Prostaglandins & Drugs

5-lipoxygenase = white cells = leukotrienes (most important clinically)

12-lipoxygenase = platlets

15-lipoxygenase = macrophages & epithelial cells

Arachodonic acid > 5-HPETE > LTA4 > LTB4

or LTA4 > LTC4 > LTD4 > LTE4 (via LTC4 synthase)

All these for slow-reacting substance (SRS) of anaphylaxis and cause bronchospams

• BTL: LTB4 in neutrophils, lung, spleen
• cysTL1: LTD4 & LTE4 in smooth muscle especially in lung
• cystTL2: LTC4 in endothelium & smooth muscle

ALL activate PLC (phospholipase C)

inhibits 5-lipoxygenase

• cysTL1 blockers
• once a day dosage
• use for persistent asthma

• inhibits both COX 1 and 2
• via acetylation

COX-1 inhibitor

Cox 1 &2 inhibitor

partially selective COX 2 inhibitor

• selective COX 2 inhibitors
• latter 2 were found to have increased risk of MI & stroke



• PGEI
• treat peripheral vascular disease
• keeps ductus arteriosus patent in infants
• PGI along with PGE2 keep ductus open in fetus

closes ductus (unknown how)

• great for asthma
• inhibits PLA-2
• therefore inhibits the production of arachodonic acid

• induce labor and abortions
• works through PLC path
• provide contractions

• reduce production of thromboxane A2 by platlet
• this inhibits platlet aggregation