Question

Write an essay on histamine as an inflammatory mediator (65%), and outline the mechanism of action and uses of drugs that affect histaminergic inflammatory signalling (35%). Give specific drug examples in your answer. (Pharmacology)

Answer 1

The inflammatory response in the body is principally mediated by a chemical released by different cells called histamine. Cells release this chemical in response to various tissue damages. Histamine is mainly formed by the decarboxylation histidine amino acid. Histamine accounts for approximately 10% of the granular weight of mast-cells. Since it has been stored in the granules, the inflammatory effects are observed soon after mast-cell activation. Histamines released from mast cells will binds to specific receptors on various downstream cells. Three important histamine receptors found in the target cells are H1, H2, and H3. Among this H1 is the important receptor because binding of histamine to the H1 receptors accounts for majority of allergic reactions.

Many anti-inflammatory drugs have ben used to suppress the action of histamine. Eg: Antihistamines have been the most useful drugs for symptoms of allergic rhinitis. Cromolyn sodium, Theophyllin, Epinephnine etc are other drugs which functions against the histamine.