Pharmacokinetics of nevirapine in human immunodeficiency virus type 1-infected pregnant women and their neonates. Pediatric AIDS Clinical Trials Group Protocol 250 Team

Prophylaxis and treatment of HIV infection in pregnancy, Swedish guidelines 2024

In May 2024, the Swedish Reference Group on Antiviral Therapy updated the guidelines on management of HIV infection in pregnancy. The most important recommendations and revisions were: (i) ART during pregnancy should be started as early as possible and continue after delivery; (ii) Suppressive ART should normally not be modified; (iii) The treatment target of HIV RNA <20 copies/ml remains; (iv) Dolutegravir/emtricitabine/tenofovir DF is the first-line drug combination also in pregnant women and women planning pregnancy; (v) There is no evidence of an increased risk of neural tube defects associated with dolutegravir; (vi) Mode of delivery for women with effective ART and HIV RNA <200 copies/ml should follow standard obstetric procedures; (vii) Caesarean section is recommended if HIV RNA ≥200 copies/ml; (viii) Scalp electrode, foetal blood sampling and/or vacuum delivery should be used on strict indications, but does not necessitate intensified infant prophylaxis; (ix) Management and mode of delivery in case of premature or full-term rupture of membranes should follow standard obstetric procedures; (x) Recommended infant antiretroviral prophylaxis has been updated; (xi) The duration of infant antiretroviral prophylaxis (gestational age ≥35 weeks and mother on effective ART and HIV RNA <200 copies/ml) has been changed from 4 to 2 weeks; (xii) Infants born to women with HIV RNA ≥200 copies/ml should receive 4 weeks of combination prophylaxis; (xiii) Fertility evaluation and assisted reproduction should be offered to women on suppressive ART according to the same principles as for other women; (xiv) Women living with HIV should still be advised against breastfeeding; (xv) Women who nevertheless opt to breastfeed should be offered intensified support and follow-up.

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

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

What babies need: accelerating access to current and novel antiretroviral drugs in neonates through pharmacokinetic studies

Although 23 antiretroviral drugs are approved for use in adults, only six are approved by regulatory authorities for use in term neonates born to women with HIV, with even fewer options for preterm neonates. A major hurdle for approvals is the delay in the generation of pharmacokinetic and safety data for antiretrovirals in neonates. The median time between the year of approval from the US Food and Drug Administration of an antiretroviral agent for adults and the first publication date for pharmacokinetic data in neonates less than 4 weeks old is 8 years (range 2-23 years). In this Viewpoint, we address pharmacokinetic research gaps and priorities for current and novel antiretroviral use in neonates. We also consider the challenges and provide guidance on neonatal clinical pharmacology research on antiretroviral agents with the goal of stimulating research and expediting the availability of safe medications for the prevention and treatment of HIV in this vulnerable population.

Safety and Experience With Combined Antiretroviral Prophylaxis in Newborn at High-risk of Perinatal HIV Infection, in a Cohort of Mother Living With HIV-infant Pairs

BACKGROUND

Perinatal transmission of HIV has dramatically decreased in high-income countries in the last few years with current rates below 1%, but it still occurs in high-risk situations, mainly pregnant women with late diagnosis of infection, poor antiretroviral adherence and a high viral load (VL). In these high-risk situations, many providers recommend combined neonatal prophylaxis (CNP). Our aim was to evaluate the safety and toxicity of CNP in infants deemed at high-risk of HIV infection among mother-infant pairs in the Madrid Cohort.

MATERIALS AND METHODS

Prospective, multicenter, observational cohort study between years 2000 and 2019. The subgroup of newborns on CNP and their mothers were retrospectively selected (cohort A) and compared with those who received monotherapy with zidovudine (cohort B). Infants with monotherapy were classified according to treatment regimes in long (6 weeks) and short (4 weeks) course.

RESULTS

We identified 227 newborns (33.3% preterm and 7 sets of twins) with CNP. A maternal diagnosis of HIV-1 infection was established during the current pregnancy in 72 cases (36.4%) and intrapartum or postpartum in 31 cases (15.7%). Most infants received triple combination antiretroviral therapy (65.6%; n = 149). The perinatal transmission rate in cohort A was 3.5% (95% confidence interval: 1.13%-5.92%). Infants from cohort A developed anemia (26.1% vs. 19.4%, P = 0.14) and neutropenia more frequently at 50-120 days (21.4% vs. 10.9%, P < 0.01), without significant differences in grade 3 and 4 anemia or neutropenia between the two cohorts. There were no differences in increased alanine aminotransferase. Neutropenia was more common in the long zidovudine regimes.

CONCLUSIONS

Our findings provide further evidence of the safety of CNP in infants with high-risk of HIV-1 perinatal transmission.

Evaluation and Management of the Infant Exposed to HIV in the United States

Pediatricians play a crucial role in optimizing the prevention of perinatal transmission of HIV infection. Pediatricians provide antiretroviral prophylaxis to infants born to women with HIV type 1 (HIV) infection during pregnancy and to those whose mother's status was first identified during labor or delivery. Infants whose mothers have an undetermined HIV status should be tested for HIV infection within the boundaries of state laws and receive presumptive HIV therapy if the results are positive. Pediatricians promote avoidance of postnatal HIV transmission by advising mothers with HIV not to breastfeed. Pediatricians test the infant exposed to HIV for determination of HIV infection and monitor possible short- and long-term toxicity from antiretroviral exposure. Finally, pediatricians support families living with HIV by providing counseling to parents or caregivers as an important component of care.

Pharmacokinetics, Placental and Breast Milk Transfer of Antiretroviral Drugs in Pregnant and Lactating Women Living with HIV

BACKGROUND

Remarkable progress has been achieved in the identification of HIV infection in pregnant women and in the prevention of vertical HIV transmission through maternal antiretroviral treatment (ART) and neonatal antiretroviral drug (ARV) prophylaxis in the last two decades. Millions of women globally are receiving combination ART throughout pregnancy and breastfeeding, periods associated with significant biological and physiological changes affecting the pharmacokinetics (PK) and pharmacodynamics (PD) of ARVs. The objective of this review was to summarize currently available knowledge on the PK of ARVs during pregnancy and transport of maternal ARVs through the placenta and into the breast milk. We also summarized main safety considerations for in utero and breast milk ARVs exposures in infants.

METHODS

We conducted a review of the pharmacological profiles of ARVs in pregnancy and during breastfeeding obtained from published clinical studies. Selected maternal PK studies used a relatively rich sampling approach at each ante- and postnatal sampling time point. For placental and breast milk transport of ARVs, we selected the studies that provided ratios of maternal to the cord (M:C) plasma and breast milk to maternal plasma (M:P) concentrations, respectively.

RESULTS

We provide an overview of the physiological changes during pregnancy and their effect on the PK parameters of ARVs by drug class in pregnancy, which were gathered from 45 published studies. The PK changes during pregnancy affect the dosing of several protease inhibitors during pregnancy and limit the use of several ARVs, including three single tablet regimens with integrase inhibitors or protease inhibitors co-formulated with cobicistat due to suboptimal exposures. We further analysed the currently available data on the mechanism of the transport of ARVs from maternal plasma across the placenta and into the breast milk and summarized the effect of pregnancy on placental and of breastfeeding on mammal gland drug transporters, as well as physicochemical properties, C:M and M:P ratios of individual ARVs by drug class. Finally, we discussed the major safety issues of fetal and infant exposure to maternal ARVs.

CONCLUSIONS

Available pharmacological data provide evidence that physiological changes during pregnancy affect maternal, and consequently, fetal ARV exposure. Limited available data suggest that the expression of drug transporters may vary throughout pregnancy and breastfeeding thereby possibly impacting the amount of ARV crossing the placenta and secreted into the breast milk. The drug transporter's role in the fetal/child exposure to maternal ARVs needs to be better understood. Our analysis underscores the need for more pharmacological studies with innovative study design, sparse PK sampling, improved study data reporting and PK modelling in pregnant and breastfeeding women living with HIV to optimize their treatment choices and maternal and child health outcomes.

Inclusion of pregnant women in antiretroviral drug research: what is needed to move forwards?

INTRODUCTION

To adequately ascertain drug safety and efficacy, drug trials need to include participants from all groups likely to receive the medication following approval. Pregnant women, however, are mostly excluded from trials, and women participating are often required to use highly effective contraception and taken off study product (even off study) if they conceive. There is little commercial incentive for including pregnant women in clinical trials, even when preclinical animal and human pharmacokinetic and safety data appear reassuring. With this conservative approach, large numbers of pregnant women are exposed to drug postlicensing with little known about drug safety and efficacy, and little done to systematically monitor outcomes of pregnancy exposure.

DISCUSSION

The article focuses on antiretrovirals for treating and preventing HIV, and presents potential approaches which could extend to other therapeutic areas, to obtaining adequate and timely data to inform use of these drugs in this population. Most importantly the pregnancy risk profile of investigational agents can be systematically stratified from low to high risk, based on guidelines from regulatory bodies. This stratification can determine the progress through preclinical work with animals and non-pregnant women to opportunistic studies among women who become pregnant on a clinical trial or within routine clinical treatment. Stratification can include pregnant women in clinical trials, concurrent with Phase II/III trials in non-pregnant adults, and ultimately to postmarketing surveillance for outcomes in pregnant women and their infants. Each step can be enabled by clear criteria from international and local regulatory bodies on progression through study phases, standardized protocols for collecting relevant data, collaborative data sharing, pregnancy outcomes surveillance systems supported by committed funding for these endeavours.

CONCLUSIONS

A formalized step-wise approach to including pregnant women in antiretroviral drug research should become the new norm. Systematic implementation of this approach would yield more timely and higher quality pregnancy dosing, safety and efficacy data. Through more vigorous action, regulatory bodies could responsibly overcome reluctance to include pregnant women in drug trials. Funders, researchers and programme implementers need to be galvanized to progressively include pregnant women in research - the use of newer, more effective drugs in women is at stake (349).

Nevirapine Concentrations During the First Month of Life and Maternal Efavirenz Washout in High-Risk HIV-Exposed Infants Receiving Triple Antiretroviral Prophylaxis

BACKGROUND

Triple-drug infant antiretroviral prophylaxis containing nevirapine (NVP) is increasingly used to prevent HIV transmission among neonates at high risk of HIV infection. Our aim was to describe NVP concentration from birth through the first month of life.

METHODS

High-risk HIV-exposed neonates were enrolled in a prospective cohort in Thailand. High-risk neonates defined as maternal HIV RNA >50 copies/mL before delivery or mother received antiretroviral treatment for <12 weeks before delivery. Neonates received zidovudine (4 mg/kg) and lamivudine (2 mg/kg) twice daily, plus NVP (4 mg/kg) once daily (no lead-in) from birth to 6 weeks of life. Infant plasma samples were collected at 1, 2, 14 or 2, 7, 28 days of life. NVP trough concentrations (C24) were estimated using a population pharmacokinetic model and target C24 was ≥0.1 mg/L. "Washout" efavirenz (EFV) concentrations were assessed in infants whose mother received EFV-based antiretroviral treatment.

RESULTS

A total of 48 infants were included: 25 (52%) were male and 12 (25%) were preterm (gestational age 34-37 weeks). Median (interquartile range) predicted NVP C24 were 1.34 mg/L (1.13-1.84), 2.24 (2.00-2.59), 2.78 (2.61-3.12), 2.20 (1.86-2.44) and 0.81 (0.58-0.98) on days 1, 2, 7, 14 and 28 of life, respectively. NVP C24 was not significantly different between term and preterm infants. All infants maintained NVP C24 ≥0.1 mg/L. EFV via placental transfer remained detectable in infants up to 7 days of life.

CONCLUSIONS

NVP 4 mg/kg daily from birth provided adequate prophylactic concentrations during the first month of life in high-risk HIV-exposed neonates.

Prophylaxis and treatment of HIV-1 infection in pregnancy - Swedish Recommendations 2017

Prophylaxis and treatment with antiretroviral drugs have resulted in a very low rate of mother-to-child transmission (MTCT) of HIV during recent years. Registration of new antiretroviral drugs, modification of clinical praxis, updated general treatment guidelines and increasing knowledge about MTCT have necessitated regular revisions of the recommendations for 'Prophylaxis and treatment of HIV-1 infection in pregnancy'. The Swedish Reference Group for Antiviral Therapy (RAV) has updated the recommendations from 2013 at an expert meeting 19 September 2017. In the new text, current treatment guidelines for non-pregnant are considered. The most important revisions are that: (1) Caesarean section and infant prophylaxis with three drugs are recommended when maternal HIV RNA >150 copies/mL (previously >50 copies/mL). The treatment target of undetectable HIV RNA remains unchanged <50 copies/mL; (2) Obstetric management and mode of delivery at premature rupture of the membranes and rupture of the membranes at full term follow the same procedures as in HIV negative women; (3) Vaginal delivery is recommended to a well-treated woman with HIV RNA <150 copies/mL regardless of gestational age, if no obstetric contraindications are present; (4) Treatment during pregnancy should begin as soon as possible and should continue after delivery; (5) Ongoing well-functioning HIV treatment at pregnancy start should usually be retained; (6) Recommended drugs and drug combinations have been updated.

Prevention and treatment of HIV infection in neonates: evidence base for existing WHO dosing recommendations and implementation considerations

INTRODUCTION

Antiretroviral drugs are used in neonates for prevention and treatment of HIV infection. Use of antiretrovirals to prevent perinatal HIV transmission is well established. Early identification of neonates infected with HIV and rapid initiation of combination antiretroviral treatment during the neonatal period is now recommended by WHO and DHHS. However, few antiretrovirals are available in formulations suitable for neonates and there are limited safety and pharmacokinetic data for most antiretrovirals in neonates. Areas covered: We summarize existing neonatal antiretroviral safety and pharmacokinetic information and discuss implementation considerations for programs providing antiretrovirals to neonates and young infants. Expert commentary: Antiretrovirals currently recommended by WHO for use in neonates are zidovudine, lamivudine, lopinavir/ritonavir, nevirapine, and raltegravir. Significant implementation challenges exist to the widespread use of these antiretrovirals in neonates. Optimal, feasible treatment of HIV-exposed and HIV-infected newborns will require development of practical neonatal dosage forms and their study in neonates for a wide range of antiretrovirals.

Assessment of Nevirapine Prophylactic and Therapeutic Dosing Regimens for Neonates

BACKGROUND

Nevirapine (NVP) is a key component of antiretroviral prophylaxis and treatment for neonates. We evaluated current World Health Organization (WHO) weight-band NVP prophylactic dosing recommendations and investigated optimal therapeutic NVP dosing for neonates.

METHODS

The PHPT-5 study in Thailand assessed the efficacy of "Perinatal Antiretroviral Intensification" to prevent mother-to-child transmission of HIV in women with <8 weeks of antiretroviral treatment before delivery (NCT01511237). Infants received a 2-week course of zidovudine/lamivudine/NVP (NVP syrup/once daily: 2 mg/kg for 7 days; then 4 mg/kg for 7 days). Infant samples were assessed during the first 2 weeks of life. NVP population pharmacokinetics (PK) parameters were estimated using nonlinear mixed-effects models. Simulations were performed to estimate the probability of achieving target NVP trough concentrations for prophylaxis (>0.10 mg/L) and for therapeutic efficacy (>3.0 mg/L) using different infant dosing strategies.

RESULTS

Sixty infants (55% male) were included. At birth, median (range) weight was 2.9 (2.3-3.6) kg. NVP concentrations were best described by a 1-compartment PK model. Infant weight and postnatal age influenced NVP PK parameters. Based on simulations for a 3-kg infant, ≥92% would have an NVP trough >0.1 mg/L after 48 hours through 2 weeks using the PHPT-5 and WHO-dosing regimens. For NVP-based therapy, a 6-mg/kg twice daily dose produced a trough >3.0 mg/L in 87% of infants at 48 hours and 80% at 2 weeks.

CONCLUSION

WHO weight-band prophylactic guidelines achieved target concentrations. Starting NVP 6 mg/kg twice daily from birth is expected to achieve therapeutic concentrations during the first 2 weeks of life.

Nevirapine Pharmacokinetics and Safety in Neonates Receiving Combination Antiretroviral Therapy for Prevention of Vertical HIV Transmission

BACKGROUND

Nevirapine (NVP)-based combination antiretroviral therapy is routinely prescribed to infants deemed at high risk of vertical HIV infection in our centers. We evaluated NVP pharmacokinetics and safety of this regimen.

METHODS

Neonates were recruited prospectively between September 2012 and April 2015 or enrolled retrospectively if treated similarly before prospective study initiation. NVP was dosed at 150 mg/m daily for 14 days, then twice daily for 14 days. NVP levels were drawn at weeks 1, 2, and 4 [target trough (NVP-T): 3-8 mg/L].

RESULTS

Thirty-three neonates were included (23 prospectively). Median gestational age (GA) and birth weight were 38 weeks (32-41 weeks) and 2.9 kg (1.5-4.2 kg), respectively. Median NVP-Ts were 8.2 mg/L (1.6-25.1 mg/L), 3.5 mg/L (1.6-6.8 mg/L), and 4.3 mg/L (0.1-19.9 mg/L) at weeks 1, 2, and 4, respectively. The proportions with therapeutic NVP-T were 42%, 61%, and 73% at these same timepoints. Median apparent oral clearance (CL/F) increased from 0.05 L·kg·h (0.01-0.50 L·kg·h) at week 2 to 0.18 L·kg·h (0.01-0.78 L·kg·h) at week 4. Increased drug exposure [area under the curve (AUCτ)] correlated with younger GA (r = 0.459, P = 0.032) and lower birth weight (r = 0.542, P = 0.009). The most common adverse events potentially attributable to combination antiretroviral therapy were transient asymptomatic hyperlactatemia (26%), anemia (24.7%), and neutropenia (22.1%).

CONCLUSIONS

Treatment dose NVP was generally well-tolerated and associated with normalization of trough levels over time in most cases without dose adjustment. Lower empiric dosing is recommended for infants <34 weeks of GA. Routine therapeutic drug monitoring may not be required for infants ≥34 weeks of GA.

Are Prophylactic and Therapeutic Target Concentrations Different?: the Case of Lopinavir-Ritonavir or Lamivudine Administered to Infants for Prevention of Mother-to-Child HIV-1 Transmission during Breastfeeding

The ANRS 12174 trial assessed the efficacy and tolerance of lopinavir (LPV)-ritonavir (LPV/r) prophylaxis versus those of lamivudine (3TC) prophylaxis administered to breastfed infants whose HIV-infected mothers were not on antiretroviral therapy. In this substudy, we assessed LPV/r and 3TC pharmacokinetics to evaluate the percentage of infants with therapeutic plasma concentrations and to discuss these data in the context of a prophylactic treatment. Infants from the South African trial site underwent blood sampling for pharmacokinetic study at weeks 6, 26, and 38 of life. We applied a Bayesian approach to derive the 3TC and LPV pharmacokinetic parameters on the basis of previously published pharmacokinetic models for HIV-infected children. We analyzed 114 LPV and 180 3TC plasma concentrations from 69 infants and 92 infants, respectively. A total of 30 LPV and 20 3TC observations were considered missing doses and discarded from the Bayesian analysis. The overall population analysis showed that 30 to 40% of the infants did not reach therapeutic targets, regardless of treatment group. The median LPV trough concentrations at weeks 6, 26, and 38 were 2.8 mg/liter (interquartile range [IQR], 1.7 to 4.4 mg/liter), 5.6 mg/liter (IQR, 3.2 to 7.7 mg/liter), and 3.4 mg/liter (IQR, 2.3 to 7.3 mg/liter), respectively. The median 3TC area under the curve from 0 to 12 h after the last drug intake were 5.6 mg · h/liter (IQR, 4.1 to 7.8 mg · h/liter), 5.9 mg · h/liter (IQR, 5.1 to 7.5 mg · h/liter), and 7.3 mg · h/liter (IQR, 4.9 to 8.5 mg · h/liter) at weeks 6, 26, and 38, respectively. Use of the therapeutic doses recommended by the WHO would have resulted in a higher proportion of infants achieving the targets. However, no HIV-1 infection was reported among these infants. These results suggest that the prophylactic targets for both 3TC and LPV may be lower than the therapeutic ones. For treatment, the WHO dosing guidelines should be suitable to maintain values above the therapeutic pharmacokinetic targets in most infants. (This study has been registered at ClinicalTrials.gov under identifier NCT00640263.).

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

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

Safety of HIV-1 Perinatal Transmission Prophylaxis With Zidovudine and Nevirapine in Rural South India

BACKGROUND

The authors assessed acceptance and safety of, and adherence to, perinatal HIV-1 transmission prophylaxis at 2 public hospitals in rural Tamil Nadu, India.

METHODS

Eligible HIV-1-infected women were offered zidovudine (ZDV) beginning at 28-weeks gestation until delivery. Their infants received ZDV for 6 weeks. A subsequent revision to the protocol added 1 dose of nevirapine (NVP) for mother and infant.

RESULTS

Sixty of 67 women (90%) met inclusion criteria for the cohort study. Thirty-four of 36 eligible women and all 19 eligible live born infants received prophylaxis on study. Infant, but not maternal, adherence to ZDV varied by antiretroviral prophylaxis group (those receiving combined prophylaxis with ZDV and NVP had lower median adherence) (P = .02). Neutropenia (usually transient) was the most common severe adverse event. Only 1 of 5 women with neutropenia possibly related to ZDV permanently discontinued ZDV. ZDV was not discontinued for any infant.

CONCLUSION

With the exception of neutropenia, usually transient and always without clinical consequences, long-term ZDV (with or without NVP prophylaxis) is well tolerated.

Randomized noninferiority trial of two maternal single-dose nevirapine-sparing regimens to prevent perinatal HIV in Thailand

OBJECTIVES

Perinatal single-dose nevirapine (sdNVP) selects for resistance mutations. The objective of this trial was to compare two maternal sdNVP-sparing regimens with standard zidovudine (ZDV)/sdNVP prophylaxis.

DESIGN

PHPT-5 was a randomized, partially double-blind placebo-controlled, noninferiority trial in Thailand (NCT00409591). Study participants were women with CD4 of at least 250 cells/μl and their infants.

METHODS

All women received ZDV from 28 weeks' gestation and their newborn infants for one week. Women were also randomized to receive NVP-NVP (reference): maternal intrapartum sdNVP with a 7-day 'tail' of ZDV along with lamivudine, and infant NVP (one dose immediately, another 48 h later); infant-only NVP: maternal placebos for sdNVP and the 'tail', with infant NVP; LPV/r: maternal LPV/r starting at 28 weeks. Infants were formula-fed. HIV-diagnosis was determined by DNA-PCR.

RESULTS

Four-hundred and thirty-five women were randomized between January 2009 and September 2010. Accrual was terminated prematurely following a change in Thai guidelines recommending antiretroviral combination therapy for all pregnant women. Data on 405 mothers and 407 live-born children were analyzed. Baseline characteristics were similar between arms. Intent-to-treat transmission rates were 3.8% (95% confidence interval: 1.2-8.6) in NVP-NVP, 1.6% (0.2-5.6) in infant-only NVP, and 1.4% (0.4-5.1) in LPV/r arms. As-treated rates were 2.2% (0.5-6.4), 3.2% (0.9-7.9), and 1.5% (0.2-5.2), respectively. Factors independently associated with transmission were prophylaxis duration less than 8 weeks (adjusted odds ratio 15.5; 3.6-66.1) and viral load at baseline at least 4 log10copies/ml (adjusted odds ratio 10.9; 1.3-91.5). Regimens appeared well tolerated.

CONCLUSION

Transmission rates in all arms were low but noninferiority was not proven. Antiretroviral prophylaxis for at least 8 weeks before delivery is necessary to minimize transmission risk.

Protecting the fetus against HIV infection: a systematic review of placental transfer of antiretrovirals

BACKGROUND

Maternal-to-fetal transfer of antiretroviral drugs contributes to prevention of vertical transmission of HIV.

OBJECTIVE

This systematic review discusses published studies containing data pertaining to the pharmacokinetics of placental transfer of antiretrovirals in humans, including paired cord and maternal plasma samples collected at the time of delivery as well as ex vivo placental perfusion models.

METHODS

Articles pertaining to placental transfer of antiretrovirals were identified from PubMed, from references of included articles, and from US Department of Health and Human Services Panel on Treatment of HIV-infected Pregnant Women and Prevention of Perinatal Transmission guidelines. Articles from non-human animal models or that had no original maternal-to-fetal transfer data were excluded. PRISMA guidelines were followed.

RESULTS

A total of 103 published studies were identified. Data across studies appeared relatively consistent for the nucleoside reverse transcriptase inhibitors (NRTIs) and the non-nucleotide reverse transcriptase inhibitors (NNRTIs), with cord to maternal ratios approaching 1 for many of these agents. The protease inhibitors atazanavir and lopinavir exhibited consistent maternal-to-fetal transfer across studies, although the transfer may be influenced by variations in drug-binding proteins. The protease inhibitors indinavir, nelfinavir, and saquinavir exhibited unreliable placental transport, with cord blood concentrations that were frequently undetectable. Limited data, primarily from case reports, indicate that darunavir and raltegravir provide detectable placental transfer.

CONCLUSION

These findings appear consistent with current guidelines of using two NRTIs plus an NNRTI, atazanavir/ritonavir, or lopinavir/ritonavir to maximize placental transfer as well as to optimally suppress maternal viral load. Darunavir/ritonavir and raltegravir may reasonably serve as second-line agents.

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.

Nevirapine, sodium concentration and HIV-1 RNA in breast milk and plasma among HIV-infected women receiving short-course antiretroviral prophylaxis

Introduction

Risk factors for breast milk transmission of HIV-1 from mother to child include high plasma and breast milk viral load, low maternal CD4 count and breast pathology such as mastitis.

Objective

To determine the impact of nevirapine and subclinical mastitis on HIV-1 RNA in maternal plasma and breast milk after intrapartum single-dose nevirapine combined with either 1-week tail of Combivir (zidovudine/lamivudine) or single-dose Truvada (tenofovir/emtricitabine).

Methods

Maternal plasma and bilateral breast milk samples were collected between April 2008 and April 2011 at 1, 4 and 6 weeks postpartum from HIV-infected Tanzanian women. Moreover, plasma samples were collected at delivery from mother and infant.

Results

HIV-1 RNA was quantified in 1,212 breast milk samples from 273 women. At delivery, 96% of the women and 99% of the infants had detectable nevirapine in plasma with a median (interquartile range, IQR) of 1.5 μg/mL (0.75–2.20 μg/mL) and 1.04 μg/mL (0.39–1.71 μg/mL), respectively (P < 0.001). At 1 week postpartum, 93% and 98% of the women had detectable nevirapine in plasma and breast milk, with a median (IQR) of 0.13 μg/mL (0.13–0.39 μg/mL) and 0.22 μg/mL (0.13–0.34 μg/mL), respectively. Maternal plasma and breast milk HIV-1 RNA correlated at all visits (R = 0.48, R = 0.7, R = 0.59; all P = 0.01). Subclinical mastitis was detected in 67% of the women at some time during 6 weeks, and in 38% of the breast milk samples. Breast milk samples with subclinical mastitis had significantly higher HIV-1 RNA at 1, 4 and 6 weeks (all P < 0.05).

Conclusion

After short-course antiretroviral prophylaxis, nevirapine was detectable in most infant cord blood samples and the concentration in maternal plasma and breast milk was high through week 1 accompanied by suppressed HIV-1 RNA in plasma and breast milk.

Evaluation of adherence measures of antiretroviral prophylaxis in HIV exposed infants in the first 6 weeks of life

BACKGROUND

Adherence to an antiretroviral regimen is imperative for treatment success in both HIV infected adults and children. Likewise, adherence to antiretroviral prophylaxis is critical in HIV prevention. Studies on pediatric adherence are limited, particularly the prophylactic use of antiretroviral drugs and treatment adherence in very young infants. The HIV Prevention Trials Network (HPTN) 046 study (Clinical Trial Registration NCT00074412) determined the safety and efficacy of an extended regimen of nevirapine suspension in infants born to HIV-1 infected women for the prevention of vertical HIV transmission during breastfeeding. As per protocol, adherence to nevirapine prophylaxis was measured by maternal verbal reports. In addition, the pharmacy assessed the unused returned suspension. The aim of this sub-study was to determine the reliability of maternal verbal reports in measuring adherence to antiretroviral prophylaxis in infants in the first 6 weeks of life and evaluating the unused returned nevirapine as an alternative method of measuring adherence.

METHODS

Maternal verbal reports and pharmacy returns indicative of "missed < 2 doses" were evaluated against a plasma nevirapine concentration of >100 ng/ml in a subgroup of infants at 2, 5 and 6 weeks of age. Plasma nevirapine concentration of >100 ng/ml was used as a marker of adherence (10 times the in vitro IC50 against HIV).

RESULTS

Adherence was 87.7% (maternal verbal report) and 71.3% (unused returned medication), as compared to 85.6% by plasma nevirapine concentration. Evaluated against plasma nevirapine concentration <100 ng/ml, the sensitivity and specificity of maternal verbal reports to detect a missed dose in the last 3 days were 75% and 78% (p = 0.03) respectively. Overall, among infants who were classified as adherent based on missed doses by maternal verbal reports and unused returned medication, 88.4% and 87.4% of infants attained a nevirapine concentration above 100 ng/ml respectively.

CONCLUSION

Maternal verbal reports are a reliable measure of adherence to infant antiretroviral prophylaxis in the first 6 weeks of life and could be useful in assessing adherence to antiretroviral treatment in infants younger than 6 weeks. In the absence of resources or expertise to determine plasma drug concentration, we would recommend random assessments of unused returned medication.

[Hepatotoxicity in healthy infants exposed to nevirapine during pregnancy]

BACKGROUND

The use of nevirapine in HIV-infected pregnant women is discouraged due to its potential to cause hepatotoxicity. There is limited information available on the toxicity in non-HIV infected newborn exposed to this drug during pregnancy. The aim of the study is to determine the extent of hepatotoxicity in the newborn exposed to nevirapine and HIV during pregnancy.

METHODS

A cross-sectional, observational, multicenter study was conducted on a cohort of healthy infants born to HIV-infected mothers, in whom the first determination of alanine aminotransferase (ALT), before 6weeks of age, was collected. Patients were allocated to 2groups according to exposure to nevirapine during pregnancy. Hepatotoxicity was rated according to the AIDS Table for Grading the Severity of Adult and Pediatric Adverse Events (DAIDS).

RESULTS

This study included 160newborns from 159pregnancies (88exposed to nevirapine-based regimens and 71 exposed to protease inhibitors-based therapies). No cases of hepatotoxicity were observed according to the DAIDS Table for Grading. Two cases of ALT above normal values (2.8%; 95%CI: 0.3-9.8%) were observed in patients not exposed to nevirapine, and one case (1.1%; 95%CI: 0.0-6.1%) in the group exposed to nevirapine (P=.585).

CONCLUSION

The lack of differences between groups suggests that highly active antiretroviral treatment regimens including nevirapine administered during pregnancy do not involve a higher risk of liver disease compared to other treatment combinations.

Nevirapine concentrations in preterm and low birth weight HIV-exposed infants: implications for dosing recommendations

World Health Organisation guidelines recommend nevirapine 2 mg/kg/d for HIV-exposed infants <2 kg, but 4-6 mg/kg/d for infants >2 kg. In 116 low birth weight infants, nevirapine 2 mg/kg/d until 14 days, and 4 mg/kg/d thereafter, was safe (1 mild possibly related rash) and achieved target plasma concentrations. Concentrations decreased with treatment duration. Routine dose increase at 14 days should be considered.

Frequency of Antiretroviral Resistance Mutations among Infants Exposed to Single-Dose Nevirapine and Short Course Maternal Antiretroviral Regimens: ACTG A5207

Background

Intrapartum single-dose nevirapine (sdNVP) reduces HIV-1 perinatal transmission but selects NVP resistance among mothers and infants. We evaluated the frequency of antiretroviral resistance among infants with intrauterine HIV-1 infection exposed to sdNVP and maternal antenatal or breastfeeding antiretroviral therapy.

Methods

This analysis included 429 infants from sub-Saharan Africa, India and Haiti whose 422 mothers received sdNVP plus maternal study treatment. At entry mothers had CD4>250/μL and were ART-naïve except for antenatal ZDV per local standard of care. Maternal study treatment started intrapartum and included ZDV/3TC, TDF/FTC or LPV/r for 7 or 21 days in a randomized factorial design. Infants received sdNVP study treatment and ZDV if local standard of care. Infant HIV RNA or DNA PCR and samples for genotype were obtained at birth and weeks 2, 4 and 12; infants who ever breast-fed were also tested at weeks 16, 24, 48 and 96. Samples from HIV-1-infected infants were tested for drug resistance by population genotype (ViroSeq). NVP or NRTI resistance mutations were assessed using the IAS-USA mutation list.

Results

Perinatal HIV-1 transmission occurred in 17 (4.0%) infants including 12 intrauterine infections. Resistance mutations were detected among 5 (42%) intrauterine-infected infants; of these, 3 had mutations conferring resistance to NVP alone, 1 had resistance to NRTI alone, and 1 had dual-class resistance mutations. Among the 2 infants with NRTI mutations, one (K70R) was likely maternally transmitted and one (K65R) occurred in the context of breastfeeding exposure to maternal antiretroviral therapy.

Conclusions

Infants with intrauterine HIV infection are at risk of acquiring resistance mutations from exposure to maternal antiretroviral medications intrapartum and/or during breastfeeding. New approaches are needed to lower the risk of antiretroviral resistance in these infants.

Prophylaxis and treatment of HIV-1 infection in pregnancy: Swedish recommendations 2013

Prophylaxis and treatment with antiretroviral drugs and elective caesarean section delivery have resulted in very low mother-to-child transmission of HIV during recent years. Updated general treatment guidelines and increasing knowledge about mother-to-child transmission have necessitated regular revisions of the recommendations for the prophylaxis and treatment of HIV-1 infection in pregnancy. The Swedish Reference Group for Antiviral Therapy (RAV) updated the recommendations from 2010 at an expert meeting on 11 September 2013. The most important revisions are the following: (1) ongoing efficient treatment at confirmed pregnancy may, with a few exceptions, be continued; (2) if treatment is initiated during pregnancy, the recommended first-line therapy is essentially the same as for non-pregnant women; (3) raltegravir may be added to achieve rapid reduction in HIV RNA; (4) vaginal delivery is recommended if at > 34 gestational weeks and HIV RNA is < 50 copies/ml and no obstetric contraindications exist; (5) if HIV RNA is < 50 copies/ml and delivery is at > 34 gestational weeks, intravenous zidovudine is not recommended regardless of the delivery mode; (6) if HIV RNA is > 50 copies/ml close to delivery, it is recommended that the mother should undergo a planned caesarean section, intravenous zidovudine, and oral nevirapine, and the infant should receive single-dose nevirapine at 48-72 h of age and post-exposure prophylaxis with 2 drugs; (7) if delivery is preterm at < 34 gestational weeks, a caesarean section delivery should if possible be performed, with intravenous zidovudine and oral nevirapine given to the mother, and single-dose nevirapine given to the infant at 48-72 h of age, as well as post-exposure prophylaxis with 2 additional drugs.

Antiretroviral bioanalysis methods of tissues and body biofluids

Research in the many areas of HIV treatment, eradication and prevention has necessitated measurement of antiretroviral (ARV) concentrations in nontraditional specimen types. To determine the knowledgebase of critical details for accurate bioanalysis, a review of the literature was performed and summarized. Bioanalytical assays for 31 ARVs, including metabolites, were identified in 205 publications measuring various tissues and biofluids. 18 and 30% of tissue or biofluid methods, respectively, analyzed more than one specimen type; 35-37% of the tissue or biofluid methods quantitated more than one ARV. 20 and 76% of tissue or biofluid methods, respectively, were used for the analysis of human specimens. HPLC methods with UV detection predominated, but chronologically MS detection began to surpass. 40% of the assays provided complete intra- and inter-assay validation data, but only 9% of publications provided any stability data with even less for the prevalent ARV in treatments.

In-home HIV testing and nevirapine dosing by traditional birth attendants in rural Zambia: a feasibility study

INTRODUCTION

Access to lifesaving prevention of mother-to-child transmission (PMTCT) services is problematic in rural Zambia. The simplest intervention used in Zambia has been 2-dose nevirapine (NVP) administration in the peripartum period, a regimen of 1 NVP tablet to the mother at the onset of labor and 1 dose in the form of syrup to the newborn within 4 to 72 hours after birth. This 2-dose regimen has been shown to reduce MTCT by nearly 50%. We set out to demonstrate that in-home HIV testing and NVP dosing by traditional birth attendants (TBAs) is feasible and acceptable by women in rural Zambia.

METHODS

This was a pilot program using TBAs to perform rapid saliva-based HIV testing and administer single-dose NVP in tablet form to the mother at the onset of labor and syrup to the infant after birth.

RESULTS

A total of 280 pregnant women were consented and enrolled into the program, of whom 124 (44.3%) gave birth at home with the assistance of a trained TBA. Of those, 16 (12.9%) were known to be HIV positive, and 101 of the remaining 108 (93.5%) accepted a rapid HIV test. All these women tested HIV negative. In the subset of 16 mothers who were HIV positive, 13 (81.3%) took single-dose NVP administered by a TBA between 1 and 24 hours prior to birth and 100% of exposed newborns (16 of 16) received NVP syrup within 72 hours after birth, 80% of whom were dosed in the first 24 hours of life.

DISCUSSION

With the substantial shortage of human resources in public health care throughout sub-Saharan Africa, it is extremely valuable to utilize lay health care workers to help extended services beyond the level of the facility. Given the high uptake of PMTCT services we believe that TBAs with proper training and support can successfully provide country-approved PMTCT.

Pharmacokinetic optimization of antiretroviral therapy in pregnancy

Antiretroviral therapy suppresses replication of HIV allowing restoration and/or preservation of the immune system. Providing combination antiretroviral therapy during pregnancy can treat maternal HIV infection and/or reduce perinatal HIV transmission. However, providing treatment to pregnant women is challenging due to physiological changes that can alter antiretroviral pharmacokinetics. Suboptimal drug exposure can result in HIV RNA rebound, the selection of resistant virus or an increased risk of HIV-1 transmission to the infant. Increased drug exposure can produce unwarranted maternal adverse effects and/or fetal toxicity. Subsequently, dose adjustments may be necessary during pregnancy to achieve comparable antiretroviral exposure to non-pregnant adults. For several antiretrovirals, systemic exposure is decreased during the last trimester of pregnancy. By 6-12 weeks postpartum, concentrations return to those prior to pregnancy. Also, the extent of antiretroviral placental transfer to the fetus and degree of antiretroviral excretion into breast milk varies within, and between, antiretroviral drug classes. It is necessary to consider the pharmacological characteristics of each antiretroviral when optimizing combination therapy during pregnancy to treat maternal HIV infection and prevent perinatal HIV transmission.

Greater suppression of nevirapine resistance with 21- vs 7-day antiretroviral regimens after intrapartum single-dose nevirapine for prevention of mother-to-child transmission of HIV

BACKGROUND

Nevirapine (NVP) resistance emerges in up to 70% of women exposed to single-dose (sd) NVP for prevention of mother-to-child transmission of human immunodeficiency virus (HIV).

METHODS

HIV-infected pregnant women were randomized to receive sdNVP and either zidovudine/lamivudine (3TC), tenofovir/emtricitabine (FTC), or lopinavir/ritonavir for either 7 or 21 days. The primary endpoint was the emergence of new NVP resistance mutations as detected by standard population genotype at 2 and 6 weeks after treatment. Low-frequency NVP- or 3TC/FTC-resistant mutants at codons 103, 181, and 184 were sought using allele-specific polymerase chain reaction (ASP).

RESULTS

Among 484 women randomized, 422 (87%) received study treatment. Four hundred twelve (98%) women had primary endpoint results available; of these, 5 (1.2%) had new NVP resistance detected by population genotype: 4 of 215 in the 7-day arms (1.9%; K103N in 4 women with Y181C, Y188C, or G190A in 3 of 4) and 1 of 197 (0.5%; V108I) in the 21-day arms (P = .37). Among women with ASP results, new NVP resistance mutations emerged significantly more often in the 7-day arms (13/74 [18%]) than in the 21-day arms (3/66 [5%], P = .019). 3TC/FTC-resistant mutants (M184V/I) emerged infrequently (7/134 [5%]), and their occurrence did not differ by arm.

CONCLUSIONS

Three short-term antiretroviral strategies, begun simultaneously with the administration of sdNVP, resulted in a low rate (1.2%) of new NVP-resistance mutations when assessed at 2 and 6 weeks following completion of study treatment by standard genotype. ASP revealed that 21-day regimens were significantly better than 7-day regimens at preventing the emergence of minor NVP resistance variants. Clinical Trials Registration.NCT00099632.

Therapeutic levels of lopinavir in late pregnancy and abacavir passage into breast milk in the Mma Bana Study, Botswana

BACKGROUND

Pharmacokinetic data for lopinavir in late pregnancy and in breastfeeding are limited, and no data for abacavir in breast milk are available.

METHODS

Women in the Mma Bana Study initiated HAART from 18 to 34 weeks of gestation. We determined trough plasma and whole breast milk concentrations of lopinavir (LPV), abacavir (ABC), nevirapine (NVP), lamivudine (3TC) and zidovudine (ZDV) among separate subsets of pregnant and breastfeeding women, and in plasma of exposed infants. Lopinavir was measured 1 month after starting HAART or 1 month postpartum, and other drugs were measured 1 month postpartum.

RESULTS

Sampling occurred a median of 14 h (range 11-17) from last maternal drug ingestion. Although 50% higher median LPV levels were seen in postpartum than antepartum plasma (8.29 μg/ml versus 5.51 μg/ml; P = 0.02), antepartum levels with standard LPV dosing were therapeutic for all women (> 1.0 μg/ml). Very low LPV levels (< 0.25 μg/ml) were detected in breast milk. Median ABC levels in breast milk were 85% of those in plasma (0.057 μg/ml versus 0.067 μg/ml). Breast milk concentrations of NVP and 3TC were 27% and 74% of plasma levels, respectively. At these trough maternal time points, only NVP was detectable in potentially inhibitory levels in breastfeeding infants, and most infants had non-detectable levels of LPV, ABC, ZDV and 3TC via maternal breast milk.

CONCLUSIONS

Standard LPV dosing achieved therapeutic levels in pregnancy and no appreciable concentrations in breast milk. ABC is detectable in breast milk at similar concentrations to plasma, but does not result in appreciable infant exposure.

Pharmacotherapy of pediatric HIV infection

The delivery of safe and effective antiretroviral therapy to children and adolescents is crucial to save the lives of millions of children worldwide. The immunologic response to human immunodeficiency infection is closely related to a child's development and creates age-specific parameters for the evaluation of therapeutic response to antiretroviral therapy. Similarly, the development and maturation of organ systems involved in drug absorption, distribution, metabolism, and elimination determines significant changes in the pharmacokinetics of antiretroviral drugs throughout childhood. The authors review the evolution in treatment of pediatric HIV from infancy through adolescence.

Pharmacotherapy in pregnancy; effect of ABC and SLC transporters on drug transport across the placenta and fetal drug exposure

Pharmacotherapy during pregnancy is often inevitable for medical treatment of the mother, the fetus or both. The knowledge of drug transport across placenta is, therefore, an important topic to bear in mind when deciding treatment in pregnant women. Several drug transporters of the ABC and SLC families have been discovered in the placenta, such as P-glycoprotein, breast cancer resistance protein, or organic anion/cation transporters. It is thus evident that the passage of drugs across the placenta can no longer be predicted simply on the basis of their physical-chemical properties. Functional expression of placental drug transporters in the trophoblast and the possibility of drug-drug interactions must be considered to optimize pharmacotherapy during pregnancy. In this review we summarize current knowledge on the expression and function of ABC and SLC transporters in the trophoblast. Furthermore, we put this data into context with medical conditions that require maternal and/or fetal treatment during pregnancy, such as gestational diabetes, HIV infection, fetal arrhythmias and epilepsy. Proper understanding of the role of placental transporters should be of great interest not only to clinicians but also to pharmaceutical industry for future drug design and development to control the degree of fetal exposure.

Pharmacokinetic study of saquinavir 500 mg plus ritonavir (1000/100 mg twice a day) in HIV-positive pregnant women

Antiretroviral therapy during pregnancy is critical to preventing human immunodeficiency virus vertical transmission. Physiological changes during pregnancy can alter drug kinetics. The aim of this study was to assess the pharmacokinetics (PK) of saquinavir (SQV) boosted with ritonavir during pregnancy and postpartum. Fourteen human immunodeficiency virus-positive pregnant women started SQV 500 mg new tablet formulation plus ritonavir at a dose of 1000/100 mg twice a day + 2 nucleoside retrotranscriptase inhibitors during pregnancy. At weeks 24 and 34 of pregnancy and 6 weeks postpartum, a 12-hour PK study was conducted. PK parameters were calculated using Win Nolin software version 4.1. At week 24, the geometric mean values for SQV area under the plasma concentration-time curve from 0-12 hours (AUC₀₋₁₂), the maximum observed plasma concentration (C(max)), trough plasma concentration (C(min)), and the elimination half-life (t(1/2)) were 24.80 mg·h⁻¹·mL⁻¹, 4.66 mg/mL, 0.93 mg/mL, and 4.31 hours, respectively. At week 34, AUC₀₋₁₂, C(max), C(min), and t(1/2) were 12.71 mg·h⁻¹·mL⁻¹, 3.23 mg/mL, 0.26 mg/mL, and 4.06 hours, respectively. Finally, at 6 weeks postpartum, mean values for SQV AUC₀₋₁₂, C(max), C(min), and t(1/2) were 28.94 mg·h⁻¹·mL⁻¹, 3.92 mg/mL, 0.86 mg/mL, and 3.60 hours, respectively. Although PK parameters in week 24 and postpartum were very similar, those for week 34 showed an important reduction: -71.20%, -30.61%, -48.73%, and -5.81% in C(min), C(max), AUC₀₋₁₂, and t(1/2), respectively, compared with week 24, but no statistically significant differences were shown between patients. No vertical transmissions were reported. Therapeutic drug monitoring of SQV during pregnancy should be considered, mainly during the third trimester, to ensure adequate drug exposure throughout the entire pregnancy.

Pharmacokinetics of antiretroviral drugs in anatomical sanctuary sites: the fetal compartment (placenta and amniotic fluid)

HIV resides within anatomical 'sanctuary sites' where local drug exposure and viral dynamics may differ significantly from the systemic compartment. Widespread implementation of antiretroviral therapy has seen a significant decline in the incidence of mother-to-child transmission (MTCT) of HIV. In addition to suppression of maternal plasma/genital viral loads, antiretroviral agents that cross the placenta and achieve adequate concentrations in the fetal compartment may exert a greater prophylactic effect. Penetration of antiretrovirals in the fetal compartment is expressed by accumulation ratios derived from the measurement of drug concentrations in paired maternal plasma and umbilical cord samples. The nucleoside analogues and nevirapine accumulate extensively in cord blood and in the surrounding amniotic fluid, whereas the protease inhibitors (PIs) exhibit low-to-moderate placental accumulation. Early data suggest that high placental/neonatal concentrations are achieved with raltegravir, but to a lesser extent with etravirine and maraviroc (rank order of accumulation: raltegravir/nucleoside reverse transcriptase inhibitor [tenofovir > zidovudine/lamivudine/emtricitabine/stavudine/abacavir] > non-nucleoside reverse transcriptase inhibitor [nevirapine > etravirine] > PI > maraviroc/enfuvirtide). More comprehensive in vivo pharmacokinetic data are required to justify the potential use of these agents as safe and effective options during pregnancy.

Emergence of minor drug-resistant HIV-1 variants after triple antiretroviral prophylaxis for prevention of vertical HIV-1 transmission

BACKGROUND

WHO-guidelines for prevention of mother-to-child transmission of HIV-1 in resource-limited settings recommend complex maternal antiretroviral prophylaxis comprising antenatal zidovudine (AZT), nevirapine single-dose (NVP-SD) at labor onset and AZT/lamivudine (3TC) during labor and one week postpartum. Data on resistance development selected by this regimen is not available. We therefore analyzed the emergence of minor drug-resistant HIV-1 variants in Tanzanian women following complex prophylaxis.

METHOD

1395 pregnant women were tested for HIV-1 at Kyela District Hospital, Tanzania. 87/202 HIV-positive women started complex prophylaxis. Blood samples were collected before start of prophylaxis, at birth and 1-2, 4-6 and 12-16 weeks postpartum. Allele-specific real-time PCR assays specific for HIV-1 subtypes A, C and D were developed and applied on samples of mothers and their vertically infected infants to quantify key resistance mutations of AZT (K70R/T215Y/T215F), NVP (K103N/Y181C) and 3TC (M184V) at detection limits of <1%.

RESULTS

50/87 HIV-infected women having started complex prophylaxis were eligible for the study. All women took AZT with a median duration of 53 days (IQR 39-64); all women ingested NVP-SD, 86% took 3TC. HIV-1 resistance mutations were detected in 20/50 (40%) women, of which 70% displayed minority species. Variants with AZT-resistance mutations were found in 11/50 (22%), NVP-resistant variants in 9/50 (18%) and 3TC-resistant variants in 4/50 women (8%). Three women harbored resistant HIV-1 against more than one drug. 49/50 infants, including the seven vertically HIV-infected were breastfed, 3/7 infants exhibited drug-resistant virus.

CONCLUSION

Complex prophylaxis resulted in lower levels of NVP-selected resistance as compared to NVP-SD, but AZT-resistant HIV-1 emerged in a substantial proportion of women. Starting AZT in pregnancy week 14 instead of 28 as recommended by the current WHO-guidelines may further increase the frequency of AZT-resistance mutations. Given its impact on HIV-transmission rate and drug-resistance development, HAART for all HIV-positive pregnant women should be considered.

Quantifying the impact of nevirapine-based prophylaxis strategies to prevent mother-to-child transmission of HIV-1: a combined pharmacokinetic, pharmacodynamic, and viral dynamic analysis to predict clinical outcomes

Single-dose nevirapine (sd-NVP) and extended NVP prophylaxis are widely used in resource-constrained settings to prevent vertical HIV-1 transmission. We assessed the pharmacokinetics of sd-NVP in 62 HIV-1-positive pregnant Ugandan woman and their newborns who were receiving sd-NVP prophylaxis to prevent mother-to-child HIV-1 transmission. Based on these data, we developed a mathematical model system to quantify the impact of different sd-NVP regimens at delivery and of extended infant NVP prophylaxis (6, 14, 21, 26, 52, 78, and 102 weeks) on the 2-year risk of HIV-1 transmission and development of drug resistance in mothers and their breast-fed infants. Pharmacokinetic parameter estimates and model-predicted HIV-1 transmission rates were very consistent with other studies. Predicted 2-year HIV-1 transmission risks were 35.8% without prophylaxis, 31.6% for newborn sd-NVP, 19.1% for maternal sd-NVP, and 19.7% for maternal/newborn sd-NVP. Maternal sd-NVP reduced newborn infection predominately by transplacental exchange, providing protective NVP concentrations to the newborn at delivery, rather than by maternal viral load reduction. Drug resistance was frequently selected in HIV-1-positive mothers after maternal sd-NVP. Extended newborn NVP prophylaxis further decreased HIV-1 transmission risks, but an overall decline in cost-effectiveness for increasing durations of newborn prophylaxis was indicated. The total number of infections with resistant virus in newborns was not increased by extended newborn NVP prophylaxis. The developed mathematical modeling framework successfully predicted the risk of HIV-1 transmission and resistance development and can be adapted to other drugs/drug combinations to a priori assess their potential in reducing vertical HIV-1 transmission and resistance spread.

The role of therapeutic drug monitoring in the management of patients with human immunodeficiency virus infection

Therapeutic drug monitoring (TDM) is a well-established method to optimize dosing regimens in individual patients for drugs that are characterized by a narrow therapeutic range and large interindividual pharmacokinetic variability. For some antiretroviral drugs, mainly nonnucleoside reverse transcriptase inhibitors and protease inhibitors, TDM has been proposed as a means to improve the response in human immunodeficiency virus-infected patients. In contrast, nucleoside reverse transcriptase inhibitors do not show a predictable plasma concentration-response (toxicity, efficacy) relationship, and intracellular analyses are expensive. Therefore, TDM is generally not recommended for this class of drugs. TDM has been successfully applied in the clinical practice for certain antiretroviral drugs, but there are ongoing research efforts on the use and refinement of TDM for human immunodeficiency virus treatment, and convincing data from randomized trials are still needed. The best pharmacokinetic measures of drug exposure such as trough and peak concentrations or concentration ratios have not been unambiguously established.

Antiretrovirals for reducing the risk of mother-to-child transmission of HIV infection

BACKGROUND

Antiretroviral drugs reduce viral replication and can reduce mother-to-child transmission of HIV either by lowering plasma viral load in pregnant women or through post-exposure prophylaxis in their newborns. In rich countries, highly active antiretroviral therapy (HAART) which usually comprises three drugs, has reduced the mother-to-child transmission rates to around 1-2%, but HAART is not always available in low- and middle-income countries. In these countries, various simpler and less costly antiretroviral regimens have been offered to pregnant women or to their newborn babies, or to both.

OBJECTIVES

To determine whether, and to what extent, antiretroviral regimens aimed at decreasing the risk of mother-to-child transmission of HIV infection achieve a clinically useful decrease in transmission risk, and what effect these interventions have on maternal and infant mortality and morbidity.

SEARCH STRATEGY

We sought to identify all relevant studies regardless of language or publication status by searching the Cochrane HIV/AIDS Review Group Trials Register, The Cochrane Library, MEDLINE, EMBASE and AIDSearch and relevant conference abstracts. We also contacted research organizations and experts in the field for unpublished and ongoing studies. The original review search strategy was conducted in 2002 and updated in 2006 and again in 2009.

SELECTION CRITERIA

Randomised controlled trials of any antiretroviral regimen aimed at decreasing the risk of mother-to-child transmission of HIV infection compared with placebo or no treatment, or compared with another antiretroviral regimen.

DATA COLLECTION AND ANALYSIS

Two authors independently selected relevant studies, extracted data and assessed trial quality. For the primary outcomes, we used survival analysis to estimate the probability of infants being infected with HIV (the observed proportion) at various specific time-points and calculated efficacy at a specific time as the relative reduction in the proportion infected. Efficacy, at a specific time, is defined as the preventive fraction in the exposed group compared to the reference group, which is the relative reduction in the proportion infected: 1-(Re/Rf). For those studies where efficacy and hence confidence intervals were not calculated, we calculated the approximate confidence intervals for the efficacy using recommended methods. For analysis of results that are not based on survival analyses we present the relative risk for each trial outcome based on the number randomised. No meta-analysis was conducted as no trial assessed identical drug regimens.

MAIN RESULTS

Twenty-five trials including 18,901 participants with a median trial sample size of 627 ranging from 50 to 1,844 participants were included in this update. Twenty-two trials randomised mothers (18 pre-natally and four in labour) and followed up their infants, and three trials randomised infants. The first trial began in April 1991 and assessed zidovudine (ZDV) versus placebo and since then, the type, dosage and duration of drugs to be compared has been modified in each subsequent trial. We present the results stratified by regimen and type of feeding.Antiretrovirals versus placebo In breastfeeding populations, three trials found that:ZDV given to mothers from 36 to 38 weeks gestation, during labour and for 7 days after delivery significantly reduced HIV infection at 4-8 weeks (Efficacy 32.00%; 95% CI 1.50 to 62.50), 3 to 4 months (Efficacy 33.07%; 95% CI 5.57 to 60.57), 6 months (Efficacy 34.55%; 95% CI 9.05 to 60.05), 12 months (Efficacy 34.31%; 95% CI 9.30 to 59.32) and 18 months (Efficacy 29.74%; 95% CI 2.73 to 56.75).ZDV given to mothers from 36 weeks gestation and during labour significantly reduced HIV infection at 4 to 8 weeks (Efficacy 43.78%; 95% CI 8.78 to 78.78) and 3 to 4 months (Efficacy 36.95%; 95% CI 2.94 to 70.96) but not at birth.ZDV plus lamivudine (3TC) given to mothers from 36 weeks gestation, during labour and for 7 days after delivery and to babies for the first 7 days after birth (PETRA 'regimen A') significantly reduced HIV infection (Efficacy 62.75%; 95% CI 40.76 to 84.74) and a combined endpoint of HIV infection or death (Efficacy 62.75 [, ]61.00%; 95% CI 40.76 to 84.74) at 4 to 8 weeks but these effects were not sustained at 18 months.ZDV plus 3TC given to mothers from the start of labour until 7 days after delivery and to babies for the first 7 days after birth (PETRA 'regimen B') significantly reduced HIV infection (Efficacy 41.83%; 95% CI 12.82 to 70.84) and HIV infection or death at 4 to 8 weeks (Efficacy 35.91%; 95% CI 8.41 to 63.41) but the effects were not sustained at 18 months.ZDV plus 3TC given to mothers during labour only (PETRA 'regimen C') with no treatment to babies did not reduce the risk of HIV infection at either 4 to 8 weeks or 18 months.In non-breastfeeding populations, three trials found that:ZDV given to mothers from 14 to 34 weeks gestation and during labour and to babies for the first 6 weeks after birth significantly reduced HIV infection in babies at 18 months (Efficacy 66.22%; 95% CI 33.94 to 98.50).ZDV given to mothers from 36 weeks gestation and during labour with no treatment to babies ('Thai-CDC regimen') significantly reduced HIV infection at 4 to 8 weeks (Efficacy 50.26%; 95% CI 13.80 to 86.72) but not at birthZDV given to mothers from 38 weeks gestation and during labour with no treatment to babies did not influence HIV transmission at 6 months.Longer versus shorter regimens using the same antiretrovirals One trial in a breastfeeding population found that:ZDV given to mothers during labour and to their babies for the first 3 days after birth compared with ZDV given to mothers from 36 weeks and during labour (similar to 'Thai-CDC') resulted in HIV infection rates that were not significantly different at birth, 4-8 weeks, 3 to 4 months, 6 months and 12 months.Three trials in non-breastfeeding populations found that:ZDV given to mothers from 28 weeks gestation during labour and to infants for the first 3 days after birth compared with ZDV given to mothers from 35 weeks gestation through labour and to infants from birth to 6 weeks significantly reduced HIV infection rate at 6 months (Efficacy 45.35 %; 95% CI 1.39 to 89.31) but compared with the same regimen ZDV given to mothers from 28 weeks gestation through labour and to infants from birth to 6 weeks did not result in a statistically significant difference in HIV infection at 6 months. ZDV given to mothers from 35 weeks gestation during labour and to infants for the first 3 days after birth was considered ineffective for reducing transmission rates and this regimen was discontinued.An antenatal/intrapartum course of ZDV used for a median of 76 days compared with an antenatal/intrapartum ZDV regimen used for a median 28 days with no treatment to babies in either group did not result in HIV infection rates that were significantly different at birth and at 3 to 4 months.In a programme where mothers were routinely receiving ZDV in the third trimester of pregnancy and babies were receiving one week of ZDV therapy, a single dose of nevirapine (NVP) given to mothers in labour and to their babies soon after birth compared with a single dose of NVP given to mothers only resulted in HIV infection rates that were not significantly different at birth and 6 months. However the reduction in risk of HIV infection or death at 6 months was marginally significant (Efficacy 45.00%; 95% CI -4.00 to 94.00).Antiretroviral regimens using different drugs and durations of treatmentIn breastfeeding populations, three trials found that:A single dose of NVP given to mothers at the onset of labour plus a single dose of NVP given to their babies immediately after birth ('HIVNET 012 regimen') compared with ZDV given to mothers during labour and to their babies for a week after birth resulted in lower HIV infection rates at 4-8 weeks (Efficacy 41.00%; 95% CI 11.84 to 70.16), 3-4 months (Efficacy 38.91%; 95% CI 11.24 to 66.58), 12 months (Efficacy 35.98 [9.25, 62.71]36.00%; 95% CI 8.56 to 63.44) and 18 months (Efficacy 39.15%; 95% CI 13.81 to 64.49). In addition, the NVP regimen significantly reduced the risk of HIV infection or death at 4-8 weeks (Efficacy 41.74%; 95% CI 14.30 to 69.18), 3 to 4 months (Efficacy 40.00%; 95% CI 14.34 to 65.66), 12 months (Efficacy 32.17%; 95% CI 8.51 to 55.83) and 18 months (Efficacy 32.57 [9.93, 55.21]33.00%; 95% CI 9.93 to 55.21).The 'HIVNET 012 regimen' plus ZDV given to babies for 1 week after birth compared with the 'HIVNET 012 regimen' alone did not result in a statistically significant difference in HIV infection at 4 to 8 weeks.A single dose of NVP given to babies immediately after birth plus ZDV given to babies for 1 week after birth compared with a single dose of NVP given to babies only significantly reduced the HIV infection rate at 4 to 8 weeks (Efficacy 36.79%; 95% CI 3.57 to 70.01).Five trials in non-breastfeeding populations found that:In a population in which mothers were receiving 'standard' antiretroviral for HIV infection a single dose of NVP given to mothers in labour plus a single dose of NVP given to babies immediately after birth ('HIVNET 012 regimen') compared with placebo did not result in a statistically significant difference in HIV infection rates at birth and at 4 to 8 weeks.The 'Thai CDC regimen' compared with the 'HIVNET 012 regimen' did not result in a significant difference in HIV infection at 4 to 8 weeks.A single dose of NVP given to babies immediately after birth compared to ZDV given to babies for the first 6 weeks after birth did not result in a significant difference in HIV infection rates at 4-8 weeks and 3 to 4 months. (ABSTRACT TRUNCATED)

Role of low-frequency HIV-1 variants in failure of nevirapine-containing antiviral therapy in women previously exposed to single-dose nevirapine

In the OCTANE/A5208 study of initial antiretroviral therapy (ART) in women exposed to single-dose nevirapine (sdNVP) ≥ 6 mo earlier, the primary endpoint (virological failure or death) was significantly more frequent in the NVP-containing treatment arm than in the lopinavir/ritonavir-containing treatment arm. Detection of NVP resistance in plasma virus at study entry by standard population genotype was strongly associated with the primary endpoint in the NVP arm, but two-thirds of endpoints occurred in women without NVP resistance. We hypothesized that low-frequency NVP-resistant mutants, missed by population genotype, explained excess failure in the NVP treatment arm. Plasma samples from 232 participants were analyzed by allele-specific PCR at study entry to quantify NVP-resistant mutants down to 0.1% for 103N and 190A and to 0.3% for 181C. Of 201 women without NVP resistance by population genotype, 70 (35%) had NVP-resistant mutants detected by allele-specific PCR. Among these 70 women, primary endpoints occurred in 12 (32%) of 38 women in the NVP arm vs. 3 (9%) of 32 in the lopinavir/ritonavir-containing arm (hazard ratio = 3.84). The occurrence of a primary endpoint in the NVP arm was significantly associated with the presence of K103N or Y181C NVP-resistant mutations at frequencies >1%. The risk for a study endpoint associated with NVP-resistant mutant levels did not decrease with time. Therefore, among women with prior exposure to sdNVP, low-frequency NVP-resistant mutants were associated with increased risk for failure of NVP-containing ART. The implications for choosing initial ART for sdNVP-exposed women are discussed.

Nevirapine once daily: pharmacology, metabolic profile and efficacy data of the new extended-release formulation

INTRODUCTION

Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, has been an important component of HIV infection treatment for many years. Currently, twice-a-day dosing is required for the successful application of NVP immediate release (IR), but there is potential for a more convenient once-a-day antiretroviral combination.

AREAS COVERED

The purpose of this article is to review the recent data on once-daily NVP extended release (XR) looking at all the important pharmacologic, pharmacokinetic and clinical data on NVP IR/XR through a systematic MEDLINE database search as well as a review of abstracts presented at international HIV meetings on NVP XR studies up to December 2010. The article provides the reader with an overview of all the pharmacodynamic and pharmacokinetic aspects of NVP IR/XR, as well as its preclinical and clinical efficacy and its safety.

EXPERT OPINION

NVP XR is as effective as NVP IR among HIV-infected patients with a similar safety profile. NVP XR requires careful monitoring during initiation, but its favorable lipid profile may be of clinical benefit in reducing the risk for coronary artery disease in HIV-infected patients who are receiving long-term antiretroviral therapy. Further research is needed to predict short-term toxicity.

Medication persistence in the treatment of HIV infection: a review of the literature and implications for future clinical care and research

Persistence, continuous treatment with a prescribed medication or intervention, is an important, but underrecognized aspect of medication treatment, especially for HIV. In contrast to adherence, which measures the percentage of patient behavior to a prescribed therapy, persistence measures the duration during which a patient remains on a prescribed therapy. Decreased persistence for HIV treatment, or shorter duration on therapy, is associated with increased rates of virological failure, development of antiretroviral resistance, and increased morbidity and mortality. Additionally, frequency and duration of nonpersistent episodes rather than adherence may be a better predictor of clinical outcomes in HIV-infected patients on certain regimens. In this review, we codify the constructs of persistence and adherence, and further define persistence as either patient or regimen persistence. Furthermore, current literature on the clinical consequences of and factors associated with suboptimal persistence is summarized. Finally, methods to measure persistence as well as interventions that may improve persistence and clinical outcomes are suggested.