Pharmacokinetic studies of cimetidine in patients with liver disease.

The tolerability and metabolism of cimetidine administered for over 7 days were studied in 30 patients with liver diseases and 19 control subjects who had peptic ulcers. Cimetidine was well tolerated by these patients without any side effects. The cimetidine in the serum and urine was determined by high-performance liquid chromatography. The serum cimetidine levels and pharmacokinetic parameters of the patient group did not significantly differ from those of the control group after oral administration. Following intravenous administration, the half-life of cimetidine increased and cimetidine clearance decreased in the liver disease group. These differences seem to be totally explicable by the impaired renal function associated with the liver disease. Furthermore, accumulation of cimetidine in serum did not occur following continuous treatment with cimetidine in these patients. It was concluded that a reduction of cimetidine dosage is not necessary in patients with liver disease as far as their renal function is not disturbed, since the metabolism of cimetidine was not affected by the liver dysfunction itself.