[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Beta-2 adrenergic agonists](https://durgical.com/en/pharmacology/classes/beta-2-adrenergic-agonists/) › Salmeterol

[Pharmacology](https://durgical.com/en/pharmacology/) · [Beta-2 adrenergic agonists](https://durgical.com/en/pharmacology/classes/beta-2-adrenergic-agonists/)

# Salmeterol

A long-acting beta-2 agonist with a slow onset, used twice a day. In asthma it is always combined with an inhaled corticosteroid; never a reliever.

Updated 2026-11-01

- Class: [Beta-2 adrenergic agonists](https://durgical.com/en/pharmacology/classes/beta-2-adrenergic-agonists/)
- Receptor: Beta-2 adrenergic receptor
- ATC code: R03AC12

◎**Beta-2 adrenergic receptor**Salmeterol

ⓘ The figure shows salmeterol bound to the human beta-2 adrenergic receptor (crystal structure of an engineered receptor).

**Target in 3D:** Beta-2 adrenergic receptor. PDB structure 6MXT (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6MXT) · Drag to rotate · pinch to zoom

## Mechanism of action

Salmeterol is a lipophilic, selective partial agonist of the beta-2 receptor. Its long side chain anchors it near the receptor, so the head group keeps activating the receptor for about twelve hours. The resulting rise in cyclic AMP relaxes airway smooth muscle. Its onset is slow, so it cannot relieve an acute attack.

- Salmeterol's long tail anchors it near the beta-2 receptor
- The head group repeatedly activates the receptor
- Cyclic AMP rises and airway muscle relaxes
- Bronchodilation starts slowly but lasts about twelve hours

## Pharmacokinetics

**Metabolism**
Extensively hydroxylated by CYP3A4 in the liver

**Elimination**
Mainly in the faeces

**Half-life**
Terminal half-life about 12 hours

**Onset and duration**
Slow onset, so it is not suitable for acute symptoms

## Indications

- Asthma, combined with an inhaled corticosteroid (for example fluticasone + salmeterol) [Asthma →](https://durgical.com/en/conditions/asthma/)
- Maintenance treatment of COPD [Chronic obstructive pulmonary disease (COPD) →](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/)
- Prevention of exercise-induced bronchospasm

## Adverse effects

### Common

- Headache
- Tremor and palpitations
- Nasopharyngitis and cough

### Serious (rare, important)

- Serious asthma-related events, including death, when used without an inhaled corticosteroid
- Paradoxical bronchospasm
- Tachycardia, arrhythmia and QT prolongation, especially with strong CYP3A4 inhibitors
- Hypokalaemia and hyperglycaemia

## Contraindications

- Use without an inhaled corticosteroid in asthma
- Primary treatment of status asthmaticus or acute episodes
- Severe hypersensitivity to milk proteins (lactose-containing powder inhalers) or any component

## Key interactions

**Strong CYP3A4 inhibitors (ketoconazole, ritonavir)**
Large rise in salmeterol levels with QT prolongation and palpitations; avoided

**Beta blockers**
Block its effect and may cause severe bronchospasm

**Non-potassium-sparing diuretics**
Additive hypokalaemia and ECG changes

**Monoamine oxidase inhibitors or tricyclic antidepressants**
Stronger effects on the vascular system

## What is monitored

- Asthma control and reliever use
- Heart rate and rhythm
- Potassium in high-risk patients

## Administration and safety

- Oral inhalation by dry powder or pressurised inhaler, usually in a combination product with fluticasone
- Not used for sudden symptoms; a short-acting reliever is kept at hand
- Not combined with another LABA product
- After a combination inhaler with a steroid, the mouth is rinsed and the water spat out

## Nursing care

- Check that an inhaled corticosteroid is part of the asthma treatment
- Teach that it does not relieve an attack and that the reliever is a different inhaler
- Check heart rate and ask about palpitations and tremor
- Review the medicine list for strong CYP3A4 inhibitors

## Pregnancy and breastfeeding

Human data are limited; asthma control is the priority, because poorly controlled asthma harms mother and fetus.

## Memory aid

SALMeterol is a SLOW SALMON: a long tail anchors it, it swims in slowly and stays twelve hours; never alone in asthma.

## Test yourself

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

## Why is salmeterol never used as a reliever?

Its onset of action is slow; relief of sudden symptoms needs a fast agent such as salbutamol.

## What feature of the salmeterol molecule explains its long action?

A long lipophilic side chain that anchors it near the beta-2 receptor, so the head group keeps activating it.

## Which antifungal greatly increases salmeterol levels and the risk of QT prolongation?

Ketoconazole, a strong CYP3A4 inhibitor (ritonavir does the same).

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

## Related drugs

- [Formoterol](https://durgical.com/en/pharmacology/formoterol/)
- [Salbutamol](https://durgical.com/en/pharmacology/salbutamol/)
- [Fluticasone](https://durgical.com/en/pharmacology/fluticasone/)

## Related conditions

- [Asthma](https://durgical.com/en/conditions/asthma/)
- [Chronic obstructive pulmonary disease (COPD)](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/)

[← Back to the class: Beta-2 adrenergic agonists](https://durgical.com/en/pharmacology/classes/beta-2-adrenergic-agonists/)

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

Sources: [Salmeterol Oral Inhalation: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a695001.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - FLUTICASONE PROPIONATE AND SALMETEROL powder, metered](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=43a27267-2f2b-410d-9c30-9cb95f35d9a1) (DailyMed (U.S. National Library of Medicine), 2024); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=R03AC12) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 44 (McGraw Hill, 2023).

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Representative model, for educational purposes only.

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