Cinnarizine and flunarizine, potent inhibitors of anaphylactic shock in guinea-pigs.

Histamine-induced paw oedema and anaphylactic shock were studied simultaneously in ovalbumin-sensitized guinea-pigs and cinnarizine and flunarizine were evaluated quantitatively with regard to protection from the two types of challenge. Both compounds were markedly more active in preventing lethal anaphylaxis (ED50's of 0.67 and 0.53 mg/kg OR) than in reducing histamine oedema (ED50's of 2.77 and 1.54 mg/kg OR). The high anti-anaphylactic potency after oral administration may be an important finding in view of the therapeutic applications of cinnarizine and flunarizine.