Studies of the "antihistaminic" effect of pyribenzamine administered by various routes.

Utilizing histamine electrophoresis, the degree and duration of "antihistaminic" effect of varying doses of Pyribenzamine(R) administered by different routes were studied. Delayed action Pyribenzamine in 50 mg. and 100 mg. dosage exerted a small but measurable anti-whealing effect five hours after ingestion. The larger dose exerted approximately twice the effect of the smaller. The anti-whealing activity lasted five to six hours. Pyribenzamine given intravenously affected the whealing response one hour after administration. A peak of activity was reached two to two and a half hours after injection, and "antihistaminic" effect continued for a total of five hours. The inunction of 250 mg. and 500 mg. of Pyribenzamine in an ointment base resulted in sufficient absorption of the drug to produce a measurable anti-whealing effect. The "antihistaminic" activity was noted three hours after application and lasted 10 to 12 hours from the time of inunction.