Erythromycin and clindamycin absorption and elimination in pregnant women.

Thirty-nine pregnant women admitted for therapeutic abortions during early or mid pregnancy were given erythromycin estolate, erythromycin base, or clindamycin hydrochloride orally in single or multiple doses. Peak serum levels of clindamycin were 3.4 to 9.0 mug/ml following a single dose of 450 mg, whereas peak serum levels of erythromycin were 0.29 to 7.2 mug/ml following 500 mg in a single dose. The individual variability of serum concentrations of erythromycin was greater than that reported in normal men and nonpregnant women, whereas the serum levels of clindamycin were rather uniform, and similar to what has been reported in nonpregnant individuals. Following multiple doses of each antibiotic, high serum levels were obtained in virtually all subjects, and urine levels were also higher. Following single doses the mean urinary recovery was 2% for erythromycin and 16.8% for clindamycin.