Evidence-Based Reviews

Abuse of psychiatric medications: Not just stimulants and benzodiazepines

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The European Medicine Agency’s EudraVigilance database included 4,301 reports of gabapentin misuse, abuse, or dependence, and 7,639 such reports for pregabalin, from 2006 to 2015 (rising sharply after 2012), with 86 gabapentin-related and 27 pregabalin-related fatalities.104 Data from the Drug Diversion Program of the Researched Abuse, Diversion, and Addiction-Related Surveillance System from 2002 to 2015 have likewise revealed that gabapentin diversion increased significantly in 2013.105

While the prevalence of gabapentinoid M/A is not known, rates appear to be significantly lower than for traditional drugs of abuse such as cannabis, cocaine, 3,4-methylenedioxymethamphetamine (MDMA), and opioids.106,107 However, gabapentin and pregabalin M/A appears to be increasingly common among individuals with SUDs and in particular among those with opioid use disorders (OUDs). For example, a 2015 report indicated that 15% of an adult cohort in Appalachian Kentucky with nonmedical use of diverted prescription opioids reported gabapentin M/A, an increase of nearly 3,000% since 2008.108 Based on data from a US insurance enrollment and claims database, researchers found that the rate of gabapentin overuse among those also overusing opioids was 12% compared with only 2% for those using gabapentin alone.109 It has also been reported that gabapentin is sometimes used as a “cutting agent” for heroin.110

Those who use gabapentinoids together with opioids report that gabapentin and pregabalin potentiate the euphoric effects of methadone111 and endorse specific beliefs that pregabalin increases both the desired effects of heroin as well as negative effects such as “blackouts,” loss of control, and risk of overdose.112 Indeed, sustained M/A of gabapentin and opioids together has been found to increase emergency department utilization, drug-related hospitalization, and respiratory depression.113 Based on a case-control study of opioid users in Canada, co-prescription of gabapentin and opioids was associated with a 50% increase in death from opioid-related causes compared with prescription of opioids alone.114

Case reports documenting tolerance, withdrawal, craving, and loss of control suggest a true addictive potential for gabapentinoids, but Bonnet and Sherbaum100 concluded that while there is robust evidence of abusers “liking” gabapentin and pregabalin (eg, reward), evidence of “wanting” them (eg, psychological dependence) in the absence of other SUDs has been limited to only a few anecdotal reports with pregabalin. Accordingly, the risk of true addiction to gabapentinoids by those without preexisting SUDs appears to be low. Nonetheless, the M/A potential of both gabapentin and pregabalin is clear and in the context of a nationwide opioid epidemic, the increased morbidity/mortality risk related to combined use of gabapentinoids and opioids is both striking and concerning. Consequently, the state of Kentucky recently recognized the M/A potential of gabapentin by designating it a Schedule V controlled substance (pregabalin is already a Schedule V drug according to the US Drug Enforcement Agency),103,113 and several other states now mandate the reporting of gabapentin prescriptions to prescription drug monitoring programs.115

Following a similar pattern to antidepressants and antipsychotics, a potential role for gabapentin in the treatment of cocaine use disorders was supported in preliminary studies,116-118 but not in subsequent RCTs.119-121 However, there is evidence from RCTs to support the use of gabapentin and pregabalin in the treatment of alcohol use disorders.122-124 Gabapentin was also found to significantly reduce cannabis use and withdrawal symptoms in patients compared with placebo in an RCT of individuals with cannabis use disorders.125 The perceived safety of gabapentinoids by clinicians, their subjective desirability by patients with SUDs, and efficacy data supporting a therapeutic role in SUDs must be balanced with recognition that approximately 80% of gabapentin prescriptions are written for off-label indications for which there is little supporting evidence,109 such as low back pain.126 Clinicians considering prescribing gabapentinoids to manage psychiatric symptoms, such as anxiety and insomnia, should carefully consider the risk of M/A and other potential morbidities, especially in the setting of SUDs and OUD in particular.

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