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.
From the aUniversity of California San Diego, San Diego, California
cChildren's Hospital Boston
dHarvard School of Public Health, Boston, Massachusetts
eUniversity of Southern California, Los Angeles, California
fPediatric, Adolescent, and Maternal AIDS Branch, NICHD, NIH, DHHS
gNIAID, Bethesda, Maryland, USA.
*See the Appendix for study members.
Received 13 September, 2005
Revised 18 October, 2005
Accepted 27 October, 2005
Correspondence to Dr B. Best, University of California San Diego, 200 West Arbor Drive, MC 8214, San Diego, California 92103–8214, USA. E-mail: firstname.lastname@example.org