HWN Suggests

Cyclobenzaprine for neck and back muscle strain/spasm

The trial-based analgesic benefits of cyclobenzaprine are about equal to the harms, with real world harms likely outweighing the benefits. Our experts do not recommend the use of cyclobenzaprine for ED patients. If using the drug, start with the lowest dose of 5mg qhs and titrate to no more than 15mg for no longer than 7 days.

read full article

Articles of Interest

Cyclobenzaprine in the Treatment of Low Back Pain

There is a recent high-quality randomized controlled trial that suggests minimal pain-relieving effect of cyclobenzaprine when used in addition to naproxen for patients with acute low back pain.4 There may be some benefit, although of questionable magnitude, to the use of cyclobenzaprine. There is a high likelihood of adverse effects.

Cyclobenzaprine vs TCA Toxicity

Fortunately, the one double bond in the central ring of cyclobenzaprine (absent in amitriptyline) makes a world of difference. A single-substance overdose with cyclobenzaprine will share the anticholinergic characteristics with amitriptyline and other TCAs. If large quantities are ingested, providers should expect symptoms consistent with anticholinergic toxicity:

Baclofen vs. Flexeril: Choosing the Best Option for Your Muscle Pain and Spasms

Generally, cyclobenzaprine is more effective in treating acute musculoskeletal pain due to an injury in the back or neck. Chronic pain from muscle spasticity related to neurological disease or injury responds best to baclofen.

Muscle Relaxers: Methocarbamol vs. Cyclobenzaprine

Studies have compared cyclobenzaprine, methocarbamol, and other skeletal muscle relaxants and found that they are equally effective in treating acute musculoskeletal conditions. Cyclobenzaprine is one of the most studied skeletal muscle relaxants, with solid evidence and systematic reviews supporting its effectiveness.

Reassessing Routine Refills for Cyclobenzaprine

Cyclobenzaprine’s main role is for adjunct treatment for short-term use in acute musculoskeletal conditions, and evidence on benefit with long-term use is sorely lacking. Non-specific low back pain without identifiable cause is typically acute and resolves within 4 weeks. In this case, patients may attribute the prolonged relief beyond to the medication, even though it’s really due to a naturally resolving acute musculoskeletal flare-up.

Relax, Don't Do It – Skeletal Muscle Relaxants

We agree with the authors’ conclusion that combination of an NSAID and a SMR does not improve acute LBP outcomes more than an NSAID plus placebo, regardless of age, sex, baseline functional impairment, or history of LBP.

Rhabdomyolysis: a manifestation of cyclobenzaprine toxicity

Cyclobenzaprine (flexeril) after its synthesis in 1961 was found to have limited antidepressant action with no significant advantage over other tricyclic antidepressants. However it was found to act as a centrally acting muscle relaxant and has been widely used ever since.

The Relative Efficacy of Seven Skeletal Muscle Relaxants. An Analysis of Data From Randomized Studies

In conclusion, the combination of an NSAID and a SMR did not improve acute LBP outcomes more than an NSAID plus placebo, regardless of age, sex, baseline functional impairment, or history of LBP.

The skeletal muscle relaxer cyclobenzaprine is a potent non-competitive antagonist of histamine H1 receptors

While cyclobenzaprine is effective as a muscle relaxant, greater than 30% of patients experience drowsiness and sedative/hypnotic effects, yet, the mechanisms that cause this adverse effect is also undescribed.

Resources

StatPearls

Cyclobenzaprine is a centrally acting skeletal muscle relaxant structurally related to tricyclic antidepressants. Cyclobenzaprine relieves skeletal muscle spasms of local origin without interfering with muscle function. In preclinical research, cyclobenzaprine reduced skeletal muscle hyperactivity. Research indicates that it primarily acts within the central nervous system in the brain stem.