PMY 302 Lecture 30: Antihistamine

• School: University at Buffalo
• Department: Pharmacology and Toxicology
• Course: PMY 302
• Professor: Bhattacharjee Arindam

Document Summary

Stored mainly by mast cells and basophils (bronchioles and intestine): low turnover. H1: gq protein, act on blood vessels, smooth muscles, heart, cns. Increase in vascular permeability, airway constriction, mucous secretions, flushing, pruritus. H2: gs protein (so use camp), acts on gastric, heart, uterus, mucosa. H1 antagonist (competitive, reversible and metabolized by p450) H1 has higher affinity and rapid onset and decline: increase permeability of post capillary venules, contraction of the endothelial cells and the fluid leaks out to the interstitial fluid. H1: sensory nerve ending stimulant: mediate the pain and pruritus. Intradermal injection: red spot: increase in capillary dilation, wheal: exudation of the fluid from the capillary and the venules, flare: arteriolar dilation mediated by axon reflex. Parietal cells have acetylcholine, gastrin and h2 receptors. Histamine is release from the ecl (enterochromis cell) which will bind to the parietal cell h2 receptor and the hcl is released. Mast cell binds the the ige+ag complex and release histamine.