Theophylline pharmacokinetics in pregnant and lactating rats

As a preliminary investigation to a human study, we examined the pharmacokinetics of theophylline in pregnant and lactating rats. Three groups of female rats--pregnant, lactating, and virgin controls were injected IP with theophylline solution. Pregnant rats eliminated theophylline at a slower rate than both lactating rats and virgin controls, resulting in a longer half life (t1/2) and lower clearance. The approximate volume of distribution (aVd) and extrapolated peak concentration (Cp0) in the 3 groups were not different.