Antiviral dynamics and sex differences of zidovudine and lamivudine triphosphate concentrations in HIV-infected individuals

Association of tenofovir diphosphate and lamivudine triphosphate concentrations with HIV and hepatitis B virus viral suppression

OBJECTIVE

Concentrations of tenofovir diphosphate (TFV-DP) and lamivudine triphosphate (3TC-TP) in cells are correlates of medication adherence and antiviral activity. However, studies have yet to characterize the simultaneous relationship between TFV-DP and 3TC-TP concentrations with HIV and hepatitis B virus (HBV) suppression.

METHODS

Individuals with HIV/HBV coinfection on tenofovir disoproxil fumarate (TDF)-containing antiretroviral therapy (ART) were enrolled. Peripheral blood mononuclear cells (PBMCs) and dried blood spots (DBS) samples were collected and steady-state TFV-DP and 3TC-TP concentrations quantified using validated methods. The relationship between patient factors, TFV-DP, and 3TC-TP concentrations in PBMCs and DBS with HBV and HIV viral suppression were examined.

RESULTS

Of 138 participants on TDF-containing ART for a median duration (range) of 6 (0.75-15) years, the median age was 43 years and 64% were women. Overall, 128 (92.8%) and 129 (93.5%) had suppressed HIV and HBV viral loads, respectively. Of the 128 participants with suppressed HIV, 122 (95.3%) had suppressed HBV. Self-reported ART adherence, recent change to dolutegravir-based ART, TFV-DP, and 3TC-TP concentrations in PBMCs and DBS were associated with HIV RNA suppression, while HBe antigen positivity, HIV suppression, and TFV-DP concentrations in DBS were associated with HBV DNA suppression (including six persons with HBV nonsuppression and HIV suppression).

CONCLUSION

Long-term TDF/3TC-conatining ART was highly efficacious in individuals with HIV/HBV coinfection. Higher TFV-DP concentrations were predictive of suppression for both viruses. Persistent HBV viremia on TDF/3TC-containg ART requires additional research, but may represent poor adherence and the need for adherence interventions or novel antivirals.

A case for seeking sex-specific treatments in Alzheimer's disease

There is no satisfactory explanation for the sex-related differences in the incidence of many diseases and this is also true of Alzheimer's disease (AD), where females have a higher lifetime risk of developing the disease and make up about two thirds of the AD patient population. The importance of understanding the cause(s) that account for this disproportionate distribution cannot be overestimated, and is likely to be a significant factor in the search for therapeutic strategies that will combat the disease and, furthermore, potentially point to a sex-targeted approach to treatment. This review considers the literature in the context of what is known about the impact of sex on processes targeted by drugs that are in clinical trial for AD, and existing knowledge on differing responses of males and females to these drugs. Current knowledge strongly supports the view that trials should make assessing sex-related difference in responses a priority with a focus on exploring the sex-stratified treatments.

Factors associated with tenofovir diphosphate concentrations in dried blood spots in persons living with HIV

OBJECTIVES

To determine factors associated with interindividual variability in tenofovir diphosphate (TFV-DP) concentrations in dried blood spots (DBSs) among persons living with HIV (PLWH).

METHODS

PLWH who were at least 18 years old and taking tenofovir disoproxil fumarate-containing ART were prospectively recruited and enrolled from a clinical cohort and followed longitudinally (up to three visits over 48 weeks). With log-transformed TFV-DP concentrations in DBSs as the outcome, mixed-model regression analyses were used to assess associations between self-reported 3 month ART adherence, race and other clinical covariates (gender, age, BMI, CD4+ T cell count, estimated glomerular filtration rate, haematocrit, duration on current ART and anchor drug class) on TFV-DP in DBSs.

RESULTS

Five hundred and twenty-seven participants (1150 person-visits) were analysed. Adjusting for race and other clinical covariates, every 10% increase in self-reported 3 month ART adherence was associated with an average TFV-DP concentration increase in DBSs of 28% (95% CI: 24%-32%; P < 0.0001). In the same model, female participants had 20% (95% CI: 3%-40%; P = 0.02) higher TFV-DP concentrations in DBSs, compared with male participants, and every 1 kg/m2 increase in BMI was associated with a decrease in TFV-DP concentration in DBSs by 2% (95% CI: -3% to -1%; P < 0.0001).

CONCLUSIONS

Individual patient characteristics were predictive of TFV-DP concentration in DBSs in PLWH receiving tenofovir disoproxil fumarate-based ART. Future research to incorporate these predictors into the interpretation of this ART adherence biomarker, and to establish whether these associations extend to PLWH taking tenofovir alafenamide-containing ART, is needed.

Differential effects of antiretroviral drug toxicity in male versus female children who are HIV-exposed but uninfected

: In recent years, widespread use of antiretroviral therapy (ART) during pregnancy has been increasingly effective in reducing risk of vertical transmission of HIV, with over 80% of pregnant women living with HIV now accessing ART, and a 41% reduction in new infections in children between 2010 and 2018. Despite these strides, the developmental toxicity of widely administered antiretroviral drugs (ARVs) remains poorly described and existing literature often fails to account for fetal and infant sex as a variable. Recent reports have identified associations between in-utero exposure to commonly used antiretroviral regimens and alteration in neurodevelopment, growth, and metabolism amongst children who are HIV-exposed but uninfected, with findings of sex differences in the prevalence and severity of ARV toxicity. These differences are potentially explained by variable exposure to ARV drugs in utero or exacerbation of existing sex-linked risk factors. Fetal ARV exposure is mediated by placental and fetal drug transporters and metabolic enzymes, which may contribute to the manifestation of sex differences. Existing evidence of sex differences in ARV toxicity in fetal development is concerning, and demands further research to guide optimal treatment options for maternal health and prevention of vertical HIV transmission.

The reporting of observational studies of drug effectiveness and safety: recommendations to extend existing guidelines

INTRODUCTION

The use of observational data to assess drug effectiveness and safety can provide relevant information, much of which may not be feasible to obtain through randomized clinical trials. Because observational studies provide critical drug safety and effectiveness information that influences drug policy and prescribing practices, transparent, consistent, and accurate reporting of these studies is critical.

AREAS COVERED

We provide recommendations to extend existing reporting guidelines, covering the main components of primary research studies (methods, results, discussion).

EXPERT OPINION

Our recommendations include extending drug safety and effectiveness guidelines to include explicit checklist items on: study registration, causal diagrams, rationale for measures of effect, comprehensive assessment of bias, comprehensive data cleaning steps, drug equivalents, subject-level drug data visualization, sex and gender-based analyses and results, patient-oriented outcomes, and patient involvement in research.

Lamivudine/Tenofovir Disoproxil Fumarate is an Appropriate PrEP Regimen

Oral pre-exposure prophylaxis (PrEP) containing tenofovir disoproxil fumarate (TDF) co-formulated with emtricitabine (FTC) or lamivudine (3TC) is recommended as an additional prevention option for persons at substantial risk of HIV infection by both the World Health Organization (WHO) and the US President's Emergency Plan for AIDS Relief (PEPFAR). The WHO and PEPFAR consider 3TC clinically interchangeable with FTC for PrEP given comparable pharmacologic equivalence, resistance and toxicity patterns, and indirect clinical trial evidence from TDF-containing studies. Globally, FTC/TDF has been widely used in clinical trials, open-label extension studies and demonstration projects. Thus, most PrEP efficacy and safety data are based on FTC/TDF use in heterosexual women and men, men who have sex with men, and people who inject drugs. However, generic 3TC/TDF is less expensive than FTC/TDF, is already available in supply chains for HIV drugs, and has 60-70% of the global adult market share, making it particularly appealing in settings with limited availability or affordability of FTC/TDF. Compelling indirect evidence suggests that scaling up use of 3TC/TDF is potentially cost saving for HIV programs in settings where restricting drug choice to FTC/TDF would delay PrEP implementation. Guideline committees and public health decision-makers in countries should encourage flexibility in PrEP drug selection, support off-label use of 3TC/TDF, and approve use of generic formulations to decrease the cost of PrEP medications and accelerate PrEP delivery through the public and private sectors.

Impact of sex and gender on COVID-19 outcomes in Europe

BACKGROUND

Emerging evidence from China suggests that coronavirus disease 2019 (COVID-19) is deadlier for infected men than women with a 2.8% fatality rate being reported in Chinese men versus 1.7% in women. Further, sex-disaggregated data for COVID-19 in several European countries show a similar number of cases between the sexes, but more severe outcomes in aged men. Case fatality is highest in men with pre-existing cardiovascular conditions. The mechanisms accounting for the reduced case fatality rate in women are currently unclear but may offer potential to develop novel risk stratification tools and therapeutic options for women and men.

CONTENT

The present review summarizes latest clinical and epidemiological evidence for gender and sex differences in COVID-19 from Europe and China. We discuss potential sex-specific mechanisms modulating the course of disease, such as hormone-regulated expression of genes encoding for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) entry receptors angiotensin converting enzyme (ACE) 2 receptor and TMPRSS2 as well as sex hormone-driven innate and adaptive immune responses and immunoaging. Finally, we elucidate the impact of gender-specific lifestyle, health behavior, psychological stress, and socioeconomic conditions on COVID-19 and discuss sex specific aspects of antiviral therapies.

CONCLUSION

The sex and gender disparities observed in COVID-19 vulnerability emphasize the need to better understand the impact of sex and gender on incidence and case fatality of the disease and to tailor treatment according to sex and gender. The ongoing and planned prophylactic and therapeutic treatment studies must include prospective sex- and gender-sensitive analyses.

Brief Report: Relationship Between ABCC4 SNPs and Hepatitis B Virus Suppression During Tenofovir-Containing Antiretroviral Therapy in Patients With HIV/HBV Coinfection

BACKGROUND

Incomplete hepatitis B virus (HBV) suppression during antiretroviral therapy (ART) in HIV and HBV coinfected patients is common, but underlying factors are not fully elucidated. We hypothesize that genetic factors that influence nucleoside analog pharmacokinetics will affect HBV treatment response.

METHODS

HIV/HBV coinfected patients on tenofovir disoproxil fumarate/lamivudine (TDF/3TC)-containing ART were enrolled. Selected ABCC4 single nucleotide polymorphisms (SNPs) with known effects on nucleoside pharmacokinetics were genotyped using TaqMan assays. Relationship between ABCC4 SNPs and unsuppressed HBV DNA (HBV DNA ≥20 IU/mL) were examined.

RESULTS

Of the 50 participants on TDF/3TC-containing ART for a median (range) of 1.5 (1-7.4) years, 20 (40%) had unsuppressed HBV DNA. Participants with unsuppressed compared with those with suppressed HBV DNA were more likely to have negative HBe antibody, lower body mass index, and lower CD4 count at enrollment. Carriers of ABCC4 rs11568695 (G3724A) variant allele were more likely than noncarriers to have unsuppressed HBV (61.1% vs. 29.0%, P = 0.038). Among 36 patients with suppressed HIV RNA (presumed good ART adherence), ABCC4 rs11568695 variant carriers were more likely than noncarriers to have unsuppressed HBV (58.8% vs. 20.0% P = 0.021). Logistic regression analysis that included genetic and nongenetic factors identified ABCC4 rs11568695 variant allele, body mass index, and male sex as predictors of unsuppressed HBV DNA.

CONCLUSIONS

We identified a novel association between ABCC4 rs11568695 SNP and poor HBV treatment response. If confirmed in further studies, ABCC4 genotyping could be used to identify individuals who may need intensified HBV therapy.

Sex differences in HIV treatment outcomes and adherence by exposure groups among adults in Guangdong, China: A retrospective observational cohort study

INTRODUCTION

We aimed to assess sex differences in treatment outcomes and adherence comparing men who have sex with women (MSW), men who have sex with men (MSM), and women who have sex with men (WSM), as well as men and women who inject drugs living with HIV on combination antiretroviral therapy (ART) in Guangdong, China.

METHODS

We performed a retrospective observational cohort study with data from the National Free Antiretroviral Treatment Program database. We included ART-naive patients aged 18 to 80 years who had contracted HIV through sex or injecting drugs, initiated first-line ART between January 2004 and December 2016, and had at least 60 days of follow-up. Participants were followed for five years. Kaplan-Meier analysis and Cox proportional hazard models were used to evaluate all-cause mortality. Cumulative incidence function and Cox proportional hazards models accounting for competing risks were used to evaluate disease progression to AIDS. Modified Poisson regression models were used to evaluate immunological and virological responses and loss to follow-up. Repeated measures analysis was used to evaluate regular CD4+ cell count, HIV viral load monitoring, ART adherence, side effects, and interruption of ART.

FINDINGS

We included 26,409 persons living with HIV. 21,779 (82·5%) people acquired HIV through sex (5118 WSM [23·5%], 8506 MSW [39·0%], 8175 MSM [37·5%]), and 4610 people (17·5%) through injection drug use (249 women [5·4%], 4361 men [94·6%]). Among those infected through sex, MSW had increased risks of all-cause mortality (adjusted hazard ratio [aHR] 1·48, 95% CI 1·20-1·83), progression to AIDS (1·27, 1·09-1·47), virological failure (adjusted incidence rates ratio [aIRR] 1·27, 95% CI 1·09-1·48), and loss to follow-up (1·22, 1·10-1·35) compared to WSM. In contrast, MSM had lower risk of all-cause mortality (aHR 0·49, 95%CI 0·32-0·76), disease progression to AIDS (0·83, 0·68-1·00), and virological failure (aIRR 0·78, 95%CI 0·65-0·94), were more likely to receive regular CD4+ cell count (1·08, 1·07-1·10) and HIV viral load monitoring (1·13, 1·12-1·15), were less likely to report missing ART doses (0·54, 0·49-0·61), interrupt ART (0·34, 0·26-0·44), or be lost to follow-up (0·56, 0·49-0·65) compared to WSM. Men who inject drugs were almost twice as likely as women who inject drugs to die (aHR 1·72, 95%CI 1·03-2·85), experience disease progression to AIDS (2·05, 1·18-3·57), virological failure (aIRR 1·81, 95%CI 1·19-2·76), report ART side effects (1·78, 1·43-2·22), and interruptions in ART (2·29, 1·50-3·50).

INTERPRETATION

Our findings highlight the importance of identifying potentially at-risk MSW and promoting HIV education and testing among them. Particular attention is warranted among men who inject drugs to improve timely HIV diagnosis, drug interaction management, and retention in treatment. Additional research from rural settings is needed to assess the long-term treatment outcomes and adherence in MSM with HIV.

Optimizing Pediatric Dosing Recommendations and Treatment Management of Antiretroviral Drugs Using Therapeutic Drug Monitoring Data in Children Living With HIV

Supplemental Digital Content is Available in the Text.

Introduction:

This review summarizes the current dosing recommendations for antiretroviral (ARV) drugs in the international pediatric guidelines of the World Health Organization (WHO), US Department of Health and Human Services (DHHS), and Pediatric European Network for Treatment of AIDS (PENTA), and evaluates the research that informed these approaches. We further explore the role of data generated through therapeutic drug monitoring in optimizing the dosing of ARVs in children.

Methods:

A PubMed search was conducted for the literature on ARV dosing published in English. In addition, the registration documentation of European Medicines Agency and the US Food and Drug Administration for currently used ARVs and studies referenced by the WHO, DHHS, and EMA guidelines were screened. Resulting publications were screened for papers containing data on the area under the concentration–time curve, trough concentration, and peak concentration. Studies with enrolled participants with a median or mean age of ≥18 years were excluded. No restriction on publishing date was applied.

Discussion and conclusion:

Pediatric ARV dosing is frequently based on data obtained from small studies and is often simplified to facilitate dosing in the context of a public health approach. Pharmacokinetic parameters of pediatric ARVs are subject to high interpatient variation and this leads to a potential risk of underdosing or overdosing when drugs are used in real life. To ensure optimal use of ARVs and validate dosing recommendations for children, it is essential to monitor ARV dosing more thoroughly with larger sample sizes and to include diverse subpopulations. Therapeutic drug monitoring data generated in children, where available and affordable, have the potential to enhance our understanding of the appropriateness of simplified pediatric dosing strategies recommended using a public health approach and to uncover suboptimal dosing or other unanticipated issues postmarketing, further facilitating the ultimate goal of optimizing pediatric ARV treatment.

A Review of Clinical Pharmacokinetic and Pharmacodynamic Profiles of Select Antiretrovirals: Focus on Differences among Chinese Patients

OBJECTIVE

To identify the pharmacokinetic differences of antiretroviral drugs between HIV-infected Chinese patients and patients of other race/ethnicities.

STUDY DESIGN

Results from prospective, open-label pharmacokinetic studies among Chinese and historical data from other race/ethnicities.

PATIENTS

Pharmacokinetics of six commonly used antiretroviral drugs, including zidovudine, lamivudine, tenofovir disoproxil fumarate, nevirapine, efavirenz and lopinavir/ritonavir, was evaluated in HIV-infected Chinese patients and compared with historical data from other race/ethnicities.

ANALYSIS

Pharmacokinetic analyses were performed at the steady state among HIV-infected Chinese patients. Safety data were collected during the follow-up. The pharmacokinetic parameters including maximal concentrations (Cmax), area-under-curve (AUC) and clearance (Cl/F) from the Chinese patients were compared to the historic data from other race/ethnicities.

RESULTS

Current evidence, though limited, suggested that these antiretroviral agents were generally safe and effective among HIV-infected Chinese patients. However, compared with other racial groups, Chinese patients exhibited higher C_max , AUC and lower Cl/F for most of the agents, and the incidences of adverse reactions, for example, liver toxicity, rash, and bone health, were more frequent.

CONCLUSIONS

These pharmacokinetic differences suggest that lower dosages for commonly prescribed antiretroviral drugs in China might be appropriate to reduce drug-related adverse reactions, while maintain the antiviral efficacy.

Intracellular Tenofovir-Diphosphate and Emtricitabine-Triphosphate in Dried Blood Spots following Directly Observed Therapy

Studies of daily emtricitabine-tenofovir disoproxil fumarate (FTC-TDF) for HIV preexposure prophylaxis (PrEP) in men who have sex with men (MSM) modeled intracellular tenofovir-diphosphate (TFV-DP) in dried blood spots (DBS) to assess adherence and corresponding PrEP outcomes. We conducted a prospective, randomized, crossover pharmacokinetic study of TFV-DP in DBS during 33%, 67%, or 100% of daily dosing under directly observed therapy (DOT). Participants were assigned to two 12-week dosing regimens, separated by a 12-week washout. Forty-eight adults (25 women) from Denver and San Francisco were included. TFV-DP exhibited a median half-life of 17 days, reaching steady state in 8 weeks. TFV-DP was dose proportional with mean (SD) steady-state concentrations of 530 (159), 997 (267), and 1,605 (405) fmol/punch for the 33%, 67%, and 100% arms, respectively. Prior work in MSM demonstrated clinically meaningful TFV-DP thresholds of 350, 700, and 1,250 fmol/punch, which were estimated 25th percentiles for 2, 4, and 7 doses/week. In the present study, corresponding TFV-DP was within 3% of the prior estimates, and subgroups by site, race, and sex were within 14% of prior estimates, although males had 17.6% (95% confidence intervals [CIs], 6.5, 27.4%) lower TFV-DP than females. The thresholds of 350, 700, and 1,250 fmol/punch were achieved by 75% of men taking ≥1.2, 3.2, and 6 doses/week and 75% of women taking ≥0.6, 2.0, and 5.3 doses/week, indicating that lower dosing reached these thresholds for both sexes. In conclusion, TFV-DP arising from DOT was similar to previous estimates and is useful for interpreting PrEP adherence and study outcomes. (This study has been registered at ClinicalTrials.gov under identifier NCT02022657.).

Gender Differences in Outcomes of Antiretroviral Treatment Among HIV-Infected Patients in China: A Retrospective Cohort Study, 2010-2015

BACKGROUD

Women now account for about half of all people living with HIV worldwide, but researchers lack clear information and large population-based study about gender differences in treatment outcomes.

METHODS

A nationwide retrospective observational cohort study with data from the China National Free Antiretroviral Treatment Program was performed. Antiretroviral-naive patients older than 18 years initiating standard antiretroviral therapy between January 1, 2010, and December 31, 2011, were included and followed up to December 31, 2015. We used modified Poisson regression models to estimate the impact of gender on virological suppression and retention in treatment, and Kaplan-Meier analysis and Cox proportional hazard models to evaluate gender difference in mortality.

RESULTS

Sixty-eight thousand six hundred forty-six patients [46,083 (67.1%) men and 22,563 (32.9%) women] with HIV met eligibility criteria. Women were significantly more likely to achieve virological suppression than men both at 12 months [adjusted relative risk (aRR) 1.02, 95% confidence interval (CI): 1.01 to 1.03, P < 0.001] and 48 months (aRR 1.01, 95% CI: 1.00 to 1.02, P = 0.005) after initiating antiretroviral treatment. Women were also more likely to remain in treatment at 12 months (aRR 1.02, 95% CI: 1.01 to 1.02, P < 0.001) and 48 months (aRR 1.04, 95% CI: 1.03 to 1.05, P < 0.001), although the difference became insignificant in alive patients. All-cause mortality was lower in women than in men (2.34 vs. 4.03 deaths/100PY, adjusted hazard ratio 0.72, 95% CI: 0.67 to 0.77, P < 0.001).

CONCLUSIONS

In China, women are more likely to achieve virological suppression, remain in treatment, and have a significantly lower risk of death than men. Future studies could take both biological and sociobehavioral factors into analysis to clarify the influence factors.

Dose evaluation of lamivudine in human immunodeficiency virus-infected children aged 5 months to 18 years based on a population pharmacokinetic analysis

AIM

The objectives of this study were to characterize age-related changes in lamivudine pharmacokinetics in children and evaluate lamivudine exposure, followed by dose recommendations for subgroups in which target steady state area under the daily plasma concentration-time curve (AUC_0-24h ) is not reached.

METHODS

Population pharmacokinetic modelling was performed in NONMEM using data from two model-building datasets and two external datasets [n = 180 (age 0.4-18 years, body weight 3.4-60.5 kg); 2061 samples (median 12 per child); daily oral dose 60-300 mg (3.9-17.6 mg kg^-1 )]. Steady state AUC_0-24h was calculated per individual (adult target 8.9 mg·h l^-1 ).

RESULTS

A two-compartment model with sequential zero order and first order absorption best described the data. Apparent clearance and central volume of distribution (% RSE) were 13.2 l h^-1 (4.2%) and 38.9 l (7.0%) for a median individual of 16.6 kg, respectively. Bodyweight was identified as covariate on apparent clearance and volume of distribution using power functions (exponents 0.506 (20.2%) and 0.489 (32.3%), respectively). The external evaluation supported the predictive ability of the final model. In 94.5% and 35.8% of the children with a body weight >14 kg and <14 kg, respectively, the target AUC_0-24h was reached.

CONCLUSION

Bodyweight best predicted the developmental changes in apparent lamivudine clearance and volume of distribution. For children aged 5 months-18 years with a body weight <14 kg, the dose should be increased from 8 to 10 mg kg^-1  day^-1 if the adult target for AUC_0-24h is aimed for. In order to identify whether bodyweight influences bioavailability, clearance and/or volume of distribution, future analysis including data on intravenously administered lamivudine is needed.

Genotoxic and Cytotoxic Effects of Antiretroviral Combinations in Mice Bone Marrow

Commonly used guidelines for the management of human immunodeficiency virus (HIV) infection (highly active antiretroviral therapy, HAART) include drug combinations such as tenofovir disoproxil fumarate (TDF) + lamivudine (3TC) and combivir [zidovudine (AZT) + 3TC] + efavirenz (EFV). These combinations may enhance the genotoxic effects induced by such drugs individually, since the therapy requires lifelong adherence and the drugs have unknown effects during treatment. Thus, the evaluation of the benefits and risks of HAART is of great importance. In order to assess the cytotoxic and genotoxic potential of three concentrations of each of the antiretroviral combinations TDF + 3TC (800 + 400, 1600 + 800, and 3200 + 1600 mg/kg body weight, BW) and combivir + EFV (200 + 100 + 400, 400 + 200 + 800, and 800 + 400 + 1600 mg/kg BW) after two exposure periods (24 h and 48 h), in the present study the in vivo comet assay (single-cell gel electrophoresis) and the mouse bone marrow micronucleus test were used. Neither TDF + 3TC nor combivir + EFV induced DNA damage at any concentrations tested after 24 h or 48 h using the comet assay. After 24 h, both combinations increased the micronucleus frequency at all concentrations tested. After 48 h, combivir + EFV increased the micronucleated polychromatic erythrocyte (MNPCE) frequency at the two highest concentrations tested. Polychromatic erythrocytes (PCE)/normochromatic erythrocytes (NCE) ratio was high for both combinations, suggesting that they can be mitogenic. Since genotoxicity may be related to carcinogenesis, it is necessary to conduct further studies to verify the long-term mutagenic effects of these drugs.

Significant intolerability of efavirenz in HIV occupational postexposure prophylaxis

BACKGROUND

Completion of human immunodeficiency virus (HIV) occupational postexposure prophylaxis (PEP) is important for successful prophylaxis.

AIM

To determine factors associated with failure to complete the four-week HIV PEP.

METHODS

A retrospective study was conducted among healthcare workers (HCWs) accidentally exposed to blood or body fluids of patients at the Bamrasnaradura Infectious Diseases Institute, Thailand, between March 1996 and June 2014. Logistic regression analysis was used to determine factors associated with failure to complete the four-week HIV PEP.

FINDINGS

In total, 225 exposure episodes were reported. The mean age of HCWs was 33.1 (standard deviation 9.9) years, and 189 (84%) were female. Nurses (43%) were exposed most frequently. The HIV status of the source was defined in 149 (66%) episodes, and 101 (68%) of these were positive. Of 225 exposures, PEP was prescribed in 155 (69%) cases, with intentional discontinuation in 26 cases. Ninety-one of 129 (71%) HCWs completed the four-week regimen. Multi-variate analysis showed that a regimen of two nucleotide reverse transcriptase inhibitors (NRTI) + efavirenz (EFV) was the only significant factor associated with non-completion of the four-week course (odds ratio 37.8, 95% confidence interval 4.2-342.3; P < 0.01). Other factors including age, sex, staff position, status of the source and other PEP regimens were not associated with non-completion of the four-week course (P > 0.05). None of the HCWs were documented to have HIV seroconversion.

CONCLUSION

A regimen of two NRTIs + EFV was significantly associated with premature discontinuation of occupational PEP. This regimen should not be used for HIV prophylaxis following occupational exposure.

Impact of protease inhibitors on intracellular concentration of tenofovir-diphosphate among HIV-1 infected patients

Intracellular nucleoside reverse transcriptase inhibitor (NRTI) concentrations are associated with plasma HIV-1 response. Coadministration of protease inhibitors with NRTIs can affect intracellular concentrations due to protease inhibitor inhibition of efflux transporters. Tenofovir-diphosphate (TFV-DP) concentrations within peripheral blood mononuclear cells were compared among individuals receiving either atazanavir or darunavir-based regimens. There was a trend towards higher TFV-DP concentrations among women and among participants receiving atazanavir. TFV-DP intracellular concentrations were positively associated with undetectable plasma HIV-1 RNA.

Is infant exposure to antiretroviral drugs during breastfeeding quantitatively important? A systematic review and meta-analysis of pharmacokinetic studies

Objectives

The objectives of this study were to summarize antiretroviral drug concentrations in breast milk (BM) and exposure of breast-fed infants.

Methods

This was a systematic review of pharmacokinetic studies of HIV-positive women taking antiretrovirals that measured drugs in BM. The quality of pharmacokinetic and laboratory methods was assessed using pre-defined criteria. Pooled ratios and 95% CIs were calculated using the generalized inverse variance method and heterogeneity was estimated by the I² statistic. PubMed Central, SCOPUS and LactMed databases were searched. No date or language restrictions were applied. Searches were conducted up to 10 November 2014. Clinical relevance was estimated by comparing ingested dose with the recommended therapeutic dose for each drug.

Results

Twenty-four studies were included. There was substantial variability in the clinical and laboratory methods used and in reported results. Relative to maternal plasma (MP), NRTIs accumulate in BM, with BM : MP ratios (95% CI estimates) from 0.89 to 1.21 (14 studies, 1159 paired BM and MP samples). NNRTI estimates were from 0.71 to 0.94 (17 studies, 965 paired samples) and PI estimates were from 0.17 to 0.21 (8 studies, 477 paired samples). Relative to the recommended paediatric doses, a breast-fed infant may ingest 8.4% (95% CI 1.9–15.0), 12.5% (95% CI 2.6–22.3) and 1.1% (95% CI 0–3.6) of lamivudine, nevirapine and efavirenz, respectively, via BM.

Conclusions

Transfer to untreated infants appears quantitatively important for some NRTIs and NNRTIs. The pharmacokinetic methods varied widely and we propose standards for the design, analysis and reporting of future pharmacokinetic studies of drug transfer during breastfeeding.

Neurotoxic effects of AZT on developing and adult neurogenesis

Azidothymidine (AZT) is a synthetic, chain-terminating nucleoside analog used to treat HIV-1 infection. While AZT is not actively transported across the blood brain barrier, it does accumulate at high levels in cerebrospinal fluid, and subsequently diffuses into the overlying parenchyma. Due to the close anatomical proximity of the neurogenic niches to the ventricular system, we hypothesize that diffusion from CSF exposes neural stem/progenitor cells and their progeny to biologically relevant levels of AZT sufficient to perturb normal cell functions. We employed in vitro and in vivo models of mouse neurogenesis in order to assess the effects of AZT on developing and adult neurogenesis. Using in vitro assays we show that AZT reduces the population expansion potential of neural stem/progenitor cells by inducing senescence. Additionally, in a model of in vitro neurogenesis AZT severely attenuates neuroblast production. These effects are mirrored in vivo by clinically-relevant animal models. We show that in utero AZT exposure perturbs both population expansion and neurogenesis among neural stem/progenitor cells. Additionally, a short-term AZT regimen in adult mice suppresses subependymal zone neurogenesis. These data reveal novel negative effects of AZT on neural stem cell biology. Given that the sequelae of HIV infection often include neurologic deficits—subsumed under AIDS Dementia Complex (Brew, 1999)—it is important to determine to what extent AZT negatively affects neurological function in ways that contribute to, or exacerbate, ADC in order to avoid attributing iatrogenic drug effects to the underlying disease process, and thereby skewing the risk/benefit analysis of AZT therapy.

HIV protease inhibitor use during pregnancy is associated with decreased progesterone levels, suggesting a potential mechanism contributing to fetal growth restriction

BACKGROUND

Protease inhibitor (PI)-based combination antiretroviral therapy (cART) is administered during pregnancy to prevent perinatal human immunodeficiency virus (HIV) transmission. However, PI use has been associated with adverse birth outcomes, including preterm delivery and small-for-gestational-age (SGA) births. The mechanisms underlying these outcomes are unknown. We hypothesized that PIs contribute to these adverse events by altering progesterone levels.

METHODS

PI effects on trophoblast progesterone production were assessed in vitro. A mouse pregnancy model was used to assess the impact of PI-based cART on pregnancy outcomes and progesterone levels in vivo. Progesterone levels were assessed in plasma specimens from 27 HIV-infected and 17 HIV-uninfected pregnant women.

RESULTS

PIs (ritonavir, lopinavir, and atazanavir) but not nucleoside reverse transcriptase inhibitors (NRTIs) or nonnucleoside reverse transcriptase inhibitors reduced trophoblast progesterone production in vitro. In pregnant mice, PI-based cART but not dual-NRTI therapy was associated with significantly lower progesterone levels that directly correlated with fetal weight. Progesterone supplementation resulted in a significant improvement in fetal weight. We observed lower progesterone levels and smaller infants in HIV-infected women receiving PI-based cART, compared with the control group. In HIV-infected women, progesterone levels correlated significantly with birth weight percentile.

CONCLUSIONS

Our data suggest that PI use in pregnancy may lead to lower progesterone levels that could contribute to adverse birth outcomes.

Lower prevalence of drug resistance mutations at first-line virological failure to first-line therapy with atripla vs. tenofovir + emtricitabine/lamivudine + efavirenz administered on a multiple tablet therapy

BACKGROUND

Fixed-dose combination antiretroviral therapy administered as a single-tablet regimen (STR) may improve virologic suppression rates. The effect of STRs on development of resistance when virologic failure occurs on STRs is not known.

OBJECTIVES

To compare the rate of emergent drug resistance mutations (DRMs) on first-line therapy with coformulated tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC)/efavirenz (EFV) as an STR versus TDF, lamivudine (3TC) or FTC, and EFV given as non-STR.

METHODS

Patients from eight cohorts and four randomized clinical trials who received first-line antiretroviral therapy with Atripla (STR group) or with TDF + FTC/3TC + EFV (non-STR group) were eligible if a genotypic resistance test was available immediately after the first episode of viral failure. The DRM list from the 2013 version of IAS-USA was used.

RESULTS

One hundred and eighty-six patients were included in the final analysis, 122 (65.6%) from eight cohorts and 64 (34.1%) from four randomized clinical trials. The overall proportion of patients with at least one DRM at viral failure was 67.7%, including 53.4% (31 of 58) in the STR group vs. 74.2% (95 of 128) in the non-STR group (P = 0.005). Among patients exclusively from cohorts, at least one DRM was detected in 53.4% (31 of 58) in the STR group vs. 78.1% (50 of 64) in the non-STR group (P = 0.004). DRMs for individual drugs were: TDF, 15.5 vs. 16.4% (P = 0.87); 3TC/FTC, 31 vs. 35.2% (P = 0.58); and NNRTI, 51.7 vs. 65.6% (P = 0.07). The proportion of patients with an M184V/I among the 128 patients who received FTC was 32.8 vs. 36.2% among the 58 treated with 3TC (P = 0.65).

CONCLUSIONS

Compared to patients receiving the STR-Atripla, those receiving the same components individually in a non-STR regimen have a statistically significantly increased risk of selecting for DRMs associated with their drugs on failure.

Antiretroviral drugs for prevention of mother-to-child transmission: pharmacologic considerations for a public health approach

OBJECTIVE

Efavirenz-based antiretroviral therapy is recommended for prevention of mother-to-child transmission of HIV with two programmatic options: lifelong therapy for all women or treatment until cessation of breastfeeding. However, the risk of HIV resistance emerging after discontinuing efavirenz-based antiretroviral therapy is unclear. We review present knowledge surrounding the emergence of resistance after stopping efavirenz-based antiretroviral regimens.

DESIGN

An expert review.

METHODS

A literature review was conducted to identify studies assessing risk for emergence of efavirenz-related resistance following discontinuation of efavirenz-based antiretroviral regimens containing either lamivudine and zidovudine or tenofovir disoproxil fumarate and lamivudine. Discontinuation strategies including the use of 'pharmacologic tails' are discussed in the light of what is known about the pharmacology of the drugs.

RESULTS

We found no head-to-head comparisons between zidovudine, lamivudine and efavirenz and tenofovir disoproxil fumarate, lamivudine and efavirenz. The risk for HIV resistance exists, even with a 5-7 day tail of zidovudine and lamivudine. For tenofovir disoproxil fumarate, lamivudine and efavirenz, we found no clinical data to inform a recommendation for a tail.

CONCLUSION

In order to prevent emergence of resistance, a tail of at least 2 weeks in duration may be required when discontinuing efavirenz in a regimen containing zidovudine and lamivudine. Studies are needed to characterize the risk of resistance among women who discontinue tenofovir disoproxil fumarate, lamivudine and efavirenz.

Adverse drug reactions associated with antiretroviral therapy during pregnancy

INTRODUCTION

Antiretroviral (ARV) drug use during pregnancy significantly reduces mother-to-child HIV transmission, delays disease progression in the women and reduces the risk of HIV transmission to HIV-serodiscordant partners. Pregnant women are susceptible to the same adverse reactions to ARVs as nonpregnant adults as well as to specific pregnancy-related reactions. In addition, we should consider adverse pregnancy outcomes and adverse reactions in children exposed to ARVs during intrauterine life. However, studies designed to assess the safety of ARV in pregnant women are rare, usually with few participants and short follow-up periods.

AREAS COVERED

In this review, we discuss studies reporting adverse reactions to ARV drugs, including maternal toxicity, adverse pregnancy outcomes and the consequences of exposure to ARV in infants. We included results of observational studies, both prospective and retrospective, as well as randomized clinical trials, systematic reviews and meta-analyses.

EXPERT OPINION

The benefits of ARV use during pregnancy outweigh the risks of adverse reactions identified to date. More studies are needed to assess the adverse effects in the medium- and long term in children exposed to ARVs during pregnancy, as well as pregnant women using lifelong antiretroviral therapy and more recently available drugs.

Caring for women living with HIV: gaps in the evidence

Introduction

In the management of HIV, women and men generally undergo the same treatment pathway, with gender differences being given limited consideration. This is in spite of accumulating evidence that there are a number of potential differences between women and men which may affect response to treatment, pharmacokinetics, toxicities and coping. There are also notable psychological, behavioural, social and structural factors that may have a unique impact on women living with HIV (WLWH). Despite our increasing knowledge of HIV and advances in treatment, there are significant gaps in the data relating specifically to women. One of the factors contributing to this situation is the under-representation of women in all aspects of HIV clinical research. Furthermore, there are clinical issues unique to women, including gynaecologic and breast diseases, menopause-related factors, contraception and other topics related to women's and sexual health.

Methods

Using scoping review methodology, articles from the literature from 1980 to 2012 were identified using appropriate MeSH headings reflecting the clinical status of WLWH, particularly in the areas of clinical management, sexual health, emotional wellbeing and treatment access. Titles and abstracts were scanned to determine whether they were relevant to non-reproductive health in WLWH, and papers meeting inclusion criteria were reviewed.

Results

This review summarizes our current knowledge of the clinical status of WLWH, particularly in the areas of clinical management, sexual health, emotional wellbeing and treatment access. It suggests that there are a number of gender differences in disease and treatment outcomes, and distinct women-specific issues, such as menopause and co-morbidities, that pose significant challenges to the care of WLWH.

Conclusions

Based on a review of this evidence, outstanding questions and areas where further studies are required to determine gender differences in the efficacy and safety of treatment and other clinical and psychological issues specifically affecting WLWH have been identified. Well-controlled and adequately powered clinical studies are essential to help provide answers to these questions and to contribute to activities aimed at improving the health and wellbeing of WLWH.

Polymeric nanoparticles containing combination antiretroviral drugs for HIV type 1 treatment

The use of combination antiretroviral nanoparticles (cART NPs) was investigated as a novel treatment approach for the inhibition of HIV-1 replication. We developed nanoparticles of biodegradable polymer, poly-(dl-lactide-co-glycolic acid; PLGA) containing efavirenz (EFV) and boosted lopinavir (lopinavir/ritonavir; LPV/r) by a high-pressure homogenization method. The method resulted in >79% drug entrapment efficiency for each of the three drugs. The average size of cART NPs was 138.3±55.4 nm as measured by dynamic light scanning, confirmed by scanning electron microscopy (SEM) with an average surface charge of -13.7±4.5. Lissamine-rhodamine-labeled fluorescent PLGA NPs exhibited efficient uptake in nonimmune (HeLa cells) and immune (H9 T cells) cells as measured by confocal microscopy. Cells treated with cART NPs resulted in minimal loss of cell viability over 28 days. Subcellular fractionation studies demonstrated that HIV-1-infected H9 monocytic cells treated with cART NPs contained significantly (p<0.05) higher nuclear, cytoskeleton, and membrane antiretroviral drug levels compared to cells treated with drug solutions alone. Finally, cART NPs efficiently inhibited HIV-1 infection and transduction. The IC50 for each of the three drugs in the cART NPs was <31 nM. These experiments demonstrate the efficacy of a novel PLGA NPs formulation for the delivery of cART to inhibit HIV-1 replication.

Sex differences in prophylaxis and therapeutic treatments for viral diseases

The intensity and prevalence of viral infections are typically higher in males than in females. In contrast, disease outcome can be worse for females. Males and females also differ in their responses to prophylaxis and therapeutic treatments for viral diseases. In response to vaccines against herpes viruses, hepatitis viruses, influenza viruses, and others, females consistently mount higher humoral immune responses and experience more frequent and severe adverse reactions than males. Males and females also differ in the absorption, metabolism, and clearance of antiviral drugs. The pharmacological effects, including toxicity and adverse reactions, of antiviral drugs are typically greater in females than males. The efficacy of antiviral drugs at reducing viral load also differs between the sexes, with antiviral treatments being better at clearing HIV and hepatitis C virus in females, but showing greater reduction of herpes simplex virus and influenza A virus loads in males. Biological variables, including hormone and genes, as well as gender-specific factors related to access and compliance to drug regimens must be considered when evaluating male-female differences in responses to treatments for viral diseases. Clinicians, epidemiologists, and basic biomedical scientists should design experiments that include both males and females, develop a priori hypotheses that the sexes will differ in their responses to and the outcome of vaccines and antiviral treatments, and statistically analyze outcome data by sex. Knowledge that the sexes differ in response to prophylaxis and therapeutic treatments for viral diseases should influence the recommended course of treatment differently for males and females.

Sex influences immune responses to viruses, and efficacy of prophylaxis and treatments for viral diseases

The intensity and prevalence of viral infections are typically higher in males, whereas disease outcome can be worse for females. Females mount higher innate and adaptive immune responses than males, which can result in faster clearance of viruses, but also contributes to increased development of immunopathology. In response to viral vaccines, females mount higher antibody responses and experience more adverse reactions than males. The efficacy of antiviral drugs at reducing viral load differs between the sexes, and the adverse reactions to antiviral drugs are typically greater in females than males. Several variables should be considered when evaluating male/female differences in responses to viral infection and treatment: these include hormones, genes, and gender-specific factors related to access to, and compliance with, treatment. Knowledge that the sexes differ in their responses to viruses and to treatments for viral diseases should influence the recommended course of action differently for males and females. Editor's suggested further reading in BioEssays X-chromosome-located microRNAs in immunity: Might they explain male/female differences Abstract.

Organic cation transporters OCT1 and OCT2 determine the accumulation of lamivudine in CD4 cells of HIV-infected patients

PURPOSE

Identifying factors that determine concentrations of antiretroviral drugs in CD4 cells are important for improving therapeutic efficacy. Experimental models indicate that the nucleoside reverse transcriptase inhibitor lamivudine is transported by the organic cation transporters 1 and 2 (OCT1 and OCT2, respectively). Here, we tested whether OCT1 and OCT2 contribute to the uptake of lamivudine into native CD4 cells of human immunodeficiency virus (HIV)-infected individuals.

METHODS

CD4 cells obtained by non-activated cell sorting from 35 individuals with HIV-1 infection were incubated with lamivudine (10 μM, 30 min), and intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate were determined by liquid chromatography tandem mass spectrometry. The expression of OCT1 and OCT2 mRNA was measured by quantitative real-time polymerase chain reaction (PCR). A model of OCT2-transfected CD4 cells was established for mechanistic investigations.

RESULTS

Intracellular concentrations of lamivudine and its active metabolite lamivudine triphosphate showed strong linear correlations with each other and with the CD4 mRNA expression of OCT1 and OCT2 (r > 0.80). Coincubation with protease inhibitors (ritonavir, nelfinavir) that inhibit OCT1 and OCT2 yielded decreased intracellular concentrations of lamivudine and lamivudine triphosphate. Incubation of CD4 cells from healthy donors transfected with an OCT2 expression vector yielded increased concentrations of lamivudine and lamivudine triphosphate.

CONCLUSION

Our studies indicate a role of OCT1 and OCT2 for the cellular accumulation of lamivudine in HIV-infected individuals.

Effect of HIV-1 infection and sex on the cellular pharmacology of the antiretroviral drugs zidovudine and lamivudine

The cellular pharmacology of zidovudine (ZDV) and lamivudine (3TC) in vivo is not completely understood. This prospective longitudinal study investigated the relationship between HIV-1 serostatus, sex, race, and time on therapy with intracellular and plasma ZDV and 3TC concentrations. Of 20 HIV-seronegative and 23 HIV-seropositive volunteers enrolled, 16 (8 women) and 21 (5 women) completed all 12 study days, respectively. Volunteers began ZDV-3TC therapy (plus a third active drug in HIV-seropositive volunteers), and steady-state concentrations (C(ss)) were determined after days 1, 3, 7, and 12. A repeated-measures mixed model was utilized. HIV-seronegative status was associated with 22% (95% confidence interval [CI], 0%, 50%) and 37% (15%, 67%) higher C(ss) estimates compared to those of HIV-seropositive individuals for intracellular ZDV-TP and 3TC-TP levels, respectively. African-Americans had 36% (8%, 72%) higher ZDV-TP estimates than non-African-Americans. Sex was not associated with ZDV-TP or 3TC-TP (P > 0.19). Women had 36% (4%, 78%) higher plasma ZDV, but the effect was lessened when normalized by lean body weight (5% [-19%, 38%]; P = 0.68). Plasma 3TC was 19% (0%, 41%) higher in HIV-seropositive volunteers and 22% (0%, 48%) higher in African American volunteers, but these effects were not significant when corrected for creatinine clearance (7% [-9%, 20%] and -5% [-26%, 12%] for HIV serostatus and race, respectively; P > 0.35). These results suggest that HIV-seropositive status decreases and African American race elevates the cellular triphosphates of ZDV and 3TC. This information extends knowledge of ZDV and 3TC cellular pharmacology in vivo and provides new leads for future cellular pharmacology studies aimed at optimizing HIV prevention/treatment with these agents.

Pharmacokinetics of abacavir and its anabolite carbovir triphosphate without and with darunavir/ritonavir or raltegravir in HIV-infected subjects

BACKGROUND

Here, we aimed to investigate the pharmacokinetics of abacavir and carbovir triphosphate (CBV-TP) with darunavir/ritonavir 900/100 mg once daily or raltegravir 400 mg twice daily.

METHODS

HIV-infected subjects on abacavir (600 mg once daily) underwent steady-state pharmacokinetic assessments without and with darunavir/ritonavir or raltegravir. Within-subject changes in plasma and intracellular pharmacokinetic parameters were evaluated by geometric mean ratios (GMRs) and 90% CIs.

RESULTS

A total of 19 patients completed the study. With darunavir/ritonavir (versus abacavir alone), abacavir GMRs (90% CI) were 0.73 (0.66, 0.80), 0.62 (0.50, 0.77) and 0.78 (0.69, 0.87) for area under the curve (AUC), trough concentration (C(trough)) and maximum concentration (C(max)), respectively. With raltegravir, they were 1.03 (0.97, 1.10), 0.83 (0.62, 1.11) and 1.06 (0.95, 1.18), respectively. Intracellular CBV-TP GMRs (90% CI) were 0.88 (0.72, 1.07), 0.68 (0.48, 0.95) and 0.98 (0.79, 1.23) for AUC, C(trough) and C(max), respectively, with darunavir/ritonavir, and 0.96 (0.76, 1.20), 0.57 (0.33, 1.00) and 1.07 (0.85, 1.35), respectively, with raltegravir.

CONCLUSIONS

There was a 27% decrease in abacavir plasma exposure with darunavir/ritonavir and no changes with raltegravir. CBV-TP C(trough) was significantly decreased with darunavir/ritonavir (32%) and showed a high inter-individual variability with raltegravir.

Iatrogenic mitochondriopathies: a recent lesson from nucleoside/nucleotide reverse transcriptase inhibitors

The use of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) has revolutionized the treatment of infection by human immunodeficiency virus (HIV) and hepatitis-B virus. NRTIs can suppress viral replication in the long-term, but possess significant toxicity that can seriously compromise treatment effectiveness. The major toxicity of NRTIs is mitochondrial toxicity. This manifests as serious side effects such as myopathy, peripheral neuropathy and lactic acidosis. In general, it is believed that the mitochondrial pathogenesis is closely related to the effect of NRTIs on mitochondrial DNA polymerase-γ. Depletion and mutation of mitochondrial DNA during chronic NRTI therapy may lead to cellular respiratory dysfunction and release of reactive oxidative species, resulting in cellular damage. It is now apparent that the etiology is far more complex than originally thought. It appears to involve multiple mechanisms as well as host factors such as HIV per se, inborn mitochondrial mutation, and sex. Management of mitochondrial toxicity during NRTI therapy remains a challenge. Interruption of NRTI therapy and substitution of the causative agents with alternative better-tolerated NRTIs represents the mainstay of management for mitochondrial toxicity and its clinical manifestations. A range of pharmacological approaches has been proposed as treatments and prophylaxes.

Pharmacokinetics of lamivudine and lamivudine-triphosphate after administration of 300 milligrams and 150 milligrams once daily to healthy volunteers: results of the ENCORE 2 study

There is interest in evaluating the efficacy of lower doses of certain antiretrovirals for clinical care. We determined here the bioequivalence of plasma lamivudine (3TC) and intracellular 3TC-triphosphate (3TC-TP) concentrations after the administration of two different doses. ENCORE 2 was a randomized crossover study. Subjects received 3TC at 300 and 150 mg once daily for 10 days (arm 1; n = 13) or vice versa (arm 2; n = 11), separated by a 10-day washout. Pharmacokinetic (PK) profiles (0 to 24 h) were assessed on days 10 and 30. Plasma 3TC and 3TC-TP levels in peripheral blood mononuclear cells were quantified by high-performance liquid chromatography-tandem mass spectrometry. Within-subject changes in PK parameters (the area under the concentration-time curve from 0 to 24 h [AUC(0-24)], the trough concentration of drug in plasma at 24 h [C(24)], and the maximum concentration of drug in plasma [C(max)]) were evaluated by determining the geometric mean ratios (GMRs) adjusted for study arm, period, and intra-individual variation. Regimens were considered bioequivalent if the 90% confidence interval (90% CI) fell within the range of 0.8 to 1.25. A total of 24 subjects completed the study. The GM (90% CI) 3TC AUC(0-24)), expressed as ng·h/ml, for the 300- and 150-mg doses were 8,354 (7,609 to 9,172) and 4,773 (4,408 to 5,169), respectively. Bioequivalence in 3TC PK following the administration of 300 and 150 mg was not demonstrated: the GMRs for AUC(0-24), C(24), and C(max) were 0.57 (0.55 to 0.60), 0.63 (0.59 to 0.67), and 0.56 (0.53 to 0.60), respectively. The GM (90% CI) 3TC-TP AUC(0-24) values (pmol·h/10(6) cells) for the 300- and 150-mg doses were 59.5 (51.8 to 68.3) and 44.0 (38.0 to 51.0), respectively. Bioequivalence in 3TC-TP PK following the administration of 300 and 150 mg was not demonstrated: the GMRs for AUC(0-24), C(24), and C(max) were 0.73 (0.64 to 0.83), 0.82 (0.68 to 0.99), and 0.70 (0.61 to 0.82), respectively. We found that 3TC at 150 mg is not bioequivalent to the standard regimen of 300 mg, indicating that saturation of cytosine phosphorylation pathways is not achieved at a dose of 150 mg.

Sex differences in lopinavir and ritonavir pharmacokinetics among HIV-infected women and men

The authors compared the pharmacokinetics of lopinavir (LPV) and ritonavir (RTV) between women and men. This 2-step, multicenter, pharmacokinetic study enrolled human immunodeficiency virus (HIV)-infected adults on lopinavir/ritonavir (LPV/r) capsules (400/100 mg bid) plus 1 or more nucleoside reverse transcriptase inhibitors. All participants underwent 12-hour pharmacokinetic sampling. The pharmacokinetic sampling was repeated in participants receiving the LPV/r tablet formulation. Step 1 enrolled 37 women and 40 men; step 2 included 42 participants from step 1 plus 35 new participants (39 women and 38 men). LPV pharmacokinetics in women and men were not significantly different with either formulation. Women had significantly higher median RTV AUC(0-12 h) with both the soft-gel capsule (SGC) and tablet formulations (SGC: 5395 vs 4119 ng·h/mL, P = .026; tablet: 5310 vs 3941 ng·h/mL, P = .012), higher median C(max) (SGC: 802 vs 635 ng/mL, P = .032; tablet: 773 vs 570 ng/mL, P = .006), and lower median CL/F (SGC: 18.54 vs 24.31 L/h, P = .026; tablet: 18.83 vs 25.37 L/h, P = .012). RTV CL/F was slower in women after weight adjustment with both formulations. The pharmacokinetics of LPV in the SGC and tablet formulations are comparable in HIV-infected patients. Women had higher RTV AUC(0-12 h) and lower CL/F with both formulations. The mechanism of the sex difference in RTV CL/F warrants elucidation.

Gender differences in retention and survival on antiretroviral therapy of HIV-1 infected adults in Malawi

BACKGROUND; There is currently a dearth of knowledge on gender differences in mortality among patients on ART in Africa.

METHODS

Using data from the national ART monitoring and evaluation system, a survival analysis of all healthcare workers, teachers, and police/army personnel who accessed ART in Malawi by June, September and December 2006 respectively, was undertaken. Gender differences in survival were analysed using Kaplan-Meier estimates and rate ratios were derived from Poisson regression adjusting for confounding.

RESULTS

4670 ART patients (49.8% female) were followed up for a median of 8.7 months after starting ART. Probability of death was significantly higher for men than women (p < 0.001). Controlling for age, WHO clinical stage and occupation, men experienced nearly 2 times the mortality of women RR 1.90 [95% CI: 1.57-2.29]. A higher proportion of men initiated ART in WHO stage 4 (p < 0.001).

CONCLUSION

Among healthcare workers, teachers, police/army personnel, men have higher mortality on ART than women. Possible reasons are unclear but could be biological or because men present for ART at a later clinical stage or have poorer adherence to therapy. Improving early access to ART may reduce mortality, especially among men. A gender difference in adherence to therapy needs further investigation.

Sex differences in antiretroviral treatment outcomes among HIV-infected adults in an urban Tanzanian setting

OBJECTIVE

To determine the relationship between sex and antiretroviral therapy (ART) outcomes in an urban Tanzanian setting.

DESIGN

Longitudinal analysis of a cohort of HIV-infected adult men and women on ART enrolled at the Management and Development for Health (MDH)-President's Emergency Plan For AIDS Relief (PEPFAR) HIV care and treatment program in Dar es Salaam, Tanzania.

METHODS

Clinical and immunologic responses to ART were compared between HIV-infected men and women enrolled from November 2004 to June 2008. Cox regression analyses were used to study sex differences with regard to mortality, immunologic failure (WHO, 2006) and loss to follow-up, after adjusting for other risk factors for the outcomes.

RESULTS

Four thousand, three hundred and eighty-three (34%) men and 8459 (66%) women were analyzed. Men were significantly more immunocompromised than women at enrollment in terms of stage IV disease (27 vs. 23%, P < 0.001) and mean CD4⁺ cell count (123 vs. 136 cells/μl, P < 0.001). In multivariate analyses, men had a significantly higher risk of overall mortality [hazard ratio 1.19, 95% confidence interval (CI) 1.05-1.30, P < 0.001], immunologic nonresponse defined as CD4 cell count less than 100 cells/μl after at least 6 months of initiating ART (hazard ratio 1.74, 95% CI 1.44-2.11, P < 0.001) and loss to follow-up (hazard ratio 1.19, 95% CI 1.10-1.30, P < 0.001) than that in women. Associations did not change significantly when restricting analyses to the period of good adherence for all patients.

CONCLUSION

Nonadherence to care and advanced immunodeficiency at enrollment explained only 17% of the inferior mortality in HIV-infected men in this resource-limited setting. Additional study of behavioral and biologic factors that may adversely impact treatment outcomes in men is needed to reduce these sex disparities.

Joint population pharmacokinetic analysis of zidovudine, lamivudine, and their active intracellular metabolites in HIV patients

The population pharmacokinetic parameters of zidovudine (AZT), lamivudine (3TC), and their active intracellular metabolites in 75 naïve HIV-infected patients receiving an oral combination of AZT and 3TC twice daily as part of their multitherapy treatment in the COPHAR2-ANRS 111 trial are described. Four blood samples per patient were taken after 2 weeks of treatment to measure drug concentrations at steady state. Plasma AZT and 3TC concentrations were measured in 73 patients, and among those, 62 patients had measurable intracellular AZT-TP and 3TC-TP concentrations. For each drug, a joint population pharmacokinetic model was developed and we investigated the influence of different covariates. We then studied correlations between the mean plasma and intracellular concentrations of each drug. A one-compartment model with first-order absorption and elimination best described the plasma AZT concentration, with an additional compartment for intracellular AZT-TP. A similar model but with zero-order absorption was found to adequately described concentrations of 3TC and its metabolite 3TC-TP. The half-lives of AZT and 3TC were 0.81 h (94.8%) and 2.97 h (39.2%), respectively, whereas the intracellular half-lives of AZT-TP and 3TC-TP were 10.73 h (69%) and 21.16 h (44%), respectively. We found particularly a gender effect on the apparent bioavailability of AZT, as well as on the mean plasma and intracellular concentrations of AZT, which were significantly higher in females than in males. Relationships between mean plasma drug and intracellular metabolite concentrations were also highlighted both for AZT and for 3TC. Simulation with the model of plasma and intracellular concentrations for once- versus twice-daily regimens suggested that a daily dosing regimen with double doses could be appropriate.

Mass spectrometry in the quantitative analysis of therapeutic intracellular nucleotide analogs

Nucleoside analogs are widely used in anti-cancer, anti-(retro)viral, and immunosuppressive therapy. Nucleosides are prodrugs that require intracellular activation to mono-, di-, and finally triphosphates. Monitoring of these intracellular nucleotides is important to understand their pharmacology. The relatively involatile salts and ion-pairing agents traditionally used for the separation of these ionic analytes limit the applicability of mass spectrometry (MS) for detection. Both indirect and direct methods have been developed to circumvent this apparent incompatibility. Indirect methods consist of de-phosphorylation of the nucleotides into nucleosides before the actual analysis. Various direct approaches have been developed, ranging from the use of relatively volatile or very low levels of regular ion-pairing agents, hydrophilic interaction chromatography (HILIC), weak anion-exchange, or porous graphitic carbon columns to capillary electrophoresis and matrix-assisted light desorption--time of flight (MALDI-TOF) MS. In this review we present an overview of the publications describing the quantitative analysis of therapeutic intracellular nucleotide analogs using MS. The focus is on the different approaches for their direct analysis. We conclude that despite the technical hurdles, several useful MS-compatible chromatographic approaches have been developed, enabling the use of the excellent selectivity and sensitivity of MS for the quantitative analysis of intracellular nucleotides.

Pharmacological considerations for tenofovir and emtricitabine to prevent HIV infection

The use of antiretroviral medications in HIV-negative individuals as pre-exposure prophylaxis (PrEP) is a promising approach to prevent HIV infection. Tenofovir disoproxil fumarate (TDF) and emtricitabine exhibit desirable properties for PrEP including: favourable pharmacokinetics that support infrequent dosing; few major drug-drug or drug-food interactions; an excellent clinical safety record; and pre-clinical evidence for efficacy. Several large, randomized, controlled clinical trials are evaluating the safety and efficacy of TDF and emtricitabine for this new indication. A thorough understanding of variability in drug response will help determine future investigations in the field and/or implementation into clinical care. Because tenofovir and emtricitabine are nucleos(t)ide analogues, the HIV prevention and toxicity effects depend on the triphosphate analogue formed intracellularly. This review identifies important cellular pharmacology considerations for tenofovir and emtricitabine, which include drug penetration into relevant tissues and cell types, race/ethnicity/pharmacogenetics, gender, cellular activation state and appropriate episodic or alternative dosing strategies based on pharmacokinetic principles. The current state of knowledge in these areas is summarized and the future utility of intracellular pharmacokinetics/pharmacodynamics for the PrEP field is discussed.

Effect of nucleoside and nucleotide analog reverse transcriptase inhibitors on cell-mediated immune functions

Nucleoside analog reverse transcriptase inhibitors (NRTIs) constitute the most commonly used drugs in antiretroviral therapy. NRTIs differ with respect to their host cell toxicity. We compared the in vitro effect of zidovudine (AZT; 2 μg/ml), lamivudine (3TC; 5 μg/ml), stavudine (d4T; 1 μg/ml), and tenofovir (TFV; 1 μg/ml) on Candida cell-mediated immunity (CMI) of peripheral blood mononuclear cells (PBMCs). The concentrations of the active derivative AZT-triphosphate were 4-fold higher in Candida-stimulated compared with unstimulated PBMCs (p = 0.01), but those of 3TC-triphosphate and TFV-diphosphate did not differ significantly. AZT treatment decreased proliferation of unstimulated and Candida-stimulated PBMCs and IFN-γ ELISPOT responses; 3TC decreased proliferation of unstimulated PBMCs only; d4T and TFV decreased proliferation of Candida-stimulated PBMCs only. AZT, but not the other NRTIs, increased unstimulated PBMC apoptosis measured by caspase 3 activity. All NRTIs increased annexin-V-measured apoptosis of Candida-stimulated PBMCs. The effect of d4T on apoptosis of Candida-stimulated PBMCs strongly correlated with its inhibitory effect on mitochondrial DNA synthesis (r² = 0.94; p = 0.007). The other NRTIs did not significantly decrease the mitochondrial:nuclear DNA ratios in Candida-stimulated or unstimulated cultures, suggesting that other mechanisms mediated their effect on apoptosis and CMI. In conclusion, AZT had the most pronounced inhibitory effect on CMI. Further studies are warranted to determine the clinical significance of this observation.

Determinants of individual variation in intracellular accumulation of anti-HIV nucleoside analog metabolites

Individual variation in response to antiretroviral therapy is well-known, but it is not clear if demographic characteristics such as gender, age, and ethnicity are responsible for the variation. To optimize anti-HIV therapy and guide antiretroviral drug discovery, determinants that cause variable responses to therapy need to be evaluated. We investigated the determinants of intracellular concentrations of nucleoside analogs using peripheral blood mononuclear cells from 40 healthy donors. We observed individual differences in the concentrations of the intracellular nucleoside analogs; the mean concentrations of the triphosphate metabolite of ethynylstavudine (4'-Ed4T), zidovudine (AZT), and lamivudine (3TC) were 0.71 pmol/10(6) cells (minimum and maximum, 0.10 and 3.00 pmol/10(6) cells, respectively), 0.88 pmol/10(6) cells (minimum and maximum, 0.10 and 15.18 pmol/10(6) cells, respectively), and 1.70 pmol/10(6) cells (minimum and maximum, 0.20 and 7.73 pmol/10(6) cells, respectively). Gender and ethnicity had no effect on the concentration of 4'-Ed4T and 3TC metabolites. There was a trend for moderation of the concentrations of AZT metabolites by gender (P = 0.17 for gender·metabolite concentration). We observed variability in the activity and expression of cellular kinases. There was no statistically significant correlation between thymidine kinase 1 (TK-1) activity or expression and thymidine analog metabolite concentrations. The correlation between the activity of deoxycytidine kinase (dCK) and the 3TC monophosphate metabolite concentration showed a trend toward significance (P = 0.1). We observed an inverse correlation between the multidrug-resistant protein 2 (MRP2) expression index and the concentrations of AZT monophosphate, AZT triphosphate, and total AZT metabolites. Our findings suggest that the observed variation in clinical response to nucleoside analogs may be due partly to the individual differences in the intracellular concentrations, which in turn may be affected by the cellular kinases involved in the phosphorylation pathway and ATP-binding cassette (ABC) transport proteins.

Women experience higher rates of adverse events during hepatitis C virus therapy in HIV infection: a meta-analysis

BACKGROUND

In HIV/ hepatitis C virus (HCV) coinfection, adverse events (AEs) during HCV therapy account for 12%-39% of treatment discontinuations. It is unknown whether sex influences complications.

METHODS

Meta-analysis to study the effect of sex and other predictors of AEs in 3 randomized trials, ACTG 5071, APRICOT, and ANRSHCO2-RIBAVIC of Interferon (IFN) and Pegylated IFN (PEG), both with and without Ribavirin, in HIV/HCV coinfection. Primary endpoints were AEs requiring treatment discontinuation (AETD) or first dose modification (AEDM). Multi-covariate stratified logistic regression was used to study predictors and assess interactions with sex.

RESULTS

Twenty-one percent of 1376 subjects were women; 61% had undetectable HIV RNA; 14% were antiretroviral (ARV) therapy naive at entry; median CD4 was 485 cells per cubicmillimeter. Seventeen percent had an AETD and 50% AEDM; women had more AETD than men (24% vs. 16% P = 0.003) and AEDM (61% vs. 48% P < 0.0001). AETD and AEDM occurred earlier in women; but the types of AETD and AEDM were similar between sexes. Seventy-four percent of AETDs and 49% of AEDMs involved constitutional AEs; 18% of AETD depression; and 26% of AEDM neutropenia. We identified interactions with sex and body mass index (BMI) (P = 0.04, continuous) and nonnucleoside reverse transcriptase inhibitor (P = 0.03); more AETDs were seen in men with lower BMI (P = 0.01) and in women on nonnucleoside reverse transcriptase inhibitors (P = 0.009). More AEDMs were seen with PEG [odds ratio (OR) = 2.07]; older age (OR = 1.48 per 10 years); decreasing BMI (OR = 1.04 per kg/m); HCV genotype 1, 4 (OR = 1.31); Ishak 5, 6 (OR = 1.42); decreasing Hgb (OR = 1.23 per g/dL); and decreasing absolute neutrophil count (1.04 per 500 cells/mm). Interactions between sex and ARV-naive status (P = 0.001) and zidovudine (P = 0.001) were identified: There were more AEDMs in ARV-naive women (P = 0.06) and ARV-experienced men (P = 0.001) and higher AEDMs in women with zidovudine (P = 0.0002).

CONCLUSIONS

Although there was no difference in type of AE, AETD and AEDM were more frequent and occurred earlier in women. In women, ARV regimen may be an important predictor of AETDs during HCV therapy and should be explored as a predictor of AEs in HIV/HCV coinfection trials.

Organic cation transporters and their roles in antiretroviral drug disposition

BACKGROUND

Understanding metabolising processes and drug-transporter interactions is particularly crucial to the management of patients with HIV infection, given the several antiretroviral drugs that must be taken lifelong and the use of other medications for HIV-related and non-HIV-related conditions. Several interactions of antiretroviral drugs with metabolising enzymes, especially cytochrome P450 and ATP-dependent transporter P-glycoprotein, have been described but the role of the organic cation transporters (OCTs) is less clearly defined.

OBJECTIVE

To review the relevance of the OCTs for antiretroviral drug disposition.

METHODS

Interactions of OCTs with antiretroviral drugs and evidence for clinical relevance are discussed.

RESULTS/CONCLUSION

Several antiretroviral drugs show relevant interactions with the OCTs in cell-based experiments and the OCTs are highly upregulated in HIV-infected patients. For evaluating the clinical significance, interaction studies in HIV patients and reliable in vitro models for delineation of in vivo effects are needed.