Lithium toxicity induced by triamterene-hydrochlorothiazide

Two patients on long-term lithium therapy for manic-depressive psychosis developed serious toxicity within days of being prescribed a combination of triamterene (50 mg) and hydrochlorothiazide (25 mg) for mild symptomless hypertension. Reduced clearance of lithium has been reported to follow its concurrent administration with diuretics that deplete both sodium and potassium. A combination of triamterene with thiazide has not been shown previously to precipitate lithium toxicity.