[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Prostaglandin H₂ (PGH₂)

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

# Prostaglandin H₂ (PGH₂)

PGH₂ is the unstable product of COX. Each cell type turns it into its own prostanoid: TXA₂, PGI₂, PGE₂, PGD₂ or PGF₂α.

Updated 2026-11-01

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## Key facts

- Made from PGG₂ by the peroxidase site of COX-1 or COX-2.
- Its half-life is very short, so it is converted where it is made.
- Thromboxane synthase makes TXA₂ from it in platelets; prostacyclin synthase makes PGI₂ in endothelium.

**Formula**
C₂₀H₃₂O₅

**PubChem**
[CID 445049](https://pubchem.ncbi.nlm.nih.gov/compound/445049)

## Structure

- A cyclopentane ring bridged by an endoperoxide (–O–O–), with two side chains and a 15-hydroxyl.

## Clinical notes

- All NSAIDs act upstream of PGH₂, so they lower every prostanoid.
- The balance between TXA₂ and PGI₂ made from PGH₂ shapes clotting and vascular tone.

## 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/)

## Related

- [Arachidonic acid](https://durgical.com/en/biochemistry/molecules/arachidonic-acid/)
- [Thromboxane A₂ (TXA₂)](https://durgical.com/en/biochemistry/molecules/thromboxane-a/)
- [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 enzyme activity makes PGH₂ from PGG₂?

The peroxidase activity of COX-1/COX-2.

## Why do NSAIDs lower all prostanoids?

They block COX, which makes PGH₂, the common precursor of every prostanoid.

## What do platelets and endothelium make from PGH₂?

Platelets make thromboxane A₂; endothelium makes prostacyclin (PGI₂).

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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: [Prostaglandin H2 (CID 445049)](https://pubchem.ncbi.nlm.nih.gov/compound/445049) (PubChem, NCBI, 2026) · Public domain; [Prostacyclin synthase (PTGIS) - Homo sapiens](https://www.uniprot.org/uniprotkb/Q16647/entry) (UniProt, 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/prostaglandin-h/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/prostaglandin-h/