A pharmacokinetic interaction in man between phenobarbitone and fenoprofen, a new anti-inflammatory agent.

1 The effect of repeated administration of phenobarbitone on the plasma disposition of fenoprofen (±-2-(3-phenoxyphenyl) propionic acid) was investigated in rats and man. 2 The plasma elimination rate constants increased significantly and the rats excreted proportionately more metabolized fenoprofen in the urine. These findings are consistent with an increase in the rate of metabolism of fenoprofen. 3 This interaction between phenobarbitone (and presumably other inducers of drug metabolizing enzymes) and fenoprofen should be considered when evaluating the clinical usefulness of fenoprofen.