Masahiro Moriyama (1), Syoichi Yamashita (1), Katsushi Furuno (1), Tomoaki
Sato (2), Haruyo Domoto (1), Yasuko Yamatogi (3), Hiromu Kawasaki (1) and
Yutaka Gomita (1,*)
(1) Department of Hospital Pharmacy and (3) Child Neurology, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama 700, Japan
(2) Department of Hospital Pharmacy, Faculty of Medical Sciences, Kyushu University, Fukuoka 812, Japan
(*) To whom correspondence should be addressed.
Abstract: The effect of lactation on the pharmacokinetics of phenobarbital (PB) after delivery was studied in female rats. Non-pregnant animals received PB 20 mg/kg/day twice for 6 - 7 days before mating, during pregnancy and after delivery. Chronic PB did not significantly influence changes in the body weight of rats after delivery. On the first post-delivery day, the plasma PB concentration in the PB-treated rats was significantly higher than that in PB-treated, non-pregnant rats (non-pregnant rats); and thereafter, it gradually decreased until ablactation on the 20th day. After ablactation, plasma PB concentrations gradually returned to the level before delivery. In PB-treated rats, pharmacokinetic parameters (Cmax, AUC 0 - 12) of PB between 0 and 12 hr after a single oral administration were significantly decreased during lactation. These results suggest that PB administered during lactation is transferred in part to offspring through maternal milk.
Keywords: Phenobarbital, Pharmacokinetics, Lactation, Plasma concentration