| • Adverse drug events
• Patient data
• Methadone
• The Society (5)
Letters to the Editor
|
Adverse drug events
OTC potassium citrate and hyperkalaemia
From Dr M. S. Sharif and Dr A. Broad
We report here the case of a 54-year-old woman, with a background of
ischaemic heart disease and hypertension, who presented with a three-day
history of generalised weakness, dyspnoea, palpitations and dysuria.
Her medicines were isosorbide mononitrate, simvastatin, citalopram, aspirin,
and ramipril 10mg od. For the preceding three days, she had been taking
an over-the-counter preparation for the relief of cystitis, later found
to be potassium citrate mixture.
Clinically, she was in atrial fibrillation at a rate of 37 beats per
minute, with no signs of cardiac failure. Serum potassium was 8.1mmol/L.
Following treatment for hyperkalaemia, she reverted to sinus rhythm,
70 beats per minute. Her potassium level remained within the normal range
following discharge, with cessation of the potassium citrate mixture.
The potential for potassium citrate to cause dangerous hyperkalaemia
is well documented.1–3 Angiotensin
converting enzyme inhibitor-induced hyperkalaemia has also been reported.4 In
this case, it is likely that the concomitant use of an ACE inhibitor
resulted in the development of
hyperkalaemia within a few days of taking the potassium citrate mixture.
The bottle was labelled with a precaution to “Ask your doctor before
use if you are taking any medicines which make you retain potassium in
your body including those which make you pass water more frequently”.
The BNF cautions against concomitant use of ACE-inhibitors and potassium
citrate but this specific interaction was not mentioned on the product
label and our patient was unaware of
any potential risk. Given that
ACE-inhibitors are now first-line treatment for hypertension in younger
patients, diabetic renal disease and left ventricular dysfunction (National
Institute for Health and Clinical Excellence guidelines), we think it
important to highlight such a dangerous interaction with an OTC medicine.
Only three cases of hyperkalaemia in patients taking potassium citrate
have been reported to the Medicines and Healthcare products Regulatory
Agency since 1963.
Muhammad Shahbaz Sharif
Foundation Year 2 Doctor
Andrea Broad
Specialist Registrar in Gastroenterology and General Medicine
North Tees and Hartlepool NHS Trust
References
1. Wilson RG, Fardon JR. Hyperkalaemic cardiac arrhythmia caused by
potassium citrate mixture. BMJ (Clin Res Ed) 1982;284:197–8.
2. Browning JJ, Channer KS. Hyperkalaemic cardiac arrhythmia caused
by potassium citrate mixture. BMJ (Clin Res Ed) 1981;283:1366.
3. Elizabeth JE, Carter NJ. Potassium citrate mixture: soothing but not
harmless? BMJ (Clin Res Ed) 1987;295:993.
4. Dutta D, Fischler M, McClung G. Angiotension converting enzyme inhibitor
induced hyperkalaemic paralysis. Postgraduate Medical Journal 2001;77:114–5. |
The
Pharmaceutical Journal