Metaxalone – LiverTox – NCBI Bookshelf

Last Update: September 13, 2021.

OVERVIEW

Introduction

Metaxalone is a centrally acting skeletal muscle relaxant that has been in use for more than 40 years. Metaxalone has not been associated with serum aminotransferase elevations during therapy or with clinically apparent hepatic injury.

Background

Metaxalone (me tax’ a lone) acts centrally as a skeletal muscle relaxant, but its efficacy and precise mechanism of action are not well documented. Metaxalone was approved for use in the United States in 1962 and has been a widely used muscle relaxant, but its use recently has declined. Current indications include the treatment of pain from acute musculoskeletal conditions and muscle spasms. The recommended dosage is 800 mg orally three to four times daily. Metaxalone is available by prescription only in 400 and 800 mg tablets in generic forms as well as under the commercial name Skelaxin. Sparse data are available regarding metaxalone safety. Side effects are not common, but can include drowsiness, dizziness, headache, nausea, and dry mouth. When combined with other serotonergic medications (such as serotonin reuptake inhibitors, tricyclic antidepressants, triptans, opiates and others), metaxalone can cause acute serotonin syndrome marked by agitation, confusion, hallucinations, tachycardia, hyperthermia, incoordination, neuromuscular rigidity, nausea and abdominal pain.

Hepatotoxicity

According to the product brochure, metaxalone may cause jaundice, although there are no specific case reports of hepatotoxicity from metaxalone in the literature and no prospective trials with routine monitoring of aminotransferase levels. Given its long history, metaxalone appears to be without significant hepatotoxicity.

Likelihood score: E (Unlikely cause of clinically apparent liver injury).

Drug Class: Muscle Relaxants

CHEMICAL FORMULA AND STRUCTURE

ANNOTATED BIBLIOGRAPHY

References updated: 13 September 2021

• Zimmerman HJ. Muscle spasmolytics. In, Hepatotoxicity: The Adverse Effects of Drugs and Other Chemicals on the Liver. 2nd Ed. Philadelphia: Lippincott, 1999. p. 544-45.

  (Expert review of hepatotoxicity published in 1999; dantrolene, chlorzoxazone and baclofen are discussed; mentions that metaxalone has been cited as causing jaundice but that no such case reports have appeared in the literature).

• Hibbs RE, Zambon AC. Agents acting at the neuromuscular junction and autonomic ganglia. In, Brunton LL, Chabner BA, Knollman BC, eds. Goodman & Gilman’s The pharmacological basis of therapeutics, 12th ed. New York: McGraw-Hill, 2011. p. 255-76.

  (Textbook of pharmacology and therapeutics)

• Toth PP, Urtis J. Commonly used muscle relaxant therapies for acute low back pain: a review of carisoprodol, cyclobenzaprine hydrochloride, and metaxalone. Clin Ther. 2004;26:1355–67. [PubMed: 15530999]

  (A review of safety and efficacy of muscle relaxants which states “Although rare instances of hepatic enzyme elevation and anemia have been reported [with metaxalone], this association appears to be based on a false-positive hepatic assay using the cephalin flocculation test.”).

• Chou R, Peterson K, Helfand M. Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: a systematic review. J Pain Symptom Manage. 2004;28:140–75. [PubMed: 15276195]

  (Thorough review of the pharmacology, efficacy and side effects of the muscle relaxants).

• Moore KA, Levine B, Fowler D. A fatality involving metaxalone. Forensic Sci Int. 2005;149:249–51. [PubMed: 15749367]

  (54 year old woman found dead in whom postmortem analysis indicated metaxalone overdose; liver reported as being normal).

• Poklis JL, Ropero-Miller JD, Garside D, Winecker RE. Metaxalone (Skelaxin)-related death. J Anal Toxicol. 2004;28:537–41. [PubMed: 15516312]

  (21 year old woman found dead in whom postmortem analysis indicated metaxalone overdose; no mention of liver abnormalities, although highest levels of drug were present in liver).

• Russo MW, Galanko JA, Shrestha R, Fried MW, Watkins P. Liver transplantation for acute liver failure from drug-induced liver injury in the United States. Liver Transpl. 2004;10:1018–23. [PubMed: 15390328]

  (Among ~50,000 liver transplants done in the US between 1990 and 2002, 270 [0.5%] were done for drug induced acute liver failure, but none were attributed to muscle relaxants).

• Chalasani N, Fontana RJ, Bonkovsky HL, Watkins PB, Davern T, Serrano J, Yang H, Rochon J. , Drug Induced Liver Injury Network (DILIN). Causes, clinical features, and outcomes from a prospective study of drug-induced liver injury in the United States. Gastroenterology. 2008;135:1924–34. [PMC free article: PMC3654244] [PubMed: 18955056]

  (Among 300 cases of drug induced liver disease in the US collected from 2004 to 2008, one was attributed to chlorzoxazone, but none to metaxalone).

• Reuben A, Koch DG, Lee WM., Acute Liver Failure Study Group. Drug-induced acute liver failure: results of a U.S. multicenter, prospective study. Hepatology. 2010;52:2065–76. [PMC free article: PMC3992250] [PubMed: 20949552]

  (Among 1198 patients with acute liver failure enrolled in a US prospective study between 1998 and 2007, 133 were attributed to drug induced liver injury, but none were due to metaxalone or other muscle relaxants).

• Björnsson ES, Bergmann OM, Björnsson HK, Kvaran RB, Olafsson S. Incidence, presentation and outcomes in patients with drug-induced liver injury in the General population of Iceland. Gastroenterology. 2013;144:1419–25. [PubMed: 23419359]

  (In a population based study of drug induced liver injury from Iceland, 96 cases were identified over a 2 year period, but none were attributed to metaxalone or other muscle relaxants).

• Chalasani N, Bonkovsky HL, Fontana R, Lee W, Stolz A, Talwalkar J, Reddy KR, et al. United States Drug Induced Liver Injury Network. Features and outcomes of 899 patients with drug-induced liver injury: The DILIN Prospective Study. Gastroenterology. 2015;148:1340–1352. [PMC free article: PMC4446235] [PubMed: 25754159]

  (Among 899 cases of drug induced liver injury enrolled in a US prospective study between 2004 and 2013, 5 [0.7%] were attributed to muscle relaxants, one of which was possibly related to metaxalone).

• Li Y, Delcher C, Reisfield GM, Wei YJ, Brown JD, Winterstein AG. Utilization patterns of skeletal muscle relaxants among commercially insured adults in the United States from 2006 to 2018. Pain Med. 2021:pnab088. Epub ahead of print. [PubMed: 33690860]

  (Analysis of utilization of skeletal muscle relaxants in the US over a 12 year period demonstrated an increasing use of cyclobenzaprine [65% of prescriptions], baclofen and tizanidine but decreasing use of metaxalone and carisoprodol).

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Metaxalone – Overview

Metaxalone is a medication sometimes prescribed to people in conjunction with rest and other measures for the relief of pain caused by acute musculoskeletal conditions. People who might need a metaxalone medication prescription, including metaxalone 800 mg tablets, can use Push Health to connect with a medical provider who can prescribe metaxalone medication, including generic metaxalone 800 mg tablets, when appropriate to do so.

What Is Metaxalone Used For?

Metaxalone prescription medication, marketed under the brand names Metaxall and Skelaxin, is a drug chemically known as 5-[(3,5- dimethylphenoxy) methyl]-2-oxazolidinone. Metaxalone medication, similar to cyclobenzaprine (Flexeril) and methocarbamol (Robaxin), is sometimes prescribed to people suffering from an acute and painful musculoskeletal condition. The exact mechanism as to how metaxalone works is not fully understood although it is surmised that it exerts its effects through depression of impulses at the level of the central nervous system or possibly suppression of cytokines. Metaxalone medication has not been observed to have direct effects on nerve fibers or the motor end plate. Metaxalone prescription tablets should be used in conjunction with rest, physical therapy and other conservative measures.

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Metaxalone – Dosage and Cost

Metaxalone is generally prescribed to be taken as metaxalone 800 mg tablets one or more times per day. Ultimately, the regimen of metaxalone prescribed depends on the specific health needs of the patient and the judgement of the prescribing medical provider. Following oral administration by study subjects, metaxalone reached peak plasma levels in approximately three hours. Metaxalone is metabolized in the body by the liver and excreted through the kidneys. Metaxalone is moderately affordable, costing under $1 per metaxalone 800 mg tablet at many pharmacies across the United States. Metaxalone coupons can sometimes be found online and some insurance plans may cover costs associated with a metaxalone medication prescription. Metaxalone is typically available as metaxalone 800 mg tablets.

Can I Buy Metaxalone Online?

One cannot just buy metaxalone online as metaxalone requires a prescription to be dispensed by a pharmacy in the United States. Because of this, metaxalone OTC is not available, either. The first step to getting a metaxalone medication prescription is consulting a licensed medical provider. People who might need a metaxalone tablet prescription, including generic metaxalone 800 mg tablets, can use Push Health to connect with a medical provider who can prescribe metaxalone prescription tablets when appropriate to do so.

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Metaxalone – Side Effects

Metaxalone prescription medication, like other medications, can cause side effects when used. Side effects that can occur while using metaxalone tablets include dizziness, headache, drowsiness, nausea, vomiting and gastrointestinal upset. People with a hypersensitivity to metaxalone should avoid using the medication. Serotonin syndrome has been reported is association with metaxalone use. Metaxalone and alcohol should not be used together and operating heavy machinery or driving should be avoided while using the medication. Before taking metaxalone tablets, it is important to discuss possible side effects and other concerns with a qualified medical provider.

More Metaxalone Information

• Metaxalone – Medline

Last updated October 12, 2021. Given the evolving nature of medicine and science, this information might not be accurate and should not be construed as medical advice or diagnosis / treatment recommendations. Please consult a licensed medical provider if you have additional questions. Please call 911 immediately or go to the nearest emergency room if you believe you are experiencing a medical emergency.

Metaxalone – instructions for use

Metaxalone

Instruction:

• Pharmacological action
• Pharmacokinetics
• Readings
• Contraindications
• Pregnancy and breastfeeding
• Pediatric use
• Use in elderly patients
• Dosage and Administration
• Side effects
• Precautions
• Transport management
• Classification

Pharmacological action

Metaxalone is a central muscle relaxant. The mechanism of action is not fully understood, presumably associated with a general depression of the central nervous system.

Pharmacokinetics

Absorption

Maximum plasma concentration (C _max ) – 296 mcg / ml. Time to reach maximum plasma concentration (TC _max ) – 3 hours.

Onset within 1 hour, duration 4-6 hours.

Distribution

Distribution volume (V _d ) – 800 l.

Metabolism

Biotransformed in the liver.

Elimination

Half-life (T _½ ) – 4-14 hours. About Excreted in the urine.

Indications

Painful muscle spasm in diseases and injuries of the musculoskeletal system.

Contraindications

Hypersensitivity; drug hemolytic anemia in history; significant renal/liver failure.

Pregnancy and breastfeeding

Use in pregnancy

FDA fetal category C.

Adequate and well-controlled clinical studies of the safety of metaxalone during pregnancy have not been conducted. It is not known whether the drug has immediate or delayed adverse effects on the fetus.

Animal studies showed no evidence of impaired fertility or harm to the fetus.

The use of metaxalone in pregnant women is contraindicated.

Use during breastfeeding

Special studies on the safety of the use of metaxalone during breastfeeding have not been conducted.

It is not known whether metaxalone is excreted in breast milk. A risk to the infant cannot be ruled out.

If necessary, the use of the drug during lactation should stop breastfeeding.

Pediatric use

Safety and efficacy in children under 12 years of age have not been established.

Use in elderly patients

Worse tolerated in elderly patients.

Dosage and Administration

Children over 12 years of age and adults: Orally, 800 mg 3-4 times a day.

Side effects

The frequency of occurrence of adverse reactions has not been determined: gastrointestinal disorders, nausea, vomiting, dizziness, headache, drowsiness, nervousness, hemolytic anemia (rare), leukopenia (rare), jaundice (rare), hypersensitivity (rare).

Precautions

CNS depression may occur

Increased sedation may occur when combined with other sedatives.

Bioavailability may be increased in women.

Influence on the ability to drive vehicles and control mechanisms

Due to the fact that metaxalone can cause dizziness and drowsiness, it is necessary to refrain from driving vehicles and engaging in activities that require increased concentration of attention and speed of psychomotor reactions.

Classification

• Pharmacological group

  n-anticholinergics (muscle relaxants)

• FDA pregnancy category

  C
  (risk not excluded)

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More on the topic

Find out more about the active ingredient Metaxalone: ​​

• Reviews
• Questions
• Latin name
• Chemical formula

Information about the active substance Metaxalone is intended for medical and pharmaceutical professionals, for reference purposes only. The instructions are not intended to replace professional medical advice, diagnosis or treatment. The information contained here may change over time. The most accurate information on the use of drugs containing the active substance Metaxalone is contained in the manufacturer’s instructions attached to the package.

Metaxalone (skelaxin): side effects, dosages, treatments, interactions, warnings

Relax

• What is
  • What is metaxalone and how does it work?
• Side effects
  • What side effects are associated with the use of metaxalone?
• Drug interactions
  • What other drugs interact with metaxalone?
• Warnings and precautions
  • What are the warnings and precautions for metaxalone?

Trade name: Skelaxin

Generic name: metaxalone

Drug class: skeletal muscle relaxants

What is metaxalone and how does it work?

Metaxalone is a skeletal muscle relaxant indicated for the short-term treatment of painful muscle spasms.

Metaxalone is marketed under the following trade names: Skelaxin.

Metaxalone dosages:

Dosage forms and strengths

difference between braxton and real contractions

Tablet

• 800mg

Dosage Recommendation:

Musculoskeletal pain

• Indicated for acute, painful musculoskeletal conditions

900 05 Adults: 800 mg orally every 6 to 8 hours.

• Children 12 years of age and older: 800 mg orally every 6 to 8 hours.
• Children under 12 years of age: Safety and efficacy not established.

Dosage Modifications

Renal Insufficiency

• Mild to Moderate Disorders: Use caution.
• Severe violation: contraindicated.

Liver failure

• Mild to moderate impairment: use caution.
• Severe violation: contraindicated.

What side effects are associated with the use of metaxalone?

Side effects of metaxalone include:

• Gastrointestinal drug-induced disorders
• Indigestion
• Nausea
• Vomiting
• Dizziness 9000 6
• Headache
• Drowsiness
• Nervousness
• Irritability
• Skin rash
• Hemolytic anemia (rare)
• Low white blood cell count (leukopenia) (rare)
• Immune hypersensitivity reaction (rare)

Serious side effects of metaxalone include:

• Abdominal pain
• Loss of appetite 9000 6
• Low fever
• Dark urine
• Clay colored stools
• Yellowing of the skin and eyes (jaundice) (rare)

This leaflet does not contain all possible side effects that may occur. For more information about side effects, please consult your doctor.

What other drugs interact with metaxalone?

If your doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and can monitor you for them. Do not start, stop, or change the dosage of any medicine without talking to your doctor, health care provider, or pharmacist.

Botox side effects for migraine

Severe interactions with metaxalone include:

• Idelalisib
• ivacaftor
• sodium oxybate

Metaxalone interacts moderately with at least 160 different drugs.

Mild interactions of metaxalone include:

• eucalyptus
• sage

This information does not contain all possible interactions or side effects. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Consult your healthcare professional or physician for additional medical advice, or if you have any health questions, concerns, or additional information about this medicine.

What are the warnings and precautions for metaxalone?

Warnings

This medicine contains metaxalone. Do not take skelaxin if you are allergic to metaxalone or any of the ingredients in this medicine.

Keep out of reach of children. In case of overdose, seek medical attention or contact a Poison Control Center immediately.

Contraindications.

• Hypersensitivity
• History of drug-induced hemolytic anemia
• Significant renal/hepatic impairment

Effects of drug abuse

Timolol maleate ophthalmic gel solution

• None

Short-term effects

• See “What side effects are associated with the use of metaxalone?”

Long-term effects

• See “What side effects are associated with the use of metaxalone?”

Warnings

• Central nervous system (CNS) depression may occur.
• Sedation may be increased when used with other sedatives.
• Drugs are poorly tolerated by the elderly
• Bioavailability may be increased in female patients.