The trans-hepatic extraction of nifedipine.

1. The trans-hepatic extraction of nifedipine during steady state infusion was studied in six patients undergoing cardiac catheterisation for suspected coronary disease. 2. Mean extraction ratio across the liver was 0.64 but hepatic clearance accounted for a mean of only 65% of total body clearance. 3. These results are consistent with the liver as the major site of metabolism of nifedipine, but also suggest that significant metabolism occurs outside the liver.