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1.  Efavirenz Pharmacokinetics during the Third Trimester of Pregnancy and Postpartum 
The impact of pregnancy on efavirenz pharmacokinetics is unknown.
International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) P1026s is an on-going, prospective, non-blinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving 600 mg efavirenz 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 efavirenz AUC in non-pregnant historical controls (40.0 and a trough concentration of 1 mcg/mL.
Twenty 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, gestational age 32.9 (30.1–38.7) weeks. Median (range) efavirenz AUC0-24, Cmax and C24hour were 55.4 (13.5–220.3), 5.4 mcg/mL (1.9–12.2) and 1.6 mcg/ml (0.23–8.13), respectively. Efavirenz AUC and Cmax did not differ during pregnancy and postpartum but C24hour 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 efavirenz AUC below the target and 3 of 25 (12%) had a trough concentration below 1 mcg/mL. Efavirenz 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/mL at delivery and 19 (76%) had a viral load below 50 copies/mL. One child was perinatally HIV-infected. Three women were exposed to efavirenz throughout the first 6 weeks of pregnancy. EFV was well tolerated and among the 25 infants no congenital anomalies or newborn complications were reported.
Changes in efavirenz pharmacokinetics during pregnancy compared to postpartum are not sufficiently large enough to warrant a dose adjustment during pregnancy.
PMCID: PMC3288559  PMID: 22083071
efavirenz; pregnancy; pharmacokinetics; HIV; prevention of mother-to-child transmission of HIV
2.  Pharmacokinetics and virologic response of zidovudine/lopinavir/ritonavir initiated during the third trimester of pregnancy 
AIDS (London, England)  2010;24(14):2193-2200.
To evaluate the pharmacokinetics and HIV viral load (VL) response following initiation during the third trimester of pregnancy of zidovudine (ZDV) plus standard dose lopinavir boosted with ritonavir (LPV/r), twice daily, until delivery for the prevention of mother-to-child transmission of HIV (PMTCT).
Prospective study nested within a multicenter, three arm, randomised, phase III PMTCT trial in Thailand (PHPT-5, Identifier: NCT00409591).
Women randomized to receive 300 mg ZDV and 400/100 mg LPV/r twice daily from 28 weeks’ gestation, or as soon as possible thereafter, until delivery had intensive steady-state 12-hour blood sampling performed. LPV/r pharmacokinetic parameters were calculated using non-compartmental analysis. Rules were defined a priori for a LPV/r dose escalation based on the proportion of women with an LPV AUC < 52 (10th percentile for LPV AUC in non-pregnant adults). HIV-1 RNA response was assessed during the third trimester.
Thirty-eight women were evaluable; at entry median (range) gestational age was 29 weeks (28–36), weight 59.5 kg (45.0–91.6), CD4 cell count 442 cells/mm3 (260–1327) and HIV-1 RNA viral load 7,818 copies/mL (<40–402,015). Geometric mean (90% confidence interval) LPV AUC, Cmax and Cmin were 64.6 (59.7–69.8), 8.1 mcg/mL, (7.5–8.7) and 2.7 mcg/ml (2.4–3.0), respectively. 31 of 38 (81%) women had an LPV AUC above the AUC target. All women had a HIV-1 viral load less than 400 copies/mL at the time of delivery.
A short course of ZDV plus standard dose LPV/r initiated during the 3rd trimester of pregnancy achieved adequate LPV exposure and virologic response.
PMCID: PMC3070207  PMID: 20625263
lopinavir; pregnancy; pharmacokinetics; viral load; prevention of mother-to-child transmission of HIV
3.  Detection of HIV-1 DNA resistance mutations by a sensitive assay at initiation of antiretroviral therapy is associated with virologic failure 
Antiretroviral therapy (ART) has become more available throughout the developing world during the past five years. The World Health Organization recommends nonnucleoside reverse transcriptase inhibitor-based regimens as initial ART. However, their efficacy may be compromised by resistance mutations selected by single-dose nevirapine (sdNVP) used to prevent mother-to-child-transmission of HIV-1 (PMTCT). There is no simple and efficient method to detect such mutations at initiation of ART.
181 women participating in a PMTCT clinical trial who started NVP-ART after they had received sdNVP or placebo were tested for nevirapine-resistance point-mutations (K103N, Y181C, and G190A) using 100 copies of HIV-1 DNA with a sensitive oligonucleotide ligation assay (OLA) able to detect mutants at low concentrations (≥5% of the viral population). Virologic failure was defined as plasma HIV-1 RNA confirmed >50 copies/mL between 6–18 months of NVP-ART.
At initiation of NVP-ART, resistance mutations were identified in 26% of 148 participants given sdNVP (K103N-13%, Y181C-5%, G190A-19%; ≥2 mutations-10%) at a median 9.3 months after sdNVP. The risk of virologic failure was .62 (95% confidence interval (CI), 0.46–0.77) in women with ≥1 resistance mutation, compared to 0.25 (95% CI, 0.17–0.35) in those without detectable resistance mutations (P<.0001). Failure was independently associated with resistance, an interval of <6 months between sdNVP and NVP-ART initiation, and a viral load above the median at NVP-ART initiation.
Access to simple and inexpensive assays to detect low-concentrations of NVP-resistant HIV-1 DNA prior to the initiation of ART could help improve the outcome of first-line antiretroviral therapy.
PMCID: PMC2856716  PMID: 20377404
HIV-1; resistance mutations; nevirapine; HAART; oligonucleotide ligation assay; developing countries
4.  Early Postpartum Pharmacokinetics of Lopinavir Initiated Intrapartum in Thai Women ▿ †  
Lopinavir (LPV) exposure is reduced during the third trimester of pregnancy. We report the pharmacokinetics of standard LPV-ritonavir dosing (400/100 mg twice daily) in the immediate and early postpartum period when initiated during labor. In 16 human immunodeficiency virus-infected Thai women, the median (range) LPV area under the concentration-time curve and maximum and minimum concentrations in plasma were 99.7 (66.1 to 180.5) μg·h/ml, 11.2 (8.0 to 17.5) μg/ml, and 4.6 (1.7 to 12.5) μg/ml, respectively, at 41 (12 to 74) h after delivery. All of the women attained adequate LPV levels through 30 days postpartum. No serious adverse events were reported.
PMCID: PMC2681511  PMID: 19237646

Results 1-4 (4)