Prostaglandin-endoperoxide synthase 1 (COX-1) and thromboxane-A synthase (TXAS) (COX-1/TXAS)

Prostaglandin-endoperoxide synthase 1 (COX-1) and thromboxane-A synthase (TXAS) are critical enzymes in the arachidonic acid metabolic pathway, primarily functioning in platelets to regulate hemostasis [1]. COX-1 catalyzes the initial conversion of arachidonic acid into the unstable intermediate prostaglandin H2 (PGH2) [2]. TXAS, a member of the cytochrome P450 superfamily, then converts PGH2 into thromboxane A2 (TXA2), which is a potent mediator of platelet aggregation and a strong vasoconstrictor [3]. Dysregulation or overactivity of this pathway is heavily implicated in the development of cardiovascular diseases, including myocardial infarction and ischemic stroke, due to the formation of arterial thrombi [4]. Pharmacological intervention typically involves the use of nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, which irreversibly inhibits COX-1, or specialized dual inhibitors like ridogrel that target both enzymes to suppress TXA2 production [5]. While effective in preventing thrombosis, the inhibition of COX-1 can lead to significant safety concerns, such as gastrointestinal ulceration and bleeding, because it also reduces the synthesis of protective prostaglandins in the gastric mucosa [6]. Emerging therapeutic strategies aim to achieve a more balanced inhibition that preserves the production of anti-aggregatory prostacyclin while selectively blocking thromboxane synthesis [7]. Citations: [1] UniProt (P23219, P24557); [2] PubChem (Gene ID: 5742); [3] StatPearls (Thromboxane A2); [4] PubMed (PMID: 15671061); [5] Journal of Pharmacology and Experimental Therapeutics (PMID: 2277086); [6] NIH (NCBI Bookshelf - Prostaglandins); [7] PubMed (PMID: 8103435).

Other names

PTGS1Cyclooxygenase-1CYP5A1Thromboxane synthaseTBXAS1COX1TXS

Inhibition of COX-1 prevents the formation of PGH2 from arachidonic acid, while inhibition of thromboxane synthase prevents the conversion of PGH2 to thromboxane A2, collectively reducing platelet aggregation and vasoconstriction.