What are the major pharmacokinetic differences among the nonsteroidal antiinflammatory drugs?
All the NSAIDs possess similar absorption characteristics. In general, they are rapidly absorbed after oral and rectal administration. They are highly protein-bound and metabolized primarily in the liver. However, durations of action vary markedly. Some drugs, such as ibuprofen, require dosing every 4 to 6 hours, whereas piroxicam can be given once a day. The newer COX2 inhibitors also require only once or twice daily dosing. NSAIDs encompass a broad group of medications. Salicylates have a long history in the management of both rheumatoid arthritis as well as osteoarthritis. Proprionic acid derivatives including but not limited to ibuprofen, flurbiprofen, naproxen, and ketoprofen have also been used for years. Acetic acid derivatives such as sulindac, indomethacin, and tolmetin can also be used. Failure to respond to one class of NSAID does not mean that they are ineffective. Changing class from an acetic acid derivative to a proprionic acid derivative or vice versa may at times prove effective.