[Interaction of salicyl compounds and other non-steroidal anti-inflammatory agents: pharmacokinetic study of phenylbutazone-aspirin combination in man].

The pharmacodynamic interaction between phenybutazone and aspirin was studied in 9 patients. The levels of phenylbutazone were estimated by gas-chromatography and verified by mass-spectrometry. When phenylbutazone was administered together with salicylates a decrease in the bioavailability of phenylbutazone was demonstrated, but there was no significant variation in the absorption and elimination constants or in the half-life. The variations were much less than those observed with other nonsteroid anti-inflammatory drugs (indometacine, naproxen, fenoprofen). These interactions must be taken into account in the long-term treatment of cases of inflammatory rheumatism.