Scientists find most effective drugs for common neuropathic pain

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More than 20 million people in the U.S. suffer neuropathic pain.

At least 25% of those cases are classified as unexplained and considered cryptogenic sensory polyneuropathy (CSPN).

There is no information to guide a physician’s drug choices to treat CSPN.

In a new study, researchers compared four drugs with different mechanisms of action in a large group of patients with CSPN to determine which drugs are most useful for this condition.

The research was conducted by a team from the University of Missouri.

The study involved 40 sites and enrolled 402 patients with diagnosed CSPN who were 30 years or older and reported a pain score of four or greater on a 10-point scale.

Participants were prescribed one of four medications commonly used to treat CSPN: nortriptyline, a tricyclic antidepressant; duloxetine, a serotonin-norepinephrine reuptake inhibitor; pregabalin, an anti-seizure drug; or mexiletine, an anti-arrhythmic medication.

Patients took the prescribed treatment for 12 weeks and were evaluated at four, eight, and 12 weeks.

Any participant who reported at least a 50% reduction in pain was deemed as demonstrating an efficacious result. Patients who discontinued the treatment drug because of adverse effects were also measured.

The team found nortriptyline had the highest efficacious percentage (25%), and the second-lowest quit rate (38%), giving it the highest level of overall utility.

Duloxetine had the second-highest efficacious rate (23%), and lowest drop-out rate (37%). Pregbalin had the lowest efficacy rate (15%) and Mexiletene had the highest quit rate (58%).

The team says there was no clearly superior performing drug in the study. However, of the four medications, nortriptyline and duloxetine performed better when efficacy and dropouts were both considered.

Therefore, they recommend that either nortriptyline or duloxetine be considered before the other medications tested.

There are other nonnarcotic drugs used to treat painful peripheral neuropathy, including gabapentin, venlafaxine and other sodium channel inhibitors.

The researchers say additional comparative effectiveness research studies can be performed on those drugs, so doctors can further build a library of data for the treatment of CSPN.

One author of the study is Richard Barohn, MD.

The study is published in JAMA Neurology.

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