Skeletal muscle relaxants: Nursing pharmacology

Skeletal muscle relaxants are medications that reduce muscle contraction, so they are primarily used to relieve both acute or chronic muscle spasms and spasticity.

Muscle spasms are sudden and involuntary muscle tightness or contractions, and are most often caused by muscle fatigue or injury.

On the other hand, muscle spasticity is a sustained muscle spasm associated with decreased dexterity that originates from the central nervous system, which can occur due to damage to the nerves that coordinate muscle activity, and can also be seen with chronic neurological disorders, such as multiple sclerosis and stroke; as well as in cerebral palsy and spinal cord damage.

Now, skeletal muscle relaxants can further be divided into centrally-acting and direct-acting muscle relaxants. Centrally-acting muscle relaxants include cyclobenzaprine, methocarbamol, metaxalone, chlorzoxazone, tizanidine, baclofen, carisoprodol, and orphenadrine.

Other medications can also act as centrally-acting muscle relaxants, such as benzodiazepines, but they’re most commonly used as anxiolytics, sedatives, or anticonvulsants. On the other hand, direct-acting muscle relaxants include dantrolene.

All of these medications can be taken orally. Additionally, methocarbamol can also be administered intravenously or intramuscularly, while dantrolene can be given intravenously, and baclofen can be given intrathecally.

Once administered, centrally-acting muscle relaxants act on the neurons of the central nervous system or CNS to interfere with muscle reflexes and decrease the skeletal muscle tone.