Verapamil deleterious effects in chronic renal failure.

Three hypertensive patients with chronic renal failure treated with slow-release verapamil at the recommended doses for high blood pressure experienced acute deleterious effects shortly after treatment (6 h to 3 days). Patients developed slow cardiac rhythms (junctional bradycardia or atrial fibrillation), hypotension and hyperkalemia. Consequently they also had oliguria and worsening of the renal function. Inotropic support, fluid therapy and potassium-lowering measures were able to restore the renal function and sinus rhythm after 10-12 h. Only 7 similar cases have been described so far. It is suggested that slow-release formulations of verapamil must be used with caution in hypertensive patients with impaired renal function.