The pharmacokinetics of trichlormethiazide in hypertensive patients with normal and compromised renal function

The pharmacokinetics of trichlormethiazide (TCZ) was studied in twelve patients after a single 4 mg dose. Seven patients had normal renal function with creatinine clearance greater than 90 ml/min. Five patients had compromised renal function with creatinine clearances averaging 48 +/- 29 ml/min. The TCZ plasma half life and area under the plasma concentration-time curve (AUC) were significantly greater in patients with impaired function, compared to patients with normal renal function. There were no significant differences between the two patient groups in terms of either rate of drug absorption or total urinary recovery of unchanged drug. Furthermore, there was no correlation between peak drug levels or AUC and renal excretion of water or electrolytes.