[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [GnRH analogues (agonists and antagonists)](https://durgical.com/en/pharmacology/classes/gnrh-analogues/) › Relugolix

# Relugolix

## GnRH analogues (agonists and antagonists)?

GnRH analogues (agonists and antagonists)

## High alert?

An error with this medicine can cause serious harm: double checks and protocols are used.

Oral non-peptide GnRH antagonist taken once a day for advanced prostate cancer. Testosterone falls fast with no flare; watch the QT and heart.

Updated Nov 1, 2026

## Quick facts

**Group**
[GnRH analogues (agonists and antagonists)](https://durgical.com/en/pharmacology/classes/gnrh-analogues/)

**Target**
Gonadotropin-releasing hormone receptor (GnRH-R) on pituitary gonadotroph cells

**Used for**
Advanced prostate cancer

**Key effects**
Hot flushes · Muscle · Tiredness

**Monitor**
Glucose · Signs of heart attack or stroke

**ATC**
L02BX04

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

On this page

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

- Clinical What the labels mean

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

- Study Test yourself

- Connections Connections

## Mechanism of action

Relugolix is an orally active, non-peptide antagonist that competes reversibly with GnRH at its pituitary receptor. LH and FSH fall quickly and, with them, testicular testosterone reaches castrate levels, without the initial testosterone surge (flare) that GnRH agonists cause. Prostate cancer cells that depend on testosterone slow or stop growing.

- Relugolix blocks pituitary GnRH receptors
- LH and FSH fall fast, with no flare
- Testosterone drops to castrate levels; the tumour slows

## Indications

- Advanced prostate cancer. [Prostate cancer →](https://durgical.com/en/conditions/prostate-cancer/)

## Adverse effects

### Common

- Hot flushes, sweating, flushing
- Muscle, back, joint and bone pain
- Tiredness, diarrhoea, constipation
- Less sexual desire or ability; breast enlargement; weight gain
- Raised glucose, triglycerides and liver enzymes; anaemia

### Serious (rare, important)

- QT prolongation and arrhythmia
- Heart attack and stroke
- Severe allergic reactions with facial swelling or trouble breathing

## Contraindications

- Not stated in the sources used; congenital long QT and uncorrected electrolyte problems call for great caution

## Key interactions

**P-glycoprotein inhibitors (e.g., erythromycin)**
Raise relugolix levels.

**Rifampicin and St John's wort (inducers of P-glycoprotein and CYP3A4)**
Lower relugolix levels and may reduce testosterone suppression.

**Drugs that prolong the QT interval**
May add to the QT prolongation that relugolix can cause.

## What is monitored

- PSA and testosterone to confirm the response
- ECG and electrolytes when there are QT risk factors
- Glucose, triglycerides, liver tests and haemoglobin
- Signs of heart attack or stroke

## Administration and safety

- Oral tablet once a day at about the same time, swallowed whole.
- If more than a week of doses is missed, treatment is restarted with a loading dose after talking to the doctor.
- Every new medicine and St John's wort is reviewed with the pharmacist.

## Pregnancy and breastfeeding

Can harm a fetus or cause pregnancy loss; men with partners who could become pregnant use effective contraception during treatment and for two weeks after the last dose.

## Nursing care

- Ask about long QT syndrome (personal or family), electrolyte problems, heart failure, diabetes, high triglycerides, anaemia and liver problems.
- Teach the warning signs of heart attack and stroke, and to report fainting or a racing heart.
- Explain hot flushes and sexual side effects, and ask about mood.
- Tell the laboratory before tests that the patient takes relugolix.

## Pharmacokinetics

**Absorption**
Oral tablet once a day, with or without food; a loading dose starts treatment, and steady state comes in about a week. P-glycoprotein limits its absorption.

**Metabolism**
Mainly CYP3A4.

**Elimination**
Mostly in the faeces as metabolites.

## Memory aid

RELUgolix = RELIEF from the flare, by mouth: castration with no testosterone surge. The price: QT, heart and metabolic checks.

## Test yourself

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

## What advantage does relugolix share with degarelix over leuprorelin in prostate cancer?

No initial testosterone flare, because it blocks the GnRH receptor instead of first stimulating it.

## How is relugolix given, compared with degarelix?

Relugolix is an oral daily tablet; degarelix is a subcutaneous depot injection.

## Which ECG change is a serious risk with relugolix?

QT prolongation.

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

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

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 3

- [Degarelix](https://durgical.com/en/pharmacology/degarelix/)
- [Leuprorelin](https://durgical.com/en/pharmacology/leuprorelin/)
- [Elagolix](https://durgical.com/en/pharmacology/elagolix/)

## Related conditions 1

- [Prostate cancer](https://durgical.com/en/conditions/prostate-cancer/)

[← Back to the class: GnRH analogues (agonists and antagonists)](https://durgical.com/en/pharmacology/classes/gnrh-analogues/)

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

Sources: [Relugolix: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a621006.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L02BX04) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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