eicosanoids

biosynthesis

required - not stored - have very short duration

synthesized from arachedonic acids

arachedonic acid is synthesized from all membrane phospholipids → hormones - immunoglubins - phagocytosis -trauma interact with plasma membrane bound receptors which are coupled with G protein resulting in activation of phospholypase A2 and/or C OR increase cytosolic CA

one step by phospholipase A2 → blocked by lipocortin

two steps of phospholipase C then DAG

phospholipase A2 acts on

phospholipids

phospholipase C

diglyceride inosital phosphate

cox → prostaglandins

VD of vascular bed

spasmogenic action on bronchi and GIT

potent algesic

LOX → HPEITS - HEITS

activation of pro hormones

PGE2 - PGI2

arteriolar dilators

PGF2 alpha

contact bronchi - uterus - relax arteries

LBT4

chemotatic for polymorphs - eosinophils - monocytes

TXA2

contacts arteries and veins and bronchi

PGF2A - TXA2 - D4 - LTC4

contact bronchi

PGF2A

contacts uterus

PGE1 - PGE2

protect stomach against ulcer

inhibitors of eicosanoid biosynthesis

glucocorticoids → stimulate the synthesis of lipocortoin

NSAIDS

ibuprofen → inhibit cyclo-oxygenase but not lipoxygenase

anti-leukotrine drugs →

zileuton = inhibit 5-lipoxygenase

montelukast - zafirlukast = block cysteinyl leukotriene

sulfasalazine = LBT4 blocker - treatment of of ulcerative colitis

dazoxiben = selexctive TXA2 inhibitor - inhibit platelet aggregation

uses

PGF2a - PGE2 = abortion and labor

PGE2 = bronchodilatation

PGE2 analogs - misoprostol = peptic ulcer

PGE1 = IC in treatment of impotence

PGE1 = maintain patency of ductus arteriosus presurgical in neonates suffering from transdiposition of great arteries or pulmonary atresia

latanoprost = PGF2a derivative - glaucoma

epoprostenol = decrease platelet aggregation

NSAIDS uses

anti inflammatory

analgesic - antipyretic

dysmenorrhea

tocolytic in premature labor

induce medical closure pf patent ductus arteriosus