About Misoprostol A synthetic prostaglandin E1 (PGE1) analogue, Anti ulcer(antisecretory and protective),Abortifacient. Mechanism of Action of Misoprostol Misoprostol is a synthetic Prostaglandin E1 analog. It binds to the EP3 receptor on the basolateral membrane of the parietal cells and stimulates the inhibitory G protein (Gi) receptors. This will leads to decrease in intracellular cyclic AMP level and inhibits proton pump (H+K+ATPase) which exchange the extracellular K+ for intracellular H+ ion. By inhibiting the proton pump Misoprostol decreases gastric acid secretion. Misoprostol also binds to the EP3 receptor on the superficial epithelial cells of the lumen and stimulates the mucin and bicarbonate secretion and decreases nocturnal, basal and stimulated gastric acid secretion.