Muscle relaxants are used to treat muscle spasms, which are painful contractions of the muscles. The term "muscle relaxants" refers to medications that have been approved by the FDA to relieve either spasticity, prolonged contraction of muscles due to neurological problems, or musculoskeletal conditions. Other medications can be used to treat the same conditions, but do not fall under the classification of muscle relaxants.
Cyclobenzaprine
Cyclobenzaprine is used to treat muscle spasms caused by strain and injuries. It's taken between 2 to 4 times a day. In general, it is intended for short-term use and shouldn't be used for more than several weeks. Side effects include drowsiness and dry mouth. According to the National Center for Biotechnology Information, it should not be used in adults over 65 as there are safer alternatives, and in this age group the risks outweigh the benefits. Caution should be used when combining it with other drugs that affect the nervous system, and it shouldn't be given within two weeks of using MAOIs, a type of antidepressant.
Baclofen
Baclofen is used to treat spasticity associated with various neurological conditions including spinal cord injuries, multiple sclerosis and stiff person syndrome. The latter, as explained by "Adams and Victor's Principles of Neurology" is an autoimmune disorder where muscles in the trunk and limbs become rigid. Baclofen is taken several times a day. It can be used on a long-term basis. Side effects include drowsiness and confusion. When the decision is made to stop treatment, it should be tapered slowly rather than discontinued abruptly because of the risk of withdrawal symptoms, which can include seizures.
Dantrolene
Dantrolene is used to treat spasticity associated with neurological disorders. As MayoClinic.com explains, it's also used in the treatment of malignant hyperthermia, a severe reaction to anesthetics. Symptoms include fever, rapid heart rate and severe muscle spasms. Malignant hyperthermia is fatal unless treated. Dantrolene is also used to treat muscle rigidity in a similar condition called serotonin syndrome, which is caused by an excess of serotonergic medications. Dantrolene may cause hepatitis and liver failure.
References
- National Center for Biotechnology Information: Comparing Muscle Relaxants; Laura Dean M.D.
- National Center for Biotechnology Information: Cyclobenzaprine
- "Kaplan and Sadock's Study Guide and Self Examination Review in Psychiatry"; Benjamin J. Sadock, Virginia A. Sadock and Ze'ev Levin; 2007
- Drugs.com: Dantrolene
- "Adams and Victor's Principles of Neurology, 7th edition"; Maurice Victor and Allan Ropper; 2001
