Prediction of human analgesic dosages of nonsteroidal anti-inflammatory drugs (NSAIDs) from analgesic ED50 values in mice.

The oral analgesic activities (ED50's) of 15 NSAIDs were determined in the phenylquinone-induced writhing test in mice. ED50 values (mg/kg) were: acetylsalicylic acid (182), fenclofenac (168), phenylbutazone (129), ibuprofen (82.2), diflunisal (55.6), benoxaprofen (25.4), naproxen (24.1), mefenamic acid (20.7), indomethacin (19.0), meclofenamate sodium (9.60), sulindac (7.20), fenoprofen calcium (3.70), tolmetin (1.30), zomepirac sodium (0.70), and piroxicam (0.44). Significant linear correlations were found between mouse ED50 values and the various recommended human analgesic or anti-inflammatory dosages. Thus, analgesic ED50 values (mg/kg p.o.) in mice (X) may be used to predict human dosages (Y) of NSAIDs according to the equation Y = 8.26X + 535, where Y is the projected human daily dosage (mg).