Gabapentin prescriptions are rising in addiction treatment despite weak evidence

Doctors are increasingly prescribing the nerve pain medication gabapentin to patients undergoing treatment for substance use disorders, even as researchers note a lack of strong evidence supporting this practice. At the same time, patients using the drug without a prescription account for nearly double the rate of those who have a formal prescription, though this unprescribed use appears to be slowly declining. These patterns were detailed in a large study recently published in Drug and Alcohol Dependence.

Gabapentin is originally approved by the United States Food and Drug Administration to treat partial seizures and specific types of nerve pain. In clinical practice, physicians routinely prescribe the medication “off-label,” meaning they use it to treat conditions outside of its approved uses. For patients in substance use treatment, doctors often recommend gabapentin to help ease withdrawal symptoms. Clinicians also prescribe it to manage co-occurring issues such as anxiety, insomnia, and chronic pain.

Many medical professionals have traditionally viewed gabapentin as a safe alternative to medications with high potential for addiction, such as opioids and benzodiazepines. Medical literature evaluating gabapentin’s effectiveness in treating substance use disorders remains sparse. Reviews of past research show mixed results regarding the drug’s ability to reduce heavy drinking or opioid withdrawal. Medical trials have shown no benefit for treating cocaine or methamphetamine use disorders.

Despite this limited evidence, national prescribing rates for gabapentin have climbed steadily over the past two decades. Public health monitoring systems have simultaneously tracked a rise in nonmedical use of the drug, particularly among individuals with a history of substance use. People taking gabapentin without a prescription often report doing so to self-medicate for pain, sleep problems, or withdrawal symptoms. Others use it seeking euphoria or attempting to enhance the effects of other substances.

Psychiatry researcher Matthew S. Ellis of Washington University in St. Louis led a research team to investigate these dual trends. The researchers wanted to identify how often gabapentin was being used with and without a prescription inside substance use treatment centers. They also sought to understand the demographic traits, medical diagnoses, and other drug use patterns associated with gabapentin consumption. Penn Whitley and Steven D. Passik of the testing laboratory Millennium Health co-authored the paper.

To track these patterns, the researchers designed a retrospective study analyzing patient data gathered over an eight-year period. They examined 206,161 urine drug test results collected between January 2016 and October 2023. These tests came from patients aged 18 and older at 2,053 substance use treatment facilities across all 50 U.S. states. The researchers selected one test per patient based on their earliest specimen collection date.

The laboratory analyzed the urine specimens using a technique called liquid chromatography-tandem mass spectrometry. This process separates the individual chemical components in a sample and measures their mass to identify specific drugs. The researchers looked for the presence of gabapentin alongside a range of other prescription and illicit drugs, including cocaine, methamphetamine, fentanyl, heroin, and alcohol. They then compared the laboratory results against the medication lists provided by the clinics to determine if the patient had a documented gabapentin prescription.

Following this data collection, the researchers applied statistical models to assess the relationship between gabapentin use and various patient characteristics. They evaluated age, sex, insurance type, and clinic location. The models also accounted for specific medical diagnoses, such as alcohol, opioid, or sedative use disorders, as well as psychiatric conditions like mood disorders and anxiety.

The analysis revealed that 5.9 percent of the total sample had a documented prescription for gabapentin. Over the course of the study period, the prescribing rate nearly doubled, rising from 3.9 percent in 2016 to 7.6 percent in 2023. Prescriptions increased across all categories of substance use disorders. Patients with a sedative use disorder saw the highest prescribing rates by the end of the study period.

Certain demographic groups were more likely to receive a gabapentin prescription. Patients aged 55 and older had the highest likelihood of being prescribed the medication compared to young adults. Women were more likely to receive a prescription than men. Medical conditions including anxiety, mood disorders, insomnia, and pain were also highly associated with receiving a gabapentin prescription.

The data showed a different trajectory for patients taking the medication without a doctor’s guidance. The researchers identified gabapentin use without a prescription in 11.3 percent of the total sample. This rate was nearly double the proportion of patients who were formally prescribed the drug. Unlike the upward trend in prescribing, the rate of unprescribed use steadily decreased over time, dropping from 15.2 percent in 2016 to 9.9 percent in 2023.

Unprescribed gabapentin use shared several demographic similarities with prescribed use, occurring more frequently in older adults and patients with Medicare or private insurance. People diagnosed with an opioid or sedative use disorder were highly likely to use gabapentin outside of a prescription. Patients with psychiatric diagnoses like anxiety and mood disorders were also more likely to engage in unprescribed use.

The researchers found a strong association between unprescribed gabapentin use and the presence of other drugs in the patient’s system. Detection rates for all analyzed drug classes were higher among individuals taking gabapentin without a prescription compared to those with a prescription. Cannabis was the most frequently detected substance in both groups. Among patients without a gabapentin prescription, the detection of fentanyl increased from 12 percent to 29 percent during the study period.

The study design relies on urine drug tests submitted to a single national laboratory, which may not represent the entire population of individuals in substance use treatment. The accuracy of the prescription data also depends entirely on the medication lists provided by the treating clinicians. If a doctor failed to record a patient’s gabapentin prescription on the test order form, that patient’s authorized drug use would be incorrectly categorized as unprescribed.

The measure of unprescribed use in this study operates as a proxy for nonmedical use, but it may undercount the true scope of the issue. Patients who possess a valid prescription might still engage in nonmedical use by taking the drug in higher doses or at different frequencies than directed. Urine testing alone cannot distinguish between a patient following their doctor’s orders and one misusing their own prescription. Patients might also consume gabapentin unknowingly if it is mixed into the illicit drug supply as an adulterant.

Future research will need to explore the specific origins of gabapentin prescriptions for patients in substance use treatment. It remains unknown whether addiction specialists are prescribing the medication directly or if patients are receiving it from outside healthcare providers for unrelated conditions. Researchers also hope to investigate whether high rates of polysubstance use among these patients reflect intentional mixing of drugs or a broader symptom of gaps in treating multiple co-occurring illnesses.

The study, “Use of gabapentin with or without a prescription in substance use treatment settings: A national analysis of urine drug testing data, 2016 – 2023,” was authored by Matthew S. Ellis, Penn Whitley, and Steven D. Passik.