Neuromodulators, Muscle Relaxants Found Ineffective for RA Pain

A pair of evidence-based reviews confirm what some patients with rheumatoid arthritis (RA) know all too well: If DMARDs are not able to solve their pain, little else works either.

In separate studies, rheumatologists in Australia carried out systematic reviews of randomized trials that have tested two classes of drugs, neuromodulators and muscle relaxants, for pain management in RA. Studies are so small and poorly designed, with a high risk of bias, that they conclude there is little evidence for either of these strategies to relieve pain in RA.

The study found only four controlled trials of neuromodulators suitable for inclusion in a systematic review. Two of these involved nefopam (not approved in the United States), which had four times placebo's risk of adverse effects. The other two trials in the review were small, evaluating topical capsaicin in 31 participants and oromucosal cannabis in 58.

Capsaicin effectively relieved pain during two weeks' topical application, but 44% of patients experienced burning pain at the site of application and 2% quit treatment because of it. Cannabis also relieved pain, but caused significant side effects: dizziness, light-headedness, and dry mouth.

The researchers state that they can have little confidence in these results, although capsaicin "could be considered as an add-on."

Their separate analysis of muscle relaxants (antispasmodics and anti-spasticity medications) for RA pain found only six trials worthy of assessment, all of which had a high risk of bias. Treatment duration was brief in all of them, lasting no longer than 2 weeks. Overal,l the studies found no beneficial effect on pain intensity, function, or quality of life, whether muscle relaxants were administered alone or alongside nonsteroidal anti-inflammatory drugs (NSAIDs). The two trials that assessed treatment duration of longer than 24 hours found significant adverse effects, predominantly dizziness and drowsiness.

Bringing the RA disease process under control with adequate DMARD treatment should be the first priority and should ordinarily control RA pain, commented rjeumatologist Kiran Farheen, MD, of the University of Texas Health Science Center at Houston. Unfortunately some patients with RA have concomitant chronic regional pain with fibromyalgia-like symptoms, he added, and for these people DMARDs would not relieve pain. Unfortunately neither will any other medication strategy yet tested in a controlled trial.

Both studies (Neuromodulators for pain management in rheumatoid arthritis  and Muscle relaxants for pain management in rheumatoid arthritis) appear in the Cochrane Library of Systematic Reviews.