[A correlation between the species differences in anti-inflammatory activity of AD-1590, a non-steroidal anti-inflammatory drug, and its plasma level].

Authors have reported that the oral potency ratio of AD-1590 to indomethacin varies with the animal models employed; the ratio is 4, 2.3 and 31 in the tests of acetic acid-induced vascular permeability (male mice), carrageenan hind paw edema (male rats) and UV-erythema (female guinea pigs), respectively. Thus, the relationship between the difference in the anti-inflammatory activity of AD-1590 among animal models and the species difference of the plasma AD-1590 level was investigated in experimental animals in order to ascertain the cause of the difference in the potency ratio. Inhibitory potency of AD-1590 on UV-erythema and increased vascular permeability induced by acetic acid in male rats was about 2.1 and 2.3 times, respectively, that of indomethacin. On the other hand, after a single oral administration of 5 mg/kg, the highest plasma AD-1590 level was seen in female guinea pigs (AUC9-8 hr = 63.1 micrograms.hr/ml); and followed by that in mice (male, 32.1; female, 36.1) greater than male dogs (11.5) greater than or equal to rats (male, 9.02; female, 12.5), male rabbits (9.17) greater than male monkeys (9.34 at 6 mg/kg). Hucker et al. have reported that the plasma level of indomethacin in rats is several times higher than that in guinea pigs, rabbits and monkeys. These results suggest that most of the species difference in the relative potency of AD-1590 to indomethacin in the anti-inflammatory activity results from the species difference in the plasma level of both drugs.