Issues for surgery
For treatment of hypertension – loss of blood pressure (BP) control if omitted.
For treatment of angina – exacerbation of angina if omitted.
For treatment of arrhythmias – exacerbation of arrhythmias if omitted.
For treatment of cluster headache - exacerbation of symptoms if omitted.
Risk of hypotension when continued.
Advice in the perioperative period
Elective and emergency surgery
Continue – monitor BP and heart rate.
Post-operative advice
Restart post-operatively when next dose is due.
Monitor BP and heart rate.
Interactions with common anaesthetic agents
Inhalational Anaesthetics
See also Hypotension below.
Verapamil may reduce the minimum alveolar concentration (MAC) of inhalational anaesthetics by up to 20%.
Hypotension
Verapamil can increase the risk of hypotension when used concomitantly with remifentanil or inhalational / intravenous anaesthetics.
Concomitant use of verapamil with alfentanil / fentanyl may increase the risk of hypotension.
Bradycardia
Verapamil can increase the risk of bradycardia when used concomitantly with the following:
- alfentanil, fentanyl or remifentanil (also see below)
- neostigmine
- propofol
- suxamethonium
Alfentanil, fentanyl and remifentanil
See also Bradycardia and Hypotension above.
Verapamil may increase the effects of alfentanil, fentanyl and remifentanil – monitor for opioid adverse effects (e.g. prolonged sedation, respiratory depression) and adjust dose as necessary.
Midazolam
Verapamil may increase the plasma concentration and prolong the half-life of midazolam. Care should be taken when prescribing short-acting benzodiazepines metabolised by the CYP3A4 pathway. Consider using a lower initial dose (a 50% reduction has been suggested).
Neuromuscular blocking drugs (NMBDs)
Verapamil may prolong neuromuscular blockade when used concomitantly with NMBDs. The clinical significance is unknown, but bear the potential interaction in mind in case of unexpected response to treatment.
Dantrolene
Intravenous dantrolene potentially increases the risk of acute hyperkalaemia and cardiovascular collapse when given with verapamil. It is recommended that co-administration of verapamil with dantrolene should be avoided.
Interactions with other common medicines used in the perioperative period
Hypotension
Verapamil can increase the risk of hypotension when used concomitantly with droperidol or prochlorperazine.
Oxycodone
Verapamil are predicted to increase the exposure to oxycodone – monitor for prolonged sedation and respiratory depression. The dose of oxycodone may need to be reduced.
Macrolide antibiotics
Macrolide antibiotics (e.g. clarithromycin, erythromycin), which are inhibitors of CYP3A4, may increase the effects of verapamil leading to hypotension and bradycardia. Monitor the patient and consider reducing the dose of the verapamil if necessary.
Whilst single surgical prophylactic doses should not pose a problem, continued post-operative treatment may require close monitoring. Consult current product literature.
Further information
None relevant.
References
The Joint Task Force on non-cardiac surgery: cardiovascular assessment and management of the European Society of Cardiology (ESC) and the European Society of Anaesthesiology (ESA). 2014 ESC/ESA Guidelines on non-cardiac surgery: cardiovascular assessment and management. European Heart Journal. 2014; 35:2383-2431
Scarth E, Smith S. Drugs in Anaesthesia and Intensive Care, 5th Edition. Oxford University Press; 2016
British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 12th April 2019]
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 12th April 2019]
Dantrolene Sodium. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 9th October 2019]
Diazepam. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 12th April 2019]
Verapamil. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 9th October 2019]
Summary of Product Characteristics – Securon SR® (verapamil). Mylan. Accessed via www.medicines.org.uk 09/10/2019 [date of revision of the text May 2017]