By Pat Anson, Editor
A drug that is often prescribed as an alternative to opioid pain medication is increasingly being abused by patients, according to a small study that found one out of five patients taking the drug illicitly.
Gabapentin – which is sold by Pfizer under the brand name Neurontin -- is approved by the Food and Drug Administration to treat epilepsy and neuropathic pain caused by shingles.
It is also prescribed “off-label” for a variety of other conditions, including depression, migraine, fibromyalgia and bipolar disorder.
In a study of urine samples from 323 patients being treated at pain clinics and addiction treatment centers, 70 patients were found to be taking gabapentin without a prescription.
“The high rate of misuse of this medication is surprising and it is also a wakeup call for prescribers. Doctors don’t usually screen for gabapentin abuse when making sure patients are taking medications, such as opioids, as prescribed. These findings reveal that there is a growing risk of abuse and a need for more robust testing,” said Poluru Reddy, PhD, medical director of ARIA Diagnostics in Indianapolis, IN. Reddy presented his study at the annual meeting of the American Association for Clinical Chemistry in Philadelphia.
Researchers found that of those patients taking gabapentin illicitly, over half (56%) were taking it with an opioid, about a quarter (27%) with an opioid and muscle relaxant or anxiety medication, and the rest with other substances. The urine samples came primarily from pain clinics in Indiana, Arizona, and Massachusetts.
“Little information exists regarding the significance of Gabapentin abuse among clinical patients. Until recently, it was considered to have little potential for abuse however this review has shown that a significant amount of patients are taking Gabapentin without physician consent. This could be due to the fact that recent studies have revealed that Gabapentin may potentiate the ‘high’ obtained from other central nervous system acting drugs,” wrote Reddy.
"Patient safety is Pfizer’s utmost priority. We strongly support and recommend the need for appropriate prescribing and use of all our medicines," a spokesperson for Pfizer said in an email to Pain News Network.
Gabapentin is not scheduled as a controlled substance and when taken alone there is little potential for abuse. But when taken with other drugs, such as opioids, muscle relaxants, and anxiety medications like Valium and Xanax, researchers say gabapentin can have a euphoric effect.
Between 2008 and 2011 the number of emergency room visits for misuse or abuse of gabapentin increased by nearly five times, according to the Drug Abuse Warning Network. Side effects from gabapentin include weight gain, dizziness, ataxia, somnolence, nervousness and fatigue.
Increased Prescribing of Gabapentin
A report by IMS Health found that 57 million prescriptions for gabapentin were written in the U.S. in 2015, a 42% increase since 2011.
Gabapentin is one of several medications being promoted by the Centers for Disease Control and Prevention as a "safer" alternative to opioids. The American Pain Society recently recommended that gabapentin be considered for post-operative pain relief.
But the growth in gabapentin prescribing is drawing scrutiny in the UK, where the Advisory Council on the Misuse of Drugs (ACMD) recommended earlier this year that gabapentin and pregabalin (Lyrica) be reclassified as Class C controlled substances, which would make them harder to obtain.
“Both pregabalin and gabapentin are increasingly being reported as possessing a potential for misuse. When used in combination with other depressants, they can cause drowsiness, sedation, respiratory failure and death,” said Professor Les Iverson, ACMD chairman, in a letter to Home Office ministers.
“Pregabalin causes a ‘high’ or elevated mood in users; the side effects may include chest pain, wheezing, vision changes and less commonly, hallucinations. Gabapentin can produce feelings of relaxation, calmness and euphoria. Some users have reported that the ‘high’ from snorted gabapentin can be similar to taking a stimulant.”
Gabapentin is "one of the most abused and diverted drugs” in the U.S. prison system, according to Jeffrey Keller, MD, the chief medical officer of Centurian, a private company that provides prison healthcare services.
“Inmates show up at my jails all the time with gabapentin on their current medication list,” Keller wrote in Corrections.com. “It produces euphoria, a marijuana-like high, sedation, and, at high enough doses, dissociative/psychedelic effects. It works so well that it is used in the drug community to mellow out methamphetamine tweaking and to cut heroin. Since drug abusers know about these illicit uses of gabapentin on the streets, once they get to jail they often view gabapentin as an obtainable ‘jail substitute’ for their preferred drugs.
“Unfortunately, the abuse potential of gabapentin is not recognized much outside of jails and prisons. Community prescribers are generally unaware that gabapentin can be misused and (in my experience) are often incredulous and even disbelieving when told about ‘the dark side’ of gabapentin.”
Gabapentin (Neurontin) has a checkered history. Originally developed as a nerve drug, Pfizer agreed to pay $430 million in fines to resolve criminal and civil charges for illegally marketing Neurontin to treat conditions it was not approved for. According to some estimates, over 90% of Neurontin sales are for off-label uses.
In 1999, a Pfizer executive was so mystified by Neurontin’s popularity he called it the “snake oil of the twentieth century.”