Metaxalone (Skelaxin) - Uses, Dose, Side effects, MOA, Brands

Metaxalone (Skelaxin) is used as a muscle relaxant.

The exact mechanism of action of the drug is not known, however, it causes central nervous system depression.

Metaxalone (Skelaxin) Uses:

  • Musculoskeletal conditions:

    • It helps ease the discomfort of sudden muscle problems like pain and spasms.

    • Other medicines for muscle spasms are Tizanidine (Ternaline), Baclofen (Baclin), and Chlorzoxazone.

Metaxalone (Skelaxin) Dose in Adults:

Metaxalone (Skelaxin) Dose in the Musculoskeletal conditions:

  • Take 800 milligrams by mouth three or four times a day.

Use in Children:


For adults, the recommended dosage is 800 milligrams taken orally three or four times a day.

Metaxalone (Skelaxin) Pregnancy Risk Category: C

  • In studies with animals, no harmful effects on fetal development were found.
  • However, it's crucial to use the medication during pregnancy only if you believe that the advantages outweigh the potential risks, particularly in the first trimester.

Use of metaxalone while breastfeeding

  • We don't know if the medication passes into breast milk.

  • It's recommended to avoid using it while breastfeeding, as advised by the manufacturer.

Dose in Kidney Disease:


If someone has significant kidney problems, it's not recommended to use the medication.

The manufacturer's instructions do not provide dosage recommendations for individuals with mild to moderate kidney dysfunction. Caution should be exercised in such cases.

Dose in Liver disease:

If someone has severe liver disease, it is not advisable to use the medication.

The manufacturer's instructions do not provide dosage recommendations for individuals with mild to moderate liver impairment.

Care should be taken in such cases.

Side effects of Metaxalone (Skelaxin)

  • Central nervous system:

    • Drowsiness
    • Irritability
    • Headache
    • Nervousness
    • Dizziness
  • Dermatologic:

    • Skin rash (with or without pruritus)
  • Gastrointestinal:

    • Gastrointestinal distress
    • Vomiting
    • Nausea
  • Hematologic & oncologic:

    • Leukopenia
    • Hemolytic anemia
  • Hepatic:

    • Jaundice
  • Hypersensitivity:

    • Hypersensitivity reaction
    • Anaphylaxis
    • Anaphylactoid reaction (rare)

Contraindications to Metaxalone (Skelaxin):

  • Do not use the drug if you have allergies to any of its components, severe kidney or liver problems, or a history of drug-induced hemolytic anemia or other types of anemia.

Warnings and precautions

  • Depression in the CNS:

    • The drug can cause CNS depression, which may result in drowsiness and impaired physical and mental abilities.

    • People who need to stay alert for tasks that require mental or physical focus, especially those operating heavy machinery or driving, should be cautioned.

  • Serotonin syndrome

    • When taken along with other serotonergic drugs like SSRIs, SNRIs, TCAs, triptans, 5-HT3 receptor antagonists, or MAO inhibitors, this medication can lead to serotonin syndrome.
    • Serotonin syndrome can be serious and may occur when starting or adjusting the dose.
    • Patients should closely monitor for symptoms such as changes in mental state (anxiety, sleepiness, hallucinations), autonomic instability (hyperthermia, fluctuating blood pressure, tachycardia), neuromuscular changes (hyperreflexia, myoclonus, incoordination), and gastrointestinal symptoms (nausea, vomiting, diarrhea).
    • Symptoms of serotonin syndrome can appear within 24 hours, and if they occur, it's crucial to stop all treatment immediately.
  • Hepatic impairment

    • Regular liver function tests should be conducted during the course of therapy.

    • If a patient has a severe liver impairment, they should avoid taking the medication.

  • Renal impairment

    • Individuals with impaired renal function or severe renal impairment should avoid taking the drug.

Metaxalone: Drug Interaction

Risk Factor C (Monitor therapy)

Alcohol (Ethyl)

Alcohol's CNS depressing effect may be amplified by CNS depressants (Ethyl).


CNS depressants may have an enhanced CNS depressant impact.

Botulinum Toxin-Containing Products

Centrally acting muscle relaxants may intensify the harmful/toxic effects of products containing botulinum  toxin. In particular, there may be a greater likelihood of developing muscle weakness.


Brexanolone's CNS depressing effects may be amplified by other CNS depressants.

Brimonidine (Topical)

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Chlorphenesin Carbamate

CNS depressants may have an enhanced CNS depressant impact.

CNS Depressants

CNS depressants may have an enhanced CNS depressant impact.

Dimethindene (Topical)

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact. Management: The producer of the pregnancy-safe drug Diclegis (doxylamine/pyridoxine) particularly advises against combining it with other CNS depressants.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Kava Kava

CNS depressants may have an enhanced CNS depressant impact.


May enhance the CNS depressant effect of CNS Depressants. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs.

Magnesium Sulfate

May enhance the CNS depressant effect of CNS Depressants.


CNS Depressants may enhance the sedative effect of MetyroSINE.

Minocycline (Systemic)

May enhance the CNS depressant effect of CNS Depressants.


May enhance the CNS depressant effect of CNS Depressants.


Piribedil's CNS depressing effects may be enhanced by other CNS depressants.


The sedative effects of pramipexole might be enhanced by CNS depressants.


The sedative effects of CNS depressants may increase those of ROPINIRole.


Rotigotine's sedative effects may be boosted by CNS depressants.


CNS depressants' harmful or toxic effects could be increased. Particularly, drowsiness and lightheadedness  could be worsened.

Serotonergic Agents (High Risk)

Serotonergic agents' serotonergic effects may be enhanced by methylxalone (High Risk). Serotonin syndrome  might occur from this. When these medications are taken together, it is important to watch out for  any signs  and symptoms of serotonin syndrome or serotonin poisoning, such as hyperreflexia,  clonus, hyperthermia,  diaphoresis, tremor, autonomic instability, and changes in mental status.


CNS depressants may have an enhanced CNS depressant impact.

Tetrahydrocannabinol and Cannabidiol

CNS depressants may have an enhanced CNS depressant impact.


CNS depressants may have an enhanced CNS depressant impact.

Risk Factor D (Consider therapy modification)


Blonanserin's CNS depressing effects may be enhanced by other CNS depressants.


The CNS depressing impact of buprenorphine may be enhanced by CNS depressants. Treatment: If a patient  has a high risk of abusing or injecting  themselves with buprenorphine, consider reducing the doses of other  CNS depressants and avoiding such medications. Buprenorphine should be started at lower doses  in  individuals who are currently taking CNS depressants.


CNS depressants may have an enhanced CNS depressant impact. Management: Keep a close eye out for signs  of severe CNS depression. If such a combination is required, it should be taken at a dose that has been suitably  lowered,  according to the instructions for chlormethiazole.


May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Risk


Flunitrazepam's CNS depressing effects may be enhanced by other CNS depressants.


The CNS depressive action of HYDROcodone may be enhanced by CNS depressants. Management: Whenever  feasible,  refrain from using hydrocodone and benzodiazepines or other CNS depressants concurrently. Only in  the event that other treatment choices are insufficient should these medications be combined. Limit the  duration and dosage of each medicine when used together.


CNS depressants may have an enhanced CNS depressant impact. Management: Due to the possibility of additive  CNS  depressant effects when lemborexant and concurrent CNS depressants are administered concurrently,  dosage  modifications  may be required. Effects of CNS depressants must be closely monitored.


The CNS depressing action of methotrimeprazine may be enhanced by CNS depressants. The CNS depressant action of  CNS Depressants may be strengthened by methotrimeprazine. Management: Start concurrent methotrimeprazine therapy  while  reducing  the adult dose of CNS depressants by 50%. Only once a clinically effective dose of methotrimeprazine  has been  established should additional CNS depressant dosage modifications be made.

Opioid Agonists

Opioid agonists' CNS depressing effects may be amplified by CNS depressants. Management: When at all possible,  refrain from using benzodiazepines or other CNS depressants concurrently with opioid agonists. Only in the  event that  other treatment choices are insufficient should these medications be combined. Limit the duration and  dosage of each  medicine when used together.


The CNS depressing effects of OxyCODONE may be enhanced by CNS depressants. Management: Whenever feasible,  refrain from using oxycodone and benzodiazepines or other CNS depressants concurrently. Only in the  event that  other treatment choices are insufficient should these medications be combined. Limit the duration and dosage of each  medicine when used together.


CNS depressants may have an enhanced CNS depressant impact. Treatment: Until they have experience  using the  combination, patients taking perampanel along with any other medication that has CNS depressive effects should  avoid complex and high-risk activities, especially those like driving that call for awareness and coordination.

Sodium Oxybate

CNS depressants may have an enhanced CNS depressant impact. Management: Take into account substitutes for  combined use. Reduce the doses of one or more medications when simultaneous use is necessary. It is not advised to  use sodium oxybate with alcoholic beverages or hypnotic sedatives.


Suvorexant's CNS depressing effects may be amplified by other CNS depressants. Treatment: Suvorexant and/or  any other CNS depressant dosage reduction may be required. Suvorexant shouldn't be taken with alcohol, and it  shouldn't  be  taken for sleeplessness with any other medication either.


CNS depressants may have an enhanced CNS depressant impact. Treatment: When feasible, refrain from using  tapentadol and benzodiazepines or other CNS depressants simultaneously. Only in the event that  other treatment  choices are insufficient should these medications be combined. Limit the duration and dosage of each medicine when  used together.


May intensify the negative or harmful effects of muscle relaxants (Centrally Acting). Management: If tolperisone is used  with  other centrally acting muscle relaxants, watch for signs of increased sedation or CNS effects. If these medications  are taken together, think about lowering the tolperisone dosage.


CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk

Risk Factor X (Avoid combination)

Azelastine (Nasal)

Azelastine's CNS depressing impact may be amplified by CNS depressants (Nasal).


CNS depressants may have an enhanced CNS depressant impact.


The CNS depressing action of orphenadrine may be enhanced by CNS depressants.


CNS depressants may have an enhanced CNS depressant impact.


The CNS depressing effects of paraldehyde may be enhanced by CNS depressants.


The CNS depressing effect of thalidomide may be enhanced by CNS depressants.


Monitoring Parameters:

The manufacturer's labeling does not specify any particular conditions, but it is recommended to monitor liver and renal functions regularly.

How to administer Metaxalone (Skelaxin)?

  • You can take the medication with or without food.
  • However, having it with food can enhance the drug's absorption, resulting in higher levels in the blood and intensifying its effects on the central nervous system.
  • The impact of eating habits on the drug's clinical effectiveness is not known.

Mechanism of action of Metaxalone (Skelaxin):

  • The exact mechanism of action of the drug is unclear.

  • It is likely that the effects of the medication result from depressing the central nervous system.

  • However, the drug does not affect motor end plates, nerve fibers, or striated muscles.


  • The drug undergoes metabolism in the liver through various cytochrome P450 enzymes, including CYP1A2, CYP2D6, CYP2E1, and CYP3A4.
  • Additionally, to a lesser extent, it is metabolized by CYP2C8, CYP2C9, and CYP2C19 enzymes. However, the bioavailability of the drug is not provided in the information provided.


  • The bioavailability of the drug may be increased when taken with food.

Half-life elimination:

  • It takes about 9 hours for the drug to reduce its strength by half, and this time can vary by around 4.8 hours.

Time to peak:

  • Around 3 hours


  • The drug's byproducts or breakdown products are eliminated through urine.

International Brands of Metaxalone:

  • Metaxall
  • Skelaxin
  • Flexura
  • Sabaxolone
  • Sketarest
  • Striolaxone

Metaxalone Brand Names in Pakistan:

  • No Brands Available in Pakistan.