Antiretroviral Drug Exposure Research Articles

Assessing the risk of birth defects associated with atazanavir exposure in pregnancy

Purpose of the study: The Antiretroviral Pregnancy Registry (APR) is an international collaborative operation which utilizes a prospective exposure-registration design to study antiretroviral (ARV) drug exposures during pregnancy. This study assessed the potential for human teratogenic risk of atazanavir (ATV), a protease inhibitor used to treat HIV infection in combination with other ARV agents. ATV exposures are increasingly reported to the APR in this population, reinforcing the need to better understand the risk of birth defects. Supplement: Abstracts of the Tenth International Congress on Drug Therapy in HIV Infection http://www.biomedcentral.com/content/pdf/1758-2652-13-S4-info.pdf Conference: Tenth International Congress on Drug Therapy in HIV Infection 7-11 November 2010 Glasgow, UK (Published: 8 November 2010) doi:10.1186/1758-2652-13-S4-P113 Cite this article as: Esker et al.: Assessing the risk of birth defects associated with atazanavir exposure in pregnancy. Journal of the International AIDS Society 2010 13(Suppl 4):P113. Full text: PubMed Central: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3112888/

Effect of Maternal HIV-1 Status and Antiretroviral Drugs on Haematological Profiles of South African Infants in Early Life

Maternal HIV-1 status and antiretroviral drug exposure may influence the haematological profiles of infants. We recruited infants from 118 uninfected control women and from 483 HIV-1 infected women who received no antiretroviral drugs (n=28), or received single-dose Nevirapine (sdNVP) (n=424) or triple-drug combination therapy (n=31) to reduce HIV-1 transmission. Blood was drawn from infants within 24 hours of delivery or 6-12 weeks post-delivery and full blood counts performed using a fully automated AcT-5-diff haematology analyser and reference controls. Exposed uninfected (EU; no NVP) differed from control infants only in having lower basophil counts and percentages. In all infant groups, leukocyte profiles showed characteristic quantitative changes with age in the first 6 weeks of life. HIV-1 infected infants displayed by 6 weeks elevations in white blood cells, lymphocyte, monocyte and basophil counts, and monocyte and basophil percentages, when compared to EU infants. At birth EU NVP-treated infants exhibited elevated monocyte percentages and counts and basophil counts that did not persist at 6 weeks. Interestingly, EU newborns of mothers with high CD4 counts (> 500 cells/μl) that had taken sdNVP had significantly elevated white blood cell, monocyte and basophil counts when compared to newborn infants of mothers with similar CD4 counts that had not taken sdNVP; this was not evident in infants of mothers with CD4 counts <200 cells/μl. These previously undescribed features may affect immune response capability in early life and clinical consequences of such changes need to be further investigated.

Efavirenz is associated with severe vitamin D deficiency and increased alkaline phosphatase

To identify factors (including exposure to specific antiretroviral drugs) associated with severe vitamin D deficiency (VDD) in HIV-infected individuals and to explore the effects of severe VDD and antiretroviral drug exposure on serum alkaline phosphatase (ALP) as surrogate marker of bone turnover. Cross-sectional survey of vitamin D status among HIV-infected patients attending for routine clinical care at a large London HIV clinic. Severe VDD was defined as 25(OH)D levels of less than 10 microg/l (<25 nmol/l). Multivariate logistic regression analysis was used to identify factors associated with severe VDD and upper quartile ALP levels. Vitamin D levels were measured in 1077 patients and found to be suboptimal in 91%. One-third of patients had severe VDD. Black ethnicity, sampling in winter, nadir CD4 cell count less than 200 cells/microl, and exposure to combination antiretroviral therapy were associated with severe VDD. In analyses restricted to patients on combination antiretroviral therapy, current efavirenz use was significantly associated with severe VDD [adjusted odds ratio 2.0 (95% confidence interval 1.5-2.7)]. Current tenofovir [adjusted odds ratio 3.5 (95% confidence interval 2.3-5.2)] and efavirenz use [adjusted odds ratio 1.6 (95% confidence interval 1.02-2.4)], but not severe VDD [odds ratio 1.1 (0.8-1.5)], were associated with increased bone turnover (upper quartile ALP). Efavirenz was associated with severe VDD, a condition associated with multiple adverse health outcomes, and efavirenz and tenofovir with increased ALP. The clinical significance of these findings requires further investigation, given the widespread use of efavirenz and tenofovir in first-line combination antiretroviral therapy.

Positive and Negative drug Selection Pressures on the N348I Connection Domain Mutation: New Insights from in vivo Data

There is conflicting evidence on specific reverse transcriptase inhibitors to which the N348I mutation in the connection domain of HIV type-1 reverse transcriptase confers resistance. Here, we examined associations between the emergence of N348I and antiretroviral history in a large clinical database. We analysed 5,353 resistance tests (that were sequenced beyond codon 348) among 2,266 antiretroviral-experienced patients. Associations between N348I and individual antiretroviral drug exposure were estimated using a matched case-control approach. Cases were defined as the first resistance test where N348I was detected; for each case, the 10 closest (in calendar time) N348N tests were selected as controls. Odds ratios (ORs) adjusted for effects of all other drugs were estimated by conditional logistic regression. N348I was detected in 198 (8.7%) cases. Drugs that were statistically significantly positively associated with N348I were efavirenz (OR 1.55, 95% confidence interval [CI] 1.08-2.23; P=0.017) and nevirapine (OR 2.06, 95% CI 1.49-2.85; P<0.001). Tenofovir disoproxil fumarate (TDF) was significantly negatively associated (OR 0.27, 95% CI 0.15-0.48; P<0.001) with N348I. Similar findings were observed when the analysis was repeated to include only those tests within 2 years of the resistance test. Effects for zidovudine and stavudine were evident only in an additional analysis, which considered exposure to both drugs jointly within 2 years prior to the resistance test: exposure to zidovudine alone (OR 4.61, 95% CI 1.83-11.61; P<0.001) and exposure to stavudine alone (OR 3.39, 95% CI 1.32-8.71; P=0.011). This is the first clinical evidence to suggest that efavirenz might select for N348I in addition to nevirapine, that stavudine might select for N348I in addition to zidovudine and that TDF might protect against the mutation.

Role of viral replication, antiretroviral therapy, and immunodeficiency in HIV-associated atherosclerosis

HIV-seropositive patients are at higher risk for atherosclerosis than HIV-seronegative persons. This has been variably attributed to antiretroviral drug toxicity, immunodeficiency, and/or HIV-associated inflammation. To evaluate the contributions of these factors to HIV-associated atherosclerosis, we assessed carotid artery intima-media thickness in a diverse cohort of HIV-seronegative and seropositive adults, including a unique group of HIV-infected patients who were untreated, had undetectable viral loads, and had preserved CD4 T-cell counts (HIV controllers). Carotid intima-media thickness was measured in 494 participants, including 33 HIV controllers and 93 HIV-seronegative controls. HIV controllers had higher intima-media thickness than seronegative controls even after adjustment for traditional risk factors (P = 0.003). Intima-media thickness in controllers was similar to antiretroviral-untreated patients with detectable viremia. Across all participants, intima-media thickness was strongly associated with the presence of HIV disease rather than viral load or CD4 T-cell count. C-reactive protein was higher in HIV controllers than HIV-seronegative persons. Antiretroviral drug exposure was also associated with higher intima-media thickness. Increased atherosclerosis with HIV infection can occur in the absence of antiretroviral therapy, detectable viremia, or overt immunodeficiency. Chronic inflammation - which is higher in controllers than in HIV-uninfected persons - may account for early atherosclerosis in these patients.

HIV-1 integrase polymorphisms are associated with prior antiretroviral drug exposure

In a recent summary of integrase sequences, primary integrase inhibitor mutations were rare. In a review of integrase inhibitor-naïve Australian HIV-1 sequences, primary mutations were not identified, although the accessory mutation G140S was detected. A link with previous antiretroviral therapy, intra-subtype B divergence across the integrase gene and transmission of integrase polymorphisms were also noted. Based on these findings, we would recommend ongoing surveillance of integrase mutations, and integrase region sequencing for patients prior to commencement of integrase inhibitors.

Simplification Strategies to Reduce Antiretroviral drug Exposure: Progress and Prospects

Current U.S. guidelines for initial therapy of HIV type-1 (HIV-1) infection recommend daily, lifelong treatment with a combination of three antiretroviral drugs consisting of two nucleoside analogue reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. Although this approach has been successful in reducing morbidity and mortality from HIV-1 infection, concerns remain about adverse events from chronic drug exposure, the requirement for daily medication adherence, the risk of HIV-1 drug resistance and high treatment costs. The availability of antiretrovirals that are coformulated and dosed once daily have reduced pill burden and have simplified dosing schedules, but have not lowered drug exposure or cost. These limitations have stimulated research into drug-sparing strategies including intermittent therapy and simplified maintenance regimens. Randomized clinical trials have shown greater mortality with intermittent therapy compared with continuous therapy leading to rejection of this strategy. Pilot studies of simplified maintenance therapy with a ritonavir-boosted protease inhibitor alone have shown more promise, although concerns remain. This article reviews progress in the simplification of antiretroviral therapy, recent clinical trial results and prospects for the future.

HIV Pharmacogenetics in Clinical Practice: Recent Achievements and Future Challenges

It has long been recognized that drug metabolism and drug toxicity may vary greatly between individuals, affecting both efficacy and toxicity. Pharmacogenetics could benefit HIV therapeutics because of the high prevalence of drug-related adverse events and the long term nature and complexity of combination therapy. In recent years a number of associations between human genetic variants and predisposition to drug toxicity and risk of virologic failure have been described. This review summarizes the existing literature on pharmacogenetic determinants of antiretroviral drug exposure, toxicity, and activity. Studies across the world have consistently demonstrated that HLA-B*5701 predicts the likelihood of hypersensitivity reactions to abacavir. As a consequence, pharmacogenetic screening for HLA-B*5701 has entered routine clinical practice and is recommended in most guidelines before starting an abacavir containing regimen. Moreover, prospective clinical trials and cohort studies have identified a number of associations between human genetic variants, drug metabolism and toxicity. These include nevirapine hypersensitivity and hepatotoxicity, efavirenz plasma levels and central nervous system side effects, indinavir- and atazanavir-associated hyperbilirubinemia, antiretroviral drug-associated peripheral neuropathy, lipodystrophy and hyperlipidaemia, NRTI-related pancreatitis, and tenofovir-associated renal proximal tubulopathy. Thus, pharmacogenetics is expected to play an important role in HIV treatment in the near future. The aim of the present paper is to provide HIV clinicians with a comprehensive review of recent achievements and future prospects for HIV pharmacogenetics.

Viral efficacy maintained and safety parameters improved with a reduced dose of stavudine: a pilot study

Stavudine (d4T) is a potent but potentially toxic nucleoside reverse transcriptase inhibitor that is still widely used in developing countries. This study's aim was to determine the efficacy and safety profile of lower-dose d4T. Multi-centre, open-label, single-arm, pilot, 48-week study in French patients weighing >60 kg with viral load <400 HIV-1 RNA copies/mL who were receiving d4T 40 mg twice daily and then switched to 30 mg twice daily. The primary endpoint was the proportion with plasma viral load <400 copies/mL at week 24. Secondary endpoints included the proportion with <50 copies/mL at weeks 24 and 48, changes in mitochondrial DNA, CD4 cell count and pharmacokinetics, and clinical and laboratory safety. Fifty-seven patients enrolled. Baseline CD4 count was 584 cells/microL; viral loads were <400 copies/mL and <50 copies/mL in 100% and 89%, respectively. Prior antiretroviral drug exposure was 6.9 years, d4T exposure was 6.3 years. Fifty-six out of 57 (98%) patients had viral load <400 copies/mL and 51 (89%) had viral load <50 copies/mL at week 24. Median CD4 count increased by 63 cells/microL at week 48 (P=0.006). At 48 weeks, total cholesterol decreased by 0.24 mmol (P=0.02), high-density lipoprotein cholesterol by 0.15 mmol (P=0.0001) and alanine aminotransferase by 5.74 mg/dL (P=0.01). Paired baseline DNA and week 24 RNA mutations were unchanged. Mitochondrial DNA (copies/cell) content increased from 672+/-254 to 682+/-269. d4T area under the plasma concentration time curve (AUC) decreased by 31% (P=0.003) and C(max) by 44% (P=0.004). Clinical and laboratory parameters improved or were unchanged. Reduced-dose d4T is effective with improved safety parameters.

Detection of low-frequency K103N mutants after unstructured discontinuation of efavirenz in the presence of the CYP2B6 516 TT polymorphism

To measure antiretroviral drug plasma levels in newly diagnosed HIV-1 seropositive persons who presented with an undetectable plasma HIV-1 RNA load but gave no history of antiretroviral drug exposure and to determine the impact of interrupting undisclosed or unknown antiretroviral therapy on the emergence of drug resistance. Five newly diagnosed, reportedly drug-naive HIV-1 seropositive persons were included in the study. Drug resistance was determined by population and clonal sequencing of reverse transcriptase and protease. CYP2B6 polymorphisms were assayed by real-time PCR allelic discrimination on pre-amplified exons. Efavirenz was detected in the plasma of one of the five persons coinciding with a viral load <40 copies/mL by two different assays. When efavirenz became undetectable, the viral load rebounded. The patient was CYP2B6-516T homozygous. Population sequencing showed wild-type subtype D virus, whereas clonal sequencing detected low-frequency (2%) K103N. The patient firmly denied antiretroviral exposure but described the use of Ugandan remedies. In migrating populations seeking HIV testing, careful and compassionate counselling is required to facilitate the disclosure of previous diagnosis and therapy. The use of remedies of dubious content should also be discussed and investigated.

Pharmacological enhancement of protease inhibitors with ritonavir: an update

Advances in HIV treatment since the approval of the first antiretroviral (ARV) medication have occurred at a rapid pace. However, resistance to these medications can occur quickly owing to inadequate plasma concentrations resulting from poor adherence related to intolerable drug toxicities and complex dosing schedules. Drug–drug and drug–food interactions can also result in inadequate ARV drug exposure. Ritonavir is a potent cytochrome P450 3A4 inhibitor and low doses can be used in combination with almost all protease inhibitors to overcome most drug–drug and drug–food interactions. Little toxicity can be attributed to the addition of low-dose ritonavir to an ARV regimen, and most patients find that the added pills do not adversely affect adherence. This article reviews the pharmacological use of ritonavir for pharmacokinetic enhancement (or boosting) and updates the clinical use of boosted protease inhibitors.

Antiretroviral drug resistance among antiretroviral-naïve persons with recent HIV infection in Thailand

To evaluate the prevalence and patterns of antiretroviral (ARV) drug resistance (ARV-DR) among ARV drug-naïve, recently infected persons with HIV in the 4-year interval (2003-2006) after the inception of the National Access to ARV Programme for People who have AIDS in Thailand. Cross-sectional study of patients with recent HIV infection for HIV risks, ARV-DR risks and baseline ARV-DR. Seven of the 305 patients (2%) had baseline ARV-DR. Via contract tracing, all seven patients with transmitted ARV-DR identified sexual partners with prior ARV treatment failure and had documented low (<75%) ARV adherence. Annual ARV-DR increased from 0 to 5.2% (P=0.06) between 2003 and 2006. Report of sexual partners with potential HIV and ARV drug exposures can prompt baseline ARV-DR testing of at-risk individuals, while behavioural interventions for adherence and safer sex are refined to minimize the emergence of resistance to generic, fixed-dose combination stavudine, lamivudine and nevirapine (GPO-VIR) therapy.

Pharmacogenetics of Anti-HIV Drugs

Pharmacogenetics holds promise in HIV treatment because of the complexity and potential toxicity of multidrug therapies that are prescribed for long periods. Thus far, few candidate genes have been examined for a limited number of allelic variants, but a number of confirmed associations have already emerged. A change in paradigm emerges from the availability of the HapMap, the wealth of data on less-common genetic polymorphisms, and new genotyping technology. This review presents a comprehensive analysis of the existing literature on pharmacogenetic determinants of antiretroviral drug exposure, drug toxicity, as well as genetic markers associated with the rate of disease progression. It is expected that larger-scale comprehensive genome approaches will profoundly change the landscape of knowledge in the future.

Ten-Year Predicted Coronary Heart Disease Risk in HIV-Infected Men and Women

Highly active antiretroviral therapy (HAART), in addition to traditional vascular risk factors, may affect coronary heart disease (CHD) risk in individuals with human immunodeficiency virus (HIV) infection. Among HIV-infected (931 men and 1455 women) and HIV-uninfected (1099 men and 576 women) adults, the predicted risk of CHD was estimated on the basis of age, sex, lipid and blood pressure levels, the presence of diabetes, and smoking status. Among HIV-infected men, 2% had moderate predicted risk of CHD (10-year CHD risk, 15%-25%), and 17% had high predicted risk (10-year CHD risk of > or = 25% or diabetes). Among HIV-infected women, 2% had moderate predicted CHD risk, and 12% had high predicted CHD risk. Compared with users of protease inhibitor-based HAART, the adjusted odds ratio (OR) for moderate-to-high risk of CHD was significantly lower among HAART-naive individuals (OR, 0.57; 95% confidence interval [CI], 0.36-0.89). Users of HAART that was not protease inhibitor based (OR, 0.74; 95% CI, 0.53-1.01) and former HAART users (OR, 0.68; 95% CI, 0.46-1.03) were also less likely than users of protease inhibitor-based HAART to have moderate-to-high CHD risk, although 95% CIs overlapped the null. Low income was associated with increased likelihood of moderate-to-high CHD risk (for annual income < $10,000 vs. > $40,000: OR, 2.32; 95% CI, 1.51-3.56 ). Elevated body mass index (calculated as weight in kilograms divided by the square of height in meters) predicted increased likelihood of moderate-to-high CHD risk (for BMI of 18.5-24.9 vs. BMI of 25-30: OR, 1.41 [95% CI, 1.03-1.93]; for BMI of 18.5-24.9 vs. BMI > or = 30: OR, 1.79 [95% CI, 1.25-2.56]). Among HIV-infected adults, in addition to antiretroviral drug exposures, being overweight and having a low income level were associated with increased predicted CHD risk. This suggests a need to target HIV-infected men and women with these characteristics for vascular risk factor screening.

Antiretroviral drug exposure in the female genital tract: implications for oral pre- and post-exposure prophylaxis

To describe first dose and steady state antiretroviral drug exposure in the female genital tract. Non-blinded, single center, open-label pharmacokinetic study in HIV-infected women. Twenty-seven women initiating combination antiretroviral therapy underwent comprehensive blood plasma and cervicovaginal fluid sampling for drug concentrations during the first dose of antiretroviral therapy and at steady-state. Drug concentrations were measured by validated HPLC/UV or HPLC-MS/MS methods. Pharmacokinetic parameters were estimated for 11 drugs by non-compartmental analysis. Descriptive statistics and 95% confidence intervals were generated using Intercooled STATA Release 8.0 (Stata Corporation, College Station, Texas, USA). For all antiretroviral drugs, genital tract concentrations were detected rapidly after the first dose. Drugs were stratified according to the genital tract concentrations achieved relative to blood plasma. Median rank order of highest to lowest genital tract concentrations relative to blood plasma at steady state were: lamivudine (concentrations achieved were 411% greater than blood plasma), emtricitabine (395%), zidovudine (235%) tenofovir (75%), ritonavir (26%), didanosine (21%), atazanavir (18%), lopinavir (8%), abacavir (8%), stavudine (5%), and efavirenz (0.4%). This is the first study to comprehensively evaluate antiretroviral drug exposure in the female genital tract. These findings support the use of lamivudine, zidovudine, tenofovir and emtricitabine as excellent pre-exposure/post-exposure prophylaxis (PrEP/PEP) candidates. Atazanavir and lopinavir might be useful agents for these applications due to favorable therapeutic indices, despite lower genital tract concentrations. Agents such as stavudine, abacavir, and efavirenz that achieve genital tract exposures less than 10% of blood plasma are less attractive PrEP/PEP candidates.

Teratogenicity risk of antiretroviral therapy in pregnancy

Highly active antiretroviral regimens are recommended for use in pregnancy to prevent vertical transmission of HIV, and many women enter pregnancy already on these regimens for their own health. Sources of data on the potential teratogenicity of antiretroviral drugs include animal studies, cohort studies, the Antiretroviral Pregnancy Registry, and case reports, but data on newly approved drugs are often limited. Thus far, concerns have been identified regarding a potential association between first trimester efavirenz exposure and neural tube defects based on a study in monkeys and case reports in humans, a possible association between first trimester exposure to zidovudine and an increased risk of hypospadias based on one cohort study, and an increased risk of septal heart defects in animals with delavirdine. Additional data on risks of antiretrovirals during pregnancy are needed. Providers should report cases of antiretroviral drug exposures during pregnancy to the Antiretroviral Pregnancy Registry.

Sudden infant death syndrome in infants born to HIV-infected and opiate-using mothers

Objective: This study was undertaken to determine the role of opiate use during pregnancy as a predisposing factor for sudden infant death syndrome (SIDS) in infants born to HIV-infected mothers....

First Italian Consensus Statement on Diagnosis, Prevention and Treatment of Cardiovascular Complications in HIV-infected Patients in the HAART Era (2006)

The present document contains recommendations for assessment, prevention and treatment of cardiovascular risk for HIV-infected patients. All recommendations were graded according to the strength and quality of the evidence and were voted on by 73 members of the Italian Cardiovascular Risk Guidelines Working Group which includes both experts in HIV/AIDS care and in cardiovascular and metabolic medicine. Since antiretroviral drug exposure represents only one risk factor, continued emphasis on an integrated management is given. This should include prevention and treatment of known cardiovascular risk factors (such as dyslipidaemia, diabetes, insulin resistance, healthy diet, physical activity, avoidance of smoking), but also rational switch of antiretroviral drugs. A rational switch strategy should consider both metabolic and anthropometric disturbances and effectiveness of antiretroviral regimens.

Antiretroviral drug exposure in the female genital tract: implications for oral pre- and post-exposure prophylaxis

Antiretroviral drug exposure in the female genital tract: implications for oral pre- and post-exposure prophylaxis

Genotypic predictors of human immunodeficiency virus type 1 drug resistance

Understanding the genetic basis of HIV-1 drug resistance is essential to developing new antiretroviral drugs and optimizing the use of existing drugs. This understanding, however, is hampered by the large numbers of mutation patterns associated with cross-resistance within each antiretroviral drug class. We used five statistical learning methods (decision trees, neural networks, support vector regression, least-squares regression, and least angle regression) to relate HIV-1 protease and reverse transcriptase mutations to in vitro susceptibility to 16 antiretroviral drugs. Learning methods were trained and tested on a public data set of genotype-phenotype correlations by 5-fold cross-validation. For each learning method, four mutation sets were used as input features: a complete set of all mutations in > or =2 sequences in the data set, the 30 most common data set mutations, an expert panel mutation set, and a set of nonpolymorphic treatment-selected mutations from a public database linking protease and reverse transcriptase sequences to antiretroviral drug exposure. The nonpolymorphic treatment-selected mutations led to the best predictions: 80.1% accuracy at classifying sequences as susceptible, low/intermediate resistant, or highly resistant. Least angle regression predicted susceptibility significantly better than other methods when using the complete set of mutations. The three regression methods provided consistent estimates of the quantitative effect of mutations on drug susceptibility, identifying nearly all previously reported genotype-phenotype associations and providing strong statistical support for many new associations. Mutation regression coefficients showed that, within a drug class, cross-resistance patterns differ for different mutation subsets and that cross-resistance has been underestimated.