Study of the possible interactions of indoprofen on the diuretic effect of furosemide

Twelve elderly in-patients undergoing chronic furosemide treatment (25 mg/day), with stable diuresis, were admitted to a cross-over, double-blind study to investigate the possible interactions between indoprofen and the diuretic. Indoprofen (200 mg t.i.d.) and identical placebo tablets were administered in randomized sequences for 4 days each. The sequence were preceded by a 4-day run-in observation period and followed by a 4-day follow-up. 24-hour urinary volume and the excretion of Na, K and endogenous creatinine were monitored, with serum Na, K, creatinine and creatinine clearance. Blood pressure and heart rate were measured and routine clinical blood chemistry tests and urinalysis were made for safety. The findings of this pilot study suggest that indoprofen does not alter the natriuretic action of furosemide; a tendency was noted towards a reduction of glomerular filtrate and urine volume, but the values after indoprofen were not significantly different from those after placebo.