Betamethasone Clearance In Fetal Lambs Following Fetal Or Maternal Intramuscular Administration.

Antenatal betamethasone (BETA) administration is recommended in most instances of threatened premature delivery. To provide fetal BETA pharmacokinetic data, we assessed plasma BETA levels in chronically catheterized fetal lambs following maternal or direct fetal BETA treatments as follows (mg/kg): Ewe 0.2 (n=4), Ewe 0.5 (n=3), Fetal 0.2 (n=3) and Fetal 0.5(n=3). Plasma BETA levels were determined by HPLC and are presented graphically. Conclusions: 1) Maternal betamethasone administration increases fetal plasma levels within 90 minutes, and 2) Despite large differences in initial plasma BETA levels, fetal plasma levels are similar by 4 hrs regardless of route of administration. Figure