Metaxalone


Generic Medicine Info
Indications and Dosage
Oral
Acute musculoskeletal disorders
Adult: As a treatment adjunct: 800 mg 3-4 times daily.
Child: >12 years Same as adult dose.
Contraindications
Drug-induced haemolytic anaemia or other anaemias. Significantly impaired hepatic or renal function.
Special Precautions
Concomitant use with serotonergic agents (e.g. SSRIs, SNRIs, TCAs, triptans, 5-HT3 receptor antagonists, MAOIs). Hepatic and renal impairment. Pregnancy and lactation.
Adverse Reactions
Significant: CNS depression.
Blood and lymphatic system disorders: Haemolytic anaemia, leucopenia.
Gastrointestinal disorders: Nausea, vomiting, gastrointestinal distress.
Immune system disorders: Hypersensitivity reaction, anaphylaxis. Rarely, anaphylactoid reaction.
Nervous system disorders: Dizziness, headache, drowsiness, nervousness, irritability.
Skin and subcutaneous tissue disorders: Rash (with or without pruritus), jaundice.
Potentially Fatal: Serotonin syndrome when used with serotonergic agents (e.g. SSRIs, SNRIs, TCAs, triptans, 5-HT3 receptor antagonists, MAOIs).
Patient Counseling Information
This medicine may cause drowsiness or dizziness, if affected, do not drive or operate machinery.
Overdosage
Symptoms: Serotonin syndrome, death. Management: Supportive therapy. Perform gastric lavage.
Drug Interactions
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.
Food Interaction
Enhanced CNS depressant effect with alcohol.
Lab Interference
May cause false-positive results for glucose determinations using cupric sulfate (e.g. Benedict’s solution, Fehling’s solution).
Action
Description: 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.
Onset: Within 1 hour.
Duration: 4-6 hours.
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.
Chemical Structure

Chemical Structure Image
Metaxalone

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 15459, Metaxalone. https://pubchem.ncbi.nlm.nih.gov/compound/Metaxalone. Accessed Apr. 28, 2021.

Storage
Store between 15-30°C.
MIMS Class
References
Anon. Metaxalone. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 18/02/2021.

Anon. Metaxalone. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 18/02/2021.

Buckingham R (ed). Metaxalone. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 18/02/2021.

Metaxalone (Actavis Pharma, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 18/02/2021.

Skelaxin (Pfizer Laboratories Div Pfizer Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 18/02/2021.

Disclaimer: This information is independently developed by MIMS based on Metaxalone from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2021 MIMS. All rights reserved. Powered by MIMS.com
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