Published: 2 September 2021

Publications

Reminder: hyperkalaemia caused by amiloride or spironolactone

Published: 2 September 2021
Prescriber Update 42(3): 37–38
September 2021

Key Messages

  • Hyperkalaemia is a well-established risk of treatment with potassium-sparing diuretics such as spironolactone and amiloride.
  • The risk of hyperkalaemia is increased in patients with renal or hepatic impairment, the elderly, and those receiving concomitant medicines that can increase potassium.
  • Regular monitoring of serum potassium is recommended.


The Centre for Adverse Rections Monitoring (CARM) has recently received two reports of severe hyperkalaemia in patients taking spironolactone or amiloride monotherapy. Spironolactone and amiloride are potassium-sparing diuretics that can cause hyperkalaemia.

Spironolactone is indicated for a number of conditions, including congestive heart failure and essential hypertension.1

There are currently no approved amiloride monotherapy products in New Zealand. There are approved fixed-dose combination products containing amiloride and furosemide or hydrochlorothiazide. Amiloride can be used for potassium conservation as an adjunct to thiazide or loop diuretic therapy for congestive heart failure and hypertension, or cirrhosis with ascites. It can also be used as monotherapy for oedema.2

Monitoring and management of hyperkalaemia

Severe hyperkalaemia is defined as a serum potassium concentration 7.0 mmol/L or greater, or 5.4 mmol/L or greater with symptoms and/or electrocardiogram changes.3

Serum potassium levels should be monitored at frequent intervals, especially when therapy is initiated, when dosages are changed or with any illness that may cause renal dysfunction. The incidence of hyperkalaemia is greater in patients with renal impairment and in the elderly.1,2,4

Concomitant use with other medicines that can increase potassium is not recommended. Examples of medicines that increase potassium include angiotensin-converting enzyme inhibitors (ACEis), angiotensin receptor blockers (ARBs) and non-steroidal anti-inflammatory drugs (NSAIDs).1

Severe hyperkalaemia is associated with fatal cardiac arrhythmias and requires urgent treatment. Discontinue the causative medicine and initiate corrective treatment in secondary care.1,3

New Zealand case reports

Up to 30 June 2021, CARM has received a total of 12 reports of hyperkalaemia with spironolactone or amiloride. Some of these cases involved concomitant treatment with ACEis or ARBs.

More information

See the following Prescriber Update articles:

References

  1. Mylan New Zealand Ltd. 2020. Spiractin New Zealand Data Sheet 9 October 2020. URL: medsafe.govt.nz/profs/Datasheet/s/Spiractintab.pdf (accessed 15 July 2021).
  2. New Zealand Formulary. 2021. New Zealand Formulary v109: Amiloride hydrochloride 1 July 2021. URL: nzf.org.nz/nzf_1037 (accessed 15 July 2021).
  3. bpacnz. 2011. A primary care approach to sodium and potassium imbalance. Best Tests 12: 2–14. URL: bpac.org.nz/BT/2011/September/imbalance.aspx (accessed 15 July 2021).
  4. Lexicomp. 2021. Amiloride: drug information. In: UpToDate. URL: uptodate.com/contents/amiloride-drug-information (accessed 26 July 2021).
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