Dataset Information

Model-Based Analysis of Unbound Lopinavir Pharmacokinetics in HIV-Infected Pregnant Women Supports Standard Dosing in the Third Trimester.

ABSTRACT: Physiological changes during pregnancy can affect drug pharmacokinetics. Here we present a population pharmacokinetic model to describe the longitudinal change of unbound lopinavir/ritonavir (LPV/RTV) PK parameters with gestational age, and to predict unbound LPV concentrations under different dosing regimens. The changes in apparent intrinsic clearances of LPV and RTV during pregnancy are described using an exponential function of gestational age. The unbound fractions of LPV/RTV are not significantly different between pregnancy and postpartum. Simulation reveals that despite increases in LPV intrinsic clearance, effective LPV inhibitory quotient (IQ) values are predicted with the standard dosing (400/100 mg b.i.d.) in >90% of simulations, with ≤4-fold increase in viral IC50. As viral susceptibility decreases, higher doses increase the likelihood of efficacy. With ≥40-fold increases in IC50, IQs suggest alternate regimens be considered. This approach refines previous LPV PK reports, and supports that standard dosing is effective with susceptible virus.

SUBMITTER: Chen J

PROVIDER: S-EPMC4807435 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Model-Based Analysis of Unbound Lopinavir Pharmacokinetics in HIV-Infected Pregnant Women Supports Standard Dosing in the Third Trimester.

Chen J J Malone S S Prince H M A HM Patterson K B KB Dumond J B JB

CPT: pharmacometrics & systems pharmacology 20160322 3

Physiological changes during pregnancy can affect drug pharmacokinetics. Here we present a population pharmacokinetic model to describe the longitudinal change of unbound lopinavir/ritonavir (LPV/RTV) PK parameters with gestational age, and to predict unbound LPV concentrations under different dosing regimens. The changes in apparent intrinsic clearances of LPV and RTV during pregnancy are described using an exponential function of gestational age. The unbound fractions of LPV/RTV are not signif ...[more]

PMID: 27069778

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Project description:BackgroundThe impact of pregnancy on efavirenz (EFV) pharmacokinetics is unknown.MethodsInternational Maternal Pediatric Adolescent AIDS Clinical Trials P1026s is an on-going, prospective, nonblinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving 600 mg EFV once daily as part of combination antiretroviral therapy. Intensive steady-state 24-hour blood sampling was performed during the third trimester and at 6-12 weeks postpartum. Maternal and umbilical cord blood samples were drawn at delivery. Pharmacokinetics targets were the estimated 10th percentile EFV area under the curve (AUC) in nonpregnant historical controls (40.0 mcg·hr(-1)·mL(-1)) and a trough concentration of 1 mcg/mL.ResultsTwenty-five women were enrolled during the third trimester: median (range) age was 29.3 (18.9-42.9) years, weight 69.0 (40-130) kg, and gestational age 32.9 (30.1-38.7) weeks. Median (range) EFV AUC(0-24), C(max), and C(24 hours) were 55.4 mcg·hr(-1)·mL(-1) (13.5-220.3), 5.4 mcg/mL (1.9-12.2), and 1.6 mcg/mL (0.23-8.13), respectively. EFV AUC and C(max) did not differ during pregnancy and postpartum but C(24 hours) was lower during the third trimester (1.6 vs. 2.1 mcg/mL, P = 0.01). During the third trimester, 5 of 25 (20%) women had an EFV AUC below the target and 3 of 25 (12%) had a trough concentration below 1 mcg/mL. EFV cord blood/maternal concentration ratio was 0.49 (0.37-0.74). All women had a HIV-1 RNA viral load less than 400 copies per milliliter at delivery and 19 (76%) had a viral load below 50 copies per milliliter. One child was perinatally HIV infected. Three women were exposed to EFV throughout the first 6 weeks of pregnancy. EFV was well tolerated, and among the 25 infants, no congenital anomalies or newborn complications were reported.ConclusionsChanges in EFV pharmacokinetics during pregnancy compared with postpartum are not sufficiently large enough to warrant a dose adjustment during pregnancy.

Project description:BACKGROUND:Rilpivirine pharmacokinetics is defined by its absorption, distribution, metabolism, and excretion. Pregnancy can affect these factors by changes in cardiac output, protein binding, volume of distribution, and cytochrome P450 (CYP) 3A4 activity. Rilpivirine is metabolized by CYP3A4. The impact of pregnancy on rilpivirine pharmacokinetics is largely unknown. METHODS:International Maternal Pediatric Adolescent AIDS Clinical Trials P1026s is a multicenter, nonblinded, prospective study evaluating antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving rilpivirine 25 mg once daily as part of their combination antiretrovirals for clinical care. Thirty-two women were enrolled in this study. Intensive pharmacokinetic sampling was performed at steady state during the second trimester, the third trimester, and postpartum. Maternal and umbilical cord blood samples were obtained at delivery. Plasma rilpivirine concentration was measured using liquid chromatography-mass spectrometry; lower limit of quantitation was 10 ng/mL. RESULTS:Median (range) AUC0-24 were 1969 (867-4987, n = 15), 1669 (556-4312, n = 28), and 2387 (188-6736, n = 28) ng·h/mL in the second trimester, the third trimester, and postpartum, respectively (P < 0.05 for either trimester vs postpartum). Median (range) C24 were 63 (37-225, n = 17), 56 (<10-181, n = 30), and 81 (<10-299, n = 28) ng/mL (P < 0.05 for either trimester vs postpartum). High variability in pharmacokinetic parameters was observed between subjects. Median (range) cord blood/maternal concentration ratio was 0.55 (0.3-0.8, n = 21). Delivery HIV-1 RNA was ?50 copies per milliliter in 70% and ?400 copies per milliliter in 90% of women. Cmin were significantly lower at 15 visits with detectable HIV-1 RNA compared with 61 visits with undetectable HIV-1 RNA, 29 (<10-93) vs 63 (15-200) ng/mL (P = 0.0001). Cmin was below the protein binding-adjusted EC90 concentration (12.2 ng/mL) at 4 visits in 3 of 31 women (10%). CONCLUSIONS:Rilpivirine exposure is lower during pregnancy compared with postpartum and highly variable. Ninety percent of women had minimum concentrations above the protein binding-adjusted EC90 for rilpivirine.

Dataset Information

Model-Based Analysis of Unbound Lopinavir Pharmacokinetics in HIV-Infected Pregnant Women Supports Standard Dosing in the Third Trimester.

Publications

Model-Based Analysis of Unbound Lopinavir Pharmacokinetics in HIV-Infected Pregnant Women Supports Standard Dosing in the Third Trimester.

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