Metaxalone (2 brand names, 1 dosage form, 1 route)
Available dosage forms: TABLET.
Routes of administration: ORAL.
Brand Names
- METAXALONE
- SKELAXIN
Indications and Usage
Metaxalone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions in adults and pediatric patients 13 years of age and older.
Dosage and Administration
The recommended dosage of metaxalone in adults and pediatric patients 13 years of age and older is 800 mg orally three to four times a day [see Use in Specific Populations ( 8)] . Metaxalone Tablets 800 mg are not substitutable on a mg to mg basis with Metaxalone Tablets, 640 mg [see Clinical Pharmacology ( 12.3)] . When it is appropriate to switch: Switch only in patients who have been taking Metaxalone Tablets, 640 mg on an empty stomach. Stop Metaxalone Tablets, 640 mg three times a day and start Metaxalone Tablets 800 mg three times a day on an empty stomach, OR stop Metaxalone Tablets 640 mg four times a day and start Metaxalone Tablets 800 mg four times a day on an empty stomach. Do not switch from Metaxalone Tablets, 640 mg to Metaxalone Tablets, 800 mg when the patient is taking food during administration.
Contraindications
Metaxalone is contraindicated in patients with: Known hypersensitivity to any component of metaxalone. Known tendency to drug induced, hemolytic, or other anemias. Severe renal or hepatic impairment.
Adverse Reactions
The following adverse reactions associated with the use of metaxalone were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The most frequent reactions to metaxalone were: CNS: drowsiness, dizziness, headache, and nervousness or “irritability”. Digestive: nausea, vomiting, gastrointestinal upset. Other adverse reactions were: CNS: cases of serotonin syndrome have been reported during concomitant use of metaxalone (within the recommended dosage range) and other serotonergic drugs and with the use of metaxalone as the only serotonergic drug at a dosage higher than the recommended dosage [see Warnings and Precautions ( 5.1) , Drug Interactions ( 7.1) and Overdosage ( 10)] . Hematologic: leukopenia; hemolytic anemia; Hepatobiliary: jaundice; Immune System: anaphylaxis, hypersensitivity reaction, rash with or without pruritus.
Mechanism of Action
Metaxalone’s mechanism of action has not been fully characterized, but may be related to its sedative properties. Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber.
Overdosage
Clinical Presentation of Metaxalone Overdose Deaths by deliberate or accidental overdose have occurred with metaxalone, particularly in combination with other CNS depressants (including alcohol). CNS manifestations may include CNS depression, agitation, hallucinations, delusions, seizures, respiratory depression, and coma. Cardiovascular effects may include tachycardia and hypertension; hypotension has also been reported. Serotonin syndrome, leading to muscle rigidity, tremor, and hyperthermia, has been reported [see Warnings and Precautions ( 5.1), Drug Interactions ( 7.1, 7.2)] . Treatment of Metaxalone Overdose The standard of treatment is supportive care. Monitor for CNS and respiratory depression and manage airway with oxygen as needed. Gastrointestinal decontamination procedures (including emesis) should generally be avoided because aspiration may result from CNS depression and seizures. Extracorporeal elimination such as hemodialysis or plasmapheresis have no proven clinical benefit. Consider contacting the Poison Help line (1-800-222-1222) or a medical toxicologist for additional overdose management recommendations.