Pharmacokinetic factors as causes of variability in response to non-steroidal anti-inflammatory drugs.

Even the most widely used non-steroidal anti-inflammatory drugs (NSAID's) show considerable variations in their pharmacokinetic behaviour in volunteers and moreso in patients. An evaluation of the response-related pharmacokinetic parameters of the three presently most widely used NSAID's, namely diclofenac, indomethacin and piroxicam shows some obvious reasons: While the onset of absorption and the bioavailability of diclofenac varies considerably, we find relevant differences in the terminal plasma half-life of indomethacin and particularly piroxicam. Inter-patient variability in these parameters may contribute significantly to the observed variations in clinical response.