Isoprenaline is a synthetic non-selective β adrenoreceptor agonist that is structurally similar to adrenaline. Through stimulation of both β1 and β2 adrenoceptors isoprenaline produces an increase in cardiac output by increasing both myocardial contractility and relaxation as well as heart rate and intracardiac conduction velocities. It also relaxes bronchial, gastrointestinal and uterine smooth muscle, causes peripheral vasodilatation and triggers glucagon release from the pancreas and hepatic glycogenolysis.

Isoprenaline is immediately active upon infusion with a half-life of 2.5 to 5 minutes. Conjugation in hepatic and pulmonary tissues is the major method of metabolism. Excretion occurs via urine in the form of sulfate conjugates.

This protocol is for use of isoprenaline (Isoproterenol) on the Coronary Care Unit and in the cardiac catheter laboratory only, but it would be reasonable to use the drug in other higher dependency areas following discussion with Cardiology. It is not for use on the general wards unless to facilitate transfer to CCU. The use of isoprenaline is also indicated during electrophysiology procedures to provoke tachyarrhythmias in the cardiac catheter laboratory under the direction of a cardiac electrophysiologist.

On CCU isoprenaline is indicated in low cardiac output states primarily due to bradycardia with systemic hypotension, signs of cerebral hypoperfusion, progressive heart failure, angina, or life-threatening ventricular arrhythmia.

Indications include:

1. Heart block that requires transvenous pacing, but when pacing is not immediately available. It is preferred to external pacing which often fails to capture the ventricular myocardium.

2. To prevent ventricular arrhythmias secondary to complete heart block, including torsades de pointes

3. Beta-blocker overdose

4. Electrical storm in Brugada patients

5. Ventricular fibrillation in short QT syndrome

6. Bradycardias in heart transplant patients

7. Provocation of tachyarrhythmias during electrophysiology study

1. Cardiac ischaemia - causes an increase in myocardial oxygen demand

2. Pre-existing ventricular arrhythmias (except in the specific conditions described above)

3. Digoxin intoxication (absolute contraindication)

4. Sulfa allergy - contains sulphites.

5. Diabetes - may increase blood glucose levels

6. Distributive shock - beta-2 agonism will decrease total peripheral resistance

7. Hyperthyroidism - may induce thyroid storm

8. Pregnancy or breast feeding

1. Bradycardias, including AV nodal block, sick sinus syndrome, beta-blocker overdose: 2 to 10 mcg/minute titrated to desired effect

2. Brugada syndrome (off-label): Bolus 1 to 2 mcg followed by 0.15 to 0.3 mcg/minute for 24 hours

3. Cardiogenic shock (off-label): 2 to 20mcg/minute continuous infusion

4. Refractory torsades de pointes (off-label): 2 to 10 mcg/minute continuous infusion titrated to patient response

5. Provocation of tachyarrhythmias during electrophysiology study: 2 to 10 mcg/minute titrated to desired effect

Isoprenaline has a low pH so is preferably administered via a central venous access to avoid potential venous irritation, but this is not essential. An infusion pump should be used. Isoprenaline is an unlicensed preparation. It is available in various strengths and salts.

Currently stock at FHFT is isoprenaline hydrochloride in 2

Check salt and strength of isoprenaline preparation before administering.

This medicine has a low pH and may cause venous irritation and tissue damage in cases of extravasation. If a central venous access device is unavailable, administer via a large peripheral vein monitoring insertion site closely using a recognised phlebitis scoring tool. Re-site cannula at first signs of inflammation.

Discard the injection if it is pinkish or darker than slightly yellow or contains a precipitate. Protect unopened ampoules from light. Store below 25^oC. Do not freeze.

Expiry time of infusion – 24 hours

1. Remove 10mls from a 500ml bag of 5% Glucose. (Do NOT use Sodium Chloride 0.9%).

2. Add 10mls of Isoprenaline 1mg in 5ml.

3. Agitate to mix. This provides a final concentration of 2mg in 500mls, which is equivalent to 4mcg/ml. Discard if discoloured or precipitates.

4. Commence infusion at a rate of 1mcg/min (15mls/hr).

5. Consider titrating up in steps of 1mcg/min at intervals of 2-3 minutes, until a satisfactory heart rate is achieved or adverse effects such as hypotension or ventricular arrhythmias occur (Usual max: 10mcg/min)

1. Remove 10mls from a 50ml bag of 5% Glucose. (Do NOT use Sodium Chloride 0.9%)

2. Add 10mls of Isoprenaline 1mg in 5ml. Agitate to mix. This provides a final concentration of 2mg in 50mls, which is equivalent to 40mcg/ml. Discard if discoloured or precipitates.

3. Commence infusion at a rate of 1mcg/min (1.5mls/hr)

4. Consider titrating up in steps of 1mcg/min at intervals of 2-3 minutes, until a satisfactory heart rate is achieved or adverse effects such as hypotension or ventricular arrhythmias occur (usual max: 10mcg/min)

1. Common: Headache, dizziness, upset stomach, flushing, fatigue, nervousness

2. Cardiovascular: angina, flushing, hypotension, hypertension, palpitations, ventricular arrhythmia, premature ventricular contractions, Adams-stokes syndrome

3. Respiratory: dyspnoea, oedema

4. Ophthalmic: blurred vision

5. Central Nervous System: headache, dizziness, nervousness, restlessness, seizures

6. Gastrointestinal: nausea, vomiting

7. Endocrine & Metabolic: hypokalaemia, increased serum glucose

8. Musculoskeletal: tremor, weakness

Vital signs including heart rate, respiratory rate and blood pressure should be monitored. The patient should have continuous ECG monitoring. Arterial blood gas analysis should be considered. Serum glucose levels, potassium and magnesium levels require regular measurement. The administration site should be examined for irritation.

Use Medusa.

https: www.medusaimg.nhs.uk/ or access via intranet

1. Merchant RM et al. Part 1: Executive Summary: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation [Internet]. 2020 [cited 2024 Jun 6]; 142(16 Suppl 2):S337-S357. Available from: https://doi.org/10.1161/CIR.0000000000000918 .

2. Panchal AR et al. Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation [Internet]. 2020 [cited 2024 Jun 6]; 142(16 Suppl 2);S366-S468. Available from: https://doi.org/10.1161/CIR.0000000000000916

3. Van Diepen S et al. American Heart Association Council on Clinical Cardiology; Council on Cardiovascular and Stroke Nursing; Council on Quality of Care and Outcomes Research; and Mission: Lifeline. Contemporary Management of Cardiogenic Shock: A Scientific Statement From the American Heart Association. Circulation. 2017 Oct 17;136(16):e232-e268. Optional link to full-text: https://doi.org/10.1161/CIR.0000000000000525

4. Al-Khatib SM et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. Circulation. 2018 Sep 25;138(13):e272-e391.

5. Page RL et al. 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2016 Apr 5;133(14):e506-74. doi: 10.1161/CIR.0000000000000311. Optional link to full-text: https://doi.org/10.1161/CIR.0000000000000549

6. Denis A et al. Diagnostic value of isoproterenol testing in arrhythmogenic right ventricular cardiomyopathy. Circ Arrhythm Electrophysiol. 2014 Aug;7(4):590-7. Optional link to full-text: https://doi.org/10.1161/CIRCEP.113.001224

This guideline has been registered with the Trust. However, clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt, contact a senior colleague or expert. Caution is advised when using guidelines after the review date.

This guideline is for use in Frimley Health NHS Foundation Trust hospitals only. Any use outside this location will not be supported by the Trust and will be at the risk of the individual using it.

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