Sarasota, FL (WorkersCompensation.com) – “A few years ago we would have taught you it’s not addictive, not a drug of abuse. Wow, were we ever wrong,” said Phil Walls, chief Clinical Officer of myMatrixx, an Express Scripts Company. “It is intentionally abused. It’s becoming quite a concern.”
Walls’ recent comments during the National Comp conference came as new research raises many questions about the use of gabapentin in the workers’ compensation system. While the majority of workers’ compensation claims involving gabapentinoids are for diagnoses where the medication is recommended on a trial basis, that’s not the case in many states.
“One-third [of injured workers prescribed gabapentinoids] did not have a diagnosis with neuropathic involvement – mainly sprains and strains, back and lower and upper extremities,” said Vennela Thumula, a Policy Analyst for the Workers Compensation Research Institute. “It remains to be seen as to why they are being prescribed and whether they are effective for this population.”
Among the findings in a WRCI study of 28 states Thumula discussed, was that that the simultaneous prescribing of gabapanetinoids and opioids “is common” among injured workers, something especially troubling to those studying the issue.
Gabapentin, which is prescribed under the brand name Neurontin, and pregabalin, called Lyrica, are among the most expensive medications in the workers’ compensation system. It was initially approved by the Food and Drug Administration as an anticonvulsant and nerve pain reliever for such things as shingles. Evidence from clinical or randomized controlled trials suggests it can also be effective to treat various neuropathic conditions, such as sciatica, carpal tunnel syndrome, and chronic regional pain syndrome.
The drugs can be accompanied by a host of side effects, including
Nausea and vomiting
Among he more serious potential side effects are suicidality, anaphylaxis and rhabdomyolysis, a breakdown of muscle tissue that releases a damaging protein into the blood that can damage the kidneys.
Withdrawal from gabapentin is “unique,” Walls said. “The first 24 hours there are moderate symptoms – headache, sweating and shaking. By day 3 there can be hallucinations, fever, increased heartrate and disorientation. By day 4 or 5 the symptoms start to subside, but anxiety will continue,” along with confusion and a sensitivity to light. “If you have an injured worker on this it’s not reasonable to expect a physician to just discontinue it. They have to be weaned off the drug.”
Mixed with Opioids
One of the most concerning aspects of gabapentin is the use of it in combination with opioids.
“Studies show that the concomitant prescribing of these two drugs results in respiratory depression, resulting in overdoses and deaths,” Thumula said. “The FDA added a warning label at the end of [our] study period that gabapentin taken with other central nervous system depressants may result in certain adverse events.”
Despite the increased risk, the WCRI study showed a “prevalent use of the co-prescribing of these two groups of drugs,” Thmula said. “As least a third of the claims with gabapentin also had simultaneous use of opioids in more than half the study states. And it’s up to 50 percent in some of the other states.”
Iowa had the highest rate of concomitant prescribing of gabapentin and opioids. Also higher than the median states were Kansas, Texas, Louisiana and Delaware.
“Five to 22 percent of people who use opioids will also abuse gabapentin,” Walls pointed out. “That’s very scary.”
The prevalent prescribing of opioids with gabapentin may help explain one of the WCRI findings: that recommended dosing regimens are often lower than what has been shown to be effective in clinical trials. Evidence based on systematic reviews suggests that a daily dosage of between 1,200 and 3,600 mgs is most effective for treating neuropathic pain, except for older workers and those with renal impairment. While the 99th percentile of doses in the study population was 3,600 mgs, the 75th percentile is less than 1,200 – the minimum recommended dose for efficacy.
“In most clinical trials gabapentins were used alone; but in the real world they are often prescribed with opioids, and have adverse events associated with them,” Thumula said. “Especially at high doses, the risk increases, which may be a reason gabapentin is prescribed at lower doses.”
WCRI’s research showed that in a number of the study states there were few gabapentin prescriptions. In the median state, about 20 percent of claims initiated with gabapentin prescriptions had at least four prescriptions – a proxy for continuous use. “This means that in many instances if the gabapentin were prescribed for chronic neuropathic pain that the treatment may have failed, because these prescriptions start out on a trial basis,” Thumula said. “It means that either they did not offer sufficient pain relief or the side effects were not tolerated.”