Metaxalone

Metaxalone is a skeletal muscle relaxant

Metaxalone is used in the treatment of musculoskeletal conditions and Temporomandibular disorders.

Metaxalone is absorbed from the gastrointestinal tract and May be increased with food and Extensively distributed in the tissues. Volume of distribution: Approx 800 L and get Metabolized in the liver by CYP1A2, CYP2D6, CYP2E1, CYP3A4 and to a lesser extent by CYP2C8, CYP2C9, and CYP2C19 and get excreted Via urine (as metabolites). Elimination half-life: 9±4.8 hours.

Metaxalone is available in tablets.

The common side effects of Metaxalone were Haemolytic anemia, leucopenia, Nausea, vomiting, and gastrointestinal distress.

Metaxalone is available in India, Germany, Canada, France, USA.

Precise mechanism has not been established; however, its clinical effect may be associated with general depression of the nervous system; has no direct effect on the contractile mechanism of striated muscle, the nerve fiber, or the motor end plate.

Metaxalone is available in the form of tablets.

Metaxalone is used in the treatment of mucoskeletal conditions and Temporomandibular disorder.

Metaxalone is a centrally acting muscle relaxant. The precise mechanism of action has not been established. Its effect may be associated with CNS depression. It has no direct effect on the contractile mechanism of striated muscle, the motor end plate or the nerve fibre.

Metaxalone is approved for use in the following clinical indications

Musculoskeletal conditions: Relief of discomforts associated with acute, painful musculoskeletal conditions.

Although not approved there have been certain off labelled uses documented for metaxalone which includes:

Temporomandibular disorder, acute.

Musculoskeletal conditions: Oral: 800 mg 3 to 4 times daily.

Temporomandibular disorder, acute (adjunctive therapy) (off-label use):

Note: Adjunct to a nonsteroidal anti-inflammatory drug in select patients with tenderness of the muscles of mastication.

Oral: 400 to 800 mg every 8 hours for 10 to 14 days; some patients with persistent muscular pain may require an additional 7 days of therapy.

Metaxalone is available in the dosage strength of 400 mg, 800 mg.

Metaxalone is available in the form of tablets.

• Dosage Adjustment for Pediatric Patients:

Musculoskeletal conditions: Adolescents ≥13 years: Oral: 800 mg 3 to 4 times daily.

Metaxalone is contraindicated in patients with:

Metaxalone should not be administered to animals with serious hepatic, renal or cardiac pathology, or those with a history of blood dyscrasia.

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery, driving).

• Serotonin syndrome: Potentially life-threatening serotonin syndrome (SS) has occurred with metaxalone when used in combination with other serotonergic agents (eg, selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, tricyclic antidepressants, triptans, 5-HT3 receptor antagonists, monoamine oxidase inhibitors). Monitor patients closely for signs/symptoms of SS. Symptoms generally occur within several hours to a few days, but may occur later.

Metaxalone may cause liver problems, and using it with substantial quantities of ethanol may increase that risk.

• Common Adverse effects: Hemolytic Anemia, Leucopenia, Nausea, Vomiting, Gastrointestinal Distress.

• Less Common Adverse effects: Hypersensitivity Reaction, Anaphylaxis.

• Rare Adverse Effects: Dizziness, Headache, Drowsiness, Nervousness, Irritability, Anaphylactoid Reaction.

Increased risk of serotonin syndrome with other serotonergic agents (e.g. SSRIs, SNRIs, TCAs, triptans, 5-HT3 receptor antagonists, MAOIs). Enhanced sedative effects with benzodiazepines.

The common side effects of Metaxalone include the following :

Common Side effects: Gastric pain, nausea, diarrhea, dizziness, headache and skin rashes.

Symptoms: Serotonin syndrome, death.

Management: Supportive therapy. Perform gastric lavage.

• Pharmacodynamics

Metaxalone is a centrally acting muscle relaxant. The precise mechanism of action has not been established. Its effect may be associated with CNS depression. It has no direct effect on the contractile mechanism of striated muscle, the motor end plate or the nerve fibre.

• Pharmacokinetics

Absorption: Absorbed from the gastrointestinal tract. Bioavailability: May be increased with food. Time to peak plasma concentration: Approx 3 hours.

Distribution: Extensively distributed in the tissues. Volume of distribution: Approx 800 L.

Metabolism: Metabolised in the liver by CYP1A2, CYP2D6, CYP2E1, CYP3A4 and to a lesser extent by CYP2C8, CYP2C9, and CYP2C19.

Excretion: Via urine (as metabolites). Elimination half-life: 9±4.8 hours.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1364710/
2. https://reference.medscape.com/drug/colestid-Metaxalone -342452
3. https://go.drugbank.com/drugs/DB00375
4. https://www.sciencedirect.com/topics/medicine-and-dentistry/Metaxalone
5. https://europepmc.org/article/med/6988203