Gabapentin

Loren Bonner

Toxicologists, health care practitioners, and others are noticing an alarming trend as physicians have begun prescribing fewer opioids: Gabapentin prescriptions and subsequent misuse of the painkiller have increased.

While diversion and misuse of gabapentin is well documented, a research team set out to quantify how widespread the problem really is. Using a complete database of gabapentin cases reported to poison control centers nationwide between 2013 and 2017, the researchers found that exposures to the drug increased 72% during the 5-year study period. They published their results in the journal Clinical Toxicology.

Gabapentin is recognized as a first-line agent for treatment of neuropathic pain, and many health care providers have embraced it as a safer alternative to opioids for pain management. DEA has not classified it as a controlled substance, but some individual states have made gabapentin a Schedule V controlled substance.

“This means that it has a lower potential for abuse than the other controlled substances, but that risk is still there,” said Katie Tellor, PharmD, FACC, BCPS, an associate professor at St. Louis College of Pharmacy.

Around the same time the study was published, FDA issued a warning discussing the risks of misuse and toxicity of gabapentin, particularly in combination with opioids. In a safety communication, FDA warned about breathing difficulties for patients who have respiratory risk factors and asked that new warnings be added to the prescribing information of gabapentinoids.

In addition to gabapentin exposures, the research team analyzed baclofen exposures from 2014 through 2017 and saw an increase of 36% in misuse attempts.

“The misuse of baclofen is less prevalent and less well described; however, it has been apparent in my clinical practice, as has serious illness related to both acute toxicity and withdrawal, which is consistent with our findings,” said lead study author Michael Lynch, MD, medical director of the Pittsburgh Poison Center.

Understanding the risks

Lynch said the upward trend in overall exposures and misuse for both drugs confirmed their hypothesis.

“However, the magnitude of exposures related to suicide attempts was jarring and really underscores the co-occurrence of pain and mood disorders as well as the importance of screening for and addressing depression and suicidal thoughts,” he said.

According to the study findings, suspected suicide attempts involving gabapentin increased by 81% nationwide over the study period. Another notable finding was an increase in health care use and expense associated with hospital and ICU admissions following exposures to each drug, but especially baclofen. 

Tim Atkinson, PharmD, BCPS, with the Department of Veterans Affairs Tennessee Valley Healthcare System, said it might be hard for pharmacists to reconcile these findings within practice.

“In practice, most pain specialists are trying to get patients to comply correctly with taking the drug,” he said. Consistency is key, according to Atkinson, and most patients don’t like gabapentin’s adverse effects.

“[In clinical practice,] one of the biggest medication errors I have noted with gabapentin use is inappropriate dosing,” said Tellor. “Renal function must be taken into account for each patient. Otherwise, if a patient is prescribed too high a dose for their kidney function, they are at an increased risk for experiencing adverse effects or gabapentin toxicity.”

When used correctly, gabapentin can be viewed positively, especially as efforts shift toward a multimodal approach to pain. 

“These medications have an evidence-based role in the management of some clinical conditions, but they also have risks associated with them that need to be understood so that an informed risk–benefit assessment can be made at the time of treatment initiation and to provide patients with appropriate education and therapeutic monitoring,” said Lynch.

Community pharmacists

When taken in high doses, gabapentin can give users the similar dissociative effects seen with other drugs that have a net effect on dopamine and downstream euphoria, said Jeffrey Fudin, PharmD, adjunct associate professor at Albany College of Pharmacy and Health Sciences in New York.

“Various reports have outlined that high doses of gabapentin and increased quantities are more prevalent now compared with several years ago, and community pharmacists have reported instances of early refills and overtaking gabapentinoids beyond prescribed doses and at shortened intervals,” he added.

Fudin advised pharmacists to be particularly diligent when filling prescriptions for gabapentin. They should approach each prescription as if it were a scheduled drug in their state, even if it’s not, he said.