The pharmacokinetics of the H1-receptor antagonist cetirizine were studied from 0 to 72 hours after a single dose of 20 mg in 5 patients with chronic hepatocellular liver disease (group A), in 5 patients with chronic cholestatic liver disease (group B), and in 16 healthy volunteers. The renal function of patients and volunteers was normal (creatinine clearance > or = 70 mL/min). Cetirizine pharmacokinetics were similar in the two groups of patients. The elimination t1/2 was prolonged in patients (mean +/- standard deviation; group A: 14.32 +/- 2.30 hours; group B: 13.86 +/- 3.14 hours) in comparison with the values observed in volunteers (9.42 +/- 2.4 hours). A reduced apparent oral body clearance also was observed in patients (group A: .48 +/- .23 mL/min/kg; group B: .41 +/- .09 mL/min/kg) in comparison with volunteers (.74 +/- .19 mL/min/kg). No differences were observed in the mean cumulative urinary excretion between patients (group A: 69 +/- 15%; group B: 69 +/- 13%) and volunteers (70.7 +/- 7.8%).