Lyrica is one of the most commonly prescribed drugs for neuropathic pain. (JB Reed/Bloomberg News)

A drug frequently prescribed for pain is no more effective than a placebo at controlling sciatica, a common source of pain in the lower back and leg, according to a study published Wednesday in the New England Journal of Medicine.

The researchers at the George Institute for Global Health in Australia followed 209 sciatica patients in Sydney who were randomly assigned to receive either the drug pregabalin, more commonly known as Lyrica, or a placebo. The results showed no significant differences in leg pain intensity between the group on the placebo and that on Lyrica after eight weeks taking the drug or during the rest of the year on follow-up exams. Similarly, there were no differences for other outcomes such as back pain, quality of life and degree of disability.

After Lyrica was approved in 2004, it has become the most commonly prescribed medicine for neuropathic pain, which is caused by damage to the nervous system. The drug was ranked as the 19th-highest-earning pharmaceutical in 2015, with worldwide sales rising annually at a rate of 9 percent and sale revenue of more than $3 billion in 2015 in the United States.

“We have seen a huge rise in the amount of prescriptions being written each year for patients suffering from sciatica. It’s an incredibly painful and disabling condition, so it’s no wonder people are desperate for relief and medicines such as pregabalin have been widely prescribed,” Christine Lin, one of the authors of the study and an associate professor at the George Institute for Global Health, said in a news release.

Lyrica is frequently prescribed as an off-label drug because it has shown to be effective in treating some kinds of neuropathic pain. Some guidelines for treating sciatica also recommend prescribing Lyrica

Sciatica can be particularly debilitating and is a symptom of a problem with the sciatic nerve, the largest nerve in the body. In most cases, the cause behind the pain remains unclear. The pain, often accompanied by weakness, numbness and tingling, usually radiates on one side of the body and can spread from the lower back to the lower leg including the calf, foot and toes. Sciatic symptoms eventually subside on their own, with some help from exercise, surgery or medicine.

According to the researchers, at any one time, around 12 percent of the world's population has lower back pain and around 5 to 10 percent of those with lower back pain have sciatica.

The randomized double-blind placebo study also found significantly more side effects in people who took Lyrica than those who were on the placebo. Nearly two-thirds of the participants were very satisfied or satisfied with their drug regimen — regardless of whether they were taking Lyrica or a placebo.

“It seems people associate a drop in pain being due to taking a capsule, rather than something which would happen naturally over time. General practitioners who are prescribing Lyrica should take note of these findings, and talk with their patients about other ways of managing and preventing pain,” Lin said.

Researchers from the Musculoskeletal Division at the George Institute conducted the study because they were concerned about the rising use of Lyrica for sciatica and back pain despite scarce data on its effectiveness and tolerability in this patient group.

Lyrica became the best-selling drug for Pfizer, the global pharmaceutical corporation based in the United States, after the company's patent for the statin Lipitor expired in 2012. In 2015, Lyrica sales were one of the main reasons behind why Pfizer remained the world's biggest seller of drugs that treat conditions or diseases associated with the central nervous system.

Pfizer issued a statement about the study saying, “Lyrica is currently approved in more than 130 countries and regions globally. The efficacy and safety of Lyrica for its approved indications has been demonstrated in large-scale, double blind, randomized, placebo controlled pivotal trials. Lyrica continues to be an important treatment option for the conditions for which it is approved.”

Doctors should be more cautious when prescribing Lyrica to patients with sciatica, said Chris Maher, one of the study's authors and director of the Musculoskeletal Division at the George Institute, in an interview.

“Our next step is to educate doctors that the medicine doesn't work, present the results at different conferences and raise more awareness,” he said.

Correction: This article originally stated that side effects included suicidal thoughts. The study did not find a higher incidence of suicidality in patients taking Lyrica.

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