The need for adjustment of dosage regimen of penicillin V during pregnancy.

Abstract

To determine whether the normal regimen of dosage of oral penicillin V is relevant during pregnancy. Twelve pregnant and six nonpregnant women volunteered for the study. Six women were in the second trimester of pregnancy (mean +/- standard deviation 19 +/- 7 weeks' gestation) and six women were in the third trimester (35 +/- 2 weeks). All of the women took 1 x 10(6) IU phenoxymethylpenicillin orally, and multiple blood and urine samples were obtained. Assays were performed by means of a disk agar diffusion method. The results were compared by Mann-Whitney U test. Compared with nonpregnant women, pregnant women had smaller area under the curve values (433 +/- 93 minutes.IU/mL, P < .05 in the second trimester; 550 +/- 220 minutes.IU/mL in the third trimester) and a shorter half-life (57 +/- 56 minutes in the second trimester; 34 +/- 21 minutes, P < .05 in the third trimester). Plasma and renal clearances were faster in the pregnant women. Elimination of penicillin V is enhanced during pregnancy, necessitating either a shorter dosing interval (6-8 hours) or an increased dose with the standard dosing interval.