Intended for healthcare professionals


Co-prescription of co-trimoxazole and spironolactone in elderly patients

BMJ 2011; 343 doi: (Published 12 September 2011) Cite this as: BMJ 2011;343:d5656
  1. Li Wei, lecturer,
  2. Thomas M MacDonald, professor ,
  3. Isla S Mackenzie, clinical senior lecturer
  1. 1Medicines Monitoring Unit (MEMO) and Hypertension Research Centre (HRC), Division of Medical Sciences, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK
  1. tom{at}

The combination should be used with caution because of the risk of hyperkalaemia

Although much effort goes into understanding the risks and benefits of recently licensed drugs, less is known about many of the older drugs that are prescribed widely. For example, the phrase “safe as aspirin” is often used to extol the safety virtues of a drug, even though aspirin is one of the main culprits when it comes to hospital admissions related to an adverse drug event.1 Spironolactone and trimethoprim-sulfamethoxazole (co-trimoxazole) are two “older” drugs about which we should know more. In the linked case-control study (doi:10.1136/bmj.d5228), Antoniou and colleagues assess the risk of admission to hospital for hyperkalaemia in elderly patients treated with co-trimoxazole in combination with spironolactone.2

Spironolactone works well in congestive heart failure,3 resistant hypertension,4 hyperaldosteronism,5 and hypertension in general.6 Despite hypertension being an unlicensed indication in the United Kingdom, the new guidelines from the National Institute for Health and Clinical Excellence (NICE) on hypertension name spironolactone as an option for fourth line treatment.7 Because of these benefits, the use of …

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