[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Vasopressors and inotropes](https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/) › Isoprenaline

[Pharmacology](https://durgical.com/en/pharmacology/) · [Vasopressors and inotropes](https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/)

# Isoprenaline

A pure beta agonist given intravenously. It speeds and strengthens the heart and relaxes the bronchi; it can bridge bradycardia or heart block until pacing.

Updated 2026-11-01

- Class: [Vasopressors and inotropes](https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/)
- Receptor: Beta-1 and beta-2 adrenergic receptors
- ATC code: C01CA02

## ⚠ High-alert medication

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

Also called: Isoproterenol

◎**Beta-1 and beta-2 adrenergic receptors**Isoprenaline

ⓘ The figure shows isoprenaline bound to the human beta-1 adrenergic receptor in complex with a Gs protein (cryo-EM).

**Target in 3D:** Beta-1 and beta-2 adrenergic receptors. PDB structure 8S2T (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8S2T) · Drag to rotate · pinch to zoom

## Mechanism of action

Isoprenaline is a potent non-selective beta agonist with very low affinity for alpha receptors. Beta-1 stimulation raises heart rate, conduction and contractility; beta-2 stimulation relaxes bronchial and vascular smooth muscle, lowering peripheral resistance and diastolic pressure.

- Isoprenaline stimulates beta-1 and beta-2 receptors
- Beta-1: faster rate, faster conduction, stronger contraction
- Beta-2: bronchodilation and vasodilation; diastolic pressure falls

## Pharmacokinetics

**Metabolism**
Mainly by COMT in the liver and other tissues

**Half-life**
Short; the effect fades soon after the infusion stops

## Indications

- Distributive shock or shock from low cardiac output, to improve haemodynamics
- Bronchospasm during anaesthesia
- Emergency treatment of bradycardia or heart block until pacing is available [Atrioventricular (heart) block →](https://durgical.com/en/conditions/atrioventricular-block/)

## Adverse effects

### Common

- Tachycardia and palpitations
- Nervousness, headache and dizziness
- Flushing, sweating, tremor and nausea
- Dyspnoea

### Serious (rare, important)

- Tachyarrhythmias and ventricular arrhythmias
- Angina and myocardial ischaemia
- Pulmonary oedema
- Adams-Stokes attacks

## Contraindications

- Tachycardia
- Ventricular arrhythmias
- Angina pectoris

## Key interactions

**Epinephrine**
Both stimulate the heart: serious arrhythmias; not given at the same time

**Tricyclic antidepressants, MAO inhibitors, levothyroxine and some antihistamines**
Stronger response to isoprenaline

**Beta blockers such as propranolol**
Cardiac and bronchodilating effects are antagonised

## What is monitored

- Continuous ECG and heart rate
- Blood pressure
- Chest pain and signs of ischaemia

## Administration and safety

- Intravenous infusion by pump after dilution; use the diluted solution promptly.
- Do not use the solution if it is pinkish, darker than slightly yellow or contains a precipitate.
- Do not run it at the same time as epinephrine.
- Start at the lowest rate and increase gradually according to response.

## Nursing care

- Continuous ECG: report a heart rate above the set target, new arrhythmias or chest pain.
- Check blood pressure often; diastolic pressure tends to fall.
- In heart block, the pacing team is alerted early; isoprenaline is a bridge.

## Pregnancy and breastfeeding

Human data are limited; it is used when the maternal condition requires it.

## Memory aid

ISOprenaline: ISOlated beta (no alpha): fast heart, open bronchi, low diastolic.

## Test yourself

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

## Why does isoprenaline lower diastolic pressure while raising heart rate?

It stimulates beta-2 receptors that dilate vessels (especially in skeletal muscle) and has almost no alpha effect, while beta-1 speeds the heart.

## Which three conditions contraindicate isoprenaline?

Tachycardia, ventricular arrhythmias and angina pectoris.

## Why must isoprenaline and epinephrine not be given together?

Both are direct cardiac stimulants, and their combined effect can cause serious arrhythmias.

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

## Related drugs

- [Epinephrine](https://durgical.com/en/pharmacology/epinephrine/)
- [Dobutamine](https://durgical.com/en/pharmacology/dobutamine/)
- [Propranolol](https://durgical.com/en/pharmacology/propranolol/)

## Related conditions

- [Atrioventricular (heart) block](https://durgical.com/en/conditions/atrioventricular-block/)

[← Back to the class: Vasopressors and inotropes](https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/)

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 - ISOPROTERENOL HYDROCHLORIDE injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=86b2455a-0489-405e-bd0b-9f79d3c5350d) (DailyMed (U.S. National Library of Medicine), 2022); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C01CA02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 14 (McGraw Hill, 2023).

## **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.

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