[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/) › Betamethasone

[Pharmacology](https://durgical.com/en/pharmacology/) · [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

# Betamethasone

A potent, long-acting corticosteroid. Given to the mother before a preterm birth, it helps the baby's lungs mature.

Updated 2026-11-01

- Class: [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)
- Receptor: Glucocorticoid receptor (GR), a nuclear receptor
- ATC code: H02AB01
- WHO Model List of Essential Medicines

◎**Glucocorticoid receptor (GR), a nuclear receptor**Betamethasone

ⓘ The figure shows dexamethasone in the ligand-binding pocket of the human glucocorticoid receptor; betamethasone, which differs from dexamethasone only in the orientation of one methyl group, binds the same pocket.

**Target in 3D:** Glucocorticoid receptor (GR), a nuclear receptor. PDB structure 1M2Z (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1M2Z) · Drag to rotate · pinch to zoom

## Mechanism of action

Betamethasone is a fluorinated glucocorticoid that binds the glucocorticoid receptor; the complex enters the nucleus, switches on anti-inflammatory genes and represses NF-κB and AP-1. It has practically no salt-retaining effect and a long duration. It crosses the placenta well, and in the fetal lung it speeds surfactant production and maturation.

- Betamethasone binds the glucocorticoid receptor
- The complex changes gene transcription in the nucleus
- Inflammatory mediators fall; in the fetal lung, surfactant rises

## Pharmacokinetics

**Absorption**
IM injectable suspension (phosphate plus acetate), oral and topical forms

**Distribution**
Crosses the placenta more readily than cortisol, which suits fetal lung maturation

**Half-life**
Long-acting; the acetate part of the suspension is released slowly

## Indications

- Fetal lung maturation when preterm birth is expected
- Rheumatic diseases and acute gouty arthritis (intra-articular or IM) [Gout →](https://durgical.com/en/conditions/gout/)
- Severe allergic states, including allergic rhinitis [Allergic rhinitis →](https://durgical.com/en/conditions/allergic-rhinitis/)
- Inflammatory skin diseases (topical forms)

## Adverse effects

### Common

- Hyperglycaemia, including in the mother after antenatal doses
- Insomnia and mood changes
- Pain or skin changes at the injection site
- Skin thinning with topical use

### Serious (rare, important)

- Infections, which the drug can also mask
- Adrenal suppression: adrenal insufficiency if stopped abruptly after prolonged use
- Osteoporosis and fractures with long use
- Peptic ulcer and gastrointestinal bleeding, especially with NSAIDs
- Posterior subcapsular cataract and glaucoma
- Psychiatric reactions (euphoria, depression, psychosis)

## Contraindications

- Systemic fungal infections
- Hypersensitivity to the product
- Live or live attenuated vaccines during immunosuppressive doses

## Key interactions

**CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, barbiturates)**
Faster clearance and a weaker corticosteroid effect

**Strong CYP3A4 inhibitors (ketoconazole)**
Higher corticosteroid levels and more side effects

**Aspirin and other NSAIDs**
Higher risk of gastrointestinal ulcer and bleeding

**Potassium-depleting drugs (loop or thiazide diuretics, amphotericin B)**
Hypokalaemia; with digoxin, more risk of arrhythmia

## What is monitored

- Maternal glucose after antenatal doses, especially with diabetes
- Blood pressure and weight
- Potassium
- Signs of infection

## Administration and safety

- The phosphate-acetate suspension is for IM or local injection only: never IV
- The suspension is shaken before drawing it up
- Epidural injection of corticosteroids has caused serious neurological events

## Nursing care

- For antenatal courses, record the time of each injection; the course is timed in relation to delivery
- Check maternal glucose after the doses
- Watch for infection: fever and other signs may be blunted
- Watch mood and sleep; report agitation, depression or confusion

## Pregnancy and breastfeeding

Used in pregnancy on purpose for fetal lung maturation when preterm birth is expected; other uses weigh benefit against risk.

## Memory aid

BETA for the BABY: the mother's injection crosses the placenta and Brings the baby's lungs Early to maturity.

## Test yourself

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

## Why is betamethasone given to a mother at risk of preterm birth?

It crosses the placenta and speeds fetal lung maturation and surfactant production, lowering neonatal respiratory distress syndrome.

## Why is the betamethasone phosphate-acetate suspension never given IV?

It is a particulate suspension for IM or local injection; the slowly released acetate particles are not meant for the bloodstream.

## Which two common corticosteroids are stereoisomers?

Betamethasone and dexamethasone: they differ only in the orientation of the methyl group at carbon 16.

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

## Related drugs

- [Dexamethasone](https://durgical.com/en/pharmacology/dexamethasone/)
- [Prednisolone](https://durgical.com/en/pharmacology/prednisolone/)

## Related conditions

- [Gout](https://durgical.com/en/conditions/gout/)
- [Allergic rhinitis](https://durgical.com/en/conditions/allergic-rhinitis/)

[← Back to the class: Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

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

Sources: [Betamethasone Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a626077.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - BETAMETHASONE SODIUM PHOSPHATE AND BETAMETHASONE ACETATE injection, suspension](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=335f17e7-069d-456c-8507-26253692f2ee) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H02AB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 39 (McGraw Hill, 2025).

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Representative model, for educational purposes only.

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