By Pat Anson, Editor
The safety and effectiveness of Lyrica (pregabalin) and Neurontin (gabapentin) – two non-opioid drugs widely used to treat chronic pain – are drawing new scrutiny from researchers and doctors who believe the medications are over-prescribed.
In a study published in PLOS Medicine, Canadian researchers say there is little evidence that gabapentinoids – a class of nerve medication that includes Neurontin and Lyrica – are effective in treating chronic low back pain. In their review of 8 clinical studies, the researchers also found the drugs have a “significant risk of adverse effects.”
Lyrica and Neurontin are commonly prescribed for fibromyalgia and neuropathic pain, but the researchers say the drugs are increasingly prescribed for chronic back pain, even though there is “no clear rationale” for it.
"Despite their widespread use, our systematic review with meta-analysis found that there are very few randomized controlled trials that have attempted to assess the benefit of using gabapentin or pregabalin in patients of chronic low back pain," wrote lead author Harsha Shanthanna, MD, an assistant professor at McMaster University in Hamilton, Ontario.
"They necessitate prolonged use and are associated with adverse effects and increased costs. Recent guidelines from the National Health Service (NHS), England, expressed concerns on their off-label use, in addition to the risk of misuse.”
Shanthanna and his colleagues found that gabapentin showed “minimal improvement” in back pain compared to a placebo and pregabalin was “inferior” compared to other analgesics. There were no deaths or hospitalizations reported in any of the studies, but both drugs were associated with increased risk of dizziness, fatigue, visual disturbances, and diminished mental activity.
Lyrica and Neurontin are both made by Pfizer and are two of the company’s top selling drugs, generating billions of dollars in sales annually. Lyrica is approved by the FDA to treat diabetic nerve pain, fibromyalgia, post-herpetic neuralgia caused by shingles, and spinal cord injuries. It is also prescribed off-label to treat other chronic pain conditions, including lower back pain.
Neurontin is only approved by the FDA to treat epilepsy and neuropathic pain caused by shingles, but is widely prescribed off label to treat depression, ADHD, migraine, fibromyalgia and bipolar disorder. According to one estimate, over 90% of Neurontin sales are for off-label uses. Pfizer has paid $945 million in fines to resolve criminal and civil charges that it marketed Neurontin off-label to treat conditions it was not approved for.
Sales of pregabalin and gabapentin have risen steadily in recent years, in part because of CDC prescribing guidelines that recommend the two drugs as alternatives to opioid pain medication. About 64 million prescriptions were written for gabapentin in the U.S. last year, a 49% increase since 2011.
“We believe… that gabapentinoids are being prescribed excessively — partly in response to the opioid epidemic,” Christopher Goodman, MD, and Allan Brett, MD, recently wrote in a commentary published in The New England Journal of Medicine. “We suspect that clinicians who are desperate for alternatives to opioids have lowered their threshold for prescribing gabapentinoids to patients with various types of acute, subacute, and chronic noncancer pain.
“Patients who are in pain deserve empathy, understanding, time, and attention. We believe some of them may benefit from a therapeutic trial of gabapentin or pregabalin for off-label indications, and we support robust efforts to limit opioid prescribing. Nevertheless, clinicians shouldn’t assume that gabapentinoids are an effective approach for most pain syndromes or a routinely appropriate substitute for opioids.”
FDA Seeks Public Comment on Abuse of Lyrica
The U.S. Food and Drug Administration announced last week that it was seeking public comment on reports that pregabalin is being abused. The FDA action was in response to a formal notification from the World Health Organization (WHO) that it may place international restrictions on pregabalin to reduce the risk of abuse and diversion. The FDA has until September 30 to respond to WHO.
“Reports indicate that patients are self-administering higher than recommended doses to achieve euphoria, especially patients who have a history of substance abuse, particularly opioids, and psychiatric illness. While effects of excessively high doses are generally non-lethal, gabapentinoids such as pregabalin are increasingly being identified in post-mortem toxicology analyses,” the FDA said in a notice published in the Federal Register.
Pregabalin is already classified as Schedule V controlled substance in the U.S. under the Controlled Substances Act, which means the DEA considers it to have a low potential for abuse.
The idea that Lyrica and Neurontin are being abused is surprising to many patients and doctors, but there are growing signs the drugs are being used recreationally.
Both Lyrica and Neurontin have been linked to heroin overdoses in England and Wales, where prescriptions for both drugs have soared in recent years. Addicts have apparently found the medications enhance the effects of heroin and other opioids.
A small study of urine samples from patients being treated at U.S. pain clinics and addiction treatment centers found that one in five patients were taking gabapentin without a prescription.
Gabapentin and pregabalin are also being abused by prison inmates, according to Jeffrey Keller, MD, chief medical officer of Centurion, a private corrections company.
“Gabapentin is the single biggest problem drug of abuse in many correctional systems,” Keller recently wrote in Corrections.com. “There is little difference (in my opinion) between Lyrica and gabapentin in both use for neuropathic pain or for abuse potential.”
Pfizer did not respond to a request for comment.