Prostaglandin E1 (PGE1), also known as alprostadil, is a naturally occurring prostaglandin with potent vasodilatory and smooth muscle relaxing properties. Chemically, it is a 20-carbon fatty acid derivative containing a cyclopentane ring with hydroxyl and keto functional groups, a carboxylic acid moiety, and a conjugated diene system in the side chain. The molecular formula of PGE1 is C20H34O5, with a molecular weight of 354.49 g/mol. Its stereochemistry is critical to receptor selectivity and biological activity, particularly the configurations at C11, C13, and C15 of the cyclopentane ring.
PGE1 was first isolated and characterized in the 1960s during studies of prostaglandins in human semen and other tissues. Its pharmacological profile includes vasodilation, inhibition of platelet aggregation, relaxation of smooth muscle, and modulation of inflammatory responses. In clinical medicine, PGE1 has been developed as a therapeutic agent for a variety of cardiovascular and urogenital conditions. It is used intravenously or intra-arterially to treat peripheral vascular diseases, such as critical limb ischemia, by improving blood flow and reducing vascular resistance. PGE1 is also employed in neonatology to maintain patency of the ductus arteriosus in infants with congenital heart defects until corrective surgery can be performed.
The synthesis of PGE1 involves multiple stereospecific steps to ensure correct configuration at key stereocenters. Industrial production typically uses total synthesis or semi-synthetic routes starting from naturally occurring prostaglandin precursors. Advances in asymmetric synthesis have allowed large-scale production with high stereochemical purity, which is essential because the biological activity of prostaglandins is highly stereoselective.
Pharmacokinetically, PGE1 has a short half-life of a few minutes due to rapid metabolism by 15-hydroxyprostaglandin dehydrogenase and β-oxidation in the lungs, liver, and kidneys. To overcome this limitation, stable analogues and salt forms have been developed, such as alprostadil urethral and injectable formulations, which allow controlled administration and improved therapeutic effects.
PGE1 acts primarily through binding to prostanoid EP receptors, specifically EP2 and EP4 subtypes, activating adenylate cyclase and increasing intracellular cyclic AMP levels. This mechanism mediates vasodilation, inhibition of platelet aggregation, and smooth muscle relaxation. Its pharmacological effects are dose-dependent, and careful titration is necessary to balance therapeutic benefits against side effects, which may include hypotension, flushing, headache, and local irritation at the site of administration.
Clinically, PGE1 is significant for its role in cardiovascular medicine, urology, and neonatology. It represents an early example of translating prostaglandin biology into a practical therapeutic agent, demonstrating the importance of structural modifications and formulation strategies in maximizing the clinical utility of short-lived bioactive lipids. Its discovery and development have paved the way for numerous prostaglandin analogues used in diverse therapeutic areas.
References
Isolation of prostaglandin E1 from human seminal plasma. Prostaglandins and related factors. 11 509–516, 1962-09 PMID: 13867832
PROSTAGLANDINS AND RELATED FACTORS. 15. The structures of prostaglandin E1, F1-alpha, and F1-beta. The Journal of Biological Chemistry 238 3469–3475, 1963-11 PMID: 14109186
The Biological Activity of Prostaglandin E1, E2 and E3. Acta Physiologica Scandinavica 59 420–432, 1963-12 DOI: 10.1111/j.1748-1716.1963.tb02766.x
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