page_title: Prostacyclin
section_title: Biosynthesis
hierarchical_section_title: Prostacyclin / Synthesis / Biosynthesis
context_page_description: Prostacyclin is a prostaglandin member of the eicosanoid family of lipid molecules. It inhibits platelet activation and is also an effective vasodilator.
  When used as a drug, it is also known as epoprostenol. The terms are sometimes used interchangeably.
context_section_description: Prostacyclin is produced in endothelial cells, which line the walls of arteries and veins, from prostaglandin H₂ (PGH₂) by the action of the enzyme prostacyclin synthase. Although prostacyclin is considered an independent mediator, it is called PGI₂ (prostaglandin I₂) in eicosanoid nomenclature, and is a member of the prostanoids (together with the prostaglandins and thromboxane). It is important to note that COX 1 has been found to be the major prostacyclin producing cyclooxygenase in the endothelial cells of the blood vessels. 
  The series-3 prostaglandin PGH₃ also follows the prostacyclin synthase pathway, yielding another prostacyclin, PGI₃. The unqualified term 'prostacyclin' usually refers to PGI₂. PGI₂ is derived from the ω-6 arachidonic acid. PGI₃ is derived from the ω-3 EPA.
caption: Eicosanoid synthesis. (Prostacyclin near bottom center.)