ABSTRACT
Four hypertensive patients with chronic renal insufficiency who were treated with sustained release verapamil hydrochloride subsequently developed acute toxic effects. All four patients developed marked bradycardia, hypotension, hyperkalemia and metabolic aciodosis and were treated with atropine, fluid therapy, potasium lowing measure, dialysis, and temporary pacemaker, and were restored to the renal function and sinus rhythm after 12-24 hr. Patients with renal impairement who are treated with sustained release verapamil may accumulate verapamil or its metabolites and develop toxic side effects. We conclude that sustained release verapamil should be used with caution in chronic renal failure and that patients should be closely monitored for adverse cardiovascular, metaboic, and hepatic side effects.