Protein binding and stereoselectivity of nonsteroidal anti-inflammatory drugs.

Stereoselective binding of nonsteroidal anti-inflammatory drugs (NSAIDs) can be studied using various techniques. Thus the results obtained by different investigators may be poorly consistent and even contradictory. NSAIDs are bound stereoselectively to serum albumin to different degrees depending on the drug investigated (ibuprofen, indoprofen, carprofen, etodolac, ketoprofen and flurbiprofen). For other drugs, both enantiomers are bound to a similar extent (pirprofen, fenoprofen). This stereoselectivity could vary with experimental conditions, in particular with protein concentration (ketoprofen, etodolac), leading to individual differences. Finally, the stereoselectivity of protein binding and of pharmacokinetics can be compared: differences in binding between enantiomers can explain their differences in pharmacokinetics, once metabolic properties such as inversion have been taken into account.