HFHT's Practising Wisely Newsletter
For clinicians, by clinicians.
Issue 31: Muscle Relaxants - More Snake Oil?
August 1, 2017

The Therapeutics Initiative (TI) from The University of British Columbia provides a bi-monthly publication called the "Therapeutics Letter" that identifies problematic therapeutic issues and, after a literature review and approval from therapeutic specialists, develops messaging to share with health care providers.

The most recent publication posed the question: “Is cyclobenzaprine (also known as Flexeril), useful for pain?"

A response came in the form of a review of the evidence for benefits and harms of cyclobenzaprine for common pain indications, compared with placebo. Here are some facts (don't forget to check our Quick Links section for more evidence and a list of sources for evidence provided throughout this article):

  • In B.C., cyclobenzaprine is prescribed for acute pain at higher doses and for longer durations than necessary, and is frequently prescribed for unapproved long term use.
  • There is no compelling evidence that cyclobenzaprine is a muscle-relaxant. Effects on pain or overall function are likely the result of sedation.
  • If prescribed, a dose of 5 mg at bedtime should be tried first.  Evidence suggests titration based on response and tolerability to a maximum dose of 15 mg/day, for no longer than one week.

Along the same vein, Cochrane reviewed muscle relaxants for pain management in rheumatoid arthritis and concluded that they did not significantly reduce pain over two weeks, however, even short term muscle relaxant use (24 hours to 2 weeks) is associated with significant adverse events, predominantly drowsiness and dizziness.          

Another popular muscle relaxant is the Robax line of products, based on methocarbamol, an oral and parenteral centrally acting muscle relaxant indicated as an adjunct to physical therapy for the relief of acute musculoskeletal pain. Similar to many medications in this class, the exact mechanism of action is unknown, but its effects may be due to general CNS depression. Systematic reviews indicated that skeletal muscle relaxants were effective in the short-term relief of acute low back pain when compared with placebo. However, these agents were associated with a 50% increased risk of adverse events.

A deeper dive into the world of advertising reveals a telling narrative. From the MarketingMag.ca website:
Robax Canada said it wanted to evolve the creative to show what back pain sufferers may be missing out on. The popular Robax wooden puppet campaign targets people who did not realize they could take Robax for more minor incidents, such as those featured in the advertisements. Pfizer's consumer healthcare marketing director says, “We wanted to reinforce that we are the back care specialists – we understand what it means to live with back pain, and we are the brand that has your back.” We are so glad to hear a marketing director has your back! 

Quick Links:
Choosing Wisely Committee:
Follow the HFHT on Social Media: