Mepyramine
Mepyramine, or pyrilamine, targets the H1 receptor. It is a first generation antihistamine. However, it rapidly permeates the brain and so often causes drowsiness as a side effect. It has been found in over-the-counter combination products for colds and menstrual symptoms, but is considered to be an unapproved prescription medication used for cough, cold, or allergic conditions.