Muscle relaxants

Muscle relaxants are a group drugs that act as central nervous system depressants which have overall sedative and musculoskeletal relaxant properties. Examples from many different drug classes have these effects, despite their different mechanisms of action. Muscle relaxants should preferably be prescribed short-term to reduce skeletal muscle spasms, provide relief from pain, and increase mobility of the affected muscles and should where appropriate be used together with rest and physical therapy as part of an overall recovery strategy.

There is very little research regarding which type of muscle relaxant is more effective. The choice of which medication to prescribe is therefore based on other factors such as the potential for abuse, possible drug interactions and adverse side-effects.

Some commonly used muscle relaxants are:

Baclofen is a centrally acting muscle relaxant licensed to treat muscle tightness and muscle spasms, including those related to spine injuries. The medication may be helpful in treating multiple sclerosis and stabbing nerve pain.

Methocarbamol is a carbamate type, centrally acting muscle relaxant prescribed to relieve acute muscle pain. It can also be used as adjunctive therapy to control the neuromuscular manifestations of tetanus.

Tizanidine is a centrally acting muscle relaxant prescribed to manage muscle spasticity. It is given to adults with multiple sclerosis and spinal cord injury and can be prescribed for children with cerebral palsy. It should not be prescribed alongside fluvoxamine or ciprofloxacin or to patients with liver disease.

Diazepam is a centrally acting muscle relaxant licensed to treat muscle spasms of varied aetiology, including muscle spasm in cerebral spasticity, postoperative skeletal muscle spasm and muscle spasm in palliative care (oral), acute muscle spasm (intramuscular injection, or by slow intravenous injection), tetanus (i.v. injection, infusion or nasoduodenal tube). This is in addition to its uses in anxiety management, alcohol withdrawal and controlling seizure disorders such as epilepsy). Use of diazepam is usually limited to 1-2 weeks due to its habit-forming potential. BNF Muscle spasm

Dantrolene acts within the skeletal muscle and is licensed for controlling chronic spasticity, including that related to spinal injuries. It is also used for conditions such as stroke, multiple sclerosis, and cerebral palsy. It can cause liver toxicity.

The following drugs are licensed in the US but not in the UK:

Chlorzoxazone is licensed to provide relief from discomfort caused by acute, painful, musculoskeletal conditions. It can cause liver problems.

Carisoprodol relaxes muscles and eases pain and stiffness caused by acute bone and muscle problems, as may be caused by an injury. It can be habit-forming, particularly if used in conjunction with alcohol or other drugs that have a sedative effect.

Cyclobenzaprine eases stiffness and pain from muscle cramps or spasms. Its chemical structure is related to that of some antidepressant medications, although it is not an antidepressant. Cyclobenzaprine is the safest muscle relaxant for use in pregnancy.

Metaxalone is prescribed to manage pain and muscle spasms from sprains, strains, and muscle injuries. Metaxalone is the least sedative muscle relaxant. It can be prescribed for children 13 and older for musculoskeletal conditions. It should not be prescribed to patients with a known history of drug-induced, hemolytic, or other anaemias, and kidney or liver disease.