Plasma histamine and the release of histamine from blood
in vitro has been determined in patients being treated for hypertension or heart failure with captopril. This drug does not alter plasma histamine levels in either group of patients or release histamine from human basophils, rat peritoneal mast cells or guinea pig lung slices upon challenge
in vitro. We conclude that histamine release does not contribute to the cardiovascular or side effects of captopril.