5 January 2010

Doctors continuing to prescribe quinine for purposes other than malaria are putting people’s health at risk, warns the National Prescribing Service (NPS).

Quinine sulphate or bisulphate tablets (Quinate or Quinbisul) had previously been approved for the prevention of muscle cramp, however approval was withdrawn by the TGA in 2004 because the risk of thrombocytopenia (decreased platelet count) outweighs quinine’s modest efficacy. It is now a streamlined authority PBS item, subsidised only for use in malaria.

“More than 100,000 prescriptions for quinine tablets continue to be dispensed each year, which is far in excess of the quantity required to treat cases of malaria,” NPS acting CEO, Karen Kaye said.

Although total annual prescription numbers are falling (from 246,923 in 2005-06 to 154,511 in 2008-09), these figures suggest the drug is still being prescribed for leg cramps. Also of note is that PBS/RPS prescription numbers have increased over the last two years, coinciding with the streamlining of the authority item (increasing from 3863 scripts in 2006-07, the first year after streamlining, to 6395 scripts in 2008-09).

“Prescribers are reminded of the lack of efficacy of quinine in leg cramps, the risk of harm and that the only TGA-approved indication for quinine is malaria,” Ms Kaye said.

As of 2004, ADRAC had received 228 reports of thrombocytopenia involving quinine, six of which resulted in death. Typically, cases occur within the first few weeks of starting quinine although intermittent dosing may result in a longer time to onset. Symptoms can be severe, requiring hospitalisation and platelet transfusion.

“We strongly encourage doctors to ask patients to stop taking quinine for muscle cramps. While some patients may be reluctant, there is no evidence for its long-term efficacy or safety for preventing or treating leg cramp,” Ms Kaye said.

“Stretching exercises may be of benefit to some patients. While there is little evidence to support their efficacy in prevention, stretching does encourage self care and is unlikely to cause adverse effects.”

Underlying causes of cramp should also be investigated and may include electrolyte disturbance (particularly sodium and calcium deficiency), peripheral vascular disease or motor neurone disease. Possible drug causes of cramp include calcium-channel blockers, beta₂-agonists and diuretics.

To assist prescribers a fact sheet on the benefits and harms of using quinine for leg cramps has been prepared and can be accessed at www.nps.org.au/news_and_media/factsheets.

ENDS

The National Prescribing Service Limited (NPS) is an independent, not-for-profit organisation for quality use of medicines funded by the Australian Government Department of Health and Ageing.