Abstract

The effect of 23 phenothiazine derivatives on dextran-induced anaphylactoid reaction was investigated. All active compounds inhibited the fall of blood pressure in dextran-treated rats, accumulation of carbon particles at the sites of histamine and 48/80 injection, increased capillary permeability and edema formation. The removal of intravenously injected carbon was characteristically altered during the presence of edema. There was an extremely high carbon content in the blood during the anaphylactoid reaction. This alteration did not occur if active compounds were injected prior to dextran. Phenothiazine derivatives have a characteristic effect on the kinetics of edema formation, thus permitting the quantitative screening of the socalled antihistamines.