Pregabalin not effective in trauma related neuropathic pain

Pregabalin, a common painkiller, was not found effective in controlling the chronic pain that develops after traumatic nerve injury, in a new study published in the Journal of Neurology.

The results of the international study, which was driven by an effort to identify effective non-opioid pain medications, did show potential in relieving chronic pain that sometimes lingers after surgery.

John Markman, University of Rochester Medical Center, Rochester, USA, and colleagues conducted the study to assess the efficacy and tolerability of pregabalin over 3 months in patients with post-traumatic chronic neuropathic pain (PTNP).

"The unrelenting burning or stabbing symptoms due to nerve trauma are a leading reason why people seek treatment for chronic pain after a fall, car accident, or surgery," said Markman. "While these findings show that pregabalin is not effective in controlling the long-term pain for traumatic injury, it may provide relief for patients experience post-surgical pain."

Pregabalin, which is marketed by Pfizer under the name Lyrica, is approved for the treatment of chronic pain associated with shingles, spinal cord injury, fibromyalgia, and diabetic peripheral neuropathy. However, it is also commonly prescribed as an "off-label" treatment for chronic nerve injury syndromes that occur after motor vehicle accidents, falls, sports injuries, knee or hip replacement and surgeries such as hernia repair or mastectomy.

A previous eight-week study had shown that pregabalin reduced pain intensity better than placebo in these chronic, post-traumatic pain syndromes. These results led many doctors to prescribe this medication for long-term pain that does not resolve as expected.

Chronic postsurgical pain syndromes occur in approximately one or two out of every 10 surgical patients and the levels rated as intolerable after roughly one or two in every 100 operations.

The current study was conducted in 101 centres in North America, Europe, Africa, and Asia and followed 539 individuals for three months. Study participants were randomized into two groups who either prescribed pregabalin or a placebo.

"This was the first large phase 3, randomized, controlled trial designed to evaluate the analgesic efficacy of pregabalin in PTNP for registration purposes in the United States," write the authors.

Key Findings:

• A retrospective analysis of a subgroup of a study of participants, whose nerve pain was attributed to surgery, showed that the drug did provide better pain relief than placebo at 3 months.


• However, Pregabalin was superior to placebo in reducing pain severity and interference with daily function as measured by the BPI-sf ( Brief Pain Inventory-Short Form).


• Consistent with the known safety profile of pregabalin, the most common adverse events were dizziness and somnolence (14.6 and 9.9% of patients, respectively) with pregabalin (vs 4.2 and 3.4% with placebo).

"The possibility that there was pain relief for those patients who had a hernia repair, or breast surgery for cancer, or a joint replacement lays the groundwork for future studies in these post-surgical syndromes where there is so much need for non-opioid treatments," said Markman.

One major challenge is that different biological changes in the nerves and other tissues that cause pain to persist after healing from trauma vary from one patient to the next. Currently, there is no diagnostic method that allows doctors to readily identify the patients whose pain will respond to a particular type of pain treatment.

Despite employing new strategies to reduce placebo effects, the patients receiving placebo also had a steady lowering of their pain over the course of the study. The pattern of these placebo effects in longer studies has proved to be a major challenge to the development of new pain medications.

"Given the rising rates of surgery and shrinking reliance on opioids, it is critical that we understand how to study new drugs that work differently in patients like the ones included in this study," Markman added.

"Additional studies are needed to characterize the efficacy and tolerability of pregabalin for chronic, posttraumatic neuropathic pain," concluded the authors.

For further reference follow the link: https://doi.org/10.1007/s00415-018-9063-9