Doctors Should Pause Before Prescribing High Dosages of Gabapentin, Duquesne Study Finds

People who take high doses of gabapentin, more commonly known as Neurontin, are more likely to abuse illicit drugs than those taking lower doses, according to a Duquesne study.

The study discovered that patients taking 1,800 milligrams or more of gabapentin a day were twice as likely to use illegal opiates and have Hepatitis C than people taking lower doses. The findings were published in The Primary Care Companion for CNS Disorders, a publication of the American Psychiatric Association. It is the first study to create a predictive model of patients taking high doses of the drug.

“What our study found was that if a patient asks for a higher dose of gabapentin, they are twice as likely to be abusing illicit opiates and have Hepatitis C as those taking lower doses,” said Dr. Randy Tomko, associate professor of pharmacy at Duquesne who led the study. “This was found to be a correct predictor nearly 70 percent of the time.”

Gabapentin was approved by the Food and Drug Administration to treat seizures and post-herpetic neuralgia, which is a complication of shingles. Yet the drug is often prescribed for other ailments, including back pain and anxiety.

In the study, which was conducted at UPMC Mercy Hospital in Pittsburgh, 23 percent of patients admitted to inpatient psychiatric services indicated they were taking gabapentin. Of those 345 patients, 95 percent tested positive for an illicit drug of abuse, and 65 percent tested positive for multiple drug abuse.

“Before the study, we noticed that if we suggested reducing or eliminating gabapentin, many of these patients were very resistant to the idea,” Tomko said. “They were using gabapentin to enhance the effect of the illicit opioids they were taking.”

More state regulatory agencies may want to consider listing gabapentin as a controlled substance, which has occurred in some states, including Ohio.  If it’s considered a controlled substance, Tomko said, doctors will be more cautious about prescribing it.

“We hope this study will give primary care physicians pause before prescribing high dosages of gabapentin to a patient, especially patients who are insistent about having it,” he said.