Interaction of oxindanac and frusemide in man.

Oxindanac, a moderately active cyclo-oxygenase inhibitor in vitro, is a new antiinflammatory agent under clinical investigation. Its effects on frusemide-induced natriuresis have now been studied. Eight male volunteers receiving frusemide 40 mg b.d. were also given either oxindanac 300 mg b.d. or placebo in two consecutive periods separated by a treatment-free period, according to a randomized cross-over study design. Urinary prostaglandin excretion (PGF2 alpha) fell by 75% after 3 days on oxindanac. Frusemide-induced renin activity reached 66% of the control value in the presence of oxindanac. However, the natriuresis induced by frusemide did not differ significantly whether oxindanac or placebo was administered, despite the inhibitory action of the former on prostaglandin synthesis in vivo.