Non-opioid pain relievers misused too says study

Health Canada says there were more than 4,500 deaths related to opioids last year. Doctors are trying to stem the tide of opioid misuse by prescribing other less risky pain relievers. A study published Monday in the journal Clinical Toxicology has identified two non-opioid prescription drugs that are targets for misuse. 

Researchers from the University of Pittsburgh looked at over 90,000 cases of exposure to medications reported to U.S. poison control centres. The data is collected by the National Poison Data system which looks for trends in drug abuse as well as poisonings.

The researchers identified two medications that are increasingly being identified as drugs of abuse and misuse. One of these is named gabapentin and the other is named baclofen.

Both of these drugs are used extensively to treat pain. Gabapentin is an antiepileptic medication that is used to treat neuropathic pain or pain that is caused by damaged nerves. Neuropathic pain is often treated by antidepressants and antiepileptic medications like gabapentin.

Baclofen is a muscle relaxant used to treat muscle spasms, rigidity, pain caused by multiple sclerosis, spinal cord injuries and other disorders.  It is also injected around the spinal cord for management of severe spasticity. 

What the researchers found is that gabapentin abuse and misuse has been reported right across the U.S. Between 2013 and 2019, reports of misuse and intoxication with gabapentin went up just under 120 per cent.

Likewise, most states saw increases in the misuse and abuse of baclofen. Between 2014 and 2017, instances of abuse or intoxication with baclofen went up nearly 32 per cent.

The consequences of the abuse and misuse of gabapentin and baclofen were quite serious. Typically, the adverse impact of these medications can be difficult to tease out because patients frequently take a combination of medications. However, in this study, of the patients who were poisoned or intoxicated with gabapentin alone, 16.7 per cent had to be admitted to hospital.

Baclofen was even more dangerous. Of those patients who took baclofen alone, 52.1 per cent had to be admitted to hospital.

Another way of looking at the riskiness of the drugs is to look at incidents of self-harm. Researchers found that over a five-year period, attempts at self-harm with gabapentin alone with up 80.3 per cent. During a four-year period, attempts at self-harm with baclofen rose by 43 per cent.

A Cochrane review found moderate-quality evidence that oral gabapentin at doses of 1200 mg daily or more has provides some pain relief for patients with moderate or severe neuropathic pain after shingles or due to diabetes.

Another Cochrane review found that muscle relaxants like baclofen are effective in the management of low back pain, but the adverse effects require that they be used with caution. Trials are needed that evaluate if muscle relaxants are more effective than acetaminophen and anti-inflammatory drugs.

Society has known about the addiction potential of opioids for decades. The reasons why these two non-opioid drugs have been abused is less obvious. It's likely that doctors gave gabapentin a bit of a free pass in terms of addiction risk because the risk with opioids was so much greater. As the opioid crisis unfolded, doctors may have felt free prescribing as much gabapentin as patients needed.

But the risk is there. A review published in the journal Addiction found that 15 to 22 per cent of patients who abuse opioids also abuse gabapentin. As reported in STAT, patients discovered that gabapentin heightens the euphoria or high from opioid. They also found that the drug makes opioid withdrawal symptoms somewhat more tolerable. In addition, it can bypass the blocking effects of medications used for addiction treatment, enabling patients to get high while in recovery.

Like gabapentin, baclofen is not an opioid. Still, there are some reports of baclofen abuse. Baclofen has been used as an anti-craving agent for treatment of alcohol dependence. The drug's mood-elevating properties have reportedly made it a medication with abuse potential.

Both of these medications are prescribed liberally in Canada. 

In 2017, MedSask sent out a warning to health workers about an increase in overdoses of baclofen after seven patients at the Battleford Union Hospital overdosed between July and October of that year.

Safer choices needed

Concerns regarding the misuse of gabapentin have prompted action. In 2018, the U.K. reclassified the drug as a controlled substance along the same lines as opioids. Some states in the U.S. have mandated the reporting of gabapentin prescriptions.

The authors of the study say that authorities need to see whether these changes curb the misuse of these medications.

In Canada, despite awareness of their abuse potential, neither gabapentin or baclofen are controlled substances.

The authors of the study also recommend that patients who are prescribed these medications should be screened for substance use disorders, mood disorders, and thoughts of self-harm.

When it comes to medications used to treat pain, patients need better and safer choices.

Note: Baclofen can be injected into the fluid surrounding the spinal cord as an analgesic. Incorrect information appeared previously.