Total and unbound darunavir pharmacokinetics in pregnant women infected with HIV-1: results of a study of darunavir/ritonavir 600/100 mg administered twice daily

Current opinion: antiretrovirals during pregnancy and breastfeeding

PURPOSE OF REVIEW

To review the most important literature from the past 2 years on the pharmacokinetics of antiretrovirals in pregnancy, placental transfer, and breastmilk.

RECENT FINDINGS

Concentrations of antiretrovirals frequently used in pregnancy and their placental transfer are described, together with infant exposure through breastmilk. Also, applications of ex-vivo and in-silico studies, such as placenta perfusion studies and PBPK models, are discussed.

SUMMARY

Great efforts were made in the past 2 years to accelerate the availability of data on antiretrovirals during pregnancy and lactation. Bictegravir showed decreased but still sufficient concentrations during pregnancy, leading to a label change by the FDA. In-silico and clinical studies on long-acting cabotegravir and rilpivirine generated information leading to cautious use of these formulations in pregnancy. Low infant exposure to antiretrovirals through breastmilk is expected for most compounds. Despite the impact of these studies, more incentives are needed for earlier implementation, for instance, during the developmental phase of drugs, to provide women antenatally with proper information on their drugs.

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.

Daily ritonavir-boosted darunavir for viral suppression in pregnancy (DRV-P)

BACKGROUND

Ritonavir-boosted darunavir (DRV/r) is a preferred protease inhibitor in pregnant women living with HIV. Current practice at British Columbia's referral centre (the Oak Tree Clinic) is to dose DRV/r as 800/100 mg daily throughout pregnancy, although some guidelines recommend DRV/r 600/100 mg twice daily due to altered pharmacokinetics with once-daily dosing.

OBJECTIVES

We describe the effect of once-daily DRV/r on viral suppression, vertical transmission, adverse drug effects and adherence in pregnant women living with HIV.

METHODS

This was a retrospective analysis of pregnant women living with HIV in British Columbia. Eligible women gave birth between January 2015 and August 2021, and took DRV/r 800/100 mg daily at any time during pregnancy.

RESULTS

Thirty-four women were included in this study. The mean (SD) age was 33 (5) years. Thirty (88%) women were diagnosed with HIV prior to pregnancy, with 22 (73%) having viral suppression at baseline. Four (12%) were diagnosed in pregnancy, with a median baseline viral load of 9616 copies/mL (range 8370-165 000). Viral suppression was achieved by 16 (100%), 24 (75%) and 26 (74%) women in the first, second and third trimesters, respectively. No vertical transmission occurred. This combination was well tolerated, with adverse drug effects that did not result in discontinuation or change in therapy. Most women maintained >75% adherence to once-daily DRV/r at all times during pregnancy.

CONCLUSIONS

Ritonavir-boosted darunavir 800/100 mg daily appears to be an appropriate dosing strategy for pregnant women living with HIV who are able to maintain optimal adherence.

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.

Maintenance darunavir/ritonavir monotherapy to prevent perinatal HIV transmission, ANRS-MIE 168 MONOGEST study

OBJECTIVES

Because NRTIs can have fetal toxicities, we evaluated a perinatal NRTI-sparing strategy to prevent perinatal HIV transmission. Our primary objective was to determine the proportion maintaining a viral load (VL) of <50 copies/mL up to delivery on darunavir/ritonavir monotherapy, without requiring treatment intensification.

METHODS

In a one-arm, multicentre Phase 2 clinical trial, eligible patients in the first trimester of pregnancy on ART with plasma VL < 50 copies/mL received maintenance monotherapy with darunavir/ritonavir, 600/100 mg twice daily. VL was monitored monthly. ART was intensified in the case of VL > 50 copies/mL. Neonates received nevirapine prophylaxis for 14 days.

RESULTS

Of 89 patients switching to darunavir/ritonavir monotherapy, 4 miscarried before 22 weeks' gestation, 2 changed treatment for elevated liver enzymes without virological failure, and 83 were evaluable for the main outcome. Six had virological failure confirmed on a repeat sample (median VL = 193 copies/mL; range 78-644), including two before switching to monotherapy. In these six cases, ART was intensified with tenofovir disoproxil fumarate/emtricitabine. The success rate was 75/83, 90.4% (95% CI, 81.9%-95.7%) considering two patients with VL missing at delivery as failures, and 77/83, 92.8% (95% CI, 84.9%-97.3%) when considering them as successes since both had undetectable VL on darunavir/ritonavir throughout pregnancy. In ITT, the last available VL before delivery was <50 copies/mL in all of the patients. There was no case of perinatal HIV transmission.

CONCLUSIONS

Darunavir/ritonavir maintenance monotherapy required intensification in nearly 10% of cases. This limits its widespread use, thus other regimens should be evaluated in order to limit exposure to antiretrovirals, particularly NRTIs, during pregnancy.

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.

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.

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.

Risk assessment of therapeutic agents under consideration to treat COVID-19 in paediatric patients and pregnant women

AIM

Repurposing strategies to address the COVID-19 pandemic have been accelerated. As both pregnant and paediatric patients are likely to be excluded from most planned investigations, the list of repurposed options and the available data on these drugs and vaccines provide a baseline risk assessment and identify gaps for targeted investigation.

METHODS

Clinical trials have been searched and reviewed; 23 repurposed drugs and drug combinations and nine candidate vaccines have been assessed regarding the availability of relevant data in paediatrics and pregnant women and to evaluate expected or unanticipated risk.

RESULTS

Thirteen of the repurposed drugs or drug combinations are indicated for use in paediatrics in some age category albeit for indications other than COVID-19; 10 of these are indicated for use in pregnant women. Even in cases where these drugs are indicated in the populations, source data from which safety and or dosing could be extrapolated for use in COVID-19 is sparse. Vaccine trials are ongoing and generally exclude pregnant women; only in a few instances have paediatric subgroups been planned for enrolment. Data from individual case studies and RWD may suggest that subpopulations of both paediatric patients and pregnant women may be more at risk, particularly those in an increased inflammatory state.

CONCLUSION

In conjunction with more prospective collaboration, plans are evolving to ensure that we will be better prepared to address similar situations especially in paediatrics and pregnant women where experience is limited and actual practice relies heavily on leveraging data from other populations and indications.

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.

Darunavir Pharmacokinetics With an Increased Dose During Pregnancy

BACKGROUND

This study aims to evaluate the pharmacokinetics of an increased dose of darunavir (800 mg twice daily) with 100 mg ritonavir during pregnancy and postpartum.

METHODS

Darunavir (DRV) and ritonavir (RTV; r) intensive pharmacokinetic evaluations were performed at steady state during the second and third trimesters of pregnancy (DRV/r 800/100 mg bid) and 2-3 weeks postpartum (DRV/r 600/100 mg twice daily). Plasma concentrations of darunavir and ritonavir were measured using high-performance liquid chromatography. Target darunavir area under the concentration time curve (AUC) was >70% (43.6 μg × h/mL) of median AUC (62.3 μg × h/mL) in nonpregnant adults on twice daily darunavir-ritonavir 600/100 mg.

RESULTS

Twenty-four women were included in the analysis. Darunavir AUC0-12 was lower with the increased dose during the second {[geometric mean ratio (GMR) of 0.62 (IQR 0.44-0.88); P = 0.055]} and third trimesters [GMR 0.64 (IQR 0.55-0.73); P = <0.001] compared with postpartum. Darunavir apparent clearance was higher during the second [GMR 1.77 (IQR 1.24-2.51); P = 0.039] and third trimesters [GMR 2.01 (IQR 1.17-2.35); P = <0.001] compared with postpartum. Similarly, ritonavir AUC0-12 was lower during the third trimester [GMR 0.65 (IQR 0.52-0.82); P = 0.007] compared with postpartum, whereas its apparent clearance was higher during the third trimester [GMR 1.53 (IQR 1.22-1.92); P = 0.008] compared with postpartum. No major drug-related safety concerns were noted.

CONCLUSIONS

Increasing darunavir dose to 800 mg BID failed to significantly increase darunavir exposure compared with 600 mg BID. Other strategies, such as increasing the ritonavir dose should be investigated.

Pharmacokinetic Enhancement of HIV Antiretroviral Therapy During Pregnancy

Pharmacokinetic boosting of antiretroviral (ARV) therapies with either ritonavir or cobicistat is used to achieve target drug exposure, lower pill burden, and provide simplified dosing schedules. Several ARVs require boosting, including the integrase inhibitor elvitegravir as well as protease inhibitors such as darunavir, atazanavir, and lopinavir. The use of boosted regimens in pregnant women living with HIV has been studied for a variety of ARVs; however, a recent recommendation by the US Food and Drug Administration advised against cobicistat-boosted regimens in pregnancy due to substantially lower drug exposures observed in clinical pharmacokinetic studies. The objectives of this article are to review pharmacokinetic enhancement of ARVs with ritonavir and cobicistat during pregnancy and postpartum, describe clinical implications, and provide recommendations for future research.

Evaluating darunavir/ritonavir dosing regimens for HIV-positive pregnant women using semi-mechanistic pharmacokinetic modelling

BACKGROUND

Darunavir 800 mg once (q24h) or 600 mg twice (q12h) daily combined with low-dose ritonavir is used to treat HIV-positive pregnant women. Decreased total darunavir exposure (17%-50%) has been reported during pregnancy, but limited data on unbound exposure are available.

OBJECTIVES

To evaluate total and unbound darunavir exposures following standard darunavir/ritonavir dosing and to explore the value of potential optimized darunavir/ritonavir dosing regimens for HIV-positive pregnant women.

PATIENTS AND METHODS

A population pharmacokinetic analysis was conducted based on data from 85 women. The final model was used to simulate total and unbound darunavir AUC0-τ and Ctrough during the third trimester of pregnancy, as well as to assess the probability of therapeutic exposure.

RESULTS

Simulations predicted that total darunavir exposure (AUC0-τ) was 24% and 23% lower in pregnancy for standard q24h and q12h dosing, respectively. Unbound darunavir AUC0-τ was 5% and 8% lower compared with post-partum for standard q24h and q12h dosing, respectively. The probability of therapeutic exposure (unbound) during pregnancy was higher for standard q12h dosing (99%) than for q24h dosing (94%).

CONCLUSIONS

The standard q12h regimen resulted in maximal and higher rates of therapeutic exposure compared with standard q24h dosing. Darunavir/ritonavir 600/100 mg q12h should therefore be the preferred regimen during pregnancy unless (adherence) issues dictate q24h dosing. The value of alternative dosing regimens seems limited.

Therapeutic drug monitoring of darunavir/ritonavir in pregnancy

BACKGROUND

Physiological changes during pregnancy can have a significant impact on antiretroviral pharmacokinetics (PK), which may result in reduced drug efficacy. Here we describe the PK of darunavir/ritonavir (DRV/r) 800/100 once daily in a cohort of pregnant women undergoing routine therapeutic drug monitoring (TDM) as well as transplacental passage of DRV by measuring and comparing cord blood and maternal blood samples at delivery.

METHODS

Pregnant HIV-positive women received DRV/r as part of routine pre-natal care. Demographic and clinical data were collected. DRV plasma concentrations [DRV] were determined in the first (T1), second (T2) and third (T3) trimester and at postpartum (PP). The target concentration was 550 ng/ml. Where possible, paired maternal and cord blood samples were taken at delivery.

RESULTS

A total of 33 women were enrolled. Samples were taken 14-20 h post-dose and measured concentrations were extrapolated to 24 h post-dose. At the time nearest to delivery, all but four had undetectable plasma viral loads (pVL). [DRV] were determined in 1 (T1); 14 (T2); 32 (T3) and 29 (PP). 1 sample was <550 ng/ml at T2, 6 at T3 and 3 at PP. [DRV] were significantly lower at T2/T3 relative to PP.

CONCLUSIONS

[DRV] in T2 and T3 were 36-55% when compared with PP. However, DRV PK in pregnancy were not associated with a lack of virological suppression at delivery as of the 33 patients enrolled in this study, 31 had no HIV transmission from mother to child. Data regarding two candidates were not available as they delivered in a separate health-care facility.

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.

Low plasmatic concentration of intensified antiretroviral therapy in a pregnant woman: a case report

Background

Identifying the most appropriate antiretroviral regimen for pregnant women with Human Immunodeficiency Virus (HIV-1) infection can be challenging, mainly due to pregnancy-related physiological alterations which can significantly reduce maternal drug plasma concentration. We would like to report our experience as it consists of an unusual case of low plasmatic concentration of antiretroviral drugs despite regimen intensification in a HIV-positive pregnant woman. It also underlines the need for accurate monitoring and treatment adjustment in pregnant women with Human Immunodeficiency Virus (HIV).

Case presentation

A 26-year-old Brazilian woman with HIV-1 infection attending our out-patient clinic presented with low plasmatic concentration of antiretroviral drugs and persistent detectable viral load despite regimen intensification during pregnancy.

Trough plasma concentrations of dolutegravir and darunavir were measured by validated liquid chromatography–mass spectrometry. At 23 weeks of gestation it showed a lower value than expected in non-pregnant adults, compared to a normal level of plasma concentration measured at 10 weeks after delivery. Our patient and the baby had no regimen-related adverse effects.

Conclusions

Physiological changes during pregnancy can affect pharmacokinetics and reduce a mother’s bioavailability of antiretroviral drugs, potentially altering their pharmacological activity. A personalized treatment and a careful follow-up are hence mandatory for this key population.

Cobicistat-containing antiretroviral regimens are not recommended during pregnancy: viewpoint

: Product labels for cobicistat with atazanavir or darunavir, and for elvitegravir/cobicistat/emtricitabine/tenofovir (alafenamide or disoproxil fumarate) were recently updated to state that these products are not recommended for initiation during pregnancy, and an alternative regimen is recommended for those who become pregnant during therapy with these products. Herein, we present the rationale for these recommendations, which are based on studies in pregnant women evaluating the pharmacokinetics and antiviral activity of darunavir/cobicistat or elvitegravir/cobicistat-containing antiretroviral regimens. In these studies, mean steady-state minimum concentrations in the second and third trimester versus postpartum of cobicistat, darunavir, and elvitegravir were reduced by 61-83%, 89-92%, and 82-86%, respectively. In the absence of data with atazanavir/cobicistat, we leveraged the available data with darunavir/cobicistat and elvitegravir/cobicistat to make recommendations for atazanavir/cobicistat. Darunavir/ritonavir and atazanavir/ritonavir remain viable treatment options for pregnant women.

Reduced exposure to darunavir and cobicistat in HIV-1-infected pregnant women receiving a darunavir/cobicistat-based regimen

OBJECTIVES

The aim of the study was to evaluate darunavir and cobicistat pharmacokinetics in pregnant women with HIV-1 infection.

METHODS

This phase 3b, open-label study enrolled HIV-1-infected pregnant women (18-26 weeks of gestation) receiving combination antiretroviral therapy with once-daily darunavir/cobicistat 800/150 mg. The plasma pharmacokinetics of darunavir (total and unbound) and cobicistat were assessed over 24 h during the second and third trimesters (24-28 and 34-38 weeks of gestation, respectively) and 6-12 weeks postpartum. Pharmacokinetic parameters [area under the plasma concentration-time curve over 24 h (AUC_24 h ), maximum plasma concentration (C_max ) and minimum plasma concentration (C_min )] were derived using noncompartmental analysis and compared using linear mixed effects modelling (pregnancy versus postpartum). Antiviral activity and safety were evaluated.

RESULTS

Seven women were enrolled in the study; six completed it. Total darunavir exposure was lower during pregnancy than postpartum (AUC_24 h , 50-56% lower; C_max , 37-49% lower; C_min , 89-92% lower); unbound darunavir exposure was also reduced (AUC_24 h , 40-45% lower; C_max , 32-41% lower; C_min , 88-92% lower). Cobicistat exposure was also lower during pregnancy than postpartum (AUC_24 h , 49-63% lower; C_max , 27-50% lower; C_min , 83% lower). At study completion, five of six (83%) women were virologically suppressed (HIV-1 RNA < 50 copies/mL). There was one virological failure (the patient was nonadherent; no emerging genotypic resistance was observed and susceptibility to antiretrovirals was maintained). No mother-to-child transmission was detected among six infants born to the six women who completed the study. Overall, darunavir/cobicistat was well tolerated in women and infants.

CONCLUSIONS

In view of markedly reduced darunavir and cobicistat exposures during pregnancy, this combination is not recommended in HIV-1-infected pregnant women.

Evaluation of Cardiovascular Disease Risk in HIV-1-Infected Patients Treated with Darunavir

Introduction

We evaluated cardiovascular disease (CVD) risk associated with darunavir treatment and examined the demographic/clinical characteristics of darunavir users based on data from Janssen-sponsored clinical trials, post-marketing pharmacovigilance databases, and administrative claims databases.

Methods

First, selected CVD events [myocardial infarction, stroke, sudden death, invasive cardiovascular procedures (coronary artery angioplasty or bypass, or carotid endarterectomy)] were analyzed in 19 Janssen-sponsored phase 2–4 studies (incidence rates estimated from pooled data; 95% confidence intervals derived from Poisson distribution). Second, analyses were conducted to identify spontaneously reported CVD events in post-marketing pharmacovigilance databases and evaluate disproportional reporting of CVD events for darunavir (using Empirical Bayesian Geometric Mean scores). Third, baseline demographic/clinical characteristics of human immunodeficiency virus-1 (HIV-1)–infected patients in general and new users of darunavir and atazanavir were explored using three US administrative claims databases.

Results

Among 19 Janssen-sponsored clinical trials (treatment durations ≤ 6 years), the CVD event rate (95% CI) per 1000 person-years (pooled population; n = 5713) was 6.15 (2.91–11.89), and was lower for patients who used once-daily darunavir/ritonavir 800/100 mg [0.71 (0.16–3.05); n = 1326] versus twice-daily darunavir/ritonavir 600/100 mg [9.21 (4.94–16.04); n = 3058]. Trend analysis of post-marketing pharmacovigilance data showed that cumulative CVD event reporting rates for darunavir users (any dose) generally declined over time. Spontaneously reported CVD events were not disproportionately reported with darunavir versus other protease inhibitors. Compared with the general HIV-1–infected population and atazanavir users, higher proportions of darunavir users were male, older, and had comorbidities associated with CVD risk based on results from US administrative claims databases.

Conclusions

This comprehensive review of Janssen-sponsored clinical trial, post-marketing, and epidemiological data does not suggest that CVD should be considered an important risk for users of darunavir.

Electronic supplementary material

The online version of this article (10.1007/s40268-018-0238-8) contains supplementary material, which is available to authorized users.

Improving the clinical relevance of a mouse pregnancy model of antiretroviral toxicity; a pharmacokinetic dosing-optimization study of current HIV antiretroviral regimens

Animal models can be useful tools for the study of HIV antiretroviral (ARV) safety/toxicity in pregnancy and the mechanisms that underlie ARV-associated adverse events. The utility and translatability of animal model-based ARV safety/toxicity data is improved if ARVs are tested in clinically relevant concentrations. The objective of this work was to improve the clinical relevance of our mouse pregnancy model of ARV toxicity, by determining the doses of currently prescribed ARV regimens that would yield human therapeutic plasma concentrations. Pregnant mice were administered increasing doses of ARV combinations by oral gavage, followed by measurement of drug concentrations in the maternal plasma and amniotic fluid. Concentrations of ten different ARVs in maternal plasma and amniotic fluid samples of pregnant mice are presented, with dosing optimization to yield human pregnancy-relevant plasma drug concentrations. We have proposed optimal dosing for different regimen component drugs to achieve human therapeutic plasma levels, so that a clinically relevant standard dosing is established. A review of related ARV pharmacokinetic studies in (pregnant/non-pregnant) rodents and human pregnancy is also shown. We hope these data will inform and encourage the use of mouse pregnancy models in the study of ARV safety/toxicity.

Antiretroviral unbound concentration during pregnancy: piece of interest in the puzzle?

Atazanavir and darunavir total concentrations (drug bound to plasma proteins plus unbound drug) progressively decrease during pregnancy. This pharmacokinetic variation leads physicians to recommend increasing doses. Conversely, the unbound concentration (Cu), i.e. the pharmacologically active form of the drug, remains unchanged. The explanation of this desynchronization lies in the fact that the clearance of the unbound form, corresponding to the intrinsic metabolic capacity of the hepatocytes, is the only factor driving Cu, and is constant during pregnancy. The attention of HIV physicians should be attracted to this aspect of pharmacokinetics, which is often incompletely understood and could lead to inadequate dose adjustment, which could then cause overexposure of the foetus for many months, with unknown consequences.

Pharmacokinetics, Antiviral Activity, and Safety of Rilpivirine in Pregnant Women with HIV-1 Infection: Results of a Phase 3b, Multicenter, Open-Label Study

INTRODUCTION

Physiologic changes during pregnancy may impact the pharmacokinetics of drugs. In addition, efficacy and safety/tolerability concerns have been identified for some antiretroviral agents.

METHODS

Human immunodeficiency virus (HIV)-1-infected pregnant women (18-26 weeks gestation) receiving the non-nucleoside reverse transcriptase inhibitor rilpivirine 25 mg once daily were enrolled in this phase 3b, open-label study examining the impact of pregnancy on the pharmacokinetics of rilpivirine when it is given in combination with other antiretroviral agents. Blood samples (collected over the 24-h dosing interval) to assess total and unbound rilpivirine plasma concentrations were obtained during the second and third trimesters (24-28 and 34-38 weeks gestation, respectively) and 6-12 weeks postpartum. Pharmacokinetic parameters were derived using noncompartmental analysis and compared (pregnancy versus postpartum) using linear mixed effects modeling. Antiviral and immunologic response and safety were assessed.

RESULTS

Nineteen women were enrolled; 15 had evaluable pharmacokinetic results. Total rilpivirine exposure was 29-31% lower during pregnancy versus postpartum; differences were less pronounced for unbound (pharmacodynamically active) rilpivirine. At study entry, 12/19 (63.2%) women were virologically suppressed; 10/12 (83.3%) women were suppressed at the postpartum visit. Twelve infants were born to the 12 women who completed the study (7 discontinued); no perinatal viral transmission was observed among 10 infants with available data. Rilpivirine was generally safe and well tolerated in women and infants exposed in utero.

CONCLUSION

Despite decreased rilpivirine exposure during pregnancy, treatment was effective in preventing mother-to-child transmission and suppressing HIV-1 RNA in pregnant women. Results suggest that rilpivirine 25 mg once daily, as part of individualized combination antiretroviral therapy, may be an appropriate option for HIV-1-infected pregnant women.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier, NCT00855335.

Toward a universal antiretroviral regimen: special considerations of pregnancy and breast feeding

PURPOSE OF REVIEW

As optimized antiretroviral therapy (ART) regimens are prepared for introduction in low-income and middle-income countries (LMIC), we consider the current evidence related to dosing, efficacy and safety during pregnancy and breastfeeding of next-generation first-line and second-line ART regimens proposed for imminent introduction in the global marketplace.

RECENT FINDINGS

Pregnancy pharmacokinetic considerations include potentially insufficient efavirenz exposure if dosed at 400 mg/day, the need for twice daily darunavir dosing and the paucity of data related to tenofovir alafenamide and dolutegravir dosing, safety and efficacy. Increasingly evidence suggests an association with adverse birth outcomes, particularly in women conceiving on ART, and with varying risk by drug and drug combination. Clinical trials and studies are in progress or planned that aim to determine dosing, safety and efficacy of several new antiretrovirals (ARVs).

SUMMARY

Having a universal, highly potent and safe ART regimen for all individuals living with HIV in LMIC including pregnant women is clearly the most beneficial strategy to keep mothers alive and healthy and to prevent transmission of HIV to their children. It will have to be determined whether the use of this next generation of optimized ARVs will also optimize health outcomes of pregnant women and their children.

Darunavir for use in pregnant women with HIV

INTRODUCTION

Combination antiretroviral therapy is recommended during pregnancy to decrease the rate of HIV transmission to the baby and reduce morbidity in the mother. More than 50% of women are prescribed a protease inhibitor-based regimen during pregnancy. Darunavir was recently reclassified as a first-line protease inhibitor for use in pregnancy in the US Department of Health and Human Services Perinatal Guidelines. Areas covered: This is a brief review of the use of protease inhibitor therapy during pregnancy, and a discussion of darunavir's utility in this area. Clinical pharmacology and trial data are reviewed, and the safety, efficacy and dosing of darunavir during pregnancy is discussed. Expert commentary: Darunavir has become an important option in the management of HIV during pregnancy. Both once-daily dosing and twice-daily dosing regimens have shown efficacy in clinical studies. Although a significant reduction in total (protein bound and unbound) plasma concentrations of darunavir has been noted during pregnancy, antiviral activity appears to be maintained with standard dosing. This is likely due to diminished changes in unbound drug concentrations. Preterm delivery and low birth weight have been noted for pregnancies of women on darunavir-containg regimens, but a causal relationship has not yet been demonstrated.

Pharmacokinetics of Total and Unbound Etravirine in HIV-1-Infected Pregnant Women

BACKGROUND

Treatment of HIV-1-infected women during pregnancy protects maternal health and reduces the risk of perinatal transmission of HIV-1. However, physiologic changes that occur during pregnancy may affect drug pharmacokinetics. This phase IIIb, open-label study evaluated the effects of pregnancy on the pharmacokinetics of the nonnucleoside reverse transcriptase inhibitor etravirine.

METHODS

Eligible HIV-1-infected pregnant women (18-26 weeks gestation) on an individualized, highly active antiretroviral therapy regimen including etravirine 200 mg twice daily were enrolled. Blood samples to assess the pharmacokinetics of total and unbound etravirine were obtained at clinic visits during the second and third trimesters (24- to 28-weeks and 34- to 38-weeks gestation, respectively) and 6-12 weeks postpartum. At each time point, plasma concentrations were measured over 12 hours (12-hour time point was obtained before the second daily dose of etravirine); pharmacokinetic parameters were derived using noncompartmental analysis and were compared between pregnancy and postpartum using general linear models. Antiviral and immunologic response and safety were assessed at each visit.

RESULTS

Etravirine pharmacokinetic profiles were available for 13 of 15 enrolled women. Exposure to total etravirine was generally higher during pregnancy compared with 6-12 weeks postpartum (1.2- to 1.4-fold); the differences were less pronounced for unbound (pharmacodynamically active) etravirine. Virologic response was generally preserved throughout the study, and no perinatal transmission was observed. Etravirine was generally safe and well tolerated.

CONCLUSIONS

Etravirine 200 mg twice daily, as part of individualized combination antiretroviral therapy, may be a treatment option for HIV-1-infected pregnant women.

Physiologically Based Modelling of Darunavir/Ritonavir Pharmacokinetics During Pregnancy

Pregnant women are usually excluded from clinical trials. Physiologically based pharmacokinetic (PBPK) modelling may provide a method to predict pharmacokinetics in pregnant women, without the need to perform extensive in vivo clinical trials. Here, we used mechanistic modelling to delineate the potential impact of drug transporters on darunavir pharmacokinetics and to identify current knowledge gaps that limit accurate PBPK modelling of darunavir/ritonavir (darunavir/r) exposure in pregnancy. Simcyp (version 13.2) was used for PBPK modelling, using physicochemical and in vitro pharmacokinetic parameters of darunavir and ritonavir from the literature. The Michaelis-Menten constant (K m) and the maximum rate of metabolite formation (V max) for cytochrome P450 3A4-mediated darunavir biotransformation and inhibition by ritonavir were determined experimentally, while the contributions of hepatocyte influx and efflux transporters were assessed by sensitivity analysis. The simulations were compared with previously published clinical pharmacokinetic data. We found that use of a well-stirred liver model overestimated darunavir exposure substantially. A permeability-limited liver model, including hepatic uptake and efflux transporters and an efficient enterohepatic circulation step, resulted in an acceptable description of darunavir/r exposure. For the 600/100 mg darunavir/r twice-daily dose and the 800/100 mg once-daily dose, the estimated pharmacokinetic parameters were within a 2-fold range of the reported data. The predicted decreases in the area under the concentration-time curve (AUC) values during pregnancy for the twice- and once-daily doses were 27 and 41%, respectively, which were in line with the observed decreases of 17-22 and 33%. In conclusion, our data support a clinically relevant role of hepatic transporters in darunavir pharmacokinetics. By including them in our model, we successfully approximated the increase in darunavir exposure mediated by ritonavir co-administration and the decrease in darunavir exposure observed during pregnancy.

Pregnancy-Associated Changes in Pharmacokinetics: A Systematic Review

BACKGROUND

Women are commonly prescribed a variety of medications during pregnancy. As most organ systems are affected by the substantial anatomical and physiological changes that occur during pregnancy, it is expected that pharmacokinetics (PK) (absorption, distribution, metabolism, and excretion of drugs) would also be affected in ways that may necessitate changes in dosing schedules. The objective of this study was to systematically identify existing clinically relevant evidence on PK changes during pregnancy.

METHODS AND FINDINGS

Systematic searches were conducted in MEDLINE (Ovid), Embase (Ovid), Cochrane Central Register of Controlled Trials (Ovid), and Web of Science (Thomson Reuters), from database inception to August 31, 2015. An update of the search from September 1, 2015, to May 20, 2016, was performed, and relevant data were added to the present review. No language or date restrictions were applied. All publications of clinical PK studies involving a group of pregnant women with a comparison to nonpregnant participants or nonpregnant population data were eligible to be included in this review. A total of 198 studies involving 121 different medications fulfilled the inclusion criteria. In these studies, commonly investigated drug classes included antiretrovirals (54 studies), antiepileptic drugs (27 studies), antibiotics (23 studies), antimalarial drugs (22 studies), and cardiovascular drugs (17 studies). Overall, pregnancy-associated changes in PK parameters were often observed as consistent findings among many studies, particularly enhanced drug elimination and decreased exposure to total drugs (bound and unbound to plasma proteins) at a given dose. However, associated alterations in clinical responses and outcomes, or lack thereof, remain largely unknown.

CONCLUSION

This systematic review of pregnancy-associated PK changes identifies a significant gap between the accumulating knowledge of PK changes in pregnant women and our understanding of their clinical impact for both mother and fetus. It is essential for clinicians to be aware of these unique pregnancy-related changes in PK, and to critically examine their clinical implications.

Pharmacokinetics of once-daily darunavir/ritonavir in HIV-1-infected pregnant women

OBJECTIVES

HIV antiretroviral therapy during pregnancy is recommended to reduce the risk of mother-to-child transmission and for maternal care. Physiological changes during pregnancy can affect pharmacokinetics. The impact of pregnancy was evaluated for once-daily (qd) darunavir/ritonavir.

METHODS

HIV-1-infected pregnant women on an antiretroviral regimen that includes darunavir were enrolled in the study and further treated with darunavir/ritonavir 800/100 mg qd. Plasma concentrations were assessed over 24 h during the second and third trimesters and postpartum using a validated high-performance liquid chromatography tandem mass spectrometry assay for total darunavir and ritonavir, and using (14) C-darunavir-fortified plasma for unbound darunavir. Pharmacokinetic parameters were derived using noncompartmental analysis. Safety and antiviral response were assessed at all visits.

RESULTS

Data were available for 16 women. The area under the plasma concentration-time curve from 0 to 24 h (AUC24h ) for total darunavir was 34-35% lower during pregnancy vs. postpartum. Unbound darunavir AUC24h was 20-24% lower during pregnancy vs. postpartum. The minimum plasma concentration of total and unbound darunavir was 32-50% and 13-38% lower, respectively, during pregnancy vs. postpartum. The antiviral response (< 50 HIV-1 RNA copies/mL) was 59% at baseline and increased to 87-100% during the trial; the CD4 count increased over time. One serious adverse event (gestational diabetes) was judged as possibly related to study medication. All 16 infants born to women remaining in the study at delivery were HIV-1 negative (two were premature).

CONCLUSIONS

Total darunavir exposure decreased during pregnancy, but the decrease was less for unbound (active) darunavir. These changes are not considered clinically relevant. Darunavir/ritonavir 800/100 mg qd may therefore be a treatment option for HIV-1-infected pregnant women.

Pharmacokinetics of Once Versus Twice Daily Darunavir in Pregnant HIV-Infected Women

OBJECTIVE

To describe darunavir (DRV) pharmacokinetics with once-and twice-daily dosing during pregnancy and postpartum in HIV-infected women.

DESIGN

Women were enrolled in International Maternal Pediatric Adolescent AIDS Clinical Trials Network Protocol P1026s, a prospective nonblinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included separate cohorts receiving DRV/ritonavir dosed at either 800 mg/100 mg once daily or 600 mg/100 mg twice daily.

METHODS

Intensive steady-state 12- or 24-hour pharmacokinetic profiles were performed during the second trimester, third trimester, and postpartum. DRV was measured using high-performance liquid chromatography (detection limit: 0.09 μg/mL).

RESULTS

Pharmacokinetic data were available for 64 women (30 once daily and 34 twice daily dosing). Median DRV area under the concentration-time curve (AUC) and maximum concentration were significantly reduced during pregnancy with both dosing regimens compared with postpartum, whereas the last measurable concentration (Clast) was also reduced during pregnancy with once daily DRV. DRV AUC with once daily dosing was reduced by 38% during the second trimester and by 39% during the third trimester. With twice daily dosing, DRV AUC was reduced by 26% in both trimesters. The median (range) ratio of cord blood/maternal delivery DRV concentration in 32 paired samples was 0.18 (range: 0-0.82).

CONCLUSIONS

DRV exposure is reduced by pregnancy. To achieve DRV plasma concentrations during pregnancy equivalent to those seen in nonpregnant adults, an increased twice daily dose may be necessary. This may be especially important for treatment-experienced women who may have developed antiretroviral resistance mutations.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Therapeutic drug monitoring in HIV-infected pregnant women with a focus on protease inhibitors

The goals of HIV therapy in pregnant patients are to ensure health of mother and to prevent mother to child transmission of HIV to the unborn child. Pregnancy is a time of significant physiological alterations that affect all pharmacological aspects of the antiretroviral (ARV) drugs. Studies point toward lower levels of ARVs in maternal blood especially during late stages of pregnancy. Therapeutic drug monitoring is a strategy to ensure that maternal blood contains adequate level of ARVs to achieve these targets. Pharmacokinetics and therapeutic drug monitoring studies of protease inhibitors are reviewed in this article with emphasis on darunavir which is a newer protease inhibitor gaining popularity as a therapeutic choice in pregnant patients.

Darunavir: a review of its use in the management of HIV-1 infection

The latest HIV-1 protease inhibitor (PI) darunavir (Prezista™) has a high genetic barrier to resistance development and is active against wild-type HIV and HIV strains no longer susceptible to some older PIs. Ritonavir-boosted darunavir, as a component of antiretroviral therapy (ART), is indicated for the treatment of HIV-1 infection in adult and paediatric patients (aged ≥3 years), with or without treatment experience (details vary depending on region of approval). Several open-label or partially-blinded trials have evaluated the efficacy of ritonavir-boosted darunavir ART regimens for up to 192 weeks in these settings. In treatment-naïve adults, once-daily boosted darunavir was no less effective in establishing virological suppression than once- or twice-daily boosted lopinavir, yet was more effective at maintaining suppression long term. Moreover, treatment-experienced adults with no darunavir resistance-associated mutations (RAMs) had no less effective viral load suppression with once-daily than with twice-daily boosted darunavir. In treatment-experienced adults, including some with multiple major PI RAMs, twice-daily boosted darunavir was more effective than twice-daily boosted lopinavir or boosted control PIs in reducing viral load, and provided virological benefit as part of a salvage regimen in those with few remaining treatment options. Boosted darunavir also reduced viral load when administered once-daily in treatment-naïve adolescents or twice-daily in treatment-experienced children and adolescents. Boosted darunavir is generally well tolerated, with gastrointestinal disturbances and lipid abnormalities among the most common tolerability issues. It has a lipid profile more favourable than that of boosted lopinavir in terms of total cholesterol and triglyceride changes and, when administered once daily, its lipid effects are generally similar to those of boosted atazanavir. Thus, boosted darunavir is a useful option for the ART regimens of adult and paediatric patients with HIV-1 infection.

Adverse drug reactions associated with antiretroviral therapy during pregnancy

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Pharmacokinetics of total and unbound darunavir in HIV-1-infected pregnant women

OBJECTIVES

To describe the pharmacokinetics of darunavir in pregnant HIV-infected women in the third trimester and post-partum.

PATIENTS AND METHODS

This was a non-randomized, open-label, multicentre, Phase IV study in HIV-infected pregnant women recruited from HIV treatment centres in Europe. HIV-infected pregnant women treated with darunavir (800/100 mg once daily or 600/100 mg twice daily) as part of their combination ART were included. Pharmacokinetic curves were recorded in the third trimester and post-partum. A cord blood sample and maternal sample were collected. The study is registered at ClinicalTrials.gov under number NCT00825929.

RESULTS

Twenty-four women were included in the analysis [darunavir/ritonavir: 600/100 mg twice daily (n=6); 800/100 mg once daily (n=17); and 600/100 mg once daily (n=1)]. Geometric mean ratios of third trimester versus post-partum (90% CI) were 0.78 (0.60-1.00) for total darunavir AUC0-tau after 600/100 mg twice-daily dosing and 0.67 (0.56-0.82) for total darunavir AUC0-tau after 800/100 mg once-daily dosing. The unbound fraction of darunavir was not different during pregnancy (12%) compared with post-partum (10%). The median (range) ratio of darunavir cord blood/maternal blood was 0.13 (0.08-0.35). Viral load close to delivery was <300 copies/mL in all but two patients. All children were tested HIV-negative and no congenital abnormalities were reported.

CONCLUSIONS

Darunavir AUC and Cmax were substantially decreased in pregnancy for both darunavir/ritonavir regimens. This decrease in exposure did not result in mother-to-child transmission. For antiretroviral-naive patients, who are adherent, take darunavir with food and are not using concomitant medication reducing darunavir concentrations, 800/100 mg of darunavir/ritonavir once daily is adequate in pregnancy. For all other patients 600/100 mg of darunavir/ritonavir twice daily is recommended during pregnancy.

Placental transfer of darunavir in an ex vivo human cotyledon perfusion model

Placental transfer of the HIV protease inhibitor darunavir was investigated in 5 term human cotyledons perfused with darunavir (1,000 ng/ml) in the maternal to fetal direction. The mean (± the standard deviation [SD]) fetal transfer rate (FTR) (fetal/maternal concentration at steady state from 30 to 90 min) was 15.0%±2.1%, and the mean (±SD) clearance index (darunavir FTR/antipyrine FTR) was 40.3%±5.8%. This shows that darunavir crosses the placenta at a relatively low rate, resulting in fetal exposure.

Pharmacokinetics and pharmacodynamics of boosted once-daily darunavir

The ability to dose antiretroviral agents once daily simplifies the often complex therapeutic regimens required for the successful treatment of HIV infection. Thus, once-daily dosing can lead to improved patient adherence to medication and, consequently, sustained virological suppression and reduction in the risk of emergence of drug resistance. Several trials have evaluated once-daily darunavir/ritonavir in combination with other antiretrovirals (ARTEMIS and ODIN trials) or as monotherapy (MONET, MONOI and PROTEA trials) in HIV-1-infected adults. Data from ARTEMIS and ODIN demonstrate non-inferiority of once-daily darunavir/ritonavir against a comparator and, together with pharmacokinetic data, have established the suitability of once-daily darunavir/ritonavir for treatment-naive and treatment-experienced patients with no darunavir resistance-associated mutations. The findings of ARTEMIS and ODIN have led to recent updates to treatment guidelines, whereby once-daily darunavir/ritonavir, given with other antiretrovirals, is now a preferred treatment option for antiretroviral-naive adult patients and a simplified treatment option for antiretroviral-experienced adults who have no darunavir resistance-associated mutations. Once-daily dosing with darunavir/ritonavir is an option for treatment-naive and for treatment-experienced paediatric patients with no darunavir resistance-associated mutations based on the findings of the DIONE trial and ARIEL substudy. This article reviews the pharmacokinetics, efficacy, safety and tolerability of once-daily boosted darunavir. The feasibility of darunavir/ritonavir monotherapy as a treatment approach for some patients is also discussed. Finally, data on a fixed-dose combination of 800/150 mg of darunavir/cobicistat once daily are presented, showing comparable darunavir bioavailability to that obtained with 800/100 mg of darunavir/ritonavir once daily.

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

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