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# Coagulation factor VIII

Plasma-derived or recombinant factor VIII infused to prevent and treat bleeding in haemophilia A.

Updated 2026-11-01

- Class: [Coagulation factor replacement and haemophilia agents](https://durgical.com/en/pharmacology/classes/coagulation-factor-replacement-and-haemophilia-agents/)
- Target: Factor VIII itself (cofactor of factor IXa in the tenase complex)
- ATC code: B02BD02
- WHO Model List of Essential Medicines

Also called: antihaemophilic factor

◆**Factor VIII itself (cofactor of factor IXa in the tenase complex)**Coagulation factor VIII

ⓘ The figure shows human coagulation factor VIII, the replaced protein itself.

**Target in 3D:** Factor VIII itself (cofactor of factor IXa in the tenase complex). PDB structure 2R7E (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/2R7E) · Drag to rotate · pinch to zoom

## Mechanism of action

Factor VIII circulates bound to von Willebrand factor. Thrombin activates it to factor VIIIa, which acts as the cofactor that speeds up factor X activation by factor IXa on the platelet surface. In haemophilia A the factor is missing or faulty; the infused concentrate temporarily restores its level, so thrombin and a stable clot can form.

- Infused factor VIII replaces the missing protein
- Thrombin activates it to factor VIIIa
- VIIIa helps factor IXa activate factor X
- Thrombin and a stable fibrin clot form

## Pharmacokinetics

**Distribution**
Stays in plasma, bound to von Willebrand factor

**Half-life**
Short, so prophylaxis needs repeated infusions; extended half-life products exist

## Indications

- Haemophilia A: prophylaxis, treatment of bleeds and cover for surgery [Haemophilia A and B →](https://durgical.com/en/conditions/haemophilia-a-and-b/)
- Von Willebrand disease (intermediate-purity concentrates that contain von Willebrand factor) [Von Willebrand disease →](https://durgical.com/en/conditions/von-willebrand-disease/)

## Adverse effects

### Common

- Infusion reactions
- Headache

### Serious (rare, important)

- Inhibitor development (neutralising antibodies), with loss of response
- Allergic reactions, including anaphylaxis

## Contraindications

- Known severe allergy to the product or its components

## Key interactions

**Emicizumab**
In patients on emicizumab, standard laboratory inhibitor tests do not work; specialised testing is needed

## What is monitored

- Factor VIII activity levels
- Inhibitor testing when response falls
- Clinical response of the bleed

## Administration and safety

- Intravenous infusion after reconstitution; patients and families can learn to infuse at home
- Doses are calculated from weight and the factor level needed; products are not interchangeable without a new calculation

## Nursing care

- Record the product name and lot number of every infusion
- Watch for allergic reactions during and after the infusion
- Teach the family to recognise joint and muscle bleeds early and to treat them quickly
- Report bleeding that does not respond as usual: it may mean an inhibitor

## Pregnancy and breastfeeding

Haemophilia A is rare in women; female carriers may receive it around delivery when their levels are low.

## Memory aid

«A for Eight»: haemophilia A, factor VIII; «B for Nine»: haemophilia B, factor IX.

## Test yourself

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

## What role does factor VIIIa play in coagulation?

Cofactor for factor IXa in activating factor X (tenase complex).

## Why is a recombinant product preferred when available?

It avoids the residual risk of agents transmitted through pooled plasma.

## What suggests an inhibitor?

Bleeding that no longer responds to the usual infusion.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/coagulation-factor-viii/)

## Related drugs

- [Coagulation factor IX](https://durgical.com/en/pharmacology/coagulation-factor-ix/)
- [Emicizumab](https://durgical.com/en/pharmacology/emicizumab/)
- [Desmopressin](https://durgical.com/en/pharmacology/desmopressin/)
- [Tranexamic acid](https://durgical.com/en/pharmacology/tranexamic-acid/)

## Related conditions

- [Haemophilia A and B](https://durgical.com/en/conditions/haemophilia-a-and-b/)
- [Von Willebrand disease](https://durgical.com/en/conditions/von-willebrand-disease/)

[← Back to the class: Coagulation factor replacement and haemophilia agents](https://durgical.com/en/pharmacology/classes/coagulation-factor-replacement-and-haemophilia-agents/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Treatment of Hemophilia | Hemophilia | CDC](https://www.cdc.gov/hemophilia/treatment/index.html) (Centers for Disease Control and Prevention, 2026); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 34 (McGraw Hill, 2025); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=B02BD02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/coagulation-factor-viii/