Cardiac Glycosides – Digoxin



 Issues for Surgery


For treatment of atrial fibrillation or flutter – risk of cardiac arrhythmias if omitted.

For treatment of heart failure – risk of exacerbation of heart failure symptoms if omitted.

Potential for digoxin toxicity if continued.


  Advice in the Perioperative period


Elective and Emergency Surgery

Continue – monitor heart rate.

Post-operative Advice

Restart post-operatively as soon as next dose is due.

Consider monitoring serum digoxin levels if toxicity suspected (see Interaction(s) with Common Anaesthetic Agents, Interaction(s) with other Common Medicines used in the Perioperative Period and Further Information).


  Interaction(s) with Common Anaesthetic Agents


Neuromuscular Blocking Drugs (NMBDs)

Serious cardiac arrhythmias can develop in patients taking digoxin if they are given suxamethonium or pancuronium due to rapid removal of potassium from myocardial cells (resulting in hyperkalaemia) – concomitant use of these agents with digoxin should be undertaken with care and the patient monitored1, 2, 3, 4.

Cisatracurium can increase the risk of bradycardia1.

Sympathomimetics

Sympathomimetic drugs have direct positive chronotropic effects that can promote cardiac arrhythmias and may lead to hypokalaemia, which can lead to or worsen cardiac arrhythmias4.

Opioids

Concomitant use of digoxin and alfentanil, fentanyl or remifentanil can increase the risk of bradycardia1.


  Interaction(s) with other Common Medicines used in the Perioperative Period


Corticosteroids

Dexamethasone and hydrocortisone may increase the risk of digoxin toxicity due to potassium loss – manufacturer advises caution. Monitor for digoxin adverse effects (i.e. bradycardia) and monitor potassium levels1, 2, 4.

Whilst single perioperative doses should not pose a problem, continued post-operative treatment may require close monitoring. Consult current product literature.

Non-Steroidal Anti-inflammatory Drugs (NSAIDs)

NSAIDs have the potential to cause renal impairment, reducing the renal clearance of digoxin with a subsequent increase in plasma levels. Aspirin, diclofenac and ibuprofen have all been shown to increase plasma concentrations of digoxin but this may only be clinically significant in patients with impaired renal function. Consider the possibility of an interaction if there is any unexplained increase in digoxin adverse effects (i.e. bradycardia)2, 3, 4.

Digoxin levels should be monitored whenever an NSAID is initiated or discontinued2, 4.

Antimicrobials

Digoxin levels can be increased by gentamicin – the interaction seems rare. Monitor for digoxin adverse effects if both medicines are given, particularly in patients with renal impairment2.


  Further Information


Fluid and Electrolyte Imbalances

Anaesthesia and surgery increase the risk of electrolyte imbalances, which affect sensitivity to digoxin. The effects of digoxin are enhanced by hypokalaemia, hypomagnesaemia and hypoxia3. In addition, the increased risk of hypovolaemia associated with surgery may exacerbate renal impairment, which could lead to digoxin accumulation and increased digoxin adverse effects.

Cardiac Surgery

Patients undergoing cardiac surgery appear to have increased sensitivity to digoxin toxicity and so increased risk of arrhythmias3.

 

  References


  1. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 4th May 2019]
  2. Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 4th May 2019]
  3. Digoxin. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 4th May 2019]
  4. Summary of Product Characteristics – Digoxin Tablet BP 125 micrograms. Accord-UK Ltd. Accessed via www.medicines.org.uk 04/05/2019 [date of revision of the text February 2019]