Pharmacokinetic Enhancement of HIV Antiretroviral Therapy During Pregnancy

Efficacy and safety of 2-drug regime dolutegravir/lamivudine in pregnancy and breastfeeding - clinical implications and perspectives

OBJECTIVES

To assess the efficacy and safety of a two-drug regimen (2DR) with dolutegravir (DTG) and lamivudine (3TC) in maintaining viral suppression during pregnancy and breastfeeding, and to evaluate its potential as an alternative to the recommended three-drug regimen (3DR) in preventing mother-to-child transmission (MTCT) of HIV.

METHODS

We present a case of a 34-year-old pregnant woman who, after discontinuing 3DR due to side effects and poor adherence, was switched to DTG/3TC at gestational week 23. Maternal viral load (VL) and infant HIV status were monitored throughout pregnancy and a ten-month breastfeeding period. Data on pharmacokinetic changes in pregnancy and the risks associated with 2DR were reviewed.

RESULTS

The patient's VL remained suppressed (<20 copies/mL) from gestational week 23 until the end of the breastfeeding period. A healthy HIV-negative baby was born at 39 weeks, and the child remained HIV-negative after ten months of breastfeeding. The 2DR was well-tolerated, improved adherence, and reduced fetal drug exposure. Despite limited experience with 2DR in pregnancy, no viral rebound occurred, and no adverse effects were observed.

CONCLUSIONS

Although 3DR remains the preferred therapy during pregnancy and breastfeeding, this case indicates that DTG/3TC may be an effective alternative for patients experiencing intolerance or poor adherence to 3DR. Further studies are needed to explore the impact of pharmacokinetic changes in pregnancy on 2DR efficacy and to confirm its safety and role in preventing MTCT.

Ritonavir: 25 Years' Experience of Concomitant Medication Management. A Narrative Review

Ritonavir is a potent inhibitor of the cytochrome P450 3A4 enzyme and is commonly used as a pharmacokinetic (PK) enhancer in antiviral therapies because it increases bioavailability of concomitantly administered antivirals. Decades of experience with ritonavir-enhanced HIV therapies and, more recently, COVID-19 therapies demonstrate that boosting doses of ritonavir are well tolerated, with an established safety profile. The mechanisms of PK enhancement by ritonavir result in the potential for drug-drug interactions (DDIs) with several classes of drugs, thus making co-medication management an important consideration with enhanced antiviral therapies. However, rates of DDIs with contraindicated medications are low, suggesting these risks are manageable by infectious disease specialists who have experience with the use of PK enhancers. In this review, we provide an overview of ritonavir's mechanisms of action and describe approaches and resources available to mitigate adverse events and manage concomitant medication in both chronic and short-term settings.

Pharmacokinetics of Antiretroviral Agents in Pregnant Individuals Living With HIV: Current Status and Considerations for Study Design and Interpretation

Determining the appropriate dosing regimens of antiretroviral (ARV) drugs for pregnant individuals living with HIV-1 infection is critical to maximize maternal health and prevent perinatal HIV transmission. Throughout pregnancy, pharmacokinetics (PK) of ARVs can be significantly altered due to physiological, anatomic, and metabolic changes. As such, conducting PK studies of ARVs during pregnancy is crucial to optimize dosing regimens. In this article, we summarize available data, key issues, challenges, and considerations in interpreting results of ARV PK studies in pregnant individuals. Discussion topics include the choice of the reference population (postpartum vs historical control), pregnancy trimester-dependent changes in ARV PK, effects of pregnancy on once- versus twice-daily dosing, factors to consider for ARVs that are administered with a PK booster such as ritonavir and cobicistat, and considerations when evaluating the effects of pregnancy on unbound ARV concentrations. Common approaches for the translation of the results into clinical recommendations and rationales and considerations when making clinical recommendations are summarized. Currently, limited PK data in pregnancy are available with long-acting ARVs. Collection of PK data to characterize the PK profile of long-acting ARVs is an important goal shared by many stakeholders.

Physiologic Changes During Pregnancy and Impact on Small-Molecule Drugs, Biologic (Monoclonal Antibody) Disposition, and Response

Pregnancy is a unique physiological state that results in many changes in bodily function, including cellular, metabolic, and hormonal changes. These changes can have a significant impact on the way small-molecule drugs and monoclonal antibodies (biologics) function and are metabolized, including efficacy, safety, potency, and adverse effects. In this article, we review the various physiologic changes that occur during pregnancy and their effects on drug and biologic metabolism, including changes in the coagulation, gastrointestinal, renal, endocrine, hepatic, respiratory, and cardiovascular systems. Additionally, we discuss how these changes can affect the processes of drug and biologic absorption, distribution, metabolism, and elimination (pharmacokinetics), and how drugs and biologics interact with biological systems, including mechanisms of drug action and effect (pharmacodynamics) during pregnancy, as well as the potential for drug-induced toxicity and adverse effects in the mother and developing fetus. The article also examines the implications of these changes for the use of drugs and biologics during pregnancy, including consequences of suboptimal plasma drug concentrations, effect of pregnancy on the pharmacokinetics and pharmacodynamics of biologics, and the need for careful monitoring and individualized drug dosing. Overall, this article aims to provide a comprehensive understanding of the physiologic changes during pregnancy and their effects on drug and biologic metabolism to improve the safe and effective use of drugs.

Direct antiviral agents (DAAs) and their use in pregnant women with hepatitis C (HCV)

INTRODUCTION

Direct-Acting Antiviral Agents (DAAs) provide safer, efficacious, tolerable, and curative therapy for women with hepatitis C. Their preferred safety and efficacy profile make them potential therapies for the elimination of perinatal transmission of hepatitis C virus (HCV). However, DAAs are not currently recommended for use during pregnancy due to limited pharmacokinetic and safety data.

AREAS COVERED

This review covers the different DAA drug combinations, the available data on their pharmacodynamic and pharmacokinetic properties, how the physiology in pregnancy can potentially affect DAA drug disposition, known drug-drug interactions with DAAs, and available and planned epidemiological and pharmacokinetic studies on DAA use during pregnancy. Although no large randomized clinical trials or prospective cohort studies involving DAAs have been completed in pregnancy, the currently available studies demonstrate no significant changes in pharmacokinetics, and no major safety concerns in women with hepatitis C.

EXPERT OPINION

Initial pharmacokinetic and safety data suggest that DAAs have high efficacy and a low risk of adverse events during pregnancy. As more pharmacokinetic and epidemiologic data become available, DAAs could become a preferred option for treating HCV during pregnancy and elimination of perinatal transmission of hepatitis C virus.

Pharmacological approaches to prevent vertical transmission of HIV and HBV

INTRODUCTION

Mother-to-child transmission (MTCT) is mainly responsible for the global pediatric HIV and HBV epidemic. Vertical transmission can be prevented and reduced through a series of interventions at the primary healthcare level, including extensive screening of pregnant women, administration of antivirals or immune-based treatments, counselling on type of delivery and breastfeeding.

AREAS COVERED

In this narrative review, approved therapeutic options for the treatment of pregnant women living with HIV or HBV are discussed with special focus on efficacy and safety profiles of each agent or drug class examined. The search was performed using Medline (via PubMed), Web of Science, and Google Scholar to identify studies assessing vertical transmission of both HIV and HBV.

EXPERT OPINION

Elimination of MTCT of both infections is firmly endorsed by major global commitments and the integration of tailored preventive interventions into maternal and newborn health services is of strategical importance to achieve this critical target. However, further research centered on antiviral-based and immunization trials among pregnant women is urgently needed to mitigate the risk of maternal and neonatal adverse outcomes, effectively prevent transmission to the offspring and finally eliminate the pediatric HIV and HBV epidemic, one of the key global health challenges of our time.

Adherence Predictors in Pregnant Women Living with HIV on Tenofovir Alafenamide and Tenofovir Disoproxil Fumarate

BACKGROUND

Medication adherence to antiretroviral medications is critical during pregnancy in women living with HIV (WLHIV) for multiple reasons. In this study, we report medication adherence to tenofovir alafenamide (TAF) compared to tenofovir disoproxil fumarate (TDF) during pregnancy in WLHIV.

METHODS

This is a retrospective cohort study of pregnant women living with HIV aged 18-48 years who received either tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF) during pregnancy. Medication adherence was assessed during each visit in all trimesters of pregnancy, and was self-reported. Demographics and outcomes were analyzed using standard statistical tests. Logistic regression analysis models accounting for potential confounders, with adjusted odds-ratios (aORs) and associated 95% confidence intervals were reported.

RESULTS

One hundred women met inclusion criteria, with thirty-four women on TAF and sixty-six women on TDF. While medication adherence was higher in women using TAF compared to TDF, with 76% adherent to TDF vs 83% adherent to TAF; p=0.282, in the 1^st trimester; 82% adherent to TDF vs 88% adherent to TAF; p=0.924, in the 2^nd trimester, and 88% adherent to TDF vs 91% adherent to TAF; p=0.176, in the 3^rd trimester of pregnancy, these differences in medication adherence were not statistically significant. In the third trimester of pregnancy, multiparous women were more likely to be adherent to TDF/TAF antiretroviral medications compared to nulliparous women - univariable odds ratio, OR 1.31, 95% CI 1.12, 1.57; p<0.05; multivariable (adjusted odds ratio, aOR 1.23, 95% CI 1.08, 1.52; p<0.05).

CONCLUSIONS

Pregnant women living with HIV on TDF and TAF achieved high adherence, but medication adherence was better in the third trimester compared to the first or second trimesters of pregnancy. These findings support the need to continually assess medication adherence during pregnancy.

A practical clinical guide to counselling on and managing contraception, pre-conception planning, and menopause for women living with HIV

Background

Women represent one quarter of the population living with HIV in Canada and are an increasingly important sector of the HIV community. While some women's health issues such as cervical cancer screening and management are well addressed in HIV management guidelines, others are not. These include sexual and reproductive health factors such as contraception, pre-conception planning, and menopause. Existing literature has shown that while women living with HIV in Canada receive good HIV care based on HIV care cascade indicators, their women's health and sexual and reproductive health care needs are not being met.

Methods

In this article, we present a clinical guide for clinicians providing care for women living with HIV on three key women's health topics that are under-discussed during HIV care visits: (1) contraception, (2) pre-conception planning, and (3) menopause.

Results

We have summarized the most pertinent clinical factors on each topic to support straightforward counselling and present important considerations in the context of HIV-related diseases and treatment. Finally, when relevant, we have provided practical stepwise approaches for addressing each of these women's health care topics when seeing a patient during a visit.

Conclusions

It is important that HIV specialists stay well-versed in the complex clinical interactions between HIV treatment and management of women's health issues.