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Metaxalone: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on May 12, 2021.

1. How it works

  • Metaxalone may be given to relax muscles.
  • The exact way metaxalone works has not been established; however, experts suggest it suppresses brain activity which results in sedation, reducing the sensation of pain.
  • It has no direct action on muscle, the motor endplate, or the nerve fiber and does not directly relax tense skeletal muscles.
  • Metaxalone belongs to the class of medicines known as muscle relaxants.

2. Upsides

  • May be used to relieve pain and stiffness associated with certain muscle conditions, sprains, or strains.
  • Should be used in conjunction with rest and physical therapy.
  • Available as a capsule-shaped tablet that is easy to swallow.
  • Generic metaxalone is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Drowsiness, dizziness, headache, and irritability. Nausea, vomiting, abdominal discomfort, anemia, rash, and jaundice have also been reported. Rarely, anaphylaxis (a severe allergic reaction) may occur.
  • Both food and age affect the absorption of metaxalone. At a younger age (approximately 25 years), taking metaxalone with food almost doubles its maximum concentration. As people get progressively older, absorption of metaxalone both with and without food increases.
  • Usually taken three to four times daily.
  • Should not be taken by people with anemia (either drug-induced, hemolytic, or other).
  • May not be suitable for people with liver or kidney disease. Liver function monitoring may be necessary for some patients with pre-existing liver disease if the benefits of taking metaxalone are thought to outweigh the risks.
  • May enhance the effect of alcohol and other CNS depressants. Avoid alcohol.
  • Causes sedation and may affect a person's ability to drive, operate machinery, or perform other hazardous tasks.
  • May interact with other drugs including opioids, cough medicines, antidepressants, and benzodiazepines. Can cause serotonin syndrome if taken with other medications that also release serotonin or if higher than recommended dosages are taken. Symptoms include agitation or restlessness, confusion, rapid heart rate, excessive sweating, or diarrhea.
  • Needs to be taken three to four times daily.
  • False-positive Benedict's tests have been noted in people taking metaxalone. A glucose-specific test can differentiate findings.
  • Should not be used in children under 12.
  • Safe use of metaxalone during pregnancy has not been established and it is not recommended during pregnancy unless the benefits outweigh the risks.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Metaxalone is a muscle relaxant that appears to exert its effects through sedation. Taking metaxalone with food can increase its absorption and enhance its effects (such as sedation). Seniors may be more susceptible.

5. Tips

  • Take metaxalone as directed by your doctor. Swallow the tablets whole with a glass of water. Do not take more metaxalone than prescribed.
  • Taking metaxalone with food can increase its absorption and enhance its effects (such as sedation). Seniors people may be more susceptible.
  • Metaxalone causes sedation and you should not drive, operate machinery, or perform other hazardous tasks while taking this medication. Avoid alcohol.
  • May cause false-positive Benedict's tests (a test used to detect the presence of glucose in the urine).
  • Talk to your doctor if you have any worrying side effects such as shortness of breath, a rash, or feel unusually weak or tired.
  • Talk to a doctor or pharmacist before taking any other medications with metaxalone, including those bought over-the-counter, to check that they are compatible with metaxalone. Some medications can interact with metaxalone and increase the risk of side effects, such as sedation, or the likelihood of serotonin syndrome (symptoms include excessive sweating, agitation, diarrhea, or confusion).
  • Tell your doctor if you are pregnant or intending on becoming pregnant before taking metaxalone. It is not known if metaxalone is secreted into breastmilk, but generally breastfeeding should be avoided while taking metaxalone.

6. Response and effectiveness

Peak plasma concentrations of metaxalone occur within three hours of an oral dose.

7. Interactions

Medicines that interact with metaxalone may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with metaxalone. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with metaxalone include:

  • anti-anxiety medications such as flunitrazepam
  • anticonvulsants, such as phenytoin
  • antidepressants, such as amitriptyline, imipramine, nortriptyline
  • antihistamines that cause sedation, such as diphenhydramine
  • botulinum-toxin-containing products
  • buprenorphine
  • cannabidiol
  • chlormethiazole
  • duloxetine
  • minocycline
  • monoamine oxidase inhibitors, such as selegiline, isocarboxazid, or phenelzine (interaction may be life-threatening)
  • opioid analgesics such as oxycodone and morphine
  • other medicines that increase serotonin, such as fluoxetine, sumatriptan, and tramadol
  • other muscle relaxants such as methocarbamol
  • sleeping pills, such as zolpidem
  • some chemotherapy treatments
  • some medications used to treat mental illness, such as clozapine and thioridazine
  • topiramate.

Alcohol may worsen the side effects of metaxalone such as drowsiness and dizziness.

Note that this list is not all-inclusive and includes only common medications that may interact with metaxalone. You should refer to the prescribing information for metaxalone for a complete list of interactions.

References

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use metaxalone only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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