This monograph does not cover use of diltiazem cream / ointment for anal fissure.
Issues for surgery
For treatment of hypertension – loss of blood pressure (BP) control if omitted.
For treatment of angina – exacerbation of angina if omitted.
Risk of hypotension when continued.
Advice in the perioperative period
Elective and emergency surgery
Continue – monitor BP and heart rate.
For patients taking modified-release preparations of diltiazem; confirm the specific manufacturer’s brand (see Further information).
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.
Diltiazem may reduce the minimum alveolar concentration (MAC) of inhalational anaesthetics by up to 20%.
Hypotension
Diltiazem can increase the risk of hypotension when used concomitantly with remifentanil or inhalational/intravenous anaesthetics.
Concomitant use of diltiazem with alfentanil / fentanyl may increase the risk of hypotension.
Bradycardia
Diltiazem 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.
Diltiazem 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
Diltiazem 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)
Diltiazem 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 diltiazem. It is recommended that co-administration of diltiazem with dantrolene should be avoided.
Interactions with other common medicines used in the perioperative period
Hypotension
Diltiazem can increase the risk of hypotension when used concomitantly with droperidol or prochlorperazine.
Oxycodone
Diltiazem 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 diltiazem leading to hypotension and bradycardia. Monitor the patient and consider reducing the dose of the diltiazem 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
Modified-release (MR) preparations
Different MR preparations of diltiazem (> 60mg dose) may not have the same clinical effect. To avoid confusion between these different formulations, the brand should be specified.
References
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]
Diltiazem Hydrochloride. 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]
Scarth E, Smith S. Drugs in Anaesthesia and Intensive Care, 5th Edition. Oxford University Press; 2016
Summary of Product Characteristics – ADIZEM-XL® (diltiazem). Napp Pharmaceuticals Limited. Accessed via www.medicines.org.uk 09/10/2019 [date of revision of the text May 2017]
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