Mepyramine

Mepyramine, also known as pyrilamine, is an antihistamine of the ethylenediamine class. It is primarily used to treat allergic reactions such as rhinitis, urticaria, and angioedema. Mepyramine works by blocking the action of histamine, a substance in the body that plays a role in allergic responses. It is available in various formulations, including oral tablets, capsules, and topical creams.

The mechanism of action for mepyramine involves acting as an H1 receptor antagonist. By binding to histamine H1 receptors, it prevents histamine from exerting its effects, which include vasodilation, increased vascular permeability, smooth muscle contraction, and itching. This antagonism leads to a reduction in the symptoms associated with allergic reactions.

Mepyramine is generally well-tolerated, but common side effects can include drowsiness, dry mouth, dizziness, and blurred vision. Due to its sedative properties, caution is advised when operating machinery or driving after taking mepyramine. It may also interact with other central nervous system depressants. The drug is metabolized in the liver and excreted in the urine.

Historically, mepyramine was one of the earlier antihistamines developed and has been used for several decades. While newer antihistamines with fewer side effects and less sedation are now available, mepyramine continues to be used, particularly in certain regions or for specific indications where its efficacy is well-established. Its use in combination products for conditions like the common cold or cough is also observed.