The pharmacology of isamoxole [2-methyl-n-butyl-n(4-methyloxazol-2-yl) propanamide] LRCL 3950, a new anti-allergic compound.

1. Isamoxole [2-methyl-N-butyl-N(4-methyloxazol-2-yl) propanamide] is an effective orally active anti-allergic compound in animals. 2. Isamoxole inhibits the immunological release of mediators, notably slow-reacting substance of anaphylaxis (SRS-A) from sensitized human and guinea-pig chopped lung in vitro. 3. In vivo, allergic responses were inhibited in guinea-pigs and rats by doses as low as 25 mg/kg given orally 180 and 30 min before challenge. The effect of Isamoxole was still present 4 h after a single dose of 100 mg/kg orally in the guinea-pig and 3 h in the rat. 4. Isamoxole is a moderately potent, selective inhibitor of SRS-A activity on the guinea-pig ileum in vitro, at concentrations that do not antagonize histamine, 5-hydroxytryptamine, or bradykinin. 5. Isamoxole causes human bronchial muscle to relax and antagonizes the bronchoconstriction induced by SRS-A.