Prostaglandins pharmacological activity

Eicosanoids are formed from 20-carbon polyunsaturated fatty acids and make up an important group of physiologically and pharmacologically active compounds known as prostaglandins, thromboxanes, leukotrienes, and lipoxins. 

The difference between a normal immune response and a type I hypersensitive response is that in the latter, plasma cells secrete IgE. This class of antibody binds to Ec receptors on the surface of tissue mast cells and blood basophUs. Mast cells and basophUs coated by IgE are sensitised . Later exposure to the same allergen cross-links the bound IgE on sensitised cells, resulting in degranulation and the secretion of pharmacologically active mediators such as histamine, leukotrienes and prostaglandins. The principal effects of these products are vasodilation and smooth-muscle contraction (Table 15.6). 

Use Biochemical research, source of prostaglandins and other pharmacologically active compounds. 

Several pharmacologically active substances are present in superfusates of the cerebral cortex, including acetylcholine, 5-hydroxytryptamine, substance P and the prostaglandins. Members of this latter family of hydroxy-unsaturated fatty acids are released from a great variety of tissues on nerve and hormone stimulation (Ramwell and Shaw 1970), and have been shown to possess a wide range of biological activity (Horton, 1969). 

Flurbiprofen is indicated for the acute or long-term treatment of rheumatoid arthritis and osteoarthritis. It is a potent inhibitor of prostaglandin synthetase (see Figures 13 and 14). Flurbiprofen is absorbed well orally, is bound to plasma proteins to the extent of 99%, is metabolized in the liver to pharmacologically active metabolites, and the metabolites are excreted in the urine. Flurbiprofen increases the actions of oral anticoagulants and decreases the effectiveness of diuretics. Flurbiprofen is contraindicated in patients who are allergic to aspirin (see also Table 12). 

Although phosphohpids like acetal phosphatidic acid and lysolecithin have undoubted pharmacological activity, it is the opinion of this reviewer that, until they can be isolated by very mild conditions, their existence in the tissues examined must remain an open question. To say this is not to deny a lipid pharmacology, since prostaglandins in particular are lipids, but to reserve judgment on phospholipid pharmacology on present evidence. 

The more recently discovered leukotrienes result from arachidonic acid via the 5-hydroperoxide and the 5,6-epoxide (Leukotriene A4, LTA4). The leukotrienes contain a conjugated triene unit within a total of three (from 20 3, n—9), four (from 20 4, n—6), or five (from 20 5, n—3) double bonds. This total unsaturation is indicated by the numerical subscript. While the 8,11,14-triene unit provides the necessary unsaturation for prostaglandins and thromboxanes the 5,8,11-triene unit is required for leukotrienes. The various LTB, LTC, LTD and LTE compounds show a range of pharmacological activities of which the most widely studied is their relation to asthma arising from their bronchoconstricting effect. 

PACE ASCIAK CR The 6 [ 9 ] oxy cyclase pathway of prostaglandin endoperoxide metabolism, in Chemistry, biochemistry and pharmacological activity of prostanoids, Roberts SM, Scheinmann F (eds),... 

F. Pharmacological activity of PG12 and its metabolite 6-oxo-PGFl on human uterus and fallopian tubes. Prostaglandins 15 1045, 1978. 

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