[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Thromboxane A₂ (TXA₂)

[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Thromboxane A₂ (TXA₂)

TXA₂ is the platelet signal that calls more platelets and narrows vessels. Aspirin blocks its synthesis for the platelet's whole life.

Updated 2026-11-01

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## Key facts

- Made from PGH₂ by thromboxane synthase, mainly in platelets (COX-1).
- It acts on TP receptors: platelet aggregation and vasoconstriction.
- Its half-life is about 30 seconds; TXB₂ in serum or urine is measured instead.

**Formula**
C₂₀H₃₂O₅

**PubChem**
[CID 5280497](https://pubchem.ncbi.nlm.nih.gov/compound/5280497)

## Structure

- A six-membered oxane ring with a strained four-membered oxetane bridge; it breaks down within seconds to inactive TXB₂.

## Clinical notes

- Low-dose aspirin prevents arterial thrombosis by blocking platelet TXA₂.
- Excess TXA₂ relative to PGI₂ favours thrombosis, as with selective COX-2 inhibitors.
- TBXAS1 deficiency causes Ghosal hematodiaphyseal dysplasia.

## Pathways

- [Prostaglandin and thromboxane synthesis](https://durgical.com/en/biochemistry/pathways/prostaglandin-and-thromboxane-synthesis/)

## Related conditions

- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)

## Related

- [Prostaglandin H₂ (PGH₂)](https://durgical.com/en/biochemistry/molecules/prostaglandin-h/)
- [Arachidonic acid](https://durgical.com/en/biochemistry/molecules/arachidonic-acid/)
- [Cyclooxygenase (COX-1 and COX-2)](https://durgical.com/en/biochemistry/enzymes/cyclooxygenase/)
- [Eicosanoids: prostaglandins, thromboxanes and leukotrienes](https://durgical.com/en/biochemistry/topics/eicosanoids-prostaglandins-thromboxanes-and-leukotrienes/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which cell makes most thromboxane A₂, and with which COX?

The platelet, using COX-1.

## What are the two main effects of TXA₂?

Platelet aggregation and vasoconstriction.

## Why is TXB₂ measured instead of TXA₂?

TXA₂ breaks down within about 30 seconds to the stable, inactive TXB₂.

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Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Thromboxane A2 (CID 5280497)](https://pubchem.ncbi.nlm.nih.gov/compound/5280497) (PubChem, NCBI, 2026) · Public domain; [TBXAS1 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/tbxas1/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/molecules/thromboxane-a/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/thromboxane-a/