Action of tioxamast on various models of anaphylactic shock, hyperreactivity and bronchial inflammation in guinea-pigs.

Tioxamast, an anti-allergic compound inhibiting the release and synthesis of certain mediators of allergy and having no major antagonist effect towards such mediators, was experimented on various models of anaphylactic shock, hyperreactivity and bronchial inflammation in guinea-pigs. Tioxamast does not reduce passive pulmonary anaphylactic shocks induced in anaesthetized or conscious guinea-pigs by i.v. challenge of antigen. Likewise, the compound has no effect on systemic hyperreactivity towards i.v. histamine induced in anaesthetized guinea-pigs after a passive anaphylactic shock caused by i.v. challenge of antigen. On the other hand, tioxamast inhibits passive pulmonary anaphylactic shock induced in guinea-pigs by antigen aerosol in conscious guinea-pigs. Likewise, tioxamast decreases hyperreactivity to inhalation of histamine or carbamylcholine obtained after an active or passive anaphylactic shock by aerosol in conscious guinea-pigs. The oxamate derivative attenuates the increase in number of eosinophils and mononuclear cells obtained in the bronchoalveolar lavage fluid 24 hr after an active anaphylactic shock induced by aerosol. The anti-allergic activity of tioxamast on the various models carried out in guinea-pigs thus appears when these models are induced by a challenge of antigen or mediator by inhalation.