Prostaglandin therapy, indications

Tancharoen S, Jones RM, Angus PW, Michell ID, McNicol L, Hardy KJ. Prostaglandin El therapy in orthotopic fiver transplantation recipients indications and outcome. Transplant Proc 1992 24(5) 2248-9. 

Cetirizine competitively antagonizes histamine at the Hi-receptor site and is indicated in the symptomatic relief of symptoms (e.g., nasal, nonnasal) associated with seasonal and perennial allergic rhinitis treatment of uncomplicated skin manifestations of chronic idiopathic urticaria. Histamine is a potent vasodilator, bronchial smooth-muscle constrictor, and stimnlant of nociceptive itch nerves. In addition to histamine, mnltiple chemical itch mediators can act as pruritogens on C-fibers, including neuropeptides, prostaglandins, serotonin, acetylcholine, and bradykinin. Furthermore, new receptor systems such as vanilloid, opioid, and canna-binoid receptors on cutaneous sensory nerve fibers that may modulate itch offer novel targets for antipruritic therapy. 

Mefenamic acid (500 mg p.o. initially, then 250 mg every 4 hours), which inhibits prostaglandin synthesis, is indicated in the treatment of moderate pain and in the management of primary dysmenorrhea. The duration of therapy should not exceed 1 week. It is a nonsteroidal antiinflammatory agent with analgesic and antipyretic properties. Mefenamic acid is absorbed rapidly and completely from the GI tract. It is highly protein-bound and is metabolized in the hver. Mefenamic acid is excreted mainly in urine with some biliary excretion. The plasma half-life is around two hours. 

This compound may cause relaxation of skeletal muscle via general CNS depression. Aspirin inhibits prostaglandin synthesis, resulting in analgesia, antiinflammatory activity, and inhibition of platelet aggregation. It is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful, musculoskeletal conditions. 

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