A recent study has found substantial increase in prescriptions for two drugs, pregabalin and gabapentin, used for treatment of neuropathic pain, anxiety, insomnia and other mental illnesses is closely correlated with a rise in the number of overdose deaths.

According to the University of Bristol researchers, alternatives to gabapentoids need to be recommended for clinicians managing opioid dependent patients with neuropathic pain or generalised anxiety, and greater attention given to restricting diversion of gabapentoid prescriptions.These drugs have become drugs of abuse, according to new findings, which highlight that they are especially dangerous when used with heroin or other opioids.Pregabalin and gabapentin were originally used to treat epilepsy but more recently also used to treat neuropathic pain, anxiety, insomnia and other mental illnesses.

Recent figures show that prescriptions for these drugs increased from 1 million in 2004 to 10.5 million in 2015 (i.e. a 24 per cent increase year on year) and concern has arisen about their diversion and misuse.The number of deaths in England and Wales involving gabapentoids increased from less than one per year before 2009 and increase to 137 per year in 2015 of which 79 per cent also involved opioids such as heroin.Interviews with heroin users reported that pregabalin and gabapentin were easy to access and that taking them was associated with a feeling of loss of control and an enhanced effect of heroin.

The laboratory experiments demonstrated that pregabalin enhanced heroin-induced respiratory depression by reversing heroin tolerance at low doses and then at higher doses directly depressing respiration itself so increasing the likelihood of heroin overdose.The study highlights that important that doctors and people dependent on opioids are aware that the number of overdose deaths involving the combination of opioids with gabapentin or pregabalin has increased substantially and that there is evidence now that their concomitant use -- either through co-prescription or diversion of prescriptions -- increases the risk of acute overdose deaths.The findings were published in Addiction journal.