Pharmacology · Beta-2 adrenergic agonists

Terbutaline !

A short-acting beta-2 agonist given by injection, tablet or inhaler for bronchospasm. Its boxed warning forbids prolonged use to stop preterm labour.

Updated 2026-11-01

Class: Beta-2 adrenergic agonists
Receptor: Beta-2 adrenergic receptor
ATC code: R03AC03

Beta-2 adrenergic receptorTerbutaline

No structure of terbutaline on the beta-2 receptor exists. The figure shows salbutamol, a closely related short-acting agonist in the same site, bound to the human beta-2 receptor.

Target in 3D: Beta-2 adrenergic receptor. PDB structure 7DHI (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Terbutaline acts preferentially on beta-2 receptors. Raising cyclic AMP relaxes bronchial smooth muscle and also uterine and vascular smooth muscle. By injection or by mouth it reaches the whole body, so tachycardia, tremor, hypokalaemia and hyperglycaemia are more marked than with an inhaled agonist.

Terbutaline activates beta-2 receptors
Cyclic AMP rises in smooth muscle cells
Bronchial muscle relaxes and bronchospasm is reversed
Given systemically, it also relaxes the uterus and speeds the heart

Pharmacokinetics

Absorption: Given by subcutaneous injection, by mouth or by inhalation
Elimination: Mostly in urine, largely unchanged
Half-life: A few hours, with wide variation between people
Onset and duration: Within minutes after subcutaneous injection

Indications

Prevention and reversal of bronchospasm in asthma Asthma →
Reversible bronchospasm in chronic bronchitis and emphysema Chronic obstructive pulmonary disease (COPD) →

Adverse effects

Common

Tremor and nervousness
Tachycardia and palpitations
Headache and dizziness
Pain at the injection site

Contraindications

Prolonged tocolysis (injection) and any tocolysis by mouth (boxed warning)
Hypersensitivity to sympathomimetic amines
Caution in heart disease, arrhythmias, hypertension, diabetes, hyperthyroidism and seizure disorders

Key interactions

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 cardiovascular effects

What is monitored

Heart rate, rhythm and blood pressure
Potassium and glucose
Breathing and oxygen saturation
In pregnancy: maternal and fetal heart rate, and newborn glucose

Administration and safety

The injection is given subcutaneously (usually the lateral deltoid area), not as an intravenous infusion
Single-use vials: the unused part is discarded
Not used for prolonged tocolysis, or for tocolysis at home or by mouth (boxed warning)

Nursing care

Check heart rate and blood pressure before and after each dose; hold and report marked tachycardia or chest pain
Check potassium and glucose, especially with repeated doses or in diabetes
In pregnant patients, watch for breathlessness, chest pain or crackles (pulmonary oedema) and monitor the fetal heart rate
Teach that tremor and palpitations are common and to report chest pain or an irregular heartbeat

Pregnancy and breastfeeding

No adequate human studies; it is not used for prolonged or oral tocolysis because of serious maternal heart problems and deaths, and it can cause fetal tachycardia and neonatal hypoglycaemia.

Test yourself

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

What is terbutaline's boxed warning?

It must not be used for prolonged tocolysis by injection, or for any tocolysis by mouth, because of serious maternal adverse effects, including death.

Which maternal complications have been reported when terbutaline was used to stop labour?

Tachycardia, arrhythmias, pulmonary oedema, myocardial ischaemia, hypokalaemia and hyperglycaemia.

Which effect in the newborn can follow maternal terbutaline?

Hypoglycaemia (and fetal tachycardia before birth).

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

Sources: DailyMed - TERBUTALINE SULFATE injection (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - TERBUTALINE SULFATE tablet (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.