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Study shows potential misuse of off-label prescription of gabapentinoid drugs
The gabapentinoid drugs gabapentin and pregabalin, which have long been approved to treat epilepsy and neuropathic pain, are also being prescribed by physicians for use against more generalized chronic pain as an alternative to dangerous and highly addictive opioids. Though these drugs have been in use since the 1990s, Dr. Christel Renoux, of the Lady Davis Institute at the Jewish General Hospital, was surprised to discover that the rate of patients newly treated with gabapentinoids in primary care has tripled over the past decade and, moreover, that 50% of gabapentinoid prescriptions were for off-label indications, and 20% of recipients had a co-prescription for opioids.

The data comes from the Clinical Practice Research Datalink (CPRD), a United Kingdom database that is the most comprehensive source for primary care medical records. Researchers identified nearly 400,000 patients newly treated with gabapentinoids. The results were published in JAMA. The findings are relevant to Canadian physicians because these drugs are approved by Health Canada and their usage is comparable to that in the UK.

“Our findings were quite surprising,” said Dr. Renoux, an epidemiologist at the Centre for Clinical Epidemiology and an Assistant Professor in the Department of Neurology and Neurosurgery at McGill University, “because we know that these drugs are effective on neuropathic pain, but we don’t have evidence to suggest they are effective or safe for all variety of chronic pain. Gabapentinoids are being employed as a general prescription for chronic pain when, in fact, they are intended specifically for neuropathic pain. Unfortunately, chronic pain is very difficult to treat. In trying to help suffering patients, doctors may employ medications for purposes for which they were not strictly intended in the hope that it will bring them relief.”

She points out that gabapentinoids have sedative effects, not unlike opioids. Therefore, there is increased danger of adverse effects when they are taken together. Both drugs act on the central nervous system and have the unintended side effect of depressing respiration. Hence, the opportunities for misuse and addiction, as well as for overdose is magnified when they are combined.

Because the dangers of opioids are well known, doctors sometimes prefer to prescribe an alternative, of which gabapentinoids are one. However, Dr. Renoux urges caution because the side effects for off-label use are improperly understood and require further investigation. There is a need, she points out, for more evidence regarding whether it is appropriate to use them against non-neuropathic pain.

Last year, authorities in the UK acknowledged concerns over gabapentinoid use and reclassified them as a Class C controlled substance, which puts much more stringent limitations on their availability.

“Trends in First Gabapentin and Pregabalin Prescriptions in Primary Care in the United Kingdom, 1993-2017,” by François Montastruc, Simone Y. Loo, and Christel Renoux, JAMA

For media inquiries, and to arrange interviews with Dr. Renoux contact:

Tod Hoffman
Research Communications Officer
Lady Davis Institute
Tel.: 514-340-8222 x 28661

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