[Analgetic and antipyretic activity of SL-573 (author's transl)]

Potency of analgetic activity of SL-573 was between that of indomethacin and aminopyrine in chemical stimulation tests. The analgetic activity of SL-573 was 3.2 times as potent as that of aminopyrine in the phenylquinone writhing test, 4.1 times as potent as aminopyrine in the acetic acid writhing test and 6.3 times as potent as aminopyrine in the Randall and Selitto test. Thus the analgetic activity of SL-573 appears to be comparable etic to that of codeine. SL-573, unlike narcotic analgesics, showed common properties to known antipyretic analgesics and anti-inflammatory agents in the following points. (1) Analgetic activity was not evident in the mechanical stimulation or in the heat stimulation tests. (2) The analgetic activity was not antagonized by naloxone. (3) SL-573 showed no antagonistic effect to morphine. (4) Tolerance to the analgetic activity of SL-573 was not observed after a one week pretreatment with this compound. (5) SL-573 had no effect on the evoked potentials recorded from cells in the pain pathway of CNS and the site of action of analgetic effect was considered to be in peripheral sites of the sensory neurons. The antipyretic activity of SL-573 was equal to that of aminopyrine in febrile rabbits and 4 times as potent as that of aminopyrine in febrile rats. This compound did not affect normal body temperature of rabbits and rats, this observation being similar to that noted with antipyretic analgesics and nonsteroidal anti-inflammatory agents.