Histamine release from rat mast cells induced by econazole.

1. Econazole released histamine from rat mast cells in vitro. This response was not affected by the addition of calcium or by prior treatment of mast cells with EDTA or cromoglycate. 2. Rat mast cells treated with econazole were stained by the vital dye trypan blue. 3. The intradermal injection of econazole increased vascular permeability. This response was antagonized by chlorpheniramine and cyproheptadine. 4. Our results demonstrate that econazole releases histamine by the "nonselective" mechanism. It is suggested that econazole inflammatory effects may be due to histamine release from mast cells.