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Skelaxin (metaxalone) - What You Need to Know

Muscle Relaxer


Updated June 27, 2014

BRAND NAME: Skelaxin



Skelaxin (metaxalone) is available as a 400 mg round, pale rose tablet and an 800 mg oval, pink scored tablet.


Skelaxin (metaxalone) is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Skelaxin (metaxalone) does not directly relax tense skeletal muscles in man.


Known hypersensitivity to any components of this product. Known tendency to drug induced, hemolytic, or other anemias. Significantly impaired renal or hepatic function.


Skelaxin (metaxalone) may enhance the effects of alcohol and other CNS depressants.


Skelaxin (metaxalone) should be administered with great care to patients with pre-existing liver damage. Serial liver function studies should be performed in these patients. False-positive Benedict’s tests, due to an unknown reducing substance, have been noted. A glucose-specific test will differentiate findings.


The most frequent reactions to Skelaxin (metaxalone) include:

  • CNS: drowsiness, dizziness, headache, and nervousness or “irritability”
  • Digestive: nausea, vomiting, gastrointestinal upset
  • Immune system: hypersensitivity reaction, rash with or without pruritus
  • Hematologic: leukopenia, hemolytic anemia
  • Hepatobiliary jaundice

Although rare, anaphylactoid reactions have been reported with Skelaxin (metaxalone).


Skelaxin (metaxalone) may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle, especially when used with alcohol or other CNS depressants.


Skelaxin (metaxalone) may enhance the effects of alcohol, barbiturates and other CNS depressants.


The carcinogenic potential of Skelaxin (metaxalone) has not been determined.


Reproduction studies in rats have not revealed evidence of impaired fertility or harm to the fetus due to Skelaxin (metaxalone). Post marketing experience has not revealed evidence of fetal injury, but such experience cannot exclude the possibility of infrequent or subtle damage to the human fetus.

Safe use of Skelaxin (metaxalone) has not been established with regard to possible adverse effects upon fetal development. Therefore, Skelaxin (metaxalone) tablets should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgement of the physician the potential benefits outweigh the possible hazards.


It is not known whether this drug is secreted in human milk. As a general rule, nursing should not be undertaken while a patient is on a drug since many drugs are excreted in human milk. Pediatric use, safety and effectiveness in children 12 years of age and below have not been established.


The recommended dose for adults and children over 12 years of age is two 400 mg tablets (800 mg) or one 800 mg tablet three to four times a day.

Store Skelaxin (metaxalone) at Controlled Room Temperature, between 15 C and 30 C (59 F and 86 F).


The mechanism of action of Skelaxin (metaxalone) in humans has not been established, but may be due to general central nervous system depression. It has no direct action on the contractile mechanism of striated muscle, the motor end plate or the nerve fiber.

The absolute bioavailability of metaxalone from Skelaxin tablets is not known. Skelaxin (metaxalone) is metabolized by the liver and excreted in the urine as unidentified metabolites. The impact of age,gender, hepatic, and renal disease on the pharmacokinetics of Skelaxin (metaxalone) has not been determined. In the absence of such information, Skelaxin (metaxalone) should be used with caution in patients with hepatic and/or renal impairment and in the elderly.


Deaths by deliberate or accidental overdose have occurred with this class of drugs, particularly incombination with antidepressants and/or alcohol.

When determining the LD50 in rats and mice, progressive sedation, hypnosis and finally respiratoryfailure were noted as the dosage increased. In dogs, no LD50 could be determined as the higher doses produced an emetic action in 15 to 30 minutes.

Overdose Treatment: Gastric lavage and supportive therapy. Consultation with a regional poison control center is recommended.


U.S. Food and Drug Administration, NDA 13-217/S-036, Revised: August, 2002

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