Pharmacokinetic Disposition of Zidovudine during Pregnancy

Zidovudine pharmacokinetics was determined in three human immunodeficiency virus type I-seropositive women receiving zidovudine (200 mg orally every 4 h) from 19 to 39 weeks ofpregnancy and postpartum. Zidovudine concentrations were measured using high-pressure liquid chromatography, and pharmacokinetic analyses were done using model-independent methods. For the pregnant versus postpartum periods, peak zidovudine levels (mean ± 1 SD) were 3.9 ± 1.7 µmol/l versus 4.3 ± 0.04 µmol/l (P = .56); elimination half-lives were 1.3 ± 0.6 versus 1.0 ± 0.3 h (P = .41); areas under the concentration curve were 4.5 ± 1.0 µmol/l × hand 6.8 ± 0.5 µmol/l × h (P = .02); apparent total body clearances were 2.5 ± 0.6/1h/kg and 1.7 ± 0.4 l/h/kg (P = .05); and apparent steady state volumes of distribution were 3.9 ± 1.0 1/kg and 2.6 ± 0.81/kg (P = .07), respectively. Umbilical cord serum levels ranged from 113%–127% of maternal levels. No persistent adverse effects of zidovudine therapy were seen in the three women or their babies.