PHARMACOKINETICS OF FENOTEROL IN PREGNANT AND NONPREGNANT WOMEN

The pharmacokinetics of the beta2-adrenergic drug fenoterol, which is used as a tocolytic agent in pregnancy, has been investigated in pregn ant (n = 9) and nonpregnant (n = 5) women during a constant rate intra venous infusion. Clearance and mean residence time were found to be 19 90 (1879/2220; Median, Q25/Q75) ml/min and 9.2 (8.0/14.0) min in the p regnant and 2126 (1915/2130) ml/min and 16.6 (16.5/32.1) min in the no npregnant women, respectively. In addition, fenoterol clearance was es timated in 88 women from a single blood sample collected at steady sta te during IV therapy and the effect of gestational age on clearance wa s studied. Clearance displayed large interindividual variation. There was no apparent correlation between clearance and gestational age. We conclude that there is no need to adjust the dose on pharmacokinetic g rounds in the course of pregnancy.