One question that comes up repeatedly is, “Where do muscle relaxants fall into the treatment approach for different musculoskeletal conditions”?
Patients will sometimes ask about them and physicians who see these patients sometimes wonder if these drugs should be considered.
Skeletal muscle relaxants are the most widely prescribed drug class in the United States for non-specific low back pain.
In addition, this class of drugs is used for neck pain, muscle spasms, fibromyalgia, and myofascial pain.
Goals for the treatment of musculoskeletal conditions include relief of muscle pain and improvement in function and therefore, a return to normal activities of daily living.
The two primary categories of skeletal muscle relaxants are anti-spastic agents (eg, baclofen [Kemstro and Lioresal] or dantrolene [Dantrium]) for diseases like cerebral palsy, spastic torticollis, and multiple sclerosis and anti-spasmodic agents for muscle-related conditions.
Anti-spastic agents are rarely used for musculoskeletal conditions; however, some rheumatologists report success in treating fibromyalgia using baclofen. Since this is an “off-label” use, caution should be exerted and the lowest possible doses should be prescribed… and then only by specialists who have much experience. Patients should be informed as to the potential side effects.
Antispasmodic agents are much more widely used for musculoskeletal conditions.
The most often prescribed antispasmodic agents are carisoprodol [Soma}, cyclobenzaprine (Flexeril), metaxalone (Skelaxin), and methocarbamol (Robaxin). In terms of effectiveness, there appears to be no one muscle relaxant that is superior to another. Often, physicians will prescribe the muscle relaxant they are most familiar with. Another reason one is selected over another is that a physician may have samples in his closet that he can give to a patient to try before giving the patient a prescription.
The most widely studied and used agent is cyclobenzaprine. This has been shown to be effective for various musculoskeletal conditions but causes drowsiness, as does tizanidine [Zanaflex]. As a result, patients with insomnia caused by muscle spasms, may find tizanidine or cyclobenzaprine to be useful. Cyclobenzaprine is particularly helpful for many patients with fibromyalgia.
All skeletal muscle relaxants have adverse effects which include most commonly dizziness, drowsiness, and dryness of the mouth.
Methocarbamol and metaxalone may be are less sedating than tizanidine and cyclobenzaprine. However, they may also be more habituating in some cases.
Skeletal muscle relaxants are generally not considered first-line therapy for musculoskeletal conditions. Most physicians will start with acetaminophen (Tylenol) or non-steroidal-anti-inflammatory drugs (NSAIDS) first. Many clinical trials have supported the notion that NSAIDS are superior to muscle relaxants in patients suffering from acute low back pain. However, it is also known from the data that muscle relaxants are superior to placebo.
For acute low back pain syndromes, skeletal muscle relaxants may be used as additional therapy to NSAIDS.
For acute low back pain, muscle relaxants should be used short term (2 weeks). Some patients with chronic back conditions as well as patients with fibromyalgia may require chronic long-term use of muscle relaxants.
Muscle relaxants should be avoided in frail elderly patients because of the danger related to sedation and falling.