THE EFFECT OF ANTACID AND ASPIRIN ON THE BIOAVAILABILITY OF ISOFEZOLAC IN MAN

Bioavailability of isofezolac, a new nonsteroid antiinflammatory drug, with or without antacid and aspirin coadministration was investigated in 6 healthy female volunteers. Each subject received, in random order, isofezolac (50 mg) alone or associated with aspirin (1 g) or phosphalugel (11 aluminum phosphate). Isofezolac plasma concentrations were determined using a specific high performance liquid chromatographic assay procedure and salicylic acid by spectrofluorimetric method. Plasma protein binding of drugs was studied by dialysis equilibrium method. During the absorption phase isofezolac plasma levels were slightly decreased in association with isofezolac-aspirin, but bioavailability or isofezolac was not modified. Time to peak of isofezolac was comparable in the 3 treatments, as was the case with plasma half-lives. Aluminum phosphate did not modify isofezolac availability. Plasma protein binding of isofezolac was very high (99%) and did not influence salicylic acid binding.