Study finds high rate of misuse of seizure and pain drug

With increasing public attention to overdose deaths and misuse of prescription medications in the United States, researchers today presented the results of a new study looking at abuse and misuse of gabapentin, a medication used to treat seizures and relieve nerve pain often associated with shingles.

The research, presented at the 68th AACC Annual Scientific Meeting & Clinical Lab Expo in Philadelphia, found about one in five patients who are using powerful opioid pain medications and being monitored for compliance or illicit drug use tested positive for gabapentin even though they did not have a prescription for the drug.

"The high rate of misuse of this medication is surprising and it is also a wakeup call for prescribers," said Poluru L. Reddy, PhD, DABCC, the medical director of ARIA Diagnostics and ARCTIC Medical Labs. "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."

Between 2008 and 2011 the number of emergency room visits in metropolitan areas for misuse or abuse of gabapentin (also known by the brand name Neurontin) increased by nearly five times, according to the Drug Abuse Warning Network. Gabapentin is not scheduled as a controlled substance, because when taken alone there is little potential for abuse and addiction. When taken with other medications, however, such as opioids, muscle relaxants, and anxiety medications like Valium and Xanax, gabapentin can be abused to increase a patient's "high."

Researchers at ARIA Diagnostics 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 323 samples tested came from pain clinics (about 90%) and rehabilitation clinics (about 10%) primarily in Indiana, Arizona, and Massachusetts.

"This research tells doctors and prescribers that they need to be cautious in prescribing gabapentin and closely monitor patients with a history of drug abuse," said Reddy. "And patients need to know that medications that are safe alone can be dangerous when mixed without talking with a doctor."

In addition to this study, researchers will present the latest in drug abuse testing at the AACC Annual Scientific Meeting & Clinical Lab Expo, including:

•The validation of a new test designed to ensure pain management patients are using prescriptions as directed by testing for the presence of 55 drugs and metabolites with one sample. "Validation of a LC/MS-MS Method for Pain Management Confirmatory Drug Testing of 55 Drugs and Metabolites" (B-313)

•A new test to measure the presence of a morphine-like semi-synthetic opioid (buprenorphine) that has a high potential for abuse and addiction. "New Emit II Plus Buprenorphine Assay with 5 ng/mL Cutoff" (B-320)

•A new clinical laboratory test for patients in drug monitoring programs that differentiates between the presence of illicit methamphetamines and the use of legal methamphetamines found in over-the-counter decongestant inhalers. This test would make this screening more widely available. "Validation of an LCMS Method for Chiral Determination of Methamphetamine" (A-371)

•A urine test to confirm the presence of nicotine from tobacco smoke versus a nicotine patch. This test could be useful in tracking success in tobacco cessation clinics. "A Novel Dilute and Shoot LC-MS/MS Method for the Measurement of Nicotine, Cotinine, Nornicotine, and Anabasine in Human Urine" (A-351)

Source: American Association for Clinical Chemistry (AACC)