Jpn. J. Pharmacol. 73 (3), 191-196 (1997)

Influence of Lactation on Plasma Phenobarbital Concentrations in Rats

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

Copyrightę The Japanese Pharmacological Society 1997

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