[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Growth hormone receptor antagonists](https://durgical.com/en/pharmacology/classes/growth-hormone-receptor-antagonists/) › Pegvisomant

# Pegvisomant

## Growth hormone receptor antagonists?

Growth hormone receptor antagonists

An engineered form of growth hormone that blocks its receptor. Given under the skin, it brings IGF-1 back to normal in acromegaly.

Updated Nov 1, 2026

## Quick facts

**Group**
[Growth hormone receptor antagonists](https://durgical.com/en/pharmacology/classes/growth-hormone-receptor-antagonists/)

**Target**
Growth hormone receptor (GHR)

**Key effects**
Injection-site reactions · Headache · Infections

**Monitor**
IGF-1 to adjust treatment

**ATC**
H01AX01

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

◎**Growth hormone receptor (GHR)**Pegvisomant

ⓘ The figure shows natural human growth hormone bound to the extracellular part of its receptor. Pegvisomant is a modified growth hormone that occupies the same receptor but cannot switch it on.

**Target in 3D:** Growth hormone receptor (GHR). PDB structure 3HHR (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/3HHR) · Drag to rotate · pinch to zoom

Pegvisomant is human growth hormone with amino acid substitutions and attached polyethylene glycol (PEG) chains. The substitutions disrupt the second receptor-binding site, so it binds the GH receptor and causes its internalisation but cannot produce the conformational change that starts JAK-STAT signalling. IGF-1 production falls. PEG slows clearance, so the drug lasts much longer than natural GH. It does not reduce GH secretion by the tumour.

- Pegvisomant binds the GH receptor on liver and other cells
- Its altered second site cannot activate the receptor
- JAK-STAT signalling and IGF-1 production fall
- GH from the tumour keeps circulating but has no effect

## Indications

- Acromegaly with an inadequate response to surgery, radiotherapy or other drugs, alone or added to a somatostatin analogue [Acromegaly and gigantism →](https://durgical.com/en/conditions/acromegaly-and-gigantism/)

## Adverse effects

### Common

- Injection-site reactions
- Headache
- Infections (such as upper respiratory infections)
- Fatty lumps at injection sites (lipohypertrophy)

### Serious (rare, important)

- Raised liver enzymes
- Growth of the pituitary adenoma (loss of feedback)
- Systemic hypersensitivity reactions

## Contraindications

- Hypersensitivity to pegvisomant or its components
- Caution: unexplained raised liver transaminases before starting

## Key interactions

**Somatostatin analogues (octreotide, lanreotide)**
Intended combination: added when IGF-1 stays high on the analogue alone

## What is monitored

- IGF-1 to adjust treatment
- Liver function tests before and during treatment
- Pituitary MRI for tumour size
- Injection sites for lipohypertrophy

## Administration and safety

- Subcutaneous injection; sites are rotated to limit lipohypertrophy
- Laboratory GH values are not used to judge response; IGF-1 is
- Prescribed by specialists after surgery, radiotherapy or other drugs have not controlled acromegaly

## Pregnancy and breastfeeding

Information in pregnancy is limited; it is used only if the benefit justifies it.

## Nursing care

- Check liver tests before the first dose and at follow-up
- Teach injection technique and site rotation; look for lumps at sites
- Ask about headache or visual changes that could suggest tumour growth
- Ask about jaundice, dark urine or right upper abdominal pain

## Pharmacokinetics

**Absorption**
Given by subcutaneous injection; peak levels are reached days after a dose

**Elimination**
PEG chains reduce clearance

**Half-life**
About six days

## Memory aid

PEG-VISOMANT puts a PEG in the receptor's lock: the key fits but will not turn, so IGF-1 falls while GH stays high.

## Test yourself

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

## Why does GH not fall during pegvisomant treatment?

Pegvisomant blocks the GH receptor; it does not act on the pituitary tumour, and loss of IGF-1 feedback can even increase GH secretion.

## What is the role of PEG in pegvisomant?

The attached polyethylene glycol chains reduce clearance, giving a half-life of about six days instead of minutes.

## Which laboratory test is checked for safety before and during pegvisomant?

Liver function tests, because raised liver enzymes are its main laboratory adverse effect.

## Which marker shows that acromegaly is controlled on pegvisomant?

A normal IGF-1 level.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/pegvisomant/)

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

## Connections

## Related drugs 4

- [Octreotide](https://durgical.com/en/pharmacology/octreotide/)
- [Lanreotide](https://durgical.com/en/pharmacology/lanreotide/)
- [Pasireotide](https://durgical.com/en/pharmacology/pasireotide/)
- [Somatropin](https://durgical.com/en/pharmacology/somatropin/)

## Related conditions 1

- [Acromegaly and gigantism](https://durgical.com/en/conditions/acromegaly-and-gigantism/)

[← Back to the class: Growth hormone receptor antagonists](https://durgical.com/en/pharmacology/classes/growth-hormone-receptor-antagonists/)

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

Sources: [Pegvisomant for acromegaly](https://pmc.ncbi.nlm.nih.gov/articles/PMC5662428/) (Australian Prescriber (PubMed Central), 2017); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H01AX01) (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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Source: https://durgical.com/en/pharmacology/pegvisomant/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/pegvisomant/