Pharmacokinetics of the Enantiomers of Indoprofen in Man

Indoprofen, a non-steroidal analgesic and antiinflammatory drug whose activity and safety in man have been established in a large number of studies, has an asymmetric carbon atom and can therefore occur as either the (+) or the (-) enantiomer. As it has been shown that its pharmacological effects are almost entirely due to the (+) isomer (d-indoprofen), some pharmacokinetic properties of the latter have been studied in man in comparison with the racemic mixture given by oral administration, d-indoprofen is cleared from plasma and excreted in urine (as unchanged plus conjugated drug) at a slower rate than l-indoprofen. Moreover, no stereospecific inversion of d-indoprofen to the inactive enantiomer occurs after either single or repeated (one week) administration. The pharmacokinetic behaviour of d-indoprofen in the human organism appears to be the same after administration of the racemic form or of the dextro-enantiomer, when the latter is given at half the dose.