Dacemazine (INN, also known as Ahistan and Histantine)[1] is a phenothiazine derivative which acts as an histamine antagonist at the H1 subtype. First described in 1951, it was never marketed as a drug on its own, although a combination of dacemazine and di-tert-butylnaphthalenesulfonate was sold as an antispasmodic and antitussive under the trade name Codopectyl.[1] It was also assessed as a possible anticancer drug.[2]