Medicines

Abuse potential of pregabalin ‘underestimated’

Tuesday, 21 Aug 2018


Clinicians may not be aware of the ‘abuse potential’ of the gabapentinoid pregabalin say researchers who report a dramatic rise in prescriptions, particularly in groups of patients thought to be at high-risk of misuse.

Writing in their paper published in Addiction the research team led by Dr Rosie Cairns from the NSW Poisons Information Centre say that together with an increase in poisoning and deaths related to the drug, clinicians should consider completing a risk assessment before prescribing the medication which is currently registered in Australia to treat epilepsy and neuropathic pain .

From a sample of PBS data the researchers found that pregabalin dispensings rose an average of 73,424 per year between 2013 when the drug first received PBS subsidy and 2016.

This was in stark contrast to other anticonvulsants such as gabapentin and carbamazepine dispensings which remained stable over the same period.

When the research team looked at patient characteristics they found that 14.7% of patients prescribed pregabalin fell into a “high-risk” user category. These patients were more likely to refill their prescriptions early, and have more prescribers and total defined daily doses of pregabalin.

Compared to other groups “high-risk” users were more likely to be co-prescribed opioids and be younger and male.

“In 2016-2017 $191 million Australian dollars was spent on pregabalin ($154.4 million was government subsidised)… approximately half of this spend was in “high risk users,” wrote the authors.

“Increasing dispensing means the absolute number of patients in this category is on the rise, indeed it rose 3-fold. High-risk users received 50.8% of pregabalin by volume,” they noted.

When the researchers looked at calls to the NSW Poisons Information centre they saw a 53.8% increase per year in intentional pregabalin poisonings. Data from toxicology databases revealed there were 88 pregabalin associated deaths, culminating in a 57.8% yearly increase.

“We believe that Australian doctors may not be aware of the abuse potential of pregabalin, as indicated by the fact that the majority of those prescribed pregabalin in the toxicology services databases had a documented substance abuse disorder,” they wrote.

And although the absolute number of pregabalin-associated deaths in their study was small, particularly compared to deaths from opioids, they described  the magnitude of the increase as ‘worrying’.

They noted that in 2017 the UK announced an intention to reclassify the pregabalin and gabapentin as Class C controlled substances because of increasing evidence of misuse and a dramatic increase in deaths [see related story here].

They concluded that “precautions used when prescribing other pharmaceuticals with an abuse potential (e.g benzodiazepines, opioids) should be considered when prescribing pregabalin, especially in patients with a substance abuse history.

“In light of potential harms, off-label prescribing of pregabalin for indications without a strong-evidence base should be avoided… scheduling changes such as those proposed in the UK could be implemented elsewhere to curb misuse,” they added.  

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