Examination of faecal Bifidobacterium populations in breast- and formula-fed infants during the first 18 months of life.

Bifidobacteria in the infant faecal microbiota have been the focus of much interest, especially during the exclusive milk-feeding period and in relation to the fortification of infant formulae to better mimic breast milk. However, longitudinal studies examining the diversity and dynamics of the Bifidobacterium population of infants are lacking, particularly in relation to the effects of weaning. Using a polyphasic strategy, the Bifidobacterium populations of breast- and formula-fed infants were examined during the first 18 months of life. Bifidobacterium-specific denaturing gradient gel electrophoresis demonstrated that breast-fed infants harboured greater diversity than formula-fed infants and the diversity of the infants' Bifidobacterium populations increased with weaning. Twenty-seven distinctive banding profiles were observed from ∼1100 infant isolates using ribosomal intergenic spacer analysis, 14 biotypes of which were confirmed to be members of the genus Bifidobacterium. Two profiles (H, Bifidobacterium longum subsp. infantis; and I, Bifidobacterium bifidum) were common culturable biotypes, seen in 9/10 infants, while profile E (Bifidobacterium breve) was common among breast-fed infants. Overall, inter- and intra-individual differences were observed in the Bifidobacterium populations of infants between 1 and 18 months of age, although weaning was associated with increased diversity of the infant Bifidobacterium populations. Breast-fed infants generally harboured a more complex Bifidobacterium microbiota than formula-fed infants.

Impact of pregnancy on abacavir pharmacokinetics.

OBJECTIVE: To describe abacavir pharmacokinetics during pregnancy and postpartum; physiological changes during pregnancy are known to affect antiretroviral drug disposition. DESIGN: The Pediatric AIDS Clinical Trials Group P1026s study is an on-going, prospective, non-blinded pharmacokinetic study of pregnant women receiving one or more antiretroviral drugs for routine clinical care, including a cohort receiving abacavir 300 mg twice daily. METHODS: Serial plasma samples (predose, 1, 2, 4, and 6 h postdose) obtained antepartum (30-36 weeks of gestation) and again postpartum (6-12 weeks after delivery) were assayed for abacavir concentration by reversed-phase high-performance liquid chromatography. RESULTS: Antepartum evaluations were available for 25 women [mean age, 28.6 years (SD, 6); mean third-trimester weight 92 kg (SD, 35.4); and race/ethnicity 52% black, 28% Hispanic, 16% white, 4% Asian], with geometric mean abacavir area under the concentration-time curve (AUC) of 5.9 mg.h/l [90% confidence interval (CI), 5.2-6.8] and maximum plasma concentration (Cmax) of 1.9 mg/l (90% CI, 1.6-2.2). Seventeen women completed postpartum sampling, and the ratios of antepartum to postpartum AUC and Cmax were 1.04 (90% CI, 0.91-1.18) and 0.79 (90% CI, 0.65-0.98), respectively. CONCLUSIONS: Abacavir AUC during pregnancy was similar to that at 6-12 weeks postpartum and to that for non-pregnant historical controls (5.8 mg.h/l). Consequently, pregnancy does not appear to affect overall abacavir exposure significantly or to necessitate dose adjustments.

Reduced lopinavir exposure during pregnancy.

BACKGROUND: Optimal antiretroviral exposure during pregnancy is critical for prevention of mother-to-child HIV transmission and for maternal health. Pregnancy can alter antiretroviral pharmacokinetics. Our objective was to describe lopinavir/ritonavir (LPV/r) pharmacokinetics during pregnancy. METHODS: We performed intensive steady-state 12-h pharmacokinetic profiles of lopinavir and ritonavir (three capsules: LPV 400 mg/r 100 mg) at 30-36 weeks gestation and 6-12 weeks postpartum. Maternal and umbilical cord blood samples were obtained at delivery. We measured LPV and ritonavir by reverse-phase high-performance liquid chromatography. Target LPV area under concentration versus time curve (AUC) was > or = 52 microg h/ml, the estimated 10th percentile LPV AUC in non-pregnant historical controls (mean AUC = 83 microg h/ml). RESULTS: Seventeen women completed antepartum evaluations; average gestational age was 35 weeks. Geometric mean antepartum LPV AUC was 44.4 microg h/ml [90% confidence interval (CI), 38.7-50.9] and 12-h post-dose concentration (C12h) was 1.6 microg/ml (90% CI, 1.1-2.5). Twelve women completed postpartum evaluations; geometric mean LPV AUC was 65.2 microg h/ml (90% CI, 49.7-85.4) and C12h was 4.6 microg/ml (90% CI, 3.7-5.7). The geometric mean ratio of antepartum/postpartum LPV AUC was 0.72 (90% CI, 0.54-0.96). Fourteen of 17 (82%) pregnant and three of 12 (25%) postpartum women did not meet our target LPV AUC. The ratio of cord blood/maternal LPV concentration in ten paired detectable samples was 0.2 +/- 0.13. CONCLUSIONS: LPV/r exposure during late pregnancy was lower compared to postpartum and compared to non-pregnant historical controls. Small amounts of lopinavir cross the placenta. The pharmacokinetics, safety, and effectiveness of increased LPV/r dosing during the third trimester of pregnancy should be investigated.

Instability of lopinavir/ritonavir capsules at ambient temperatures in sub-Saharan Africa: relevance to WHO antiretroviral guidelines.

WHO recommends lopinavir/ritonavir as an antiretroviral option in resource-limited countries. Lopinavir/ritonavir is recommended to be stored at 2-8 degrees C until dispensing, and afterwards, may be kept at < or = 25 degrees C for < or = 2 months. Anticipating lopinavir/ritonavir use in countries lacking adequate cold-chains, we assessed its physical and chemical stability at 35 and 45 degrees C. Although maintaining chemical stability for 4 weeks at 35 degrees C, at 45 degrees C the capsules clumped after 7 days, supporting a need for more temperature-stable formulations for hotter climates.

Lopinavir exposure with an increased dose during pregnancy.

BACKGROUND: Use of standard adult lopinavir/ritonavir (LPV/RTV) dosing (400/100 mg) during the third trimester of pregnancy results in reduced LPV exposure. The goal of this study was to determine LPV exposure during the third trimester of pregnancy and 2 weeks postpartum with a higher LPV/RTV dose. METHODS: The Pediatric AIDS Clinical Trials Group Protocol 1026s is an ongoing, prospective, nonblinded study of antiretroviral pharmacokinetics in HIV-infected pregnant women that included a cohort receiving LPV/RTV 400/100 mg twice daily during the second trimester and 533/133 mg twice daily during the third trimester through 2 weeks postpartum. Intensive steady state 12-hour pharmacokinetic profiles were performed during the third trimester and at 2 weeks postpartum and were optional during the second trimester. LPV and RTV were measured by reverse-phase high-performance liquid chromatography with a detection limit of 0.09 microg/mL. RESULTS: Twenty-six HIV-infected pregnant women were studied. Median LPV area under the plasma concentration-time curve (AUCs) for the second trimester, third trimester, and postpartum were 57, 88, and 152 microg.h.mL, respectively. Median minimum LPV concentrations were 1.9, 4.1, and 8.3 microg/mL. CONCLUSIONS: The higher LPV/RTV dose (533/133 mg) provided LPV exposure during the third trimester similar to the median AUC (80 microg.h.mL) in nonpregnant adults taking standard doses. However, the AUC on this increased dose at 2 weeks postpartum was considerably higher. These data suggest that the higher LPV/RTV dose should be used in third trimester pregnant women; that it should be considered in second trimester pregnant women, especially those who are protease inhibitor experienced; and that postpartum LPV/RTV dosing can be reduced to standard dosing by 2 weeks after delivery.

A randomized controlled trial of therapeutic drug monitoring in treatment-naive and -experienced HIV-1-infected patients.

OBJECTIVE: To improve the utility of therapeutic drug monitoring (TDM) by defining the proportion of patients with and predictors of above or below target protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor (NNRTI) concentrations. METHODS: This 48-week, multicenter, open-label clinical trial randomized patients to TDM versus standard of care (SOC). Serial pharmacokinetics, including a week-2 3-sample sparse collection, and expert committee TDM recommendations were given to TDM-arm patients' providers. RESULTS: Seventy-four (39%) of 190 patients had week-2 concentrations outside of targets and 122 (64%) of 190 had nontarget exposure at least once over 48 weeks. Providers accepted 75% of TDM recommendations. Among patients with below-target concentrations, more TDM-arm than SOC-arm patients achieved targets (65% vs. 45%; P = 0.09). Increased body weight and efavirenz or lopinavir/ritonavir use were significant predictors of nontarget concentrations. Patients at target and patients who achieved targets after TDM-directed dose modifications trended toward greater viral load reductions at week 48 than patients with below-target exposures (HIV RNA reductions: 2.4, 2.3, and 1.9 log10 copies/mL, respectively; P = 0.09). CONCLUSIONS: Most patients had nontarget PI and/or NNRTI concentrations over 48 weeks. TDM recommendations were well accepted and improved exposure. Patients below TDM targets trended toward worse virologic response.

Pharmacokinetics and safety of indinavir in human immunodeficiency virus-infected pregnant women.

Human immunodeficiency virus-infected women (n=16) received indinavir (800 mg three times a day) plus zidovudine plus lamivudine from 14 to 28 weeks of gestation to 12 weeks postpartum. Two women and eight infants experienced grade 3 or 4 toxicities that were possibly treatment related. Indinavir area under the plasma concentration-time curve was 68% lower antepartum versus postpartum, suggesting increased intestinal and/or hepatic CYP3A activity during pregnancy.

Quality assurance program for pharmacokinetic assay of antiretrovirals: ACTG proficiency testing for pediatric and adult pharmacology support laboratories, 2003 to 2004: a requirement for therapeutic drug monitoring.

Proficiency testing (PT) is a mandated requirement for clinical laboratories doing therapeutic drug monitoring and is an invaluable tool to help laboratories identify and correct problems in analytical procedures. The AIDS Clinical Trial Group Pharmacology Quality Assurance Committee implemented a new antiretroviral PT program for all currently available antiretroviral drugs in 2001. The PT program was designed for the AIDS Clinical Trial Group Pharmacology Specialty Laboratories actively involved in assaying these drugs in clinical trial samples so as to comply with the Clinical Laboratory Improvement Amendments. Results from the first 3 rounds of PT have been analyzed and reported and provided support for formalizing the guidelines of the PT testing program. The PT program has expanded with the addition of nucleoside reverse transcription inhibitors (NRTIs) and atazanavir. This report includes results from rounds 4 to 7 over 2 additional years of standard operations. Additionally we include results from NRTIs for all rounds and atazanavir for a single round. There were 9 participating laboratories. Eight used high-performance liquid chromatography as the primary method of detection and 2/8 also reported LC-MS-MS results. One laboratory used LC-MS-MS as their primary detection method. All laboratories measured protease inhibitors, most measured at least 1 non-nucleoside reverse transcription inhibitor and 5 had NRTI capabilities. Results were normally distributed and the acceptance range of +/-20% best corresponded to a 95% confidence interval. Overall score for 9 participating laboratories was 96% correct out of 1826 challenges over 4 rounds. Laboratories scored 95, 98 and 97% correct for protease inhibitors, non-nucleoside reverse transcription inhibitorss and NRTIs, respectively. Three laboratories reporting LC-MS-MS results had 92% correct (347/378) challenges for all drugs. The percentage of correct results is about the same as previously reported. There is a continued need for a PT program to help participating laboratories maintain essential quality assurance and quality control.

Antiretroviral concentrations in breast-feeding infants of women in Botswana receiving antiretroviral treatment.

BACKGROUND: The magnitude of infant antiretroviral (ARV) exposure from breast milk is unknown. METHODS: We measured concentrations of nevirapine, lamivudine, and zidovudine in serum and whole breast milk from human immunodeficiency virus type 1 (HIV-1)-infected women in Botswana receiving ARV treatment and serum from their uninfected, breast-feeding infants. RESULTS: Twenty mother-infant pairs were enrolled. Maternal serum concentrations of nevirapine were high (median, 9534 ng/mL at a median of 4 h after nevirapine ingestion). Median breast-milk concentrations of nevirapine, lamivudine, and zidovudine were 0.67, 3.34, and 3.21 times, respectively, those in maternal serum. The median infant serum concentration of nevirapine was 971 ng/mL, at least 40 times the 50% inhibitory concentration and similar to peak concentrations after a single 2-mg/kg dose of nevirapine. The median infant serum concentration of lamivudine was 28 ng/mL, and the median infant serum concentration of zidovudine was 123 ng/mL, but infants were also receiving zidovudine prophylaxis. CONCLUSIONS: HIV-1 inhibitory concentrations of nevirapine are achieved in breast-feeding infants of mothers receiving these ARVs, exposing infants to the potential for beneficial and adverse effects of nevirapine ingestion. Further study is needed to understand the impact of maternal ARV treatment on breast-feeding HIV-1 transmission, infant toxicity, and HIV-1 resistance mutations among infected infants.

Quality assurance program for clinical measurement of antiretrovirals: AIDS clinical trials group proficiency testing program for pediatric and adult pharmacology laboratories.

Clinical trials designed to compare antiretroviral regimens, investigate therapeutic drug monitoring, or measure pharmacometrics often include protease inhibitors (PIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and nucleoside reverse transcriptase inhibitors, requiring the measurement of these antiretrovirals in plasma. Within the adult and pediatric AIDS Clinical Trials Group (ACTG), a network of Pharmacology Support Laboratories (PSLs) is a component of the group laboratory infrastructure and conducts these types of pharmacologic assays. The adult ACTG has developed a comprehensive quality assurance program for the conduct of clinical pharmacology protocols, one component of which is the antiretroviral proficiency testing (PT) program that has been implemented between the adult and pediatric pharmacology laboratories of the ACTG. PT testing samples were prepared and distributed in July 2001, February 2002, and July 2002. High, medium, and low concentrations of PIs (indinavir, saquinavir, amprenavir, lopinavir, ritonavir, and nelfinavir) and NNRTIs (nevirapine and efavirenz) were added to drug-free EDTA plasma and distributed, on dry ice, to eight ACTG PSLs. One testing laboratory used liquid chromatography-tandem mass spectrometry, and seven used high-performance liquid chromatography-UV analysis. A result was considered acceptable if it was within 20% deviation of the assigned concentration. For all concentrations of PIs evaluated, 96% of samples tested (430 of 448 measurements) met the acceptance criteria. For both NNRTIs, 100% of samples tested (140 of 140 measurements) met the acceptance criteria. In conclusion, the PT program results presented demonstrate excellent interlaboratory agreement for all antiretrovirals tested and provide support for the merger of plasma concentration data among laboratories for large clinical trials.