How Do Skeletal Muscle Relaxants Work?

How do skeletal muscle relaxants work?

Skeletal muscle relaxants are medications used to relieve muscle spasms and pain caused by musculoskeletal disorders. Skeletal muscle relaxants work in various ways to relax the skeletal muscles. Some muscle relaxants work on the muscle cells, some work on nerve cells, (neurons) and some depress the central nervous system (CNS).

Skeletal muscles are attached to the skeleton by tendons and are responsible for voluntary movement. Motor neurons enable muscle contraction by releasing chemicals (neurotransmitters) that activate the muscles. In the reflex contraction of muscles, input from sensory (afferent) nerves activates the motor (efferent) nerves.

The abnormal firing of motor neurons due to certain disorders may result in muscle spasms and painful contractions. Some of the ways in which skeletal muscle relaxants work to relax skeletal muscles include the following:

  • Inhibit afferent nerves from releasing excitatory neurotransmitters
  • Inhibit the activity of interneurons which connect the afferent and efferent nerves, and prevent transmission of nerve signals
  • Block the release of acetylcholine, the neurotransmitter that motor neurons release to make muscles contract
  • Interfere with calcium release within the skeletal muscle cells and block their activity
  • Increase the level of the neurotransmitter gamma aminobutyric acid (GABA), which inhibits neuronal activity
  • Produce general central nervous system depression which relaxes muscles and induces sedation

How are skeletal muscle relaxants used?

Skeletal muscle relaxants may be administered through many routes such as:

  • Oral: Tablets, solutions, capsules
  • Injections:
  • Rectal: Gel applied inside the rectum

Skeletal muscle relaxants may be used in the treatment of the following conditions:

  • Muscle spasticity: Stiff and tight muscles caused by
  • Dystonia: Neurological disorder that causes involuntary repetitive muscle contractions
  • Trigeminal neuralgia: A facial nerve disorder that causes sudden severe pain
  • Complex regional pain syndrome: A chronic pain condition caused by dysfunction in the nervous system
  • Musculoskeletal pain: Pain caused by musculoskeletal disorders
  • Muscle spasms: Muscle cramps from involuntary muscle contractions
  • Malignant hyperthermia: A condition that causes high body temperature and severe muscle contractions
  • Neuroleptic malignant syndrome: A life-threatening disorder from reaction to antipsychotic drugs, which causes fever, muscle rigidity, and altered mental status
  • Muscle pain: Muscle pain caused by conditions such as:
  • Succinylcholine-induced fasciculations and post-operative muscle pain: Muscle twitches and pain induced by succinylcholine which is used during anesthesia 
  • Wolfram syndrome: A genetic condition that affects many of the body’s systems including the neuromuscular system.
  • Organophosphate exposure: A neurotoxic substance that can cause muscle weakness, cramps, and paralysis
  • Systemic sclerosis: A systemic autoimmune connective tissue disease
  • Tetanus: Painful contractions of neck and jaw muscles caused by a bacterial infection
  • Parkinson’s disease: A progressive nervous system disorder that impairs movement

Diazepam is a skeletal muscle relaxant that is also an antianxiety and anticonvulsant agent, used in the treatment of:

What are side effects of skeletal muscle relaxants?

Side effects of skeletal muscle relaxants may include:

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

What are names of some skeletal muscle relaxant drugs?

Generic and brand names of skeletal muscle relaxant drugs include:


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