Pharmacokinetics of diltiazem in severe renal failure

The acute effects of a single dose of diltiazem (Tildiem®), a calcium antagonist, were studied in 9 patients with severely impaired renal function (GFR between 0.03 and 0.87 ml/s/1.73 m2). Control measurements were made of inulin and PAH clearance, creatinine, blood pressure, heart rate and ECG. Following administration of diltiazem 120 mg, 7 blood samples were collected in the first 12 h and after 24 h, 32 h, 48 h; urine was collected for the first 12 h, 12–24 h and 24–48 h, and blood pressure, heart rate and ECG were recorded after 6 h. Diltiazem and its main metabolite, desacetyldiltiazem, had a pharmacokinetic profile similar to that in patients with normal renal function (peak plasma concentration, half-life and urinary excretion). Diltiazem is normally eliminated in the urine to a small extent, because it is metabolized, and this also applies to desacetyldiltiazem, which is probably further metabolized.