Dolutegravir pharmacokinetics in pregnant and postpartum women living with HIV

Pharmacogenetics of Efavirenz Exposure in Cervicovaginal Fluid during Pregnancy and Postpartum

In this study, we investigated the combined influence of pregnancy and genetic polymorphisms on efavirenz pharmacokinetics in cervicovaginal fluid (CVF) of women receiving antiretroviral therapy. Women receiving efavirenz-containing antiretroviral therapy were recruited from two hospitals in Nigeria during 2017-2020. Sparse CVF and plasma samples were obtained during pregnancy to assess the possible association between drug concentration and CYP2B6 polymorphisms (stage I). Participants were stratified into three CYP2B6 516G>T (rs3745274) genotype groups and re-enrolled for intensive pharmacokinetic sampling (stage II). Overall, 159 women (142 pregnant and 12 postpartum) contributed samples in stage I (88 CVF, 81 plasma and 73 paired). CYP2B6 516G>T (rs3745274) remained independently associated with log10 efavirenz CVF concentration during pregnancy after adjusting for plasma concentration, with β (Log10 efavirenz concentration, 95%CI) of 0.204 (0.027, 0.382), P = 0.025). Median (IQR) efavirenz Cmin in CVF during pregnancy (n = 12) vs. postpartum (n = 12) was 243 ng/mL (168-402) vs. 447 ng/mL (159-974), Cmax was 1,031 ng/mL (595-1,771) vs. 1,618 ng/mL (675-2,695), and AUC0-24h was 16,465 ng.h/mL (9,356-30,417) vs. 30,715 ng.h/mL (10,980-43,714). CVF-to-plasma AUC ratio was 0.36 during pregnancy and 0.46 postpartum. Upon stratification, efavirenz clearance during pregnancy was 57.9% higher than postpartum in patients with the CYP2B6 516GT genotype; the AUC0-24h and Cmax were 33.8% and 8.6% lower, respectively. Efavirenz Cmin in CVF exceeded the protein binding-adjusted IC90 (PBIC90) of 126 ng/mL during pregnancy and postpartum. Efavirenz is well distributed into the CVF; both pregnancy and CYP2B6 polymorphisms affect the extent of exposure.

Pharmacokinetic and toxicological considerations affecting antiretroviral drug dosing in pregnant women

INTRODUCTION

To prevent mother-to-child transmission (PMTCT) of the human immunodeficiency virus (HIV) during pregnancy, the appropriate dosing regimens of antiretroviral (ARV) drugs need to be determined. Reliable data about pharmacokinetic (PK) characteristics of ARVs from randomized clinical trials (RCTs) are lacking, and post-marketing observational studies may offer valuable, but sometimes insufficient data, especially in pregnant people living with HIV (PLWHIV). This review article is focused PK and toxicological considerations affecting ARV dosing in pregnant PLWHIV.

AREAS COVERED

In our search, we included studies focused on PKs of ARVs in pregnancy available on PubMed, abstracts from recent global conferences and data from modeling studies. There are no significant changes in PKs of nucleoside/nucleotide reverse transcriptase inhibitors and non-nucleoside reverse transcriptase inhibitors throughout pregnancy. In contrast, the PKs of PIs and INSTIs are more variable, especially in the second and third trimesters.

EXPERT OPINION

Pregnant women are left out of RCTs. To the greatest extent possible, future research should include pregnant persons in RCTs, including PK studies, strictly considering maternal and fetal safety. Alternative innovative approaches/models need to be developed to obtain reliable data about rational pharmacotherapy of ARVs in the effective PMTCT of HIV, with maximum safety.

Antiretroviral Therapy in Pregnancy: A 2023 Review of the Literature

PURPOSE OF REVIEW

Selection of antiretroviral therapy during pregnancy must consider maternal physiology and resulting pharmacokinetic changes in pregnancy, resistance and efficacy profiles, tolerability and frequency of adverse effects, teratogenicity, and maternal, neonatal, and pregnancy outcomes. The objective of this review is to summarize the underlying data that informs the current clinical perinatal guidelines in the USA.

RECENT FINDINGS

Data now supports the use of dolutegravir at all stages of pregnancy with no significant increase in neural tube defects. Safety and pharmacokinetic data on newer antiretroviral medications in pregnancy continue to lag behind the general population. While there are multiple safety and tolerability concerns with older regimens, there are now multiple options of regimens that are highly efficacious and have good safety data in pregnancy. Most pregnant patients who are virally suppressed on a well-tolerated regimen are able to safely continue those medications during pregnancy.

Long-acting dolutegravir formulations prevent neurodevelopmental impairments in a mouse model

The World Health Organization has recommended dolutegravir (DTG) as a preferred first-line treatment for treatment naive and experienced people living with human immunodeficiency virus type one (PLWHIV). Based on these recommendations 15 million PLWHIV worldwide are expected to be treated with DTG regimens on or before 2025. This includes pregnant women. Current widespread use of DTG is linked to the drug's high potency, barrier to resistance, and cost-effectiveness. Despite such benefits, potential risks of DTG-linked fetal neurodevelopmental toxicity remain a concern. To this end, novel formulation strategies are urgently needed in order to maximize DTG's therapeutic potentials while limiting adverse events. In regard to potential maternal fetal toxicities, we hypothesized that injectable long-acting nanoformulated DTG (NDTG) could provide improved safety by reducing drug fetal exposures compared to orally administered native drug. To test this notion, we treated pregnant C3H/HeJ mice with daily oral native DTG at a human equivalent dosage (5 mg/kg; n = 6) or vehicle (control; n = 8). These were compared against pregnant mice injected with intramuscular (IM) NDTG formulations given at 45 (n = 3) or 25 (n = 4) mg/kg at one or two doses, respectively. Treatment began at gestation day (GD) 0.5. Magnetic resonance imaging scanning of live dams at GD 17.5 was performed to obtain T1 maps of the embryo brain to assess T1 relaxation times of drug-induced oxidative stress. Significantly lower T1 values were noted in daily oral native DTG-treated mice, whereas comparative T1 values were noted between control and NDTG-treated mice. This data reflected prevention of DTG-induced oxidative stress when delivered as NDTG. Proteomic profiling of embryo brain tissues harvested at GD 17.5 demonstrated reductions in oxidative stress, mitochondrial impairments, and amelioration of impaired neurogenesis and synaptogenesis in NDTG-treated mice. Pharmacokinetic (PK) tests determined that both daily oral native DTG and parenteral NDTG achieved clinically equivalent therapeutic plasma DTG levels in dams (4,000-6,500 ng/mL). Importantly, NDTG led to five-fold lower DTG concentrations in embryo brain tissues compared to daily oral administration. Altogether, our preliminary work suggests that long-acting drug delivery can limit DTG-linked neurodevelopmental deficits.

Brief Report: Dolutegravir Plasma Protein Binding and Unbound Concentrations During Pregnancy and Postpartum

BACKGROUND

Clinical interpretation of the reduced dolutegravir (DTG) plasma concentrations reported during pregnancy is complicated by its high plasma protein binding. Plasma proteins significantly decrease during pregnancy, and understanding changes in DTG protein binding and its therapeutically active unbound concentrations are necessary to evaluate the impact of pregnancy changes on DTG pharmacokinetics.

METHODS

Retrospective assessment of plasma samples from pregnant women living with HIV enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1026s study receiving 50 mg DTG film-coated tablets once daily as part of clinical care. Unbound and total DTG concentrations were determined predose (C0) and at maximum (Cmax) concentrations during the second trimester (2T), third trimester (3T), and postpartum (PP). Percentage unbound was calculated as the ratio of ultrafiltrate unbound DTG concentration to total DTG concentration.

RESULTS

Twenty-nine mothers were included for protein binding evaluations; 15, 27, and 23 from the 2T, 3T, and PP, respectively. DTG % unbound for C0 and Cmax were significantly different by stage of pregnancy, with 3T significantly higher compared with PP; 1.02% vs. 0.69% (P = 0.0067) for C0 and 0.76% vs. 0.46% for Cmax (P = 0.0056). Median (IQR) unbound concentrations for C0 were 6.3 (4.7-18.4) for the 2T, 8.0 (5.6-16.9) for the 3T, and 13.3 (8.4-22.7) ng/mL PP, significantly different between 2T and PP (P = 0.0039), but not different between 3T and PP (P = 0.46).

CONCLUSION

Lower total DTG plasma concentrations during pregnancy coincide with temporal decreases in DTG protein binding, resulting in comparable unbound DTG concentrations during the 3T and PP.

Haematopoietic stem-cell transplantation in an HIV endemic area: time to consider donors exposed to or living with HIV

South Africa has more than 8 million people living with HIV. However, the number of patients undergoing haematopoietic stem-cell transplantation (HSCT) in South Africa is far below the target number. Donor numbers are insufficient to meet demand. Both HSCT and solid organ transplantation have proved successful in people living with HIV. Solid organ transplantation also has good outcomes when both donors and recipients have HIV. This Personal View explores the possible inclusion of people living with HIV and umbilical cord blood from HIV-negative infants exposed to HIV as donor sources for HSCT. Beyond the risk of HIV transmission, additional complications must be considered, such as delayed or inadequate immune reconstitution and an increased risk of haematological abnormalities and malignancies. Interactions between antiretroviral drugs and drugs used in the conditioning regimen, as well as the need to maintain virological suppression when gastrointestinal absorption deteriorates, are additional complicating factors. The process also requires more stringent ethical processes to be in place to minimise physical and emotional harm. However, in an HIV endemic country, people living with HIV or donors exposed to HIV must be considered as part of a multidisciplinary collaborative effort to provide more patients with the opportunity to have a life-saving HSCT.

Total and Free Blood and Plasma Concentration Changes in Pregnancy for Medicines Highly Bound to Plasma Proteins: Application of Physiologically Based Pharmacokinetic Modelling to Understand the Impact on Efficacy

Free drug concentrations are generally considered the pharmacologically active moiety and are important for cellular diffusion and distribution. Pregnancy-related changes in plasma protein binding and blood partitioning are due to decreases in plasma albumin, alpha-1-acid glycoprotein, and haematocrit; this may lead to increased free concentrations, tissue distribution, and clearance during pregnancy. In this paper we highlight the importance and challenges of considering changes in total and free concentrations during pregnancy. For medicines highly bound to plasma proteins, such as tacrolimus, efavirenz, clindamycin, phenytoin, and carbamazepine, differential changes in concentrations of free drug during pregnancy may be clinically significant and have important implications for dose adjustment. Therapeutic drug monitoring usually relies on the measurement of total concentrations; this can result in dose adjustments that are not necessary when changes in free concentrations are considered. We explore the potential of physiologically based pharmacokinetic (PBPK) models to support the understanding of the changes in plasma proteins binding, using tacrolimus and efavirenz as example drug models. The exposure to either drug was predicted to be reduced during pregnancy; however, the decrease in the exposure to the total tacrolimus and efavirenz were significantly larger than the reduction in the exposure to the free drug. These data show that PBPK modelling can support the impact of the changes in plasma protein binding and may be used for the simulation of free concentrations in pregnancy to support dosing decisions.

Development and validation of an HPLC method for quantification of dolutegravir in human plasma

Dolutegravir (DTG) has been the first-line drug in many human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) guidelines for the treatment of naïve and experienced HIV-infected individuals, which calls for cost-effective and convenient methods for quantitative detection of DTG in human plasma for pharmacokinetic studies and patient adherence evaluation. Here, an HPLC-ultraviolet method in combination with liquid-liquid extraction with isocratic elution was developed for the first time. The analysis was performed on a CLC-ODS column (6 mm internal diameter × 15 cm, 5 μm) using a mixture of acetonitrile and phosphate buffer (40:60, v/v) as the mobile phase at the flow rate of 1 mL/min. Using triamcinolone as the internal standard, 100 μL of plasma sample was extracted by methyl tert-butyl ether, followed by evaporating under nitrogen stream, re-dissolving with 100 μL mobile phase, and injection of 20-40 μL of supernatant into the chromatographic system. The linearity of DTG was good in the range of 0.05-10 μg/mL (r = 0.9995), and the inter- and intra-day variabilities were 0.4%-4.3% (n = 10) and 1.2%-6.2% (n = 10) for the lower limit of quantification, low-, medium-, and high-concentration quality control samples (0.05, 0.1, 0.8, and 8 μg/mL), respectively, while the methodological and extraction recoveries were 98.0%-103.0% (n = 20) and 65.2%-75.7% (n = 3), respectively. This method was successfully applied to analyze DTG plasma concentration in 84 Chinese patients with HIV.

A Systematic Review on Cardiometabolic Risks and Perinatal Outcomes among Pregnant Women Living with HIV in the Era of Antiretroviral Therapy

Antiretroviral therapy (ART) regimens have been shown to cause metabolic changes in people living with HIV (PLWH), predisposing them to cardiometabolic disease (CVMD). However, such evidence is less established in pregnant women living with HIV (pWLWH) on ART. Pregnancy-induced cardiometabolic risks (CMR) can predispose to unfavourable pregnancy outcomes and further persist in the postpartum period, resolve, and recur in subsequent pregnancies, or emerge as newly diagnosed chronic diseases of ageing. Therefore, this systematic review aimed at synthesizing evidence on CMR and perinatal outcomes among pWLWH in the era of ART. We considered prospective and retrospective cohorts, case-control, cross-sectional, and interventional studies published in English. Specific keywords were used to conduct a thorough literature search on PubMed-Medline and Scopus following the Preferred Reporting Items for Systematic Review and Meta-Analysis guideline. Two investigators independently screened the search outputs and reviewed full texts of potentially eligible articles. Data extraction was conducted by one investigator and verified by the second investigator. Thirty-one relevant studies conducted on 20,904 pWLWH on ART across Africa, Asia, Europe, and America were included. Studies demonstrate inconclusive findings, especially on perinatal outcomes, but significant risks of gestational hypertension and dyslipidemia were reported in pWLWH on ART compared to the control group. Therefore, future studies should focus more on these perinatal outcomes, and their impact on postpartum maternal health and growth trajectories of uninfected infants born from pWLWH who are either on ART or ART-naïve in comparison to infants born of HIV-negative mothers over the life course, especially in HIV-burdened African countries.

Gene-nutrient interactions that impact magnesium homeostasis increase risk for neural tube defects in mice exposed to dolutegravir

In 2018, data from a surveillance study in Botswana evaluating adverse birth outcomes raised concerns that women on antiretroviral therapy (ART) containing dolutegravir (DTG) may be at increased risk for neural tube defects (NTDs). The mechanism of action for DTG involves chelation of Mg²⁺ ions in the active site of the viral integrase. Plasma Mg²⁺ homeostasis is maintained primarily through dietary intake and reabsorption in the kidneys. Inadequate dietary Mg²⁺ intake over several months results in slow depletion of plasma Mg²⁺ and chronic latent hypomagnesemia, a condition prevalent in women of reproductive age worldwide. Mg²⁺ is critical for normal embryonic development and neural tube closure. We hypothesized that DTG therapy might slowly deplete plasma Mg²⁺ and reduce the amount available to the embryo, and that mice with pre-existing hypomagnesemia due to genetic variation and/or dietary Mg²⁺ insufficiency at the time of conception and initiation of DTG treatment would be at increased risk for NTDs. We used two different approaches to test our hypothesis: 1) we selected mouse strains that had inherently different basal plasma Mg²⁺ levels and 2) placed mice on diets with different concentrations of Mg²⁺. Plasma and urine Mg²⁺ were determined prior to timed mating. Pregnant mice were treated daily with vehicle or DTG beginning on the day of conception and embryos examined for NTDs on gestational day 9.5. Plasma DTG was measured for pharmacokinetic analysis. Our results demonstrate that hypomagnesemia prior to conception, due to genetic variation and/or insufficient dietary Mg²⁺ intake, increases the risk for NTDs in mice exposed to DTG. We also analyzed whole-exome sequencing data from inbred mouse strains and identified 9 predicted deleterious missense variants in Fam111a that were unique to the LM/Bc strain. Human FAM111A variants are associated with hypomagnesemia and renal Mg²⁺ wasting. The LM/Bc strain exhibits this same phenotype and was the strain most susceptible to DTG-NTDs. Our results suggest that monitoring plasma Mg²⁺ levels in patients on ART regimens that include DTG, identifying other risk factors that impact Mg²⁺ homeostasis, and correcting deficiencies in this micronutrient might provide an effective strategy for mitigating NTD risk.

Congenital malformations and preeclampsia associated with integrase inhibitor use in pregnancy: A single-center analysis

BACKGROUND

Antiretroviral therapy (ART) decreases perinatal HIV transmission, but concerns exist regarding maternal and infant safety. We compared the incidence of congenital malformations and other adverse outcomes in pregnancies exposed to integrase inhibitor (INSTI) versus non-INSTI ART.

SETTING

Single-site review of all pregnancies among women living with HIV between 2008 and 2018.

METHODS

We used binomial family generalized estimating equations to model the relationship of congenital anomalies and pregnancy outcomes with exposure to INSTI or dolutegravir (DTG) versus non-INSTI ART.

RESULTS

Among 257 pregnancies, 77 women received ≥1 INSTI (54 DTG, 14 elvitegravir, 15 raltegravir), 167 received non-INSTI, and 3 had missing data. Fifty congenital anomalies were identified in 36 infants. Infants with first-trimester DTG or any first-trimester INSTI exposure had higher odds of congenital anomalies than infants with first-trimester non-INSTI exposure (OR = 2.55; 95%CI = 1.07-6.10; OR = 2.61; 95%CI = 1.15-5.94, respectively). Infants with INSTI exposure after the second trimester had no increased odds of anomalies. Women with INSTI exposure had higher odds of preeclampsia (OR = 4.73; 95%CI = 1.70-13.19). Among women who received INSTI, grade ≥3 laboratory abnormalities were noted in 2.6% while receiving the INSTI and 3.9% while not receiving the INSTI, versus 16.2% in women who received non-INSTI. There was no association between INSTI exposure and other pregnancy outcomes.

CONCLUSION

In our cohort, first-trimester INSTI exposure was associated with increased rates of congenital anomalies and use of INSTI during pregnancy was associated with preeclampsia. These findings underscore the need for continued monitoring of the safety of INSTI in pregnancy.

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.

Translating Clinical Pharmacology Data in Pregnancy to Evidence-Based Guideline Recommendations: Perspectives From the HIV Field

Pharmacokinetic (PK) studies in pregnant, postpartum, and breastfeeding people are critical to informing appropriate medication use and dosing. A key component of translating PK results in these complex populations into clinical practice involves the systematic review and interpretation of data by guideline panels, composed of clinicians, scientists, and community members, to leverage available data for informed decision making by clinicians and patients and offer clinical best practices. Interpretation of PK data in pregnancy involves evaluation of multiple factors such as the study design, target population, and type of sampling performed. Assessments of fetal and infant drug exposure while in utero or during breastfeeding, respectively, are also critical for informing whether medications are safe to use during pregnancy and throughout postpartum in lactating people. This review will provide an overview of this translational process, discussion of the various factors considered by guideline panels, and practical aspects of implementing certain recommendations, using the HIV field as an example.

Optimizing Therapeutic Drug Monitoring in Pregnant Women: A Critical Literature Review

BACKGROUND

More than 90% of pregnant women take at least one drug during pregnancy. Drug dose adjustments during pregnancy are sometimes necessary due to various pregnancy-induced physiological alterations frequently associated with lower plasma concentrations. However, the clinical relevance or benefits of therapeutic drug monitoring (TDM) in pregnant women have not been specifically studied. Clinical pharmacokinetic studies in pregnant women are incredibly challenging for many reasons. Despite this, regulatory agencies have made efforts to encourage the inclusion of this population in clinical trials to achieve more information on the pharmacotherapy of pregnant women. This review aims to provide support for TDM recommendations and dose adjustments in pregnant women.

METHODS

The search was conducted after a predetermined strategy on PubMed and Scopus databases using the MeSH term "pregnancy" alongside other terms such as "Pregnancy and dose adjustment," "Pregnancy and therapeutic drug monitoring," "Pregnancy and PBPK," "Pregnancy and pharmacokinetics," and "Pregnancy and physiological changes."

RESULTS

The main information on TDM in pregnant women is available for antiepileptics, antipsychotics, antidepressants, antibiotics, antimalarials, and oncologic and immunosuppressive drugs.

CONCLUSIONS

More data are needed to support informed benefit-risk decision making for the administration of drugs to pregnant women. TDM and/or pharmacokinetic studies could ensure that pregnant women receive an adequate dosage of an active drug. Mechanistic modeling approaches potentially could increase our knowledge about the pharmacotherapy of this special population, and they could be used to better design dosage regimens.

Antiretrovirals for Human Immunodeficiency Virus Treatment and Prevention in Pregnancy

Safe and effective antiretroviral medications are needed during pregnancy to reduce maternal morbidity and mortality associated with untreated human immunodeficiency virus (HIV) infection and to prevent viral transmission to the infant. Pharmacokinetic studies have helped inform the appropriate dosing of antiretroviral medications during pregnancy. However, data from these studies consistently become available years after initial regulatory approvals in nonpregnant adults. In this article, the authors provide an overview of considerations in use of antiretroviral medications in pregnant people with or at risk for HIV, pharmacokinetic studies that helped support recommended options, and therapies either under active investigation or in need of prospective study.

Inhibition of matrix metalloproteinases by HIV-1 integrase strand transfer inhibitors

More than fifteen million women with the human immunodeficiency virus type-1 (HIV-1) infection are of childbearing age world-wide. Due to improved and affordable access to antiretroviral therapy (ART), the number of in utero antiretroviral drug (ARV)-exposed children has exceeded a million and continues to grow. While most recommended ART taken during pregnancy suppresses mother to child viral transmission, the knowledge of drug safety linked to fetal neurodevelopment remains an area of active investigation. For example, few studies have suggested that ARV use can be associated with neural tube defects (NTDs) and most notably with the integrase strand transfer inhibitor (INSTI) dolutegravir (DTG). After risk benefit assessments, the World Health Organization (WHO) made recommendations for DTG usage as a first and second-line preferred treatment for infected populations including pregnant women and those of childbearing age. Nonetheless, long-term safety concerns remain for fetal health. This has led to a number of recent studies underscoring the need for biomarkers to elucidate potential mechanisms underlying long-term neurodevelopmental adverse events. With this goal in mind, we now report the inhibition of matrix metalloproteinases (MMPs) activities by INSTIs as an ARV class effect. Balanced MMPs activities play a crucial role in fetal neurodevelopment. Inhibition of MMPs activities by INSTIs during neurodevelopment could be a potential mechanism for adverse events. Thus, comprehensive molecular docking testing of the INSTIs, DTG, bictegravir (BIC), and cabotegravir (CAB), against twenty-three human MMPs showed broad-spectrum inhibition. With a metal chelating chemical property, each of the INSTI were shown to bind Zn++ at the MMP's catalytic domain leading to MMP inhibition but to variable binding energies. These results were validated in myeloid cell culture experiments demonstrating MMP-2 and 9 inhibitions by DTG, BIC and CAB and even at higher degree than doxycycline (DOX). Altogether, these data provide a potential mechanism for how INSTIs could affect fetal neurodevelopment.

HIV-1 Integrase Strand Transfer Inhibitors and Neurodevelopment

Children born to mothers, with or at risk, of human immunodeficiency virus type-1 (HIV-1) infection are on the rise due to affordable access of antiretroviral therapy (ART) to pregnant women or those of childbearing age. Each year, up to 1.3 million HIV-1-infected women on ART have given birth with recorded mother-to-child HIV-1 transmission rates of less than 1%. Despite this benefit, the outcomes of children exposed to antiretroviral drugs during pregnancy, especially pre- and post- natal neurodevelopment remain incompletely understood. This is due, in part, to the fact that pregnant women are underrepresented in clinical trials. This is underscored by any potential risks of neural tube defects (NTDs) linked, in measure, to periconceptional usage of dolutegravir (DTG). A potential association between DTG and NTDs was first described in Botswana in 2018. Incidence studies of neurodevelopmental outcomes associated with DTG, and other integrase strand transfer inhibitors (INSTIs) are limited as widespread use of INSTIs has begun only recently in pregnant women. Therefore, any associations between INSTI use during pregnancy, and neurodevelopmental abnormalities remain to be explored. Herein, United States Food and Drug Administration approved ARVs and their use during pregnancy are discussed. We provide updates on INSTI pharmacokinetics and adverse events during pregnancy together with underlying mechanisms which could affect fetal neurodevelopment. Overall, this review seeks to educate both clinical and basic scientists on potential consequences of INSTIs on fetal outcomes as a foundation for future scientific investigations.

Tuberculosis Infection in Pregnant People: Current Practices and Research Priorities

Women are significantly more likely to develop tuberculosis (TB) disease within the first 90 days after pregnancy than any other time in their lives. Whether pregnancy increases risk of progression from TB infection (TBI) to TB disease is unknown and is an active area of investigation. In this review, we discuss the epidemiology of TB and TBI in pregnancy, TBI diagnostics, and prevalence in pregnancy. We also review TBI treatment and highlight research priorities, such as short-course TB prevention regimens, drug-resistant TB prevention, and additional considerations for safety, tolerability, and pharmacokinetics that are unique to pregnant and postpartum people.

Pharmacokinetic data in pregnancy: A review of available literature data and important considerations in collecting clinical data

Pregnancy-related physiological changes can alter the absorption, distribution, metabolism and excretion of medicines which may affect the safety and efficacy of the medicines administered in pregnancy. Pharmacokinetic data can thus be instrumental in supporting dose adjustments required in this population. This review considers the availability of published pharmacokinetic data for over 200 medicines of interest for use in pregnancy in the UK, to identify whether sufficient data currently exists, in principle, for any medicine or group of medicines to support dose adjustments to maintain maternal health through pregnancy. Very limited data was found for many of the medicines of interest. Nevertheless, well documented, large changes of exposure for some drugs, where data is available, highlights the urgent need to collect more data of good quality to inform appropriate doses, when needed, in this population. In addition, clinical study methodology can have an impact on the usefulness of the data and key clinical design aspects are highlighted for consideration in future clinical study design.

Validation and Clinical Application of a Liquid Chromatography-Ultraviolet Detection Method to Quantify Dolutegravir in Dried Blood Spots

BACKGROUND

Dolutegravir is currently the preferred component of first-line antiretroviral therapy. To facilitate clinical pharmacology studies in key populations, quantitative analytical methods compatible with microsampling and adaptable to resource-limited settings are desirable. The authors developed and validated a liquid chromatography-ultraviolet detection method to quantify dolutegravir in dried blood spots (DBS).

METHODS

Calibration standards and quality control samples were prepared by spotting 50 μL of dolutegravir-spiked whole blood on each circle of DBS cards. Three spots (two 6-mm punches/spot) were extracted with methanol. Chromatographic separation was achieved with gradient elution of acetonitrile/potassium phosphate monobasic buffer (pH 5) on a reverse-phase C18 column (flow rate, 1 mL/min) using pioglitazone as the internal standard. UV detection was performed at 260 nm. In the clinical pharmacokinetic study, DBS from finger prick was collected from participants (n = 10) at 8 time points over 12 hours postdosing, with paired plasma at 1 and 12 hours. The method was used to quantify dolutegravir, estimating pharmacokinetic parameters. Agreement between DBS and plasma concentrations was evaluated using linearity and Bland-Altman plots.

RESULTS

The method was validated over the concentration range of 0.4-10 mcg/mL, accuracy was 102.4%-114.8%, and precision was 3.4%-14.7%. The mean recovery was 42.3% (%CV: 8.3). The mean (±SD) dolutegravir concentration in DBS was 37.5% (±3.8%) lower than that in the plasma. DBS-derived and measured plasma concentrations showed strong correlation with linearity (R2 = 0.9804) and Bland-Altman plots. Means (%CV) of area under curve, Cmax, and C24 from the DBS-derived plasma concentration were 37.8 (23.2) mcg·h/mL, 2.7 (24.7) mcg/mL, and 1.34 (31.6) mcg/mL, respectively.

CONCLUSIONS

The application of this simple, accurate, and precise method will expand opportunities for clinical assessment of dolutegravir in resource-limited settings.

Effect of dihydroartemisinin/piperaquine for malaria intermittent preventive treatment on dolutegravir exposure in pregnant women living with HIV

BACKGROUND

In sub-Saharan Africa, the burdens of malaria and HIV infections overlap. In settings with moderate-to-high malaria transmission intensity, pregnant women living with HIV (PLWH) require both ART and malaria intermittent preventive treatment (IPTp). Dihydroartemisinin/piperaquine has been identified as a promising alternative to sulfadoxine/pyrimethamine for IPTp. However, another antimalarial drug, artesunate/amodiaquine, similar to dihydroartemisinin/piperaquine, was previously shown to reduce dolutegravir exposure in non-pregnant adults.

OBJECTIVES

To investigate the effect of dihydroartemisinin/piperaquine on dolutegravir plasma exposure in pregnant women on dolutegravir-based ART.

METHODS

We conducted an open-label, non-randomized, fixed-sequence, pharmacokinetic study in PLWH in Malawi. Dolutegravir concentrations were measured over a 24 h period, before and after the recommended 3 day treatment dose of dihydroartemisinin/piperaquine in 12 pregnant women in their second or third trimester. Non-compartmental analysis was performed, and geometric mean ratios (GMRs) and 90% CIs were generated to compare dolutegravir pharmacokinetic parameters between the two treatment periods.

RESULTS

Co-administration of dihydroartemisinin/piperaquine and dolutegravir increased dolutegravir's overall exposure (AUC0-24) and Cmax by 30% (GMR 1.30; 90% CI 1.11-1.52) and 31% (GMR 1.31; 90% CI 1.13-1.51), respectively. The dolutegravir trough (C24) concentration increased by 42% (GMR 1.42; 90% CI 1.09-1.85). The combined treatments were well tolerated with no serious adverse events observed.

CONCLUSIONS

Dihydroartemisinin/piperaquine may be administered with dolutegravir-based ART in pregnant women as the modest increase in dolutegravir exposure, similar to pharmacokinetic parameter values published previously, ensures its efficacy without any clinically significant adverse events observed in this small study.

UK guideline for the use of HIV post-exposure prophylaxis 2021

We present the updated British Association for Sexual Health and HIV (BASHH) guidelines for post-exposure prophylaxis (PEP) to HIV following sexual exposures, occupational exposures and other nonoccupational exposures in the community. This serves as an update to the 2015 BASHH guideline on PEP following sexual exposures and the 2008 Expert Advisory Group on AIDS guidelines on HIV PEP. We aim to provide evidence-based guidance on best clinical practice in the provision, monitoring and support of PEP for the prevention of HIV acquisition following sexual, occupational and other nonoccupational exposures in the community. The guideline covers when to prescribe PEP, what antiretroviral agents to use and how to manage PEP. This includes (i) evidence of PEP efficacy; (ii) evidence relating to individual-level efficacy of antiretroviral therapy to prevent the sexual transmission of HIV; (iii) data on the detectable (transmissible) prevalence of HIV in specific populations; (iv) risk of HIV transmission following different types of sexual and occupational exposure; (v) baseline risk assessment; (vi) drug regimens and dosing schedules; (vii) monitoring PEP; (viii) baseline and follow-up blood-borne virus testing; (ix) the role of PEP within broader HIV prevention strategies, for example, HIV pre-exposure prophylaxis (PrEP). The guideline also covers special scenarios such as PEP in pregnancy, breastfeeding and chronic hepatitis B virus infection, and when PEP should be considered in people using HIV PrEP. The guidelines are aimed at clinical professionals directly involved in PEP provision and other stakeholders in the field. A proforma to assist PEP consultations is included. A public consultation process was undertaken prior to finalizing the recommendations.

Raltegravir-based Postnatal HIV Prophylaxis Therapy in a Neonate After in Utero Dolutegravir Exposure

We present a case report of a neonate receiving raltegravir-based postnatal HIV prophylaxis after in utero dolutegravir exposure. High levels of raltegravir and dolutegravir can potentially cause bilirubin toxicity as they compete for albumin binding and follow the same metabolic pathway through UGT1A1. This case suggests delaying initiation of raltegravir-based postnatal prophylaxis by 24-48 hours after in utero dolutegravir exposure.

Optimizing Dolutegravir Initiation in Neonates Using Population Pharmacokinetic Modeling and Simulation

BACKGROUND

A knowledge gap exists for dolutegravir (DTG) pharmacokinetics and safety during the first 4 weeks of life, preventing safe and effective DTG use in neonates.

SETTING

Population pharmacokinetic modeling and simulation were used to assess newborn DTG dosing requirements during the first few days of life as a function of maternal DTG dosing history before delivery.

METHODS

DTG PK data were obtained from pregnant women and infants enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1026S study. Maternal and neonate population pharmacokinetic models were separately developed. Monte Carlo simulations were performed to simulate neonatal concentrations after 2 doses of DTG after birth for infants born to mothers either receiving or not receiving DTG before delivery.

RESULTS

In DTG-naïve infants, a 5-mg DTG dose at birth with a second dose after 48 hours maintained median concentrations above the lower bound of the target range (0.77 μg/mL) and below the upper bound of the target range (7.34 μg/mL representing 2-fold above the adult Cmax value). In DTG-exposed infants, a 5-mg DTG dose at 24 hours after birth with a second dose after 48 hours maintained median concentrations within or nearly within the target range, even if the last maternal DTG dose was taken as soon as 6 hours or as long as 24 hours before delivery.

CONCLUSIONS

Newborn DTG dosing requirements during the first few days of life depend on maternal DTG dosing history before delivery. These results may help the design of future clinical studies of DTG in the neonatal population.

Pharmacokinetics and placental transfer of dolutegravir in pregnancy

Dolutegravir is currently recommended by the WHO as the preferred first-line treatment for all people with HIV, including pregnant women. Estimates indicate that, by 2024, nearly 22 million adults in low- and middle-income countries will have transitioned to dolutegravir-based ART. It is therefore critical that there is a clear appreciation and understanding of the risks that may be associated with in utero exposure to dolutegravir. In this review we consolidate data from studies on dolutegravir and the placenta. The studies have largely focused on the pharmacokinetics and placental transfer of dolutegravir in pregnancy. These include studies on transplacental transfer of dolutegravir, ex vivo placenta perfusion models, physiologically based pharmacokinetic (PBPK) models and animal studies. The data available clearly demonstrate that placental transfer of dolutegravir occurs in moderate to high concentrations. Intracellular placental dolutegravir has been demonstrated in the placental villous tissue. There are limited data suggesting that pregnancy is associated with decreased maternal dolutegravir levels. In addition, PBPK models have great potential in predicting the passage of drugs through the placenta and further contributing towards the elucidation of fetal exposure. The animal studies available demonstrate that in utero dolutegravir exposure can be associated with neural tube defects. Taking into consideration that antiretroviral exposure may be associated with poor placental development or function and increased risk of adverse effects to the fetus, it is crucially important that these risks are evaluated, especially with the rapid scale up of dolutegravir-based ART into national treatment programmes.

Comparative Clinical Pharmacokinetics and Pharmacodynamics of HIV-1 Integrase Strand Transfer Inhibitors: An Updated Review

Bictegravir, cabotegravir, dolutegravir, elvitegravir, and raltegravir are members of the latest class of antiretrovirals available to treat human immunodeficiency virus (HIV) infection, the integrase strand transfer inhibitors. Integrase strand transfer inhibitors are potent inhibitors of the HIV integrase enzyme with IC_90/95 values in the low nanogram per milliliter range and they retain antiviral activity against strains of HIV with acquired resistance to other classes of antiretrovirals. Each of the integrase strand transfer inhibitors have unique pharmacokinetic/pharmacodynamic properties, influencing their role in clinical use in specific subsets of patients. Cabotegravir, approved for use in Canada but not yet by the US Food and Drug Administration, is formulated in both oral and intramuscular formulations; the latter of which has shown efficacy as a long-acting extended-release formulation. Cabotegravir, raltegravir, and dolutegravir have minimal drug-drug interaction profiles, as their metabolism has minimal cytochrome P450 involvement. Conversely, elvitegravir metabolism occurs primarily via cytochrome P450 3A4 and requires pharmacokinetic boosting to achieve systemic exposures amenable to once-daily dosing. Bictegravir metabolism has similar contributions from both cytochrome P450 3A4 and uridine 5'-diphospho-glucuronosyltransferase 1A1. Bictegravir, dolutegravir, and raltegravir are recommended components of initial regimens for most people with HIV in the US adult and adolescent HIV treatment guidelines. This review summarizes and compares the pharmacokinetics and pharmacodynamics of the integrase strand transfer inhibitor agents, and describes specific pharmacokinetic considerations for persons with hepatic impairment, renal dysfunction, pregnancy, and co-infections.

Dolutegravir impairs stem cell-based 3D morphogenesis models in a manner dependent on dose and timing of exposure: an implication for its developmental toxicity

Dolutegravir is an anti-retroviral drug of the integrase strand transfer inhibitor class used to treat HIV infection. It is the recommended first-line regimen for most people, including women of childbearing age. However, some human and animal studies have suggested that dolutegravir causes birth defects, although its developmental toxicity remains controversial. Here, we investigated the adverse effects of dolutegravir using pluripotent stem cell-based in vitro morphogenesis models that have previously been validated as effective tools to assess the developmental toxicity of various chemicals. Dolutegravir diminished the growth and axial elongation of the morphogenesis model of mouse pluripotent stem cells at exposures of 2 μM and above in a concentration-dependent manner. Concomitantly, dolutegravir altered the expression profiles of developmental regulator genes involved in embryonic patterning. The adverse effects were observed when the morphogenesis model was exposed to dolutegravir at early stages of development, but not at later stages. The potency and molecular impact of dolutegravir on the morphogenesis model were distinct from other integrase strand transfer inhibitors. Lastly, dolutegravir altered the growth and gene expression profiles of the morphogenesis model of human embryonic stem cells at 1 μM and above. These studies demonstrate that dolutegravir impairs morphological and molecular aspects of the in vitro morphogenesis models in a manner dependent on dose and timing of exposure through mechanisms that are unrelated to its action as an integrase strand transfer inhibitor. This finding will be useful for interpreting the conflicting outcomes regarding the developmental toxicity of dolutegravir in human and animal studies.

Model-Informed Dose Optimization in Pregnancy

Pregnancy is associated with several physiological changes that can alter the pharmacokinetics (PK) and pharmacodynamics of drugs. These may require dosing changes in pregnant women to achieve drug exposures comparable to the nonpregnant population. There is, however, limited information available on the PK and pharmacodynamics of drugs used during pregnancy. Practical difficulties in performing PK studies and potential liability issues are often the reasons for the availability of limited information. Over the past several years, there has been a rapid development in the application of various modeling strategies such as population PK and physiologically based PK modeling to provide guidance on drug dosing in this special patient population. Population PK models rely on measured PK data, whereas physiologically based PK models integrate physiological, preclinical, and clinical data to quantify changes in PK of drugs in various patient populations. These modeling strategies offer a promising approach to identify the drugs with PK changes during pregnancy and guide dose adjustment in pregnant women. This review focuses on PBPK modeling to guide drug therpay in pregnancy.

Dolutegravir Inhibition of Matrix Metalloproteinases Affects Mouse Neurodevelopment

Dolutegravir (DTG) is a first-line antiretroviral drug (ARV) used in combination therapy for the treatment of human immunodeficiency virus type-1 (HIV-1) infection. The drug is effective, safe, and well tolerated. Nonetheless, concerns have recently emerged for its usage in pregnant women or those of child-bearing age. Notably, DTG-based ARV regimens have been linked to birth defects seen as a consequence of periconceptional usages. To this end, uncovering an underlying mechanism for DTG-associated adverse fetal development outcomes has gained clinical and basic research interest. We now report that DTG inhibits matrix metalloproteinases (MMPs) activities that could affect fetal neurodevelopment. DTG is a broad-spectrum MMPs inhibitor and binds to Zn⁺⁺ at the enzyme’s catalytic domain. Studies performed in pregnant mice show that DTG readily reaches the fetal central nervous system during gestation and inhibits MMP activity. Postnatal screenings of brain health in mice pups identified neuroinflammation and neuronal impairment. These abnormalities persist as a consequence of in utero DTG exposure. We conclude that DTG inhibition of MMPs activities during gestation has the potential to affect prenatal and postnatal neurodevelopment.

HIV in pregnancy: Mother-to-child transmission, pharmacotherapy, and toxicity

An estimated 1.3 million pregnant women were living with HIV in 2018. HIV infection is associated with adverse pregnancy outcomes and all HIV-positive pregnant women, regardless of their clinical stage, should receive a combination of antiretroviral drugs to suppress maternal viral load and prevent vertical fetal infection. Although antiretroviral treatment in pregnant women has undoubtedly minimized mother-to-child transmission of HIV, several uncertainties remain. For example, while pregnancy is accompanied by changes in pharmacokinetic parameters, relevant data from clinical studies are lacking. Similarly, long-term adverse effects of exposure to antiretrovirals on fetuses have not been studied in detail. Here, we review current knowledge on HIV effects on the placenta and developing fetus, recommended antiretroviral regimens, and pharmacokinetic considerations with particular focus on placental transport. We also discuss recent advances in antiretroviral research and potential effects of antiretroviral treatment on placental/fetal development and programming.

Prediction of dolutegravir pharmacokinetics and dose optimization in neonates via physiologically based pharmacokinetic (PBPK) modelling

BACKGROUND

Only a few antiretroviral drugs (ARVs) are recommended for use during the neonatal period and there is a need for more to be approved to increase treatment and prophylaxis strategies. Dolutegravir, a selective integrase inhibitor, has potential for treatment of HIV infection and prophylaxis of transmission in neonates.

OBJECTIVES

To model the pharmacokinetics of dolutegravir in neonates and to simulate a theoretical optimal dosing regimen.

METHODS

The physiologically based pharmacokinetic (PBPK) model was built incorporating the age-related changes observed in neonates. Virtual neonates between 0 and 28 days were simulated. The model was validated against observed clinical data for raltegravir and midazolam in neonates, prior to the prediction of dolutegravir pharmacokinetics.

RESULTS

Both raltegravir and midazolam passed the criteria for model qualification, with simulated data within 1.8-fold of clinical data. The qualified model predicted the pharmacokinetics for several multidose regimens of dolutegravir. Regimen 6 involved 5 mg doses with a 48 h interval from Day 1-20, increasing to 5 mg once daily on Week 3, yielding AUC and Ctrough values of 37.2 mg·h/L and 1.3 mg/L, respectively. These exposures are consistent with those observed in paediatric patients receiving dolutegravir.

CONCLUSIONS

Dolutegravir pharmacokinetics were successfully simulated in the neonatal PBPK model. The predictions suggest that during the first 3 weeks of life a 5 mg dose administered every 48 h may achieve plasma exposures needed for therapy and prophylaxis.

Therapeutic Drug Monitoring of HIV Antiretroviral Drugs in Pregnancy: A Narrative Review

To date, therapeutic drug monitoring (TDM) has played an important role in the management of pregnant HIV patients on highly active antiretroviral therapy. Historically, in pregnant women living with HIV, the third agent in triple therapy has been either non-nucleoside reverse transcriptase inhibitors or protease inhibitors (PIs). PIs have been the preferred agents because of their robustness from the perspective of viral resistance and the dominant drug class for the management of HIV during pregnancy for the previous decade. As with many drugs used during pregnancy, pharmacokinetic changes decrease exposure to these agents as the pregnancy progresses. This can lead to viral escape at the time of pregnancy and ultimately increase the risk of mother-to-child transmission (MTCT) of HIV. TDM has been well-established for this class of highly active antiretroviral therapy, and appropriate dose adjustment studies have been performed. At present, there is a shift from the traditional treatment paradigm in pregnancy to a new drug class, integrase strand transfer inhibitors (INSTIs). Although INSTIs are affected by pharmacokinetic changes during pregnancy, they do not harbor the same issues with viral escape as seen with PIs at birth and in general eliminate the need for boosting with additional agents like ritonavir (r) and cobicistat (c) [bar elvitegravir (EVG)] that can lead to interactions with treatment of other common infections in HIV, including tuberculosis. Furthermore, INSTIs are the most successful medication for rapidly reducing the viral load (VL) in HIV patients, a useful factor where VL may be unknown, or in late presenters. These merits make INSTIs the best choice in pregnancy, although their use has been hindered in recent years by a report of neural tube defects from a large African study with dolutegravir (DTG). New data from Botswana and Brazil indicate that this risk is less significant than previously reported, necessitating further data to shed light on this critical issue. Current international guidelines including DHHS, EACS, WHO, and BHIVA (for patients with VLs >100,000 copies/mL or late presenters) now recommend INSTIs as first-line agents. The role of TDM in INSTIs shifts to cases of insufficient viral suppression with standard adherence measures, cases of drug-drug interactions, or cases where EVG/c is continued throughout pregnancy, and thus remains an important aspect of HIV care in pregnancy.

The Effect of Pregnancy on the Pharmacokinetics of Total and Unbound Dolutegravir and Its Main Metabolite in Women Living With Human Immunodeficiency Virus

BACKGROUND

Pharmacokinetic and efficacy data on dolutegravir in pregnant women living with human immunodeficiency virus (HIV) are still limited but needed to support its use as one of the preferred antiretroviral agents.

METHODS

Within the multicenter Pharmacokinetics of ANtiretroviral agents in HIV-infected pregNAnt women (PANNA) study, pregnant women living with HIV and using dolutegravir once daily (50 mg, with food) underwent 24-hour pharmacokinetic profiling in their third trimester and postpartum. Dolutegravir exposure in the third trimester was considered adequate if geometric mean unbound, pharmacologically active, minimal plasma concentrations (Cmin, unbound) and ≥90% of individual Cmin, unbound levels were >0.85 µg/L, the proposed 90% inhibitory concentration for unbound dolutegravir. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) for comparison of total and unbound pharmacokinetic parameters in the third trimester and postpartum were calculated, including the metabolic ratio for dolutegravir-glucuronide. Safety and virological data were collected.

RESULTS

Seventeen women (76% black) were enrolled (25 evaluable pharmacokinetic profiles; 15 in the third trimester, 10 in postpartum). In the third trimester, geometric mean (coefficient of variation, %) Cmin, unbound was 2.87 (87) µg/L and 93% of individual Cmin, unbound levels were >0.85 µg/L. The GMR (90% CI) in the third trimester vs postpartum was 0.86 (.68-1.10) for area under the curve (AUC0-24h), and for Cmax, 0.93 (.77-1.13). GMR (90% CI) for the trough concentrations was 0.71 (.49-1.02), based on total dolutegravir concentrations. Four serious adverse events were reported, unlikely related to dolutegravir. The HIV polymerase chain reaction test was negative in 14/17 infants (result unknown for 3 infants).

CONCLUSIONS

Pharmacokinetic changes for dolutegravir in late pregnancy are not clinically relevant and support the use of dolutegravir 50 mg once daily with food in pregnancy.

CLINICAL TRIALS REGISTRATION

NCT00825929.

Physiologically Based Pharmacokinetic Modeling Framework to Predict Neonatal Pharmacokinetics of Transplacentally Acquired Emtricitabine, Dolutegravir, and Raltegravir

BACKGROUND AND OBJECTIVE

Little is understood about neonatal pharmacokinetics immediately after delivery and during the first days of life following intrauterine exposure to maternal medications. Our objective was to develop and evaluate a novel, physiologically based pharmacokinetic modeling workflow for predicting perinatal and postnatal disposition of commonly used antiretroviral drugs administered prenatally to pregnant women living with human immunodeficiency virus.

METHODS

Using previously published, maternal-fetal, physiologically based pharmacokinetic models for emtricitabine, dolutegravir, and raltegravir built with PK-Sim/MoBi^®, placental drug transfer was predicted in late pregnancy. The total drug amount in fetal compartments at term delivery was estimated and subsequently integrated as initial conditions in different tissues of a whole-body, neonatal, physiologically based pharmacokinetic model to predict drug concentrations in the neonatal elimination phase after birth. Neonatal elimination processes were parameterized according to published data. Model performance was assessed by clinical data.

RESULTS

Neonatal physiologically based pharmacokinetic models generally captured the initial plasma concentrations after delivery but underestimated concentrations in the terminal phase. The mean percentage error for predicted plasma concentrations was - 71.5%, - 33.8%, and 76.7% for emtricitabine, dolutegravir, and raltegravir, respectively. A sensitivity analysis suggested that the activity of organic cation transporter 2 and uridine diphosphate glucuronosyltransferase 1A1 during the first postnatal days in term newborns is ~11% and ~30% of that in adults, respectively.

CONCLUSIONS

These findings demonstrate the general feasibility of applying physiologically based pharmacokinetic models to predict washout concentrations of transplacentally acquired drugs in newborns. These models can increase the understanding of pharmacokinetics during the first postnatal days and allow the prediction of drug exposure in this vulnerable population.

Mechanistic Modeling of Maternal Lymphoid and Fetal Plasma Antiretroviral Exposure During the Third Trimester

Pregnancy-induced changes in plasma pharmacokinetics of many antiretrovirals (ARV) are well-established. Current knowledge about the extent of ARV exposure in lymphoid tissues of pregnant women and within the fetal compartment is limited due to their inaccessibility. Subtherapeutic ARV concentrations in HIV reservoirs like lymphoid tissues during pregnancy may constitute a barrier to adequate virological suppression and increase the risk of mother-to-child transmission (MTCT). The present study describes the pharmacokinetics of three ARVs (efavirenz, dolutegravir, and rilpivirine) in lymphoid tissues and fetal plasma during pregnancy using materno-fetal physiologically-based pharmacokinetic models (m-f-PBPK). Lymphatic and fetal compartments were integrated into our previously validated adult PBPK model. Physiological and drug disposition processes were described using ordinary differential equations. For each drug, virtual pregnant women (n = 50 per simulation) received the standard dose during the third trimester. Essential pharmacokinetic parameters, including Cmax, Cmin, and AUC (0-24), were computed from the concentration-time data at steady state for lymph and fetal plasma. Models were qualified by comparison of predictions with published clinical data, the acceptance threshold being an absolute average fold-error (AAFE) within 2.0. AAFE for all model predictions was within 1.08-1.99 for all three drugs. Maternal lymph concentration 24 h after dose exceeded the reported minimum effective concentration (MEC) for efavirenz (11,514 vs. 800 ng/ml) and rilpivirine (118.8 vs. 50 ng/ml), but was substantially lower for dolutegravir (16.96 vs. 300 ng/ml). In addition, predicted maternal lymph-to-plasma AUC ratios vary considerably (6.431-efavirenz, 0.016-dolutegravir, 1.717-rilpivirine). Furthermore, fetal plasma-to-maternal plasma AUC ratios were 0.59 for efavirenz, 0.78 for dolutegravir, and 0.57 for rilpivirine. Compared with rilpivirine (0 h), longer dose forgiveness was observed for dolutegravir in fetal plasma (42 h), and for efavirenz in maternal lymph (12 h). The predicted low lymphoid tissue penetration of dolutegravir appears to be significantly offset by its extended dose forgiveness and adequate fetal compartment exposure. Hence, it is unlikely to be a predictor of maternal virological failure or MTCT risks. Predictions from our m-f-PBPK models align with recommendations of no dose adjustment despite moderate changes in exposure during pregnancy for these drugs. This is an important new application of PBPK modeling to evaluate the adequacy of drug exposure in otherwise inaccessible compartments.

Characterization of Plasma Protein Alterations in Pregnant and Postpartum Individuals Living With HIV to Support Physiologically-Based Pharmacokinetic Model Development

Background: Alterations in plasma protein concentrations in pregnant and postpartum individuals can influence antiretroviral (ARV) pharmacokinetics. Physiologically-based pharmacokinetic (PBPK) models can serve to inform drug dosing decisions in understudied populations. However, development of such models requires quantitative physiological information (e.g., changes in plasma protein concentration) from the population of interest. Objective: To quantitatively describe the time-course of albumin and α1-acid glycoprotein (AAG) concentrations in pregnant and postpartum women living with HIV. Methods: Serum and plasma protein concentrations procured from the International Maternal Pediatric Adolescent AIDS Clinical Trial Protocol 1026s (P1026s) were analyzed using a generalized additive modeling approach. Separate non-parametric smoothing splines were fit to albumin and AAG concentrations as functions of gestational age or postpartum duration. Results: The analysis included 871 and 757 serum albumin concentrations collected from 380 pregnant (~20 to 42 wks gestation) and 354 postpartum (0 to 46 wks postpartum) women, respectively. Thirty-six and 32 plasma AAG concentrations from 31 pregnant (~24 to 38 wks gestation) and 30 postpartum women (~2-13 wks postpartum), respectively, were available for analysis. Estimated mean albumin concentrations remained stable from 20 wks gestation to term (33.4 to 34.3 g/L); whereas, concentrations rapidly increased postpartum until stabilizing at ~42.3 g/L 15 wk after delivery. Estimated AAG concentrations slightly decreased from 24 wks gestation to term (53.6 and 44.9 mg/dL) while postpartum levels were elevated at two wks after delivery (126.1 mg/dL) and subsequently declined thereafter. Computational functions were developed to quantitatively communicate study results in a form that can be readily utilized for PBPK model development. Conclusion: By characterizing the trajectory of plasma protein concentrations in pregnant and postpartum women living with HIV, our analysis can increase confidence in PBPK model predictions for HIV antiretrovirals and better inform drug dosing decisions in this understudied population.

Infant exposure to dolutegravir through placental and breastmilk transfer: a population pharmacokinetic analysis of DolPHIN-1

BACKGROUND

Rapid reduction of HIV viral load is paramount to prevent peripartum transmission in women diagnosed late in pregnancy. We investigated dolutegravir population pharmacokinetics in maternal plasma, cord, breastmilk and infant plasma of DolPHIN-1 participants (NCT02245022) presenting with untreated HIV late in pregnancy (28-36 weeks gestation).

METHODS

Pregnant women from Uganda and South Africa were randomised (1:1) to daily dolutegravir (50 mg) or efavirenz-based therapy. Dolutegravir pharmacokinetic sampling (0-24 hours) was undertaken 14 days after treatment initiation and within 1-3 weeks of delivery, with matched maternal and cord samples at delivery. Mothers switched to efavirenz and maternal and infant plasma and breastmilk samples taken 24, 48 or 72 hours post-switch. Nonlinear mixed effects (NONMEM v. 7.4) was used to describe dolutegravir in all matrices and to evaluate covariates.

RESULTS

Twenty-eight women and 22 infants were included. Maternal dolutegravir was described by a two-compartment model linked to a fetal and breastmilk compartment. Cord and breastmilk to maternal plasma ratios were 1.279 (1.209-1.281) and 0.033 (0.021-0.050), respectively. Infant dolutegravir was described by breastmilk-to-infant and infant elimination rate constants. No covariate effects were observed. Predicted infant dolutegravir half-life and time to protein adjusted-IC90 (0.064 mg/L) for those above this threshold were 37.9 hours (22.1-63.5) and 108.9 hours [(18.6-129.6); 4.5 days (0.8-5.4); n=13].

CONCLUSIONS

Breastfeeding contributed relatively little to infant plasma exposures but a median of 4.5 days additional prophylaxis to some of the breastfed infants was observed following maternal dolutegravir cessation (3-15 days postpartum), which waned with time postpartum as transplacental dolutegravir cleared.

Dolutegravir in pregnant mice is associated with increased rates of fetal defects at therapeutic but not at supratherapeutic levels

Background

Dolutegravir (DTG) is a preferred regimen for all people with HIV including pregnant women, but its effects on the fetus are not fully understood. Periconceptional exposure to DTG has been associated with increased rates of neural tube defects (NTDs), although it is unknown whether this is a causal relationship. This has led to uncertainty around the use of DTG in women of reproductive potential.

Methods

Pregnant C57BL/6J mice were randomly allocated to control (water), 1x-DTG (2.5 mg/kg-peak plasma concentration ~3000 ng/ml – therapeutic level), or 5x-DTG (12.5 mg/kg-peak plasma concentration ~12,000 ng/ml – supratherapeutic level), once daily from gestational day 0.5 until sacrifice. DTG was administered with 50 mg/kg tenofovir+33.3 mg/kg emtricitabine. Fetal phenotypes were determined, and maternal and fetal folate levels were quantified by mass-spectrometry.

Findings

352 litters (91 control, 150 1x-DTG, 111 5x-DTG) yielding 2776 fetuses (747 control, 1174 1x-DTG, 855 5x-DTG) were assessed. Litter size and viability rates were similar between groups. Fetal and placenta weights were lower in the 1x-DTG vs. control. Placental weight was higher in the 5x-DTG vs. control. Five NTDs were observed, all in the 1x-DTG group. Fetal defects, including microphthalmia, severe edema, and vascular/bleeding defects were more frequent in the 1x-DTG group. In contrast, defect rates in the 5x-DTG were similar to control. Fetal folate levels were similar between control and 1x-DTG, but were significantly higher in the 5x-DTG group.

Interpretation

Our findings support a causal relationship of DTG at therapeutic doses with increased risk for fetal defects, including NTDs at a rate that is similar that reported in the Tsepamo study for women exposed to DTG-based ART from conception. The non-monotonic dose-response relationship between DTG and fetal anomalies could explain the previous lack of fetal toxicity findings from pre-clinical DTG studies. The fetal folate levels suggest that DTG is unlikely to be an inhibitor of folate uptake.

Funding

This project has been funded with Federal funds from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, under Contract No. HHSN275201800001I.

HIV-1 Integrase Inhibitors: A Comparative Review of Efficacy and Safety

The newest class of antiretrovirals for all persons living with HIV are the integrase strand transfer inhibitors (INSTIs). Since 2007, five INSTIs have been introduced: raltegravir, elvitegravir, dolutegravir, bictegravir, and cabotegravir. The INSTIs have favorable pharmacokinetic and pharmacodynamic properties, which contribute to both their effectiveness and their ease of use. With the exception of cabotegravir, each INSTI is US Food and Drug Administration approved for treatment-naïve individuals initiating antiretroviral therapy. All of the INSTIs, except raltegravir, are approved for antiretroviral treatment simplification for virologically suppressed patients without INSTI resistance. Data also support the use of dolutegravir and raltegravir in individuals with antiretroviral resistance as part of an optimized antiretroviral regimen. INSTIs are generally well tolerated by people living with HIV compared with older classes of antiretrovirals, but emerging data suggest that some INSTIs contribute to weight gain. Due to their efficacy, safety, and ease of use, HIV treatment guidelines recommend oral INSTIs as preferred components of antiretroviral therapy for individuals initiating therapy. The newest INSTI, cabotegravir, represents an alternative to oral administration of life-long antiretroviral therapy with the availability of a long-acting injectable formulation. This review summarizes the current use of INSTIs in adults living with HIV, highlighting the similarities and differences within the class related to pharmacodynamics, pharmacokinetics, safety, dosing, and administration that contribute to their role in modern antiretroviral therapy.

Comparative efficacy, tolerability and safety of dolutegravir and efavirenz 400mg among antiretroviral therapies for first-line HIV treatment: A systematic literature review and network meta-analysis

BACKGROUND

To inform World Health Organization (WHO) global guidelines, we updated and expanded the evidence base to assess the comparative efficacy, tolerability, and safety of first-line antiretroviral therapy (ART) regimens.

METHODS

We searched Embase, Medline and CENTRAL on 28 February 2020 to update the systematic literature review of clinical trials comparing recommended first-line ART that informed previous WHO guidelines. Outcomes included viral suppression, change in CD4 cell counts, mortality, serious and overall adverse events (AEs), discontinuation, discontinuations due to AEs (DAEs); and new outcomes: drug-resistance, neuropsychiatric AEs, early viral suppression, weight gain and birth outcomes. Comparative effects were assessed through network meta-analyses and certainty in the evidence was assessed using the GRADE framework.

FINDINGS

We identified 156 publications pertaining to 68 trials for the primary population. Relative to efavirenz, dolutegravir had improved odds of viral suppression across all time points (odds ratio [OR]: 1·94; 95% credible interval [CrI]: 1·48-2·56 at 96 weeks); was protective of drug-resistance (OR: 0·13; 95%CrI: 0·04-0·48); and led to fewer discontinuations (OR: 0·58; 95%CrI: 0·48-0·70). Evidence supported dolutegravir use among TB-HIV co-infected persons and pregnant women. Adverse birth outcomes were observed in 33.2% of dolutegravir-managed pregnancies and 35.0% of efavirenz-managed pregnancies. Low-dose efavirenz had comparable efficacy and safety to standard-dose efavirenz, but led to fewer DAEs (OR: 0·70; 95%CrI: 0·50-0·92).

INTERPRETATION

The evidence supports choosing dolutegravir in combination with lamivudine/emtricitabine and tenofovir disoproxil fumarate as the preferred first-line regimen and low-dose efavirenz-based regimens as an alternative. Dolutegravir can be considered to be effective, safe and tolerable.

FUNDING

WHO.

Drug-Drug Interactions with Antiretroviral Drugs in Pregnant Women Living with HIV: Are They Different from Non-Pregnant Individuals?

Background and Objective

Although the separate effects of drug–drug interactions and pregnancy on antiretroviral drug pharmacokinetics have been widely studied and described, their combined effect is largely unknown. Physiological changes during pregnancy may change the extent or clinical relevance of a drug–drug interaction in a pregnant woman. This review aims to provide a detailed overview of the mechanisms, magnitude, and clinical significance of antiretroviral drug–drug interactions in pregnant women.

Methods

We performed a literature search and selected studies that compared the magnitude of drug–drug interactions with antiretroviral drugs in pregnant vs non-pregnant women.

Results

Forty-eight papers examining drug–drug interactions during pregnancy were selected, of which the majority focused on pharmacokinetic boosting. Other selected studies examined the drug–drug interactions between efavirenz and lumefantrine, efavirenz and tuberculosis drugs, etravirine and tenofovir disoproxil fumarate, atazanavir and tenofovir disoproxil, and mefloquine and nevirapine in pregnant compared to non-pregnant women. The clinical significance of antiretroviral drug–drug interactions changed during pregnancy from a minimal effect to a contra-indication. In almost all cases, the clinical significance of a drug–drug interaction was more relevant in pregnant women, owing to the combined effects of pregnancy-induced physiological changes and drug–drug interactions leading to a lower absolute drug exposure.

Conclusions

Multiple studies show that the clinical relevance of a drug–drug interaction can change during pregnancy. Unfortunately, many potential interactions have not been studied in pregnancy, which may place pregnant women living with human immunodeficiency virus and their newborns at risk.

Drug dosing during pregnancy-opportunities for physiologically based pharmacokinetic models

Drugs can have harmful effects on the embryo or the fetus at any point during pregnancy. Not all the damaging effects of intrauterine exposure to drugs are obvious at birth, some may only manifest later in life. Thus, drugs should be prescribed in pregnancy only if the expected benefit to the mother is thought to be greater than the risk to the fetus. Dosing of drugs during pregnancy is often empirically determined and based upon evidence from studies of non-pregnant subjects, which may lead to suboptimal dosing, particularly during the third trimester. This review collates examples of drugs with known recommendations for dose adjustment during pregnancy, in addition to providing an example of the potential use of PBPK models in dose adjustment recommendation during pregnancy within the context of drug-drug interactions. For many drugs, such as antidepressants and antiretroviral drugs, dose adjustment has been recommended based on pharmacokinetic studies demonstrating a reduction in drug concentrations. However, there is relatively limited (and sometimes inconsistent) information regarding the clinical impact of these pharmacokinetic changes during pregnancy and the effect of subsequent dose adjustments. Examples of using pregnancy PBPK models to predict feto-maternal drug exposures and their applications to facilitate and guide dose assessment throughout gestation are discussed.

Prediction of Maternal and Fetal Pharmacokinetics of Dolutegravir and Raltegravir Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Predicting drug pharmacokinetics in pregnant women including placental drug transfer remains challenging. This study aimed to develop and evaluate maternal-fetal physiologically based pharmacokinetic models for two antiretroviral drugs, dolutegravir and raltegravir.

Pharmacokinetics of HIV-Integrase Inhibitors During Pregnancy: Mechanisms, Clinical Implications and Knowledge Gaps

Prevention of mother-to-child transmission of HIV and optimal maternal treatment are the most important goals of antiretroviral therapy in pregnant women with HIV. These goals may be at risk due to possible reduced exposure during pregnancy caused by physiological changes. Limited information is available on the impact of these physiological changes. This is especially true for HIV-integrase inhibitors, a relatively new class of drugs, recommended first-line agents and hence used by a large proportion of HIV-infected patients. Therefore, the objective of this review is to provide a detailed overview of the pharmacokinetics of HIV-integrase inhibitors in pregnancy. Second, this review defines potential causes for the change in pharmacokinetics of HIV-integrase inhibitors during pregnancy. Despite increased clearance, for raltegravir 400 mg twice daily and dolutegravir 50 mg once daily, exposure during pregnancy seems adequate; however, for elvitegravir, the proposed minimal effective concentration is not reached during pregnancy. Lower exposure to these drugs may be caused by increased hormone levels and, subsequently, enhanced drug metabolism during pregnancy. The pharmacokinetics of bictegravir and cabotegravir, which are under development, have not yet been evaluated in pregnant women. New studies need to prospectively assess whether adequate exposure is reached in pregnant women using these new HIV-integrase inhibitors. To further optimize antiretroviral treatment in pregnant women, studies need to unravel the underlying mechanisms behind the changes in the pharmacokinetics of HIV-integrase inhibitors during pregnancy. More knowledge on altered pharmacokinetics during pregnancy and the underlying mechanisms contribute to the development of effective and safe antiretroviral therapy for HIV-infected pregnant women.

Use of Modeling and Simulations to Determine Raltegravir Dosing in Neonates: A Model for Safely and Efficiently Determining Appropriate Neonatal Dosing Regimens: IMPAACT P1110

BACKGROUND

Population modeling and simulations can be used to facilitate the conduct of phase I studies to develop safe and effective dosing regimens in neonates.

SETTING

P1110 is an international, multicenter trial to determine safe and effective raltegravir doses in neonates at risk for HIV infection.

METHODS

P1110 used a 2-cohort adaptive design incorporating population pharmacokinetic modeling and simulations. An initial cohort of neonates received 2 single oral doses of raltegravir with standard-of-care therapy for prevention of perinatal transmission-one within 48 hours of birth and a second at 7-10 days of life. Raltegravir concentration data after administration of these doses were combined with data from a previous study of infants aged 4 weeks to 2 years. The combined database was used for population pharmacokinetic modeling and simulations to select a daily dosing regimen for investigation in a second cohort of neonates.

RESULTS

Raltegravir concentration data from 6 neonates were combined with data from infants aged 4 weeks to 2 years receiving raltegravir twice daily. The combined data set allowed for successful development of a population pharmacokinetic model with reasonable precision of parameter estimates. Monte Carlo simulations were run to evaluate potential daily dosing regimens from birth to 6 weeks of age, allowing for selection of a regimen to be evaluated in a subsequent cohort of neonates receiving chronic raltegravir dosing.

CONCLUSIONS

An adaptive design incorporating population pharmacokinetic modeling and simulations was used to select a developmentally appropriate neonatal raltegravir dosing regimen in the first 6 weeks of life.

Dolutegravir versus efavirenz in women starting HIV therapy in late pregnancy (DolPHIN-2): an open-label, randomised controlled trial

BACKGROUND

Late initiation of HIV antiretroviral therapy (ART) in pregnancy is associated with not achieving viral suppression before giving birth and increased mother-to-child transmission of HIV. We aimed to investigate virological suppression before giving birth with dolutegravir compared with efavirenz, when initiated during the third trimester.

METHODS

In this randomised, open-label trial, DolPHIN-2, we recruited pregnant women in South Africa and Uganda aged at least 18 years, with untreated but confirmed HIV infection and an estimated gestation of at least 28 weeks, initiating ART in third trimester. Participants were randomly assigned (1:1) to dolutegravir-based or efavirenz-based therapy. HIV viral load was measured 7 days and 28 days after antiretroviral initiation, at 36 weeks' gestation, and at the post-partum visit (0-14 days post partum). The primary efficacy outcome was a viral load of less than 50 copies per mL at the first post-partum visit, and the primary safety outcome was the occurrence of drug-related adverse events in mothers and infants until the post-partum visit. Longer-term follow-up of mothers and infants continues. This study is registered with ClinicalTrials.gov, NCT03249181.

FINDINGS

Between Jan 23, and Aug 15, 2018, we randomly assigned 268 mothers to dolutegravir (135) or efavirenz (133). All mothers and their infants were included in the safety analysis, and 250 mothers (125 in the dolutegravir group, 125 in the efavirenz group) and their infants in efficacy analyses, by intention-to-treat analyses. The median duration of maternal therapy at birth was 55 days (IQR 33-77). 89 (74%) of 120 in the dolutegravir group had viral loads less than 50 copies per mL, compared with 50 (43%) of 117 in the efavirenz group (risk ratio 1·64, 95% CI 1·31-2·06). 30 (22%) of 137 mothers in the dolutegravir group reported serious adverse events compared with 14 (11%) of 131 in the efavirenz group (p=0·013), particularly surrounding pregnancy and puerperium. We found no differences in births less than 37 weeks and less than 34 weeks gestation (16·4% vs 3·3%, across both groups). Three stillbirths in the dolutegravir group and one in the efavirenz group were considered unrelated to treatment. Three infant HIV infections were detected, all in the dolutegravir group, and were considered likely to be in-utero transmissions.

INTERPRETATION

Our data support the revision to WHO guidelines recommending the transition to dolutegravir in first-line ART for all adults, regardless of pregnancy or child-bearing potential.

FUNDING

Unitaid.

Pharmacokinetics of HIV therapies in pregnant patients: an update

INTRODUCTION

Mother-to-child transmission (MTCT) of HIV is thought to account for over 90% of new pediatric infections, and is associated with poor maternal and fetal outcomes. As such ensuring further reduction in MTCT is a priority in HIV treatment and prevention programs.

AREAS COVERED

This review aims to provide a comprehensive update on the pharmacokinetics of recently approved antiretroviral drugs and novel drug formulations and delivery systems. Alongside recent recommendations for dose adjustments, and an overview of the implications of co-infections on the pharmacokinetics of antiretrovirals relevant to pregnant HIV positive patients. Additionally, potential opportunities to progress pharmacokinetic research of new treatments in this population are highlighted.

EXPERT OPINION

In order to improve our understanding of how to provide safe and effective treatment to HIV positive pregnant women, further work is required to enable their inclusion in early stages of clinical trials. Incentives must be created for this research, in the form of additional investment by key stakeholders and regulatory agencies. Furthermore, as the incidence of MTCT is reduced globally there is a need to conduct long-term pharmacovigilance studies in uninfected children exposed to HIV and antiretrovirals in utero, in order to determine the safest and most effective antiretroviral therapies.

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.