Letters
Pharmacology
Volume 176 - Issue 12

Hyponatraemia and hypokalaemia caused by indapamide

Authors:  Laurence G Howes, John McEwen and John E Marley

Med J Aust 2002; 176 (12): 53-54. || doi: 10.5694/j.1326-5377.2002.tb04578.x
Published online: 17 June 2002
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In reply: Howes writes that previous studies have not shown significant hyponatraemia with indapamide. Our article highlighted that hyponatraemia was reported in a much larger proportion of all types of adverse drug reactions to indapamide than to chlorothiazide in Australia. As we clearly acknowledged, "Voluntary reporting systems do not provide a basis for calculating incidence or robust risk estimates".

In the PROGRESS study, 1770, and not 3000, participants were exposed to 2–2.5 mg of indapamide.1 The mean age of participants given active therapy in that study was 64 years and 30% were women. Details of the eight patients withdrawn because of hyponatraemia were not published.

Importantly for indapamide, chlorothiazide and the other comparator (hydrochlorothiazide with amiloride), more than 80% of the patients with hyponatraemia in our study of Australian adverse reaction reports were aged 65 years or older (mean age for indapamide, 69.3 years, unpublished data), and at least 78% were female. Given that indapamide formulations have been promoted as a replacement for chlorothiazide notwithstanding the acknowledged limitations of the data, our article was appropriate in alerting practitioners to the possibility of hyponatraemia, particularly in elderly women.

Authors

  • Laurence G Howes MB BS, PhD, FRACP1
  • John McEwen MB BS, MSc, MPS1
  • John E Marley MD, MB ChB1
  • 1. Department of Clinical Pharmacology, St George Hospital, Kogarah, NSW.
  • 2. Adverse Drug Reactions Unit, Therapeutic Goods Administration, Woden, ACT.
  • 3. The University of Newcastle, Newcastle, NSW.

Correspondence: l.howes@unsw.edu.au

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