Prodrugs and mutual prodrugs: synthesis of some new pyrazolone and oxadiazole analogues of a few non-steroidal anti-inflammatory drugs.

Naproxen, probenecid, diclofenac, ibuprofen and indomethacin were converted to hydrazide derivatives via their methyl ester by reacting with hydrazine hydrate, which were further condensed with beta-keto esters to get the pyrazolone derivatives. The hydrazide derivatives of probenecid and diclofenac were also reacted with biphenyl acetic acid while naproxen hydrazide was reacted with p-chloro benzoic acid besides biphenyl acetic acid to synthesize their oxadiazole analogues. Some selected members of the compounds prepared were screened for their anti-inflammatory and analgesic activity.