Impairment of hemostasis in patients with severe hemophilia. Failure of diphenhydramine, chlorpromazine, and guaifenesin.

Twenty-three patients with severe hemophilia were given single or multiple doses of diphenhydramine hydrochloride, chlorpromazine hydrochloride, or guaifenesin to test their effects on hemostasis. In contrast with earlier studies with aspirin, bleeding times were not prolonged after ingestion of these three drugs. No patient had hemorrhage because of the drugs, and none recalled excessive bleeding following drug ingestion. These results greatly extend the clinical implications of prior observations carried out in normal subjects demonstrating that many antiplatelet drugs have no effects on in vivo hemostasis. We conclude that these drugs are probably safe for patients with bleeding disorders like hemophilia.