Safety and Pharmacokinetics of Antiretroviral Therapy During Pregnancy

Pharmacokinetics of Atazanavir Boosted With Cobicistat in Pregnant and Postpartum Women With HIV

BACKGROUND

This study evaluated atazanavir and cobicistat pharmacokinetics during pregnancy compared with postpartum and in infant washout samples.

SETTING

A nonrandomized, open-label, parallel-group, multicenter prospective study of atazanavir and cobicistat pharmacokinetics in pregnant women with HIV and their children.

METHODS

Intensive steady-state 24-hour pharmacokinetic profiles were performed after administration of 300 mg of atazanavir and 150 mg of cobicistat orally in fixed-dose combination once daily during the second trimester, third trimester, and postpartum. Infant washout samples were collected after birth. Atazanavir and cobicistat were measured in plasma by validated high-performance liquid chromatography-ultraviolet and liquid chromatography-tandem mass spectrometry assays, respectively. A 2-tailed Wilcoxon signed-rank test (α = 0.10) was used for paired within-participant comparisons.

RESULTS

A total of 11 pregnant women enrolled in the study. Compared with paired postpartum data, atazanavir AUC0-24 was 26% lower in the second trimester [n = 5, P = 0.1875, geometric mean of ratio (GMR) = 0.739, 90% CI: 0.527 to 1.035] and 54% lower in the third trimester (n = 6, GMR = 0.459, P = 0.1563, 90% CI: 0.190 to 1.109), whereas cobicistat AUC0-24 was 35% lower in the second trimester (n = 5, P = 0.0625, GMR = 0.650, 90% CI: 0.493 to 0.858) and 52% lower in the third trimester (n = 7, P = 0.0156, GMR = 0.480, 90% CI: 0.299 to 0.772). The median (interquartile range) 24-hour atazanavir trough concentration was 0.21 μg/mL (0.16-0.28) in the second trimester, 0.21 μg/mL (0.11-0.56) in the third trimester, and 0.61 μg/mL (0.42-1.03) in postpartum. Placental transfer of atazanavir and cobicistat was limited.

CONCLUSIONS

Standard atazanavir/cobicistat dosing during pregnancy results in lower exposure which may increase the risk of virologic failure and perinatal transmission.

Pharmacokinetics of darunavir and cobicistat in pregnant and postpartum women with HIV

OBJECTIVE

To evaluate darunavir and cobicistat pharmacokinetics during pregnancy compared with postpartum and in infant washout samples after delivery.

DESIGN

Nonrandomized, open-label, parallel-group, multicenter phase-IV prospective study of darunavir and cobicistat pharmacokinetics in pregnant women with HIV and their children in the United States.

METHODS

Intensive steady-state 24-h pharmacokinetic profiles were performed after administration of 800 mg of darunavir and 150 mg of cobicistat orally in fixed dose combination once-daily during the second trimester, third trimester, and postpartum. Infant washout samples were collected after birth. Darunavir and cobicistat were measured in plasma by validated HPLC-UV and liquid chromatography with tandem mass spectrometry detection (LC-MS)/MS assays, respectively. A two-tailed Wilcoxon signed-rank test (α = 0.10) was employed for paired within-participant comparisons.

RESULTS

A total of 29 pregnant women receiving darunavir and cobicistat once-daily enrolled in the study. Compared with paired postpartum data, darunavir AUC0--24 was 53% lower in the second trimester [n = 12, P = 0.0024, geometric mean of ratio (GMR)=0.47, 90% confidence interval (CI) 0.33 - 0.68] and 56% lower in the third trimester (n = 18, P < 0.0001, GMR = 0.44, 90% CI 0.36 - 0.54), whereas cobicistat AUC0--24 was 50% lower in the second trimester (n = 12, P = 0.0024, GMR = 0.50, 90% CI 0.36-0.69) and 56% lower in the third trimester (n = 18, P < 0.0001, GMR = 0.44, 90% CI 0.35-0.55). Placental transfer of darunavir and cobicistat was limited.

CONCLUSION

Standard darunavir/cobicistat dosing during pregnancy results in significantly lower exposure during pregnancy, which may increase the risk of virologic failure and perinatal transmission.

Therapeutic drug monitoring in a developing nation: a clinical guide

Therapeutic drug monitoring is aimed at using drug concentration measurements to manage a patient's medication requirement and optimise clinical outcome, particularly in respect of drugs with narrow therapeutic index. Typically, immunoassay methods of various techniques are employed with the advantage of rapid turnaround time and ease of operation. The chromatographic methods are specific and cost effective, though more demanding and require technical expertise. The most crucial aspect of any therapeutic drug monitoring service is the expert clinical interpretation of drug concentration measurements taking into consideration individual pharmacokinetic variability in drug disposition across different populations. The setting up of a therapeutic drug monitoring service requires enormous resources, both in terms of equipment and trained personnel. This poses considerable constraints in developing countries due to limited scarce resources, coupled with ignorance among health practitioners on the relevance of therapeutic drug monitoring in clinical practice. Consequently, the need for advocacy, training and encouragement of health practitioners on the usefulness of therapeutic drug monitoring in enhancing patient care and overall clinical outcome in a developing country such as Nigeria can never be over-emphasised.

Free and total plasma levels of lopinavir during pregnancy, at delivery and postpartum: implications for dosage adjustments in pregnant women

BACKGROUND

Physiological changes associated with pregnancy may alter antiretroviral plasma concentrations and might jeopardize prevention of mother-to-child HIV transmission. Lopinavir is one of the protease inhibitors more frequently prescribed during pregnancy in Europe. We described the free and total pharmacokinetics of lopinavir in HIV-infected pregnant and non-pregnant women, and evaluated whether significant alterations in its disposition and protein binding warrant systematic dosage adjustment.

METHODS

Plasma samples were collected at first, second and third trimester of pregnancy, at delivery, in umbilical cord and postpartum. Lopinavir free and total plasma concentrations were measured by HPLC-MS/MS. Bayesian calculations were used to extrapolate total concentrations to trough (Cmin).

RESULTS

A total of 42 HIV-positive pregnant women and 37 non-pregnant women on lopinavir/ritonavir were included in the study. Compared to postpartum and control values, total lopinavir Cmin was decreased moderately (31-39%) during pregnancy, and free Cmin minimally, showing significant alteration only at delivery (-35%). However, total and free Cmin remained in all patients above the target concentrations for wild-type virus of 1,000 ng/ml, and above the unbound IC50(WT) of 0.64-0.77 ng/ml of lopinavir, respectively. Lopinavir free fractions remained higher during pregnancy compared to postpartum and controls, and were influenced by α-1-acid-glycoprotein and albumin decrease. Free cord-to-mother ratio (0.43) was 2.7-fold higher than total cord-to-mother ratio (0.16), suggesting higher fetal exposure.

CONCLUSIONS

The moderate decrease of total lopinavir concentrations during pregnancy is not associated with proportional decrease in free concentrations. Both reach a nadir at delivery, albeit not to an extent that would put treatment-naive women at risk of insufficient exposure to the free, pharmacologically active concentrations of lopinavir. No dosage adjustment is therefore needed during pregnancy as it is unlikely to further enhance treatment efficacy but could potentially increase the risk of maternal and fetal toxicity. Nonetheless, in case of viral resistance in treatment-experienced pregnant women, loss of virological control or questionable adherence, it is justified to consider lopinavir dosage adjustment based on total plasma concentration measurement.

Utility of therapeutic drug monitoring in the management of HIV-infected pregnant women in receipt of lopinavir

The pharmacokinetics of antiretroviral drugs in pregnancy is poorly understood. We reviewed the use of therapeutic drug monitoring (TDM) in clinical settings to document plasma concentrations of lopinavir during pregnancy and investigated how clinicians acted upon TDM results. A retrospective review was carried out of all HIV-infected pregnant women taking boosted lopinavir-based highly active antiretroviral therapy (HAART) at five National Health Service (NHS) centres in the UK between May 2004 and March 2007. Seventy-three women in receipt of lopinavir were identified, of whom 89% had plasma lopinavir concentrations above the suggested minimum recommended for wild-type HIV. Initial TDM results prompted dosage change in 10% and assessment of adherence and/or pharmacist review in 11%. TDM was repeated in 29%. TDM can play an important role in the clinical management of HIV-positive pregnant women, allowing informed dose modification and an alternative measure of adherence.

Determination of unbound antiretroviral drug concentrations by a modified ultrafiltration method reveals high variability in the free fraction

Total plasma concentrations are used for therapeutic drug monitoring of antiretroviral drugs, whereas antiviral activity is expected to depend on unbound concentrations. The determination of free (unbound) concentrations by ultrafiltration may be flawed by the irreversible adsorption of many drugs onto the membrane filters and plastic components of the device. The authors describe a modified ultrafiltration method enabling the accurate measurement of unbound concentrations of 10 antiretroviral drugs by liquid chromatography-tandem mass spectroscopy, which circumvents the problem of loss by adsorption in the early ultrafiltration fractions. The method was applied to assess the variability of free fractions of antiretroviral drugs during routine therapeutic drug monitoring in 144 patients with HIV. In in vitro experiments, ultrafiltrate collected in four fractions (0-8, 8-16, 16-24, and 24-30 minutes) gave much lower and more variable free drug concentrations in the first ultrafiltrate fraction than in the last three fractions for lopinavir, nelfinavir, saquinavir, tipranavir, and efavirenz. In the last two fractions, free concentrations remained constant, indicating saturable adsorption. The adsorption was modest for indinavir, amprenavir, and ritonavir, and unnoticeable for atazanavir and nevirapine. Free fraction values obtained with this modified ultrafiltration method reveal substantial interindividual variability, suggesting that monitoring unbound antiretroviral drug concentrations may increase its clinical usefulness, especially for lopinavir, saquinavir, and efavirenz.

Antiretroviral treatment during pregnancy

OBJECTIVE

Virologic failure of HIV-positive patients is of special concern during pregnancy. We compared virologic failure and the frequency of treatment changes in pregnant and non-pregnant women of the Swiss HIV Cohort Study.

METHODS

Using data on 372 pregnancies in 324 women we describe antiretroviral therapy during pregnancy. Pregnant women on HAART at conception (n = 131) were matched to 228 non-pregnant women (interindividual comparison) and to a time period of equal length before and after pregnancy (intraindividual comparison). Women starting HAART during pregnancy (n = 145) were compared with 578 non-pregnant women starting HAART.

FINDINGS

The median age at conception was 31 years, 16% (n = 50) were infected through injecting drug use and the median CD4 cell count was 489 cells/microl. In the majority of pregnancies (n = 220, 59%), women had started ART before conception. When ART was started during pregnancy (n = 145, 39%), it was mainly during the second trimester (n = 100, 69%). Two thirds (n = 26) of 35 women starting in the third trimester were diagnosed with HIV during pregnancy. The risk of virologic failure tended to be lower in pregnant than in non-pregnant women [adjusted odds ratio 0.52 (95% confidence interval 0.25-1.09, P = 0.08)], but was similar in the intraindividual comparison (adjusted odds ratio 1.04, 95% confidence interval 0.48-2.28). Women starting HAART during pregnancy changed the treatment less often than non-pregnant women.

CONCLUSION

Despite the physiological changes occurring during pregnancy, HIV infected pregnant women are not at higher risk of virologic failure.

Pharmacokinetics and therapeutic drug monitoring of antiretrovirals in pregnant women

Highly active antiretroviral therapy is recommended for HIV-infected pregnant women to prevent mother-to-child transmission. The specific physiological background induced by pregnancy leads to significant changes in maternal pharmacokinetics, suggesting potential variability in plasma concentrations of antiretrovirals during gestation. Therapeutic drug monitoring (TDM) of protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs) is recommended in certain situations, including pregnancy, but its systematic use in HIV-infected pregnant women remains controversial. This review provides an update of the pharmacokinetic data available for PIs and NNRTIs in pregnant women and highlights the clinical interest of systematic TDM of certain antiretroviral drugs during pregnancy, including nevirapine, nelfinavir, saquinavir, indinavir and lopinavir.

Pharmacokinetics of nelfinavir in HIV-1-infected pregnant and nonpregnant women

AIMS

To compare steady-state nelfinavir (NFV) pharmacokinetics in pregnant and nonpregnant HIV-infected women.

METHODS

Twenty-five pregnant HIV-infected women were selected from an ongoing observational study evaluating the pharmacokinetics of antiretroviral agents during pregnancy. Twenty of them were in the third and five in the second trimester. Data for the control group of 21 HIV-infected nonpregnant women were taken from a previous multicentre pharmacokinetic trial. All the participating women achieved steady-state plasma concentrations while on a highly active antiretroviral therapy (HAART) regimen including NFV (1250 mg bid) and two nucleoside reverse transcriptase inhibitors (NRTIs). Blood samples for NFV measurement were collected predose (C(trough)) and at 0.5, 1, 2, 3, 4, 5, 6, 8 and 12 h post dose.

RESULTS

During the third trimester of pregnancy NFV AUC(0-12 h) median (range) values were 25.76 (12.61-42.74) microg h(-1) ml(-1), and were 32.49 (19.16-63.81) microg h(-1) ml(-1) in the control group [mean difference - 9.30 microg h(-1) ml(-1); 95% confidence interval (CI) -15.76, -2.83; P < 0.05). Median oral clearance (CL/F) was significantly higher in pregnant women than in the control group (48.5 l h(-1), range 29.3-99.1 l h(-1) vs. 38.5 l h(-1), range 19.6-65.2 l h(-1); mean difference 12.6 l h(-1); 95% CI 3.3, 21.9) but the difference disappeared when CL/F was adjusted for body weight. C(trough) was significantly (P < 0.01) lower in pregnant compared with nonpregnant women (median 0.8 microg ml(-1), range 0-2.6 microg ml(-1) vs. 1.5 microg ml(-1), range 0.5-4.9 microg ml(-1); mean difference -1.0 microg ml(-1); 95% CI -1.7, -0.31). The median elimination half-life of NFV observed during pregnancy was 3.7 h (range 1.4-6.6 h), compared with 5.2 (range 3.1-10.1 h) in the control group (mean difference -1.7; 95% CI -2.8, -0.51).

CONCLUSIONS

Our results indicate that women in the later stages of pregnancy may be exposed to subtherapeutic concentrations of NFV. Thus, adjustments in drug dosage or frequency of administration may be required.

Accouchement des patientes enceintes infectées par le VIH : étude rétrospective de 358 grossesses suivies entre 2000 et 2004

OBJECTIVE

Evaluate the mode of delivery of HIV-infected women and the risk of mother-to-child transmission.

PATIENTS AND METHODS

A retrospective study conducted on HIV-infected women who delivered at the maternity ward of Bichat Hospital in Paris between 1st January 2000 and 31(st) December 2004. Pregnancy care, antiretroviral therapy, decision of the mode of delivery and neonate treatment were conformable to the French recommendations.

RESULTS

The analysis was performed on 332 cases out of 358 pregnancies followed during this period. 75% received a Highly Active Anti Retroviral Therapy (HAART), 24% an AZT monotherapy and 1% did not receive any antiretroviral treatment. Plasmatic HIV viral load was under the level of detectability (50 copies/ml) for 64,6% of women under HAART and 28,7% of women under AZT monotherapy. Only 31,7% of women under HAART delivered vaginally. 44,7% of women under HAART with undetectable viral load at the moment of delivery delivered vaginally. 59,5% of women who were allowed to deliver vaginally had finally a vaginal delivery. 332 women gave birth to 341 babies with 9 twin pregnancies and one still-birth at 22 WA. Out of these 340 babies, 3 babies whose mother received HAART were HIV infected (2 in utero and 1 per-partum).

DISCUSSION AND CONCLUSION

The reasons why only one third of HIV-infected women could deliver vaginally in this study are primarily the persistence of a detectable HIV viral load under HAART. Women's choice of the mode of delivery comes next, which depends on the quality of the counselling about the benefits and risks of the cesarean section in the context of HIV infection. The third reason is obstetrical contra indications to vaginal delivery in the context of HIV infection. In the future, it is possible to reduce the incidence of cesarean section in HIV-infected women by elevating the level of HIV plasmatic viral load which allowed vaginal delivery (1000 copies/ml), by improving the observance to antiretroviral treatment, by adaptating antiretroviral medications posology using determination of serum protease inhibitors concentration and by modifying obstetrical management with less restrictive contra indications to vaginal delivery. However the impact of prophylactic cesarean section when plasmatic HIV viral load is undetectable must still be evaluated.

Transfer of antivirals across the human placenta

BACKGROUND

Viruses cross the placenta and infect the fetus. Antivirals are administered to pregnant women to protect them and the fetus against the viruses. It is necessary to know which antivirals cross the placenta and reach the fetal circulation in pharmacologically significant concentrations in order to plan antiviral therapy.

AIMS

This article reviews the literature on the placental transfer of antivirals against HIV. The review considers also the placental transfer of acyclovir and ganciclovir, which are used against the herpes simplex virus and the cytomegalovirus, respectively.

STUDY DESIGN

Firstly, a medline was performed with the following key words "placental transfer of antivirals". Secondly, a medline was performed with the key words "placenta transfer of..." followed by the name of a single antiviral and it was repeated for 20 antivirals. Thirdly, another medline was performed using the following key words "pharmacokinetics of antiviral in newborn" in order to collect those articles which describe in vivo transfer of antivirals. The literature was critically read and a written note was produced.

RESULTS

The literature on the placental transfer of antivirals includes studies in vitro perfusing the human placenta and studies performed in vivo in which the cord and maternal antiviral plasma concentrations are compared. Both the results obtained in vitro and in vivo show that the protease inhibitors poorly transfer the placenta because of their great molecular weight. With the exception of didanosine, the nucleoside reverse transcriptase inhibitors and nelfinavir, a non-nucleoside reverse transcriptase inhibitor, cross the placenta and the cord, and maternal plasma concentrations equilibrate.

CONCLUSIONS

In vitro and in vivo results are consistent with the view that the nucleoside reverse transcriptase inhibitors cross the human placenta and produce significant pharmacological concentrations in the fetal circulation. Nevirapine, the only studied non-nucleoside reverse transcriptase inhibitor, reach the equilibrium between the fetal and maternal concentration, whereas the protease inhibitors have a poor transfer across the human placenta.