[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Complement inhibitors](https://durgical.com/en/pharmacology/classes/complement-inhibitors/) › Pegcetacoplan

# Pegcetacoplan

## Complement inhibitors?

Complement inhibitors

A complement C3 inhibitor injected under the skin for PNH and some C3-driven kidney diseases; it raises the risk of meningococcal infection.

Updated Nov 1, 2026

## Quick facts

**Group**
[Complement inhibitors](https://durgical.com/en/pharmacology/classes/complement-inhibitors/)

**Target**
Complement component C3 (plasma protein)

**Used for**
Paroxysmal nocturnal haemoglobinuria

**Key effects**
Diarrhoea · Injection-site redness or swelling · Joint

**ATC**
L04AJ03

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

◆**Complement component C3 (plasma protein)**Pegcetacoplan

ⓘ No structure with pegcetacoplan is available; the figure shows human C3c bound to compstatin, the peptide family pegcetacoplan belongs to (it is a compstatin-based peptide joined to polyethylene glycol).

**Target in 3D:** Complement component C3 (plasma protein). PDB structure 2QKI (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/2QKI) · Drag to rotate · pinch to zoom

Pegcetacoplan binds complement C3, upstream of C5. This blocks both the coating of red cells with C3 fragments (which leads to their removal in the liver and spleen) and the later formation of the membrane attack complex. It controls PNH but does not cure it.

- Pegcetacoplan binds complement C3
- C3 is not activated, so red cells are not coated with C3 fragments
- The downstream steps, including C5 and the lytic pore, are not reached

## Indications

- Paroxysmal nocturnal haemoglobinuria [Paroxysmal nocturnal haemoglobinuria →](https://durgical.com/en/conditions/paroxysmal-nocturnal-haemoglobinuria/)
- C3 glomerulopathy or primary immune-complex membranoproliferative glomerulonephritis

## Adverse effects

### Common

- Diarrhoea, abdominal pain, nausea
- Injection-site redness or swelling, bruising
- Headache, dizziness, tiredness
- Joint, muscle or back pain
- Cough, nasal congestion, nosebleeds, leg swelling

### Serious (rare, important)

- Serious infections, especially meningococcal
- Serious infusion or allergic reactions
- Rapid red-cell breakdown and clots after stopping

## Contraindications

- Hypersensitivity to pegcetacoplan
- Certain active infections, including meningococcal infection
- Not vaccinated as required, unless antibiotic cover is given

## Key interactions

**Vaccines against meningococcus and other encapsulated bacteria**
Required at least 2 weeks before starting; boosters may be needed

## What is monitored

- Blood tests for haemolysis during treatment
- Monitoring for at least 8 weeks after stopping
- Pregnancy test before starting when relevant

## Administration and safety

- Subcutaneous infusion with a pump or on-body injector, taught by a nurse or doctor
- Brought to room temperature without heating; injection sites rotated, avoiding scarred, bruised or tattooed skin
- Available only through a risk-management (REMS) programme; a Medication Guide comes with each supply
- Needles and devices go in a sharps container

## Pregnancy and breastfeeding

It may harm the fetus: effective contraception is used during treatment and for a time after the last dose, and breastfeeding is avoided.

## Nursing care

- Confirm vaccinations before the first dose
- Teach the warning signs of meningococcal infection and to seek care at once
- Teach the patient to carry the safety card during treatment and for 2 months after
- Warn that stopping without advice can trigger haemolysis and clots

## Pharmacokinetics

**Absorption**
Subcutaneous infusion with a pump or on-body injector

## Memory aid

«PEG on C3»: pegcetacoplan sits higher up the cascade (C3) than the C5 antibodies.

## Test yourself

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

## Which complement protein does pegcetacoplan block?

C3.

## Why can a C3 inhibitor help PNH patients who stay anaemic on a C5 inhibitor?

It also stops the C3 coating that leads to red-cell removal outside the vessels.

## How is pegcetacoplan given?

By subcutaneous infusion with a pump or on-body injector.

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

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 2

- [Eculizumab](https://durgical.com/en/pharmacology/eculizumab/)
- [Ravulizumab](https://durgical.com/en/pharmacology/ravulizumab/)

## Related conditions 1

- [Paroxysmal nocturnal haemoglobinuria](https://durgical.com/en/conditions/paroxysmal-nocturnal-haemoglobinuria/)

[← Back to the class: Complement inhibitors](https://durgical.com/en/pharmacology/classes/complement-inhibitors/)

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

Sources: [Pegcetacoplan Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a621045.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L04AJ&showdescription=no) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [2QKI: Human C3c in complex with the inhibitor compstatin](https://www.rcsb.org/structure/2QKI) (RCSB Protein Data Bank, 2007).

## **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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Source: https://durgical.com/en/pharmacology/pegcetacoplan/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/pegcetacoplan/