Muscle Relaxants

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Muscle Relaxants 2016-11-17T14:16:24+00:00

What Are Muscle Relaxants?

Muscle relaxants, which are also known as skeletal muscle relaxants, are a type of medication that is typically used to reduce or prevent muscle spasms or muscle spasticity that occurs as the result of some upper motor neuron syndromes. This group of medications do not actually act on the muscles themselves. Instead, the mechanism of action is how these drugs act on both the central and peripheral nervous system.

Generally, muscle relaxants work by causing the muscles (along with other structures of the body) to relax, which then acts to reduce symptoms of both pain and discomfort.

It is generally recommended that muscle relaxants be taken at night, before bed. It is important for patients taking muscle relaxants to not operate machinery while taking this medication.

Types Of Muscle Relaxants

There are a wide variety of muscle relaxants available. Some of the most commonly prescribed muscle relaxants are discussed below.

Baclofen

Baclofen is a type of muscle relaxant that acts on the central nervous system. This medication is typically prescribed for the treatment of muscle spasticity that commonly occurs as the result of multiple sclerosis, as well as spinal cord injuries. Many physicians prefer baclofen due to the fact that there is very little evidence suggesting that it causes liver injury.

Possible side effects associated with taking baclofen include: mood changes, nausea, drowsiness, fatigue, vision disturbances, dizziness, weakness, headache, light-headedness, dry mouth, muscle aches, difficulty breathing, confusion, insomnia, nightmares, increased urges to urinate, unsteadiness, increased sweating, skin rash, or shakiness.

Carisoprodol

Carisoprodol is another type of muscle relaxant that acts on the central nervous system. This medication is typically prescribed for the treatment of acute pain associated with a number of disorders of the musculoskeletal system. This medication has not been associated with any significant hepatic injury.

Common side effects associated with taking carisoprodol include: headache, drowsiness, or dizziness.

Chlorzoxazone

Chlorzoxazone is another type of muscle relaxant that acts on the central nervous system. This medication is typically prescribed for the treatment of low back pain, as well as muscle spasms. Previous studies examining the effectiveness of chlorzoxazone have yielded mixed results. Further, there have been some reports of chlorzoxazone use being associated with acute liver injury, though these reports are rare.

Common side effects associated with taking chlorzoxazone include: tremor, headache, fatigue, dizziness, or drowsiness.

Cyclobenzaprine

Muscle-Relaxants-cyclobenzaprine10mgCyclobenzaprine is a type of muscle relaxant that also falls into the class of tricyclic antidepressant medications.

This medication is typically used to treat symptoms of painful muscle spasms associated with a variety of acute muscle conditions. Despite its relation to tricyclic antidepressant medications, cyclobenzaprine is not associated with any significant liver damage.

Common side effects associated with taking cyclobenzaprine include: dizziness, headache, sleepiness, and dry mouth.

Dantrolene 

Dantrolene is a type of muscle relaxant that acts on the peripheral nervous system rather than the central nervous system. This medication is generally used to treat symptoms of chronic spasticity. Dantrolene is also used to as a prophylaxis against and the treatment for malignant hyperthermia. Dantrolene has been associated with causing acute liver damage, which can be quite severe and may even be fatal.

Possible side effects associated with taking dantrolene include: fatigue, dizziness, drowsiness, diarrhea, general feelings of unwell, nausea, vomiting, abdominal pain, loss of appetite, headache, acne, rash, disturbances in vision or speech, chills, fever, seizures, difficulty breathing, fever, fluid in the lungs, or swelling in the tissue surrounding the heart.

Metaxalone 

Metaxalone is another type of muscle relaxant that acts on the central nervous system. This medication is used to treat symptoms of acute pain associated with various musculoskeletal conditions, as well as painful symptoms of muscle spasms. Using metaxalone has not been associated with significant hepatic injury or elevations in serum aminotransferase levels.

While side effects are not common when taking metaxalone, some possible side effects include: headache, dry mouth, nausea, drowsiness, or dizziness.

Methocarbamol 

Methocarbamol is another type of muscle relaxant that acts on the central nervous system. This medication is used to treat symptoms of acute pain associated with various musculoskeletal conditions. Using methocarbamol has not been associated with significant liver damage.

Common side effects associated with taking methocarbamol include: nausea, skin rash, blurred vision, or headache.

Orphenadrine 

Orphenadrine is another type of muscle relaxant that acts on the central nervous system. This medication is used to treat the acute symptoms of many painful musculoskeletal conditions. Using orphenadrine has not been associated with significant liver damage or clinically-relevant symptoms of liver disease.

The most common side effects associated with taking orphenadrine include: flushing, dry mouth, drowsiness, diaphoresis, disturbances in vision, or confusion.

Tizanidine

Tizanidine is another type of muscle relaxant that acts on the central nervous system. This medication is used to treat the acute symptoms of muscle spasms, as well as chronic muscle spasticity. The use of tizanidine has been associated with acute liver damage, which can be quite severe and may even be fatal.

The most common side effects associated with taking tizanidine include: dry mouth, dizziness, drowsiness, fatigue, muscular weakness, and in some instances hypotension.

Conditions Related To Muscle Relaxants

Medications that fall into the category of muscle relaxants are generally used to treat two broad groups of symptoms:

  1. Symptoms of muscle spasticity owing to upper motor neuron syndromes
  2. Muscular pain or muscle spasms associated with peripheral musculoskeletal conditions or acute injury resulting in low back pain.

Conclusion

Muscle-Relaxants-1Muscle relaxants can also be known as skeletal muscle relaxants. These medications do not act on the muscles themselves, rather they act on the central and peripheral nervous system to relax the muscles and other structures of the body, which then is believed to lead to a reduction in symptoms of pain and discomfort.

Medications that fall into this group of drugs are generally used to treat symptoms that fall into two broad groups, including symptoms of muscular spasticity associated with syndromes affecting the upper motor neurons and muscle spasms and muscular pain owing to conditions affecting the peripheral musculoskeletal system or injuries resulting in low back pain.

It is important for individuals to not operate machinery while taking these medications.

References

  1. Hibbs RE, Zambon AC. Control of muscle spasms and rigidity. Agents acting at the neuromuscular junction and autonomic ganglia. In, Brunton LL, Chabner BA, Knollman BC, eds. Goodman & Gilman’s The pharmacological basis of therapeutics, 12th ed. New York: McGraw-Hill, 2011. p. 266-76.
  2. Macaigne G, Champagnon N, Harnois F, Cheiab S, Chayette C. Baclofen-induced acute hepatitis in alcohol-dependent patient. Clin Res Hepatol Gastroenterol 2011;35:420-1.
  3. Chou R, Peterson K, Helfand M. Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: A systematic review. J Pain Symptom Manage 2004;28:140-75.
  4. Kim JY, Chun S, Bang MS, Shin HI, Lee SU. Safety of low-dose oral dantrolene sodium on hepatic function. Arch Phys Med Rehabil 2011;92:1359-63.
  5. Toth PP, Urtis J. Commonly used muscle relaxant therapies for acute low back pain: A review of carisoprodol, cyclobenzaprine hydrochloride, and metaxalone. Clin Ther 2004;26:1355-67.
  6. Richards BL, Whittle SL, Buchbinder R. Muscle relaxants for pain management in rheumatoid arthritis. Cochrane Database Syst Rev 2012;1:CD008922.

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