metaxalone

Metaxalone is a medication that relaxes the skeletal muscles and is approved by the FDA for use as an adjunct to rest, physical therapy, and other measures to relieve discomfort from painful musculoskeletal conditions. Metaxalone is also used off-label to relieve pain from acute temporomandibular disorder.

While the precise way in which metaxalone works is not established, the muscle relaxation is believed to result from the central nervous system (CNS) depressant effects of the drug. Metaxalone has no direct effect on the skeletal muscles, it may disrupt the pain-spasm-pain cycle by generally depressing the central nervous system.

• Do not use in patients who:
  • Are hypersensitive to metaxalone or any of its components
  • Have a history of drug-induced anemias, including hemolytic anemia
  • Have significant impairment of kidney or liver function.
• Metaxalone depresses the central nervous system, caution patients to avoid hazardous tasks that require physical and mental alertness.
• Metaxalone can enhance the effects of alcohol and other CNS depressants such as benzodiazepines, opioids, and tricyclic antidepressants.
• Elderly patients are more susceptible to CNS depression effects, so use with caution.
• Use metaxalone with great caution in patients with mild or moderate kidney or liver function impairment.
• Bioavailability of metaxalone may increase in women, so use with caution.
• Serotonin syndrome, a life-threatening drug reaction, may occur with concurrent use with serotonergic drugs including selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, triptans, 5-HT3 receptor antagonists, monoamine oxidase inhibitors (MAOIs). Use with caution, monitor the patient for symptoms and discontinue metaxalone if serotonin syndrome is suspected.

Common side effects of metaxalone include:

• Nausea
• Vomiting
• Gastrointestinal distress
• Irritability
• Nervousness
• Headache
• Drowsiness (somnolence)
• Dizziness

Less common side effects of metaxalone include:

• Jaundice
• Low red blood cell count due to rapid destruction (hemolytic anemia)
• Low leukocyte immune cell count (leukopenia)
• Immune hypersensitivity reaction
• Rash
• Itching (pruritus)

Rare side effects of metaxalone include:

• Serious allergic reaction (anaphylaxis)
• Serotonin syndrome with higher doses or when used concurrently with serotonergic drugs

Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

• Serious heart symptoms include fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness;
• Severe headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
• Severe nervous system reaction with very stiff muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, and feeling like you might pass out; or
• Serious eye symptoms include blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Tablet

• 400 mg
• 800 mg

Adult:

Musculoskeletal Pain

• Indicated for acute, painful musculoskeletal conditions
• 800 mg orally every 6-8 hours

Dosage Modifications

Renal impairment

• Mild to moderate impairment: Use caution
• Severe impairment: Contraindicated

Hepatic impairment

• Mild to moderate impairment: Use caution
• Severe impairment: Contraindicated

Pediatric:

Musculoskeletal Pain

• Children below 12 years: Safety and efficacy not established
• Children 12 years and above: 800 mg orally every 6-8 hours

Overdose

• Metaxalone overdose can cause progressive sedation and hypnosis, and lead to respiratory failure and death.
• Treatment is supportive, including gastric lavage to eliminate undigested drug in the stomach.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• Metaxalone has no listed severe interactions with other drugs.
• Serious interactions of metaxalone include:
  • abametapir
  • apalutamide
  • benzhydrocodone/acetaminophen
  • calcium/magnesium/potassium/sodium oxybates
  • fexinidazole
  • hydrocodone
  • idelalisib
  • ivosidenib
  • lopinavir
  • metoclopramide intranasal
  • sodium oxybate
  • sufentanil SL
  • tucatinib
  • voxelotor
• Metaxalone has moderate interactions with at least 174 different drugs.
• Mild Interactions of metaxalone include:
  • eucalyptus
  • levoketoconazole
  • ribociclib
  • sage

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or healthcare provider about all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or healthcare provider if you have any questions about the medication.

• Animal reproductive studies have not shown evidence of fetal harm, however, there are no adequate and well-controlled studies in pregnant women. Metaxalone must be used only if benefits to the mother outweigh potential fetal risks.
• It is not known if metaxalone is present in breast milk, however, many drugs are excreted in breast milk. Discontinue nursing while on metaxalone therapy.

• Take metaxalone exactly as prescribed.
• Avoid drinking alcohol and taking other CNS depressant drugs while on metaxalone therapy, they can have additive CNS depression effects.
• Metaxalone can impair physical and mental abilities, avoid hazardous activities such as driving and operating heavy machinery.
• Store safely out of reach of children.
• In case of overdose, seek immediate medical help or contact Poison Control.