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    This best practice guideline has been designed for critical care units, however, it can be applied to other areas within your health service who use vasoactive infusions, such as anaesthetics, cardiology and emergency departments.

    Mechanism of action/pharmacology

    Isoprenaline is a non-selective β-adrenergic agonist.1,2 It has positive inotropic and chronotropic effects, increasing cardiac output by increasing the heart rate and cardiac contractility.1,2 Isoprenaline also decreases diastolic blood pressure by lowering peripheral vascular resistance.1,2

    Onset of action: Immediate.3

    Duration of action (IV): 10–15 minutes.3

    Half-life: 2.5–5 minutes3

    Indications

    Heart block.2

    Bradycardia with haemodynamic compromise.2

    Precautions

    • Hypersensitivity to isoprenaline or any of the excipients4
    • Hypotension due to uncorrected hypovolaemia2,4
    • Tachyarrhythmias4
    • Recent myocardial infarction – may increase myocardial oxygen demand2,4
    • Angina – may exacerbate2
    • Heart block due to digoxin toxicity4
    • Phaeochromocytoma.2

    ​​​​​​​Medication presentation

    1 mg/5mL ampoule (1:5000)

    Also available as 200 microg/1mL ampoule (1:5000); however, due to the number of vials that would be required, this concentration is not usually used to prepare infusions.

    Medication storage

    Store ampoules below 25°C. Protect from light.5

    Infusion solutions are stable for up to 24 hours.6

    Preparation

     

    Infusion pump

    Syringe driver

    Prescribe

    6 mg in 100 mL

    3 mg in 50 mL

    Make up infusion in

    100 mL bag of glucose 5%*

    Glucose 5%* (to a total of 50 mL in the syringe)

    Volume to be removed from IV bag

    30 mL

    Not applicable

    Draw up 35 mL in the syringe

    Drug dose to be added

    6 mg (30 mL)

    3 mg (15 mL)

    Final volume

    100 mL

    50 mL

    Final concentration

    60 microg/mL

    60 microg/mL

    1mL/hr =

    1 microg/min

    1 microg/min

    *Glucose 5% is preferred for diluting all inotropes and vasopressors. However, isoprenaline is also compatible with sodium chloride 0.9%.5

    Administration - this guideline is intended for central access only

    Administer continuous intravenous infusion through a central access line.

    Infusions should be administered via a syringe driver or infusion pump, preferably with medication error reduction software enabled.

    Avoid administration in lines where other drugs or fluids may be bolused or flushed.

    Dosing

    Starting dose: 0.5 to 2 microg/min.

    Titrate in accordance with prescribed parameters – for example, by increments of 0.5 to 1 microg/min.

    Usual dose range: 2 to 10 microg/min.3

    Maximum dose: rates greater than 30microg/min have been used in advanced stages of shock.4

    Monitoring

    • Continuous blood pressure and cardiac monitoring for the duration of the infusion5
    • Daily 12-lead ECG
    • Monitor fluid balance and electrolytes at least daily, especially magnesium and potassium.

    Side effects

    • Tachycardia2
    • Hypotension2
    • Arrhythmias2
    • Angina.2

    Compatibilities

    Consult the following references, which are available online through the Clinicians Health Channel:

    Australian injectable drugs handbook

    Trissel’s™ in IV compatibility (Micromedex) – from the site homepage, select the ‘IV Compatibility’ tab.

    Important drug interactions

    • Combined use with other medications with beta-agonist effects (e.g. adrenaline) may increase the risk of arrhythmias.4
    • β-antagonists may decrease the efficacy of isoprenaline.2
    • Entacapone is a catechol-O-methyltransferase (COMT) inhibitor, which may inhibit the metabolism of isoprenaline, increasing the risk of side effects. Dose isoprenaline conservatively.2,7
    • Theophylline may potentiate hypokalaemia induced by isoprenaline, monitor potassium. Isoprenaline may also decrease theophylline concentration and consequently clinical effect. Monitor theophylline concentration and adjust accordingly.2

    References

    1. Micromedex [online] (accessed 20 January 2018)
    2. Australian medicines handbook (AMH) [online] (accessed 20 January 2018)
    3. Lexicomp [online] (accessed 20 January 2018)
    4. MIMS [online] (accessed 20 January 2018)
    5. Australian injectable drugs handbook (AIDH)[online] (accessed 20 January 2018)
    6. Injectable medicines guide (Medusa) – Isoprenaline – intravenous, Version 3 [online] (accessed 3 March 2017)
    7. Kane-Gill S, Dasta J (eds). High-risk IV medications in special patient populations. Springer-Verlag London, 2011

    Downloads

    Get in touch

    Centre of Clinical Excellence - Acute
    Safer Care Victoria

    Acknowledgements

    We would like to thank the pharmacists involved in writing the guidelines: Melissa Ankravs, Melanie Kowalski, Rachel Fyfe, Robyn Ingram, Annalie Jones, Susan Trevillian, and Lucy Sharrock. 

    Page last updated: 18 Nov 2020

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