The effect of co-administered drugs on oxaprozin binding to human serum albumin.

The binding of the non-steroidal anti-inflammatory drug oxaprozin to human serum albumin was studied by bioaffinity high-performance liquid chromatography using a column based on immobilized human serum albumin. Displacement studies using marker compounds for the major drug binding sites showed that oxaprozin has a high affinity for the benzodiazepine/indole site and binds to the warfarin site but with a significantly lower affinity. Biochromatography and ultrafiltration techniques were used to screen for possible competition and allosteric interactions between oxaprozin and potential co-administered drugs including non-steroidal anti-inflammatory drugs, antipyretics, hypoglycaemics, inhibitors of angiotensin-converting enzyme, anaesthetics, metal ions and anticancer agents. Competition occurred mainly with drugs bound at the benzodiazepine site (benzodiazepines, various non-steroidal anti-inflammatories).