drugs were thoroughly discussed. In addition, considerations for minimizing nanoparticle-drugs toxicity, ensuring enhanced permeability of nanoparticles, maximizing drug efficacy, ensuring adequate bioavailability, and formulation of HAART-NPs fabrication are well discussed.

NLRP3 Inflammasome: A Promising Therapeutic Target for Drug-Induced Toxicity

Drug-induced toxicity, which impairs human organ function, is a serious problem during drug development that hinders the clinical use of many marketed drugs, and the underlying mechanisms are complicated. As a sensor of infections and external stimuli, nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a key role in the pathological process of various diseases. In this review, we specifically focused on the role of NLRP3 inflammasome in drug-induced diverse organ toxicities, especially the hepatotoxicity, nephrotoxicity, and cardiotoxicity. NLRP3 inflammasome is involved in the initiation and deterioration of drug-induced toxicity through multiple signaling pathways. Therapeutic strategies via inhibiting NLRP3 inflammasome for drug-induced toxicity have made significant progress, especially in the protective effects of the phytochemicals. Growing evidence collected in this review indicates that NLRP3 is a promising therapeutic target for drug-induced toxicity.

Covalent Histone Modification by an Electrophilic Derivative of the Anti-HIV Drug Nevirapine

Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor widely used in combined antiretroviral therapy and to prevent mother-to-child transmission of the human immunodeficiency virus type 1, is associated with several adverse side effects. Using 12-mesyloxy-nevirapine, a model electrophile of the reactive metabolites derived from the NVP Phase I metabolite, 12-hydroxy-NVP, we demonstrate that the nucleophilic core and C-terminal residues of histones are targets for covalent adduct formation. We identified multiple NVP-modification sites at lysine (e.g., H2BK47, H4K32), histidine (e.g., H2BH110, H4H76), and serine (e.g., H2BS33) residues of the four histones using a mass spectrometry-based bottom-up proteomic analysis. In particular, H2BK47, H2BH110, H2AH83, and H4H76 were found to be potential hot spots for NVP incorporation. Notably, a remarkable selectivity to the imidazole ring of histidine was observed, with modification by NVP detected in three out of the 11 histidine residues of histones. This suggests that NVP-modified histidine residues of histones are prospective markers of the drug's bioactivation and/or toxicity. Importantly, NVP-derived modifications were identified at sites known to determine chromatin structure (e.g., H4H76) or that can undergo multiple types of post-translational modifications (e.g., H2BK47, H4H76). These results open new insights into the molecular mechanisms of drug-induced adverse reactions.

Factors Predicting the Outcome of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis: A 5-Year Retrospective Study

Background:

Clinicodemographic and laboratory parameters predicting the outcome of Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) may vary among populations owing to genotypic and environmental variations. There is a scarcity of studies evaluating these parameters in Indian population.

Aims:

To analyze clinicodemographic and laboratory parameters predicting disease outcome in patients of SJS/TEN.

Materials and Methods:

Clinical records of patients admitted with a diagnosis of SJS/TEN from January 2014 to December 2018 were reviewed retrospectively with respect to data pertaining to clinicodemographic details, laboratory parameters, and disease outcome.

Results:

Of 51 patients included in the study, 24 (47.06%) were females. Anticonvulsants [phenytoin (19.6%), carbamazepine (13.7%), others (5.88%)] were the most commonly implicated drugs followed by NSAIDs (19.6%). The overall mortality was 21.6% [SJS (0%), SJS-TEN overlap (18.8%), and TEN (28.6%)]. The mean detached body surface area (BSA) (35.4% ± 10.4% vs. 25.7% ± 11.8%; P = 0.02) was significantly higher among patients with mortality. Blood urea nitrogen, serum HCO₃⁻ levels, and random blood sugar were significantly associated with mortality. Presence of sepsis during the disease course was associated with higher mortality (9/12 vs. 2/39; P = 0.001). Other components of SCORTEN like age and heart rate were not significantly associated with poor outcome in our study. None of our patients had associated malignancy.

Conclusion:

A higher detached BSA, presence of sepsis, higher blood urea nitrogen and random blood sugar, and lower serum HCO₃⁻ levels were associated with mortality. Refinement of scoring systems predicting the outcome of SJS-TEN is needed for better disease prognostication.

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

BACKGROUND

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.

METHODS

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).

FINDINGS

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.

INTERPRETATION

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.

FUNDING

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.

Nevirapine-induced Stevens-Johnson syndrome in children living with HIV in South Africa

Background

Although adverse drug reactions resulting from the use of nevirapine (NVP) are well described in adults (estimated frequency of 6% - 10%), it has previously been considered less common in children (0.3% - 1.4%). Stock-outs of antiretroviral agents occur frequently in South Africa and result in interruptions in therapy and drug substitutions.

Objectives

To report on a case series of paediatric patients who suffered cutaneous drug reactions to NVP at rates not previously described in children.

Method

We describe a retrospective observational case series of six children living with HIV who developed Stevens-Johnson Syndrome (SJS) following exposure to NVP because of a prolonged stock-out of efavirenz 200 mg tablets in South Africa.

Results

Of the 392 paediatric patients receiving antiretroviral therapy at the institution, 172 were affected by the efavirenz stock-out. Of these, 85 children were changed to NVP of which six developed NVP-induced SJS (7.1% incidence rate). The median time between initiating NVP and developing symptoms was 27 days (range 12-35 days). All patients responded well to NVP cessation and symptomatic treatment. One patient was referred for specialist care. Two patients were successfully rechallenged with efavirenz after developing SJS and three continued lopinavir/ritonavir.

Conclusions

This is the second largest case series of NVP-induced SJS in children to date and raises the possibility that the incidence of SJS in children may be higher than previously described. Further research is required to explore the risk factors associated with NVP-induced SJS in children. This case series highlights the negative impact of drug stock-outs on patient health outcomes.

A novel association of efavirenz induced severe cutaneous adverse reactions with HLA- DRB1*03:01: A case-control study from North-East India

HIV-infected patients have a higher risk of developing cutaneous reactions to drugs than the general population. Severe cutaneous adverse reactions (SCARs) are not uncommon in patients taking antiretroviral therapy (HAART]. To evaluate HLA class I and II allele frequencies in HIV patients on HAART who develop SCARs due to nevirapine (NVP] or efavirenz (EFZ] containing regime and compare this genotype composition with HAART tolerant patients and healthy organ donors. A case-control study for 4 years was conducted with four subsets of patients hailing from north-east India:Cohort 1- HIV seropositive patients who developed SCARs due to EFZ (n = 8];Cohort 2 - HIV seropositive patients who developed SCARs due to NVP (n = 15]; Cohort 3 -HIV seropositive NVP/EFZ-tolerant patients (n = 18]; Cohort 4 - Healthy HIV seronegative organ donors (n = 169].Cohort 3 & 4 acted as control-group. These patients were genotyped for the HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1, and HLA-DPB1 by a sequence-based HLA typing method. HLA-DRB1*03:01 allele revealed a significant association with EFZ regimen-induced SCARs in 62.5% patients compared with only 5.56% observed in HAART-tolerant patients and 4.14% in healthy organ. HLA-B*3505was found to be significantly associated with NVP induced SCARs. We found significant novel association of HLA-DRB1*03:01 with EFZ induced SCARs in North-East Indian HIV patients. Thus, HLA-DRB*03:01 may be useful as a genetic marker to avoid EFZ induced serious cutaneous rashes. The molecular HLA characterization of these alleles may provide a novel insight into the immunological basis of the antiretroviral drug reactions.

LC-MS/MS Quantification of Nevirapine and Its Metabolites in Hair for Assessing Long-Term Adherence

The adherence assessment based on the combination of nevirapine (NVP) and its two metabolites (2-hydroxynevirapine and 3-hydroxynevirapine) would more comprehensively and accurately reflect long-term adherence than that of a single prototype. This study aimed to develop a specific, sensitive and selective method for simultaneous detection of the three compounds in hair and explore whether there was consistency among the three compounds in assessing long-term adherence. Furthermore, 75 HIV-positive patients who were taking the NVP drug were randomly recruited and divided into two groups (high-and low-adherence group). All participants self-reported their days of oral drug administration per month and provided their hair strands closest to the scalp at the region of posterior vertex. The concentrations of three compounds in the hair were determined using a developed LC-MS/MS method in multiple reaction monitoring. This method showed good performances in limit of quantification and accuracy with the recoveries from 85 to 115% and in precision with the intra-day and inter-day coefficients of variation within 15% for the three compounds. The population analysis revealed that patients with high-adherence showed significantly higher concentrations than those with low-adherence for all three compounds. There were significantly moderate correlations of nevirapine with 2-hydroxynevirapine and 3-hydroxynevirapin and high correlation between 2-hydroxynevirapine and 3-hydroxynevirapin. The two NVP’s metabolites showed high consistency with NVP in evaluating long-term adherence.

Novel dual HIV maintenance therapy with nevirapine plus lamivudine retain viral suppression through 144 weeks-A proof-of-concept study

OBJECTIVES

The aim of this proof-of-concept study is to test feasibility and efficacy of NVP plus Lamivudine (3TC) as novel simplified HIV maintenance dual therapy (DT) strategy.

METHODS

Patients under combined antiretroviral treatment (cART) with fully suppressed HIV plasma viral load (pVL) >24 months-whereof >6 months on an NVP- containing regimen-were switched to oral NVP plus 3TC for 24 weeks. Patients could then decide whether to continue DT or return to the previous cART. HIV pVL was monitored monthly until week 144. The primary outcome was confirmed viral failure (RNA >100 copies/ml). Low-level detection of HIV-RNA in plasma was compared in each patient with pre-study viral load measurements.

RESULTS

Twenty patients were included, switched to DT and all completed week 24. One patient decided thereafter to discontinue study participation for personal reasons. After a total of 144 observation weeks, none of the patients failed. The frequency of low- level HIV-RNA detection was not different from the period before randomization.

CONCLUSIONS

Our findings are surprising but given the nature of a proof-of-concept study, the results do not support the use of this dual regimen. However, as this dual HIV maintenance strategy was feasible and effective, over a period of 144 weeks, we suggest NVP plus 3TC warrants further evaluation as potential maintenance option in patients tolerating nevirapine. A properly sized multicentre non-inferiority trial is ongoing to further evaluate the value of this DT maintenance strategy.

Twelfth-Position Deuteration of Nevirapine Reduces 12-Hydroxy-Nevirapine Formation and Nevirapine-Induced Hepatocyte Death

Cytochrome P450-dependent metabolism of the anti-HIV drug nevirapine (NVP) to 12-hydroxy-NVP (12-OHNVP) has been implicated in NVP toxicities. We investigated the impact of twelfth-position trideuteration (12-D3NVP) on the hepatic metabolism of and response to NVP. Formation of 12-OHNVP decreased in human (10.6-fold) and mouse (4.6-fold) hepatocytes incubated with 10 μM 12-D3NVP vs NVP. An observed kinetic isotope effect of 10.1 was measured in human liver microsomes. During mouse hepatocyte treatment (400 μM) with NVP or 12-D3NVP, cell death was reduced 30% with 12-D3NVP vs NVP, while glucuronidated and glutathione-conjugated metabolites increased with 12-D3NVP vs NVP. Using mass spectrometry proteomics, changes in hepatocyte protein expression, including an increase in stress marker insulin-like growth factor-binding protein 1 (IGFBP-1), were observed with 12-D3NVP vs NVP. These results demonstrate that while deuteration can reduce P450 metabolite formation, impacts on phase II metabolism and hepatocyte protein expression should be considered when employing deuteration to reduce P450 metabolite-related hepatotoxicity.

Synthesis and evaluation of nevirapine analogs to study the metabolic activation of nevirapine

Nevirapine (NVP) is widely used as a non-nucleoside reverse transcriptase inhibitor of HIV-1, however, it is associated with severe skin and liver injury. The mechanisms of these adverse reactions are not yet clear, but the metabolic activation of NVP is thought to be related to the injury process. Until now, several metabolic activation pathways of NVP have been reported. In this study, in order to identify the reactive metabolite of NVP mainly responsible for CYP inhibition and liver injury, we synthesized five NVP analogs designed to avoid the proposed bioactivation pathway and evaluated their metabolic stabilities, CYP3A4 time-dependent inhibitory activities, and cytotoxicity. As a result, only a pyrimidine analog of NVP, which could avoid the formation of a reactive epoxide intermediate, did not inhibit CYP3A4. Outside of this compound, the other synthesized compounds, which could avoid the generation of a reactive quinone-methide intermediate, inhibited CYP3A4 equal to or stronger than NVP. The pyrimidine analog of NVP did not induce cytotoxicity in HepG2 and transchromosomic HepG2 cells, expressing major four CYP enzymes and CYP oxidoreductase. These results indicated that the epoxide intermediate of NVP might play an important role in NVP-induced liver injury.

Singularities of nevirapine metabolism: from sex-dependent differences to idiosyncratic toxicity

Nevirapine (NVP) is a first-generation non-nucleoside reverse transcriptase inhibitor widely used for the treatment and prophylaxis of human immunodeficiency virus infection. The drug is taken throughout the patient's life and, due to the availability of an extended-release formulation, it is administered once daily. This antiretroviral is one of the scarce examples of drugs with prescription criteria based on sex, in order to prevent adverse reactions. The therapy with NVP has been associated with potentially life-threatening liver and idiosyncratic skin toxicity. Multiple evidence has emerged regarding the formation of electrophilic NVP metabolites as crucial for adverse idiosyncratic reactions. The formation of reactive metabolites that yield covalent adducts with proteins has been demonstrated in patients under NVP-based treatment. Interestingly, several pharmacogenetic- and sex-related factors associated with NVP toxicity can be mechanistically explained by an imbalance toward increased formation of NVP-derived reactive metabolites and/or impaired detoxification capability. Moreover, the haptenation of self-proteins by these reactive species provides a plausible link between NVP bioactivation and immunotoxicity, further supporting the relevance of this toxicokinetics hypothesis. In the current paper, we review the existing knowledge and recent developments on NVP metabolism and their relation to NVP toxicity.

High resolution mass spectrometry-based methodologies for identification of Etravirine bioactivation to reactive metabolites: In vitro and in vivo approaches

Drug bioactivation to reactive metabolites capable of covalent adduct formation with bionucleophiles is a major cause of drug-induced adverse reactions. Therefore, elucidation of reactive metabolites is essential to unravel the toxicity mechanisms induced by drugs and thereby identify patient subgroups at higher risk. Etravirine (ETR) was the first second-generation Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) to be approved, as a therapeutic option for HIV-infected patients who developed resistance to the first-generation NNRTIs. Additionally, ETR came into market aiming to overcome some adverse effects associated with the previously used efavirenz (neurotoxicity) and nevirapine (hepatotoxicity) therapies. Nonetheless, post-marketing reports of severe ETR-induced skin rash and hypersensitivity reactions have prompted the U.S. FDA to issue a safety alert on ETR. Taking into consideration that ETR usage may increase in the near future, due to the possible use of the drug for coinfection with malaria and HIV, the development of reliable prognostic tools for early risk/benefit estimations is urgent. In the current study, high resolution mass spectrometry-based methodologies were integrated with MS³ experiments for the identification of reactive ETR metabolites/adducts: 1) in vitro incubation of the drug with human and rat liver S9 fractions in the presence of Phase I and II co-factors, including glutathione, as a trapping bionucleophile; and 2) in vivo, using urine samples from HIV-infected patients on ETR therapy. We obtained evidence for multiple bioactivation pathways leading to the formation of covalent adducts with glutathione and N-acetyl-L-cysteine. These results suggest that similar reactions may occur with cysteine residues of proteins, supporting a role for ETR bioactivation in the onset of the toxic effects elicited by the drug. Additionally, ETR metabolites stemming from amine oxidation, with potential toxicological significance, were identified in vitro and in vivo. Also noteworthy is the fact that new metabolic conjugation pathways of glucuronide metabolites were demonstrated for the first time, raising questions about their potential toxicological implications. In conclusion, these results represent not only a contribution towards the elucidation of new metabolic pathways of drugs in general but also an important step towards the elucidation of potentially toxic ETR pathways, whose understanding may be crucial for reliable risk/benefit estimations of ETR-based regimens.

Nevirapine-induced liver lipid-SER inclusions and other ultrastructural aberrations

Nevirapine (NVP) therapy is associated with a high risk of serious liver injury and skin rash. Treatment of Brown Norway rats with NVP causes an immune-mediated skin rash. Even though NVP does not cause serious liver injury in wildtype animals, incubation of hepatocytes with NVP leads to the release of presumably danger-associated molecular pattern molecules (DAMPs), which activate macrophages. In this study, we examined the liver biopsies of Brown Norway rats treated with NVP to determine the histologic correlate to the release of DAMPs by hepatocytes. In vivo, debris from necrotic hepatocytes and endothelial cells were present in the liver sinusoids, a condition that can trigger an immune response. In addition to mitochondrial, hepatocytic, and endothelial damage, the drug induced large hepatocytic inclusions composed of lipid droplets surrounded by concentric whorls of smooth endoplasmic reticulum (SER) cisternae-lipid-SER (LSER) inclusions, which were deposited in the sinusoids. NVP is lipid soluble, and these LSER inclusions may be sinks of NVP or its metabolites. LSERs are deposited in the blood stream where they may be picked up by lymph nodes and contribute to initiation of an immune response leading to serious liver injury or skin rash. LSERs migration from liver to the blood stream may signify a novel mechanism of drug exocytosis.

Neuropsychiatric Effects of HIV Antiviral Medications

The development of antiretroviral therapy (ART) has dramatically increased the lifespan of HIV patients but treatment is complicated by numerous adverse effects and toxicities. ART complications include neuropsychiatric, metabolic, gastrointestinal, cardiac, and numerous other toxicities, and clinicians often have to choose one toxicity over another to offer the best medication regimen for a patient. Some antiviral drugs cause significant neuropsychiatric complications, including depression, cognitive impairment, and sleep disturbance. Even in careful studies, it may be difficult to determine which effects are related to the virus, the immune system, or the treatment. Of the six currently marketed classes of antiviral drugs, the nucleoside reverse transcriptase inhibitors and the non-nucleoside reverse transcriptase inhibitors have been most commonly associated with neuropsychiatric complications. Within these classes, certain drugs are more likely to cause difficulty than others. We review the contention regarding the central nervous system (CNS) complications of efavirenz, as well as debate about the role of CNS penetration in drug effectiveness and toxicity. A thorough working knowledge of the neuropsychiatric consequences of ART allows clinicians to tailor treatment more successfully to individual patients as well as to identify ART more quickly as the source of a problem or symptom.

Nevirapine induced mitochondrial dysfunction in HepG2 cells

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor frequently used in combination with other antiretroviral agents for highly active antiretroviral therapy (HAART) of patients infected with the human immunodeficiency virus type 1 (HIV-1). However NVP can cause serious, life-threatening complications. Hepatotoxicity is one of the most severe adverse effects, particularly in HIV patients with chronic hepatitis C virus co-infection as these patients can develop liver toxicity after a relatively short course of treatment. However, the mechanism of NVP-associated hepatotoxicity remains unclear. This study sought to investigate the effect of NVP on protein expression in liver cells using a proteomic approach. HepG2 cells were treated or not treated with NVP and proteins were subsequently resolved by two-dimensional gel electrophoresis. A total of 33 differentially regulated proteins were identified, of which nearly 40% (13/33) were mitochondrial proteins. While no obvious differences were observed between NVP treated and untreated cells after staining mitochondria with mitotracker, RT-PCR expression analysis of three mitochondrially encoded genes showed all were significantly up-regulated in NVP treated cells. Mitochondrial dysfunction was observed in response to treatment even with slightly sub-optimal therapeutic treatment concentrations of NVP. This study shows that NVP induces mitochondrial dysregulation in HepG2 cells.

Renal histoarchitectural changes in nevirapine therapy: possible role of kolaviron and vitamin C in an experimental animal model

BACKGROUND

There is paucity of literature regarding the nephrotoxicity of antiretroviral drugs and its interaction with plant-based adjuvants. This study investigates the attenuating effect of kolaviron in nevirapine-therapy on the histological structure of the kidneys of adult male Sprague-Dawley rats.

OBJECTIVE

To determine the attenuating influence of anti-oxidant status of kolaviron on the kidneys of experimental animals following nevirapine administration.

METHODS

Forty eight pathogen-free adult male Sprague-Dawley rats were used for this study. The animals were divided into 8 groups (A-H) with 6 animals in each group. Group A was given normal saline as the control; group B was given nevirapine; group C was given kolaviron; group D was given vitamin C; group E was given nevirapine and kolaviron; group F was given nevirapine and vitamin C; Group G was given nevirapine and kolaviron (kolaviron withdrawn after day 28) and group H was given corn oil. The experiment lasted 56 days after which the animals were sacrificed, blood samples were collected through cardiac puncture for serum analysis and the kidneys were harvested and prepared for H& E histological examination.

RESULTS

Nevirapine caused histoarchitectural damage in the glomerular apparatus with resultant increase in kidney/body weight ratio (p<0.001). Adjuvant treatment with kolaviron attenuated these nephrotoxic effects. Serum anti-oxidant enzyme (SOD and CAT) activities were significantly reduced in kolaviron and vitamin C treated animals, whereas in the nevirapine group these parameters were significantly elevated (P<0.05). However, co-administration of nevirapine and vitamin C did not improve the histoarchitecture of the kidney.

CONCLUSION

Adjuvant treatment with kolaviron (an anti-oxidant) for 56 days appears to attenuate the nephrotoxicity of nevirapine in this model.

Mechanisms of Drug-Induced Hepatotoxicity

Drug-induced hepatotoxicity (DIH) is a significant cause of acute liver failure and liver transplantation. Diagnosis is challenging due to the idiosyncratic nature, its presentation in the form of other liver disease, and the lack of a definite diagnostic criteria. Generation of reactive metabolites, oxidative stress, and mitochondrial dysfunction are common mechanisms involved in DIH. Certain risk factors associated with a drug and within an individual further predispose patients to DIH.

Severe antiretroviral-associated skin reactions in South African patients: a case series and case-control analysis

PURPOSE

Severe skin reactions may complicate combination antiretroviral therapy (cART). Nevirapine is known to be associated with severe skin reactions, but there are conflicting data on risk factors in African patients. We reviewed cases of severe skin reactions admitted to a tertiary hospital in Cape Town, South Africa. We identified associations with severe skin reactions in patients on cART.

METHODS

We described severe skin reaction cases in patients taking cART admitted to Groote Schuur Hospital in Cape Town, South Africa, between 2006 and 2012. We included those patients who developed a severe skin reaction within 120 days of cART initiation in a case-control analysis. We identified control patients matched on date of cART initiation and primary care facility by linkage with the Western Cape electronic provincial HIV database. We conducted a conditional (fixed effects) logistic regression modelling.

RESULTS

We identified 169 severe skin reactions in patients on cART. The most common presentations were Stevens Johnson syndrome/toxic epidermal necrolysis (49%) and drug hypersensitivity syndrome (36%). One hundred forty-one patients were female, of which 27 were pregnant. Median duration of hospitalization was 12 days (interquartile range 8 to 19) and six patients died. We included 91 cases and 361 matched controls in the analysis. Severe skin reaction was associated with nevirapine exposure, adjusted odds ratio of 7.6 (95%CI 3.7 to 15.7) and with pregnancy, adjusted odds ratio 3.7 (95%CI 1.3 to 10.8) compared with men.

CONCLUSIONS

Severe skin reactions resulted in prolonged admission to hospital in this setting. We found that nevirapine use and pregnancy are independently associated with severe skin reaction. Copyright © 2016 John Wiley & Sons, Ltd.

HIV-Associated Toxic Epidermal Necrolysis at San Francisco General Hospital

OBJECTIVES

We sought to characterize recent cases of toxic epidermal necrolysis (TEN) in HIV-infected patients at San Francisco General Hospital (SFGH), a large HIV referral center.

METHODS

This was a retrospective analysis of HIV-infected patients diagnosed with TEN from January 2001 to May 2014 at SFGH.

RESULTS

Ten cases of TEN were identified, 50% of which occurred in HIV-infected individuals. Among the HIV-associated cases, causative agents were trimethoprim-sulfamethoxazole (TMP-SMX; n = 2), atovaquone, clindamycin, and fluconazole. No antiretroviral agents were implicated.

CONCLUSION

Although limited by small sample size, our experience is reflective of the well-recognized increased incidence of TEN in HIV-positive patients and suggests that antimicrobial agents, particularly TMP-SMX, are the most common causative agents in this population. As 3 of the 5 HIV-associated TEN cases were caused by potentially inappropriate or unnecessary use of antibiotics, our experience highlights the importance of judicious use of systemic medications in populations susceptible to severe adverse drug reactions.

Clinical Utility of Current NNRTIs and Perspectives of New Agents in This Class under Development

Highly active antiretroviral therapy (HAART) has significantly reduced the number of deaths caused by AIDS. However, the antiviral efficacy of HAART comprising protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs) is frequently accompanied by a decrease in patients' quality of life. PI-based therapies often fail due to poor adherence caused by heavy pill burden, complex dosing schedules and undesirable side effects. The current trend is to switch from PI-based to PI-sparing regimens consisting of non-nucleoside reverse transcriptase inhibitors (NNRTIs) and NRTIs. Despite some encouraging results from NNRTI-containing therapies, two major concerns in using the currently available NNRTIs remain: 1) low genetic barrier to the emergence of resistance and 2) cross-resistance due to single mutations that often render the whole class of NNRTIs ineffective. Clearly, new and improved NNRTIs are needed to address these concerns.

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.

Population pharmacokinetics of nevirapine in Malaysian HIV patients: a non-parametric approach

AIMS

Nevirapine is the first non-nucleoside reverse-transcriptase inhibitor approved and is widely used in combination therapy to treat HIV-1 infection. The pharmacokinetics of nevirapine was extensively studied in various populations with a parametric approach. Hence, this study was aimed to determine population pharmacokinetic parameters in Malaysian HIV-infected patients with a non-parametric approach which allows detection of outliers or non-normal distribution contrary to the parametric approach.

METHODS

Nevirapine population pharmacokinetics was modelled with Pmetrics. A total of 708 observations from 112 patients were included in the model building and validation analysis. Evaluation of the model was based on a visual inspection of observed versus predicted (population and individual) concentrations and plots weighted residual error versus concentrations. Accuracy and robustness of the model were evaluated by visual predictive check (VPC). The median parameters' estimates obtained from the final model were used to predict individual nevirapine plasma area-under-curve (AUC) in the validation dataset. The Bland-Altman plot was used to compare the AUC predicted with trapezoidal AUC.

RESULTS

The median nevirapine clearance was of 2.92 L/h, the median rate of absorption was 2.55/h and the volume of distribution was 78.23 L. Nevirapine pharmacokinetics were best described by one-compartmental with first-order absorption model and a lag-time. Weighted residuals for the model selected were homogenously distributed over the concentration and time range. The developed model adequately estimated AUC.

CONCLUSIONS

In conclusion, a model to describe the pharmacokinetics of nevirapine was developed. The developed model adequately describes nevirapine population pharmacokinetics in HIV-infected patients in Malaysia.

The Combination of Anti-CTLA-4 and PD1-/- Mice Unmasks the Potential of Isoniazid and Nevirapine To Cause Liver Injury

Our laboratory recently reported what we believe is the first valid animal model of idiosyncratic drug-induced liver injury (IDILI) by treating PD1-/- mice with an anti-CTLA-4 antibody and amodiaquine (AQ). PD1 and CTLA-4 are important immune checkpoint receptors that are involved in inducing immune tolerance. This model was able to produce significant liver injury that looks very similar to the liver injury seen in humans. Although this model was shown to work with AQ, the question becomes whether blocking immune tolerance would unmask the potential of other drugs to cause IDILI. In this study, we tested isoniazid and nevirapine, both drugs with significant histories of causing IDILI in humans even though they do not cause significant injury in animals with doses that result in therapeutic blood levels. Both drugs in combination with these immune checkpoint inhibitors caused mild but significant delayed onset liver injury, which is similar to the mild injury that they can cause in humans. INH-induced liver injury in this model was associated with an increase in NK cells, while NVP-induced liver injury was associated with a greater increase in CD8 T cells. Although the liver injury caused by these drugs in this model was mild, these results suggest that impairing immune tolerance may be a general method for unmasking the potential of drugs to cause IDILI and therefore provide a screening tool for drug development.

Pharmacoepidemiology of antiretroviral drugs in a teaching hospital in Lagos, Nigeria

OBJECTIVE

Prescribing, adherence, and adverse drug events to HAART in a large antiretroviral programme in Lagos was evaluated.

DESIGN

A retrospective 5 year open cohort study.

SETTING

The AIDS Prevention Initiative in Nigeria (APIN) clinic at LUTH is one of the United States Presidential Emergency Plan for AIDS Relief (PEP-FAR) funded centers for HIV relief program in Nigeria Participants The case files of 390 patients on HAART and attending the APIN clinic were reviewed sequel to random selection.

MAIN OUTCOME MEASURES

Demographics of the patients and pattern of antiretroviral (ARV) combination drugs prescribed were extracted from their case files. The details of the adverse drug events (ADEs) were extracted from drug toxicity forms regularly filled for each patient. A Chi-square test with Yates correction was used to determine the association between adherence and therapeutic outcome.

RESULTS

A total of 2944 prescriptions were assessed. Zidovudine + lamivudine + nevirapine (35.87%) and stavudine + lamivudine + nevirapine (35.63%) were the most frequently prescribed combinations. Over 2000 ADEs were reported with cough (13.3%), fever (8.75%) and skin rashes (8.01%) being the most frequently reported. Drug adherence was associated with good therapeutic outcome (χ(2) = 115.60, p<0.0001).

CONCLUSIONS

Zidovudine + lamivudine + nevirapine was the most frequently prescribed ARV combination. Cough was the most frequently reported ADE. Interventions aimed at rational prescribing of ARV drugs and improving adherence to antiretroviral drugs is essential for good therapeutic outcome in the treatment of HIV infection.

Role of dermatology in pharmacogenomics: drug-induced skin injury

Different individuals may respond diversely to the same drug, in terms of efficacy and toxicity. Adverse drug reactions cause about 6% of all hospital admissions and account for up to 9% of hospitalization costs. Drug-induced skin injury (DISI) is the most common presentation of adverse drug reactions, ranging from maculopapular eruptions to severe adverse cutaneous drug reactions (SCARs) with mortality of up to 40%. Specific genetic polymorphisms confer susceptibility to different types of DISI. Identifying patients genetically at risk for SCARs is one of the goals of pharmacogenomics. In this article, the aspects of clinical dermatology relevant to the pharmacogenetics of DISI are reviewed. Many SCARs are now preventable, with consequent reduction of morbidity, mortality and healthcare costs.

Antiviral drug allergy

Antiviral drugs used to treat HIV and hepatitis C are common causes of delayed drug hypersensitivities for which many of the more severe reactions have been recently shown to be immunogenetically mediated such as abacavir hypersensitivity where HLA-B(∗)57:01 is now used routinely as a screening test to exclude patients carrying this allele from abacavir prescription. Most antiviral drug allergies consist of mild to moderate delayed rash without other serious features (eg, fever, mucosal involvement, blistering rash, organ impairment. In these cases treatment can be continued with careful observation and symptomatic management and the discontinuation rate is low.

HIV therapy-the state of art

HIV Attachment. In this cross section, HIV is shown at the top and a target cell is shown at the bottom in blues. HIV envelope protein (A) has bound to the receptor CD4 (B) and then to coreceptor CCR5 (C), causing a change in conformation that inserts fusion peptides into the cellular membrane Antiretroviral therapy changed the face of HIV/AIDS from that of soon and certain death to that of a chronic disease in the years following introduction of highly active antiretroviral therapy in 1995-1996 (initially termed HAART, but now most often abbreviated to ART since not all combinations of regimens are equally active). Since then, many new agents have been developed and introduced in response to problems of resistance, toxicity, and tolerability, and great advances have been achieved in accessibility of HIV drugs in resource-poor global regions. Potential challenges that providers of HIV therapy will face in the coming decade include continuing problems with resistance, especially where access to drugs is inconsistent, determining how best to combine new and existing agents, defining the role of preventive treatment (pre-exposure prophylaxis or PrEP), and evaluating the potential of strategies for cure in some populations.

Quinoid derivatives of the nevirapine metabolites 2-hydroxy- and 3-hydroxy-nevirapine: activation pathway to amino acid adducts

Quinoid electrophiles from the nevirapine metabolites, 2-OH- and 3-OH-nevirapine, react with nitrogen-based bionucleophiles yielding covalent adducts.

Human sulfotransferase 1A1-dependent mutagenicity of 12-hydroxy-nevirapine: the missing link?

Nevirapine (NVP) is a frequently used anti-HIV drug. Despite its efficacy, NVP has been associated with serious skin and liver injuries in exposed patients and with increased incidences of hepatoneoplasias in rodents. Current evidence supports the involvement of reactive metabolites in the skin and liver toxicities of NVP, formed by cytochrome P450-mediated oxidations and/or subsequent phase II sulfonation. However, to date, standard in vitro genotoxicity tests have provided no evidence that NVP is either mutagenic or clastogenic. The human sulfotransferase 1A1-dependent mutagenicity of 12-hydroxy-NVP, one of the major metabolites of NVP, is demonstrated here.

Incidence and risk factors of skin rashes and hepatotoxicity in HIV-infected patients receiving nevirapine-containing combination antiretroviral therapy in Taiwan

OBJECTIVES

To retrospectively investigate the incidence of and factors associated with skin rashes and hepatotoxicity in HIV-infected patients who initiated combination antiretroviral therapy (cART) containing nevirapine plus two nucleos(t)ide reverse-transcriptase inhibitors.

METHODS

The medical records of HIV-infected adult patients who started nevirapine-containing cART and continued follow-up for ≥4 weeks were reviewed at two hospitals in Taiwan between 2000 and 2012. Clinical data obtained at baseline and during follow-up were collected and analyzed.

RESULTS

Of the 338 patients included in the analysis, 13.0% tested positive for hepatitis B virus surface antigen and 7.9% tested positive for anti-hepatitis C virus antibody. The incidence of rashes was 21.6% and of hepatotoxicity was 25.5%. On multiple logistic regression analysis, a two-fold or greater increase from the upper limit of normal levels of aminotransferases at baseline was associated with rashes (adjusted odds ratio (aOR) 3.74, 95% confidence interval (CI) 1.56-8.96); higher CD4 counts (aOR for per 50 cells/μl increase 1.51, 95% CI 1.12-2.03) and the concurrent use of trimethoprim/sulfamethoxazole (aOR 14.01, 95% CI 1.98-98.95) were associated with hepatotoxicity.

CONCLUSIONS

Abnormal liver function at baseline was significantly associated with skin rashes, while a higher CD4 count and the concurrent use of trimethoprim/sulfamethoxazole were associated with hepatotoxicity after the initiation of nevirapine-containing cART in HIV-infected Taiwanese patients.

Evaluating the utility of early laboratory monitoring of antiretroviral-induced haematological and hepatic toxicity in HIV-infected persons in Cameroon

Background

The antiretroviral therapy (ART) program of Cameroon recommends routine laboratory monitoring of haematological toxicity if a regimen contains zidovudine (AZT) and of hepatotoxicity for NVP-containing regimens on the 15^th day after ART initiation. This study aimed to assess the relevance of this repeated laboratory measurements considered to be precocious, inaccessible and unavailable in a resource limited setting.

Methods

A retrospective cohort of HIV-infected patients of age 15 years and above enrolled for first line ART at The Regional Hospital of Nkongsamba in Cameroon. We monitored liver transaminases and blood cell indices after two weeks of ART initiation for any significant change from baseline. Factors associated with abnormal changes were examined using a multivariable logistic regression model with random effects.

Results

Enrolled were 154 patients of whom 105 (68.2%) were females. The mean ALAT (alanine aminotransferase) level at baseline was 17.87 ± 20.48 U/L increasing to 19.25 ± 12.01 U/L at two weeks of follow-up (p = 0.53) while the mean ASAT (aspartate aminotransferase) level increased from 17.32 ± 11.87 U/L at baseline to 21.02 ± 14.12 U/L at two weeks of follow-up (p = 0.02). We observed a drop in the mean haemoglobin concentration from 10.86 ± 2.63 g/dL at baseline to 10.36 ± 1.92 g/dL at the second week of follow-up (p = 0.02). The prevalence of elevated liver enzymes and anaemia after two weeks of treatment were 7.5% and 39.2% respectively. Stavudine containing regimens were most likely to induce hepatotoxicity [adjusted Odd Ratio (aOR) = 36.52, 95% CI: 1.44-924.38, p=0.029]. Baseline anaemia (aOR=60.08, 95% CI: 13.36-270.20, p < 0.0001) and body weight ≥ 60kg (aOR=0.28, 95% CI: 0.09-0.83, p = 0.02) were associated with anaemia at follow-up.

Conclusion

There was no significant rise in the mean level of transaminases and thus scheduling their routine monitoring at the end of the second week could be skipped. Conversely, the drop in mean haemoglobin level had little clinical importance but the high prevalence of anaemia after a fortnight on treatment suggests a targeted instead of a routine monitoring; focusing on the high risk population with baseline anaemia and low body weight.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-519) contains supplementary material, which is available to authorized users.

HLA Class I restricted CD8+ and Class II restricted CD4+ T cells are implicated in the pathogenesis of nevirapine hypersensitivity

OBJECTIVES

This study sought to examine nevirapine hypersensitivity (NVP HSR) phenotypes and their relationship with differing major histocompatibility complex (MHC) Class I and Class II alleles and the associated CD4 and CD8 T-cell NVP-specific responses and their durability over time.

METHODS

A retrospective cohort study compared HIV-positive patients with NVP HSR, defined by fever and hepatitis and/or rash, with those tolerant of NVP for more than 3 months. Covariates included class I (HLA-A, B, C) and class II (HLA-DR) alleles. Cellular studies examined NVP-specific CD4 and CD8 T-cell responses by interferon-gamma (IFNγ) ELISpot assay and intracellular cytokine staining (ICS).

RESULTS

NVP HSR occurred in 19 out of 451 (4%) NVP-exposed individuals between March 1993 and December 2011. HLA associations were phenotype dependent with HLA-DRB1*01 : 01 associated with hepatitis (P = 0.02); HLA-B*35 : 01 and HLA-Cw4 associated with cutaneous NVP HSR (P = 0.001, P = 0.01), and HLA-Cw*08 was associated with NVP HSR with eosinophilia (P = 0.04) and multisystemic NVP HSR (P = 0.02). NVP-specific INFγ responses waned significantly more than 3 months from the original reaction and were diminished or completely abrogated when either CD4 or CD8 T cells were depleted from the peripheral blood mononuclear cells culture.

CONCLUSION

The association of specific class I and II allele pairings with specific phenotypes of NVP HSR, and cellular studies showing both CD4 and CD8 T-cell NVP-specific responses suggest that specific combinations of NVP reactive class I restricted CD8 and class II restricted CD4 T cells contribute to the immunopathogenesis of NVP HSR.

Genotyping for severe drug hypersensitivity

Over the past decade, there have been significant advances in our understanding of the immunopathogenesis and pharmacogenomics of severe immunologically-mediated adverse drug reactions. Such T-cell-mediated adverse drug reactions such as Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), drug-induced liver disease (DILI) and other drug hypersensitivity syndromes have more recently been shown to be mediated through interactions with various class I and II HLA alleles. Key examples have included the associations of HLA-B*15:02 and carbamazepine induced SJS/TEN in Southeast Asian populations and HLA-B*57:01 and abacavir hypersensitivity. HLA-B*57:01 screening to prevent abacavir hypersensitivity exemplifies a successful translational roadmap from pharmacogenomic discovery through to widespread clinical implementation. Ultimately, our increased understanding of the interaction between drugs and the MHC could be used to inform drug design and drive pre-clinical toxicity programs to improve drug safety.

Neurological and psychiatric adverse effects of antiretroviral drugs

Antiretroviral drugs are associated with a variety of adverse effects on the central and peripheral nervous systems. The frequency and severity of neuropsychiatric adverse events is highly variable, with differences between the antiretroviral classes and amongst the individual drugs in each class. In the developing world, where the nucleoside reverse transcriptase inhibitor (NRTI) stavudine remains a commonly prescribed antiretroviral, peripheral neuropathy is an important complication of treatment. Importantly, this clinical entity is often difficult to distinguish from human immunodeficiency virus (HIV)-induced peripheral neuropathy. Several clinical trials have addressed the efficacy of various agents in the treatment of NRTI-induced neurotoxicity. NRTI-induced neurotoxicity is caused by inhibition of mitochondrial DNA polymerase. This mechanism is also responsible for the mitochondrial myopathy and lactic acidosis that occur with zidovudine. NRTIs, particularly zidovudine and abacavir, may also cause central nervous system (CNS) manifestations, including mania and psychosis. The non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz is perhaps the antiretroviral most commonly associated with CNS toxicity, causing insomnia, irritability and vivid dreams. Recent studies have suggested that the risk of developing these adverse effects is increased in patients with various cytochrome P450 2B6 alleles. Protease inhibitors cause perioral paraesthesias and may indirectly increase the relative risk of stroke by promoting atherogenesis. HIV integrase inhibitors, C-C chemokine receptor type 5 (CCR5) inhibitors and fusion inhibitors rarely cause neuropsychiatric manifestations.

Drug hypersensitivity in human immunodeficiency virus-infected patient: challenging diagnosis and management

Human immunodeficiency virus (HIV)-infected patients present complex immunological alterations. Multiple drugs that usually prescribed for prevention or treatment of opportunistic infections and antiretroviral pose these patients a higher risk of developing drug hypersensitivity. All antiretroviral agents and drugs to treat opportunistic infections have been reported to cause drug hypersensitivity reactions. Allergic reactions with antiretroviral are not restricted to older agents, although newer drugs usually more tolerated. Cutaneous adverse drug reactions are the most common manifestation of drug hypersensitivity in HIV, typically manifesting as maculopapular rash with or without systemic symptoms in the presence or absence of internal organ involvement. The onset of an allergic reaction is usually delayed. Severe drug hypersensitity reactions as erythema multiforme, Stevens Johnson syndrome and toxic epidermal necrolysis develop more often in HIV-infected patients compared to other populations. Mild to moderate rash without systemic symptom or organ involvement usually do not need drug discontinuation. Appropriate diagnosis and management of drug hypersensitivity reactions are essential, especially in patients with very low CD4+ T-cell count and multiple opportunistic infections. Clinicians should aware of different half-life of each drug when decided to stop the drug. Knowledge of the metabolism, recognition of the risk factors, and the ability to suggest the probability of particular drug as causative are also important points. A step wise rechallenge test or desensitization with the offending drug might be a preferable action and more commonly used in managing drug hypersensitivity in HIV-infected patients. Desensitization protocols have been successfully done for several antiretroviral and opportunistic infection drugs.

Nevirapine in the treatment of HIV

Nevirapine (Viramune, Boehringer Ingelheim Ltd) is the first marketed non-nucleoside reverse transcriptase inhibitor. As with any antiretroviral drug, nevirapine should always be used as part of a fully suppressive regimen. Clinical studies have shown that nevirapine-containing regimens may accomplish durable virological and immunological responses in approximately half of all antiretroviral-naive patients. It can also be successfully used as a component of salvage therapies and as a part of a strategy to simplify protease inhibitor-containing regimens. Nevirapine has a beneficial effect on the lipid profile in both treatment-naive and -experienced patients. Nevirapine also has an important role in preventing mother-to-child transmission of HIV. It is usually well-tolerated with rash and liver toxicity being the most frequently reported adverse events. Nevirapine interacts with cytochrome P450 enzymes both as a substrate and as an inducer. For this reason, therapeutic drug monitoring should be recommended whenever nevirapine is used with protease inhibitors, methadone (Methadose, Rosemont Pharmaceuticals Ltd), oral contraceptives, rifampicin (Rifadin, Aventis Pharma) and other potentially interacting drugs. Nevirapine-resistant mutations are common to the non-nucleoside reverse transcriptase inhibitor family and they include K103N, V106A, Y181C, Y188C and G190A. A better understanding of the nevirapine profile will certainly contribute to ensuring that its clinical application becomes more effective and beneficial.

Stevens-Johnson syndrome and HIV in children in Swaziland

BACKGROUND

Stevens-Johnson syndrome (SJS) can be a severe and life-threatening reaction with many potential causes, including multiple medications used in HIV care and treatment. Specific risk factors, especially in children, are not currently well-understood.

METHODS

We describe a series of cases of SJS that occurred from 2006 to 2010 in an HIV-focused clinic in Mbabane, Swaziland. The electronic medical and pharmacy records of all pediatric patients <20 years old were reviewed to identify cases of SJS. Patient demographic, immunosuppression and outcome data were also collected.

RESULTS

A total of 19 cases of SJS were documented. Eighty-four percent of cases were attributed to nevirapine (NVP) exposure whereas the remaining cases were caused by cotrimoxazole (11%) and efavirenz (5%). Median symptom onset was 22 days after initiation of the offending medication (interquartile range = 14-25 days). At time of SJS, 84% had advanced or severe immunosuppression. Forty-two percent of patients required hospitalization, and no SJS-associated deaths were known to occur. Use of efavirenz was attempted in 8 NVP-associated cases after SJS resolution and was successful in all except 1.

CONCLUSIONS

SJS occurrence was rare in this population, with the majority of cases being associated with NVP. All occurred within 32 days of medication initiation, providing a target window for intensified monitoring and anticipatory guidance. SJS can occur in children at any age, with any level of immunosuppression, and can occur during the lead-in dosing period of NVP.

DRESS Syndrome due to Nevirapine Treated with Methylprednisolone

Nevirapine-induced DRESS syndrome is uncommon but a potentially life-threatening condition, with significant morbidity and mortality rates due to multiple-organ involvement. The authors report a case of a 47-year-old HIV-infected female patient who presented with fever, right hypochondrium pain, jaundice, and skin rash. The Nevirapine-induced DRESS syndrome was suspected based on clinical presentation and RegiSCAR scoring system. This case highlights the need for a high index of clinical suspicion among HIV-infected patients with severe skin eruption and systemic symptoms.