LAS VEGAS – Up to 22% of opioid abusers also abuse gabapentin, taking high doses of the antiepileptic for its psychoactive effects, or to potentiate the effect of opioids.
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The drug – the 10th most commonly prescribed in the United States – is increasingly implicated in overdose deaths. In response, several states have recently reclassified the antiepileptic as a Schedule V controlled substance. Other states have declined to go that far, but have added gabapentin (Neurontin and others) to the drugs that must be reported to state prescription monitoring programs.
“Gabapentin and pregabalin [Lyrica] are versatile and important drugs that are widely prescribed and used off label for a number of conditions from seizure disorder to fibromyalgia,” said Joseph Pergolizzi Jr., MD, who discussed the issue during the annual PAINWeek. “Abuse patterns differ somewhat from abuse patterns with prescription opioids. People who misuse gabapentinoids tend to already use other drugs inappropriately. It’s rare to find a person who only takes them recreationally, but it is increasingly common to find polydrug abusers who take gabapentinoids.”
Gabapentin abuse appears to be more common in Europe than in the United States, where it’s just beginning to emerge, Dr. Pergolizzi said. And the picture is more nuanced than it might first appear: Many of those who are misusing the drug are using it as a “do-it-yourself” opioid withdrawal aid, he said in an interview.
At the meeting, he presented a literature review comprising 46 papers on pregabalin abuse and 263 on gabapentin abuse. Several important themes arose from these papers, said Dr. Pergolizzi, cofounder and chief operating officer of NEMA Research Inc., Naples, Fla.:
- Gabapentin and pregabalin are being prescribed off label for numerous conditions, including bipolar disorder, neuropathic pain, diabetic neuropathy, complex regional pain syndrome, attention deficit disorder, restless leg syndrome, trigeminal neuralgia, periodic limb movement disorder of sleep, migraine, drug and alcohol withdrawal seizures, chronic low back pain, and even menopausal symptoms.
- About a one-third of users experience withdrawal symptoms with sudden discontinuation. Symptoms include disorientation, anxiety, insomnia, heart palpitations, diaphoresis, and abdominal cramps.
- Risk factors for abuse are emerging. These include opioid use disorders, mental illnesses, and a history of taking supratherapeutic doses of the drugs. Age and sex don’t seem to be a consistent risk factor for abuse.
- Abusers can obtain nonprescription gabapentinoids more easily each year, including street sales and online orders, Dr. Pergolizzi said. “A Google search conducted in July for ‘buy gabapentin without a prescription’ yielded 4.48 million results and ‘buy pregabalin without a prescription,’ 622,000. A similar search conducted in September 2017 yielded 1.19 million and 352,000 results, respectively.”
- Few urine drug assays screen for gabapentinoids, which makes them easy to conceal in random drug testing.
Reports of gabapentin-involved drug overdoses and even deaths have recently emerged in the United States, particularly in the opioid abuse-plagued Appalachian states. An article in May in Drug and Alcohol Dependence examined the prevalence of gabapentin in postmortem toxicology in drug overdose deaths in four Appalachian states in 2015 (Drug Alcohol Depend. 2018;186:80-5). Rates were 4% in eastern Tennessee, 15% in West Virginia, 20% in North Carolina, and 41% in Kentucky.
Three states have now added gabapentin to their list of Schedule V controlled substances: Kentucky in 2017, West Virginia this May, and Tennessee in July.
Ohio, Minnesota, Virginia, and Massachusetts have taken a different tack to controlling dispensing. In those states, all pharmacies, prescribers, and wholesalers must report all dispensing and sales of gabapentin to their prescription monitoring databases.
Dr. Pergolizzi disclosed financial relationships with numerous pharmaceutical companies.
SOURCE: Pergolizzi J et al. PAINWeek 2018, Poster 55.
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