The effect of hydralazine on steady-state plasma concentrations of metoprolol in pregnant hypertensive women.

We have studied the plasma concentrations levels of metoprolol after its twice daily administration in a dose of 50 mg for 4 days in ten, hypertensive pregnant women to the during monotherapy and in combination with 25 mg of hydralazine given twice daily. Hydralazine increased the median AUC and Cmax of metoprolol by 38% and 88% respectively, and decreased the tmax from 1.5 h to 1.0 h. Hydralazine had no effect on the plasma concentrations of alpha-OH-metoprolol. These results suggest that the effect of hydralazine on metoprolol plasma concentrations is primarily due to a reduction in first-pass elimination.