Oral contraceptive steroids impair the elimination of theophylline.

ABSTRACT

PIP: The influence of oral contraceptives (OCs) and sex differences on the disposition of theophylline has been studied in 12 healthy young men (29 +or- 4 years old), 13 healthy young women (29 +or- 12), and 10 healthy young women (24 +or- 3) receiving OCs for a period greater than 6 months. The elimination 1/2-life was longer in women taking OCs (523 +or- 110 minutes) than in women not taking OCs (386 +or- 157). Weight-normalized plasma clearance of theophylline was less in women taking OCs than in women not on OCs. Plasma binding and volume distribution were not different between the 2 groups of women. Weight-normalized clearance, weight-normalized volume of distribution, plasma 1/2-life, and plasma binding were not different between men and women not taking OCs.