Indomethacin- and Moduretic--induced hyperkalemia.

Simultaneous administration of indomethacin and Moduretic (Merck Sharp & Dohme, USA, 5 mg of amiloride HCl, 50 mg hydrochlorothiazide) to a 78-yr-old patient resulted in severe hyperkalemia twice. When administered alone, neither drug significantly changed the normal serum potassium levels. Laboratory findings suggest an alteration of the internal balance of potassium as the main mechanism of this particular drug-induced hyperkalemia.