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Metaxalone

Pronunciation

Pronunciation

(me TAKS a lone)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Metaxall: 800 mg [scored; contains fd&c red #40]

Skelaxin: 800 mg [scored]

Generic: 400 mg, 800 mg

Brand Names: U.S.

  • Metaxall
  • Skelaxin

Pharmacologic Category

  • Skeletal Muscle Relaxant

Pharmacology

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.

Distribution

Vd: ~800 L

Metabolism

Hepatic via CYP1A2, CYP2D6, CYP2E1, CYP3A4 and to lesser extent CYP2C8, CPY2C9, and CYP2C19

Excretion

Urine (as metabolites)

Time to Peak

~3 hours

Half-Life Elimination

9 ± 4.8 hours

Special Populations: Gender

An increase in bioavailability and half-life have been observed in female patients.

Use: Labeled Indications

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

Contraindications

Hypersensitivity to metaxalone or any component of the formulation; significantly impaired hepatic or renal function, tendency to drug-induced, hemolytic, or other anemias

Dosing: Adult

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

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Musculoskeletal conditions: Adolescents ≥13 years: Refer to adult dosing.

Dosing: Renal Impairment

There are no dosage adjustments provided in the manufacturer’s labeling; use with caution; contraindicated with significant renal impairment.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling; use with caution; contraindicated with significant hepatic impairment.

Administration

Administer with or without food. However, serum concentrations may be increased when administered with food (especially in elderly patients), enhancing general CNS depression; clinical significance has not been established.

Dietary Considerations

Administration with food may increase serum concentrations.

Storage

Store at 15°C to 30°C (59°F to 86°F).

Drug Interactions

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Exceptions: Levocabastine (Nasal). Monitor therapy

Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification

Hydrocodone: CNS Depressants may enhance the CNS depressant effect of Hydrocodone. Management: Consider starting with a 20% to 30% lower hydrocodone dose when using together with any other CNS depressant. Dose reductions in the other CNS depressant may also be warranted. Consider therapy modification

HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

Metyrosine: CNS Depressants may enhance the sedative effect of Metyrosine. Monitor therapy

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: When oxycodone is combined with another CNS depressant, a dose reduction of one or both agents should be considered. The extended release oxycodone starting dose should be reduced 50% to 67% when initiated in patients already receiving CNS depressants. Consider therapy modification

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Serotonin Modulators: Metaxalone may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification

Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Start tapentadol at a dose of one-third to one-half of the normal dose if being initiated in a patient who is taking another drug with CNS depressant effects. Monitor closely for evidence of excessive CNS depression. Consider therapy modification

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification

Test Interactions

False-positive Benedict's test

Adverse Reactions

Frequency not defined.

Central nervous system: Dizziness, drowsiness, headache, irritability, nervousness

Dermatologic: Skin rash (with or without pruritus)

Gastrointestinal: Gastrointestinal upset, nausea, vomiting

Hematologic & oncologic: Hemolytic anemia, leukopenia

Hepatic: Jaundice

Hypersensitivity: Anaphylactoid reaction (rare), hypersensitivity reaction

Warnings/Precautions

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 which require mental alertness (eg, operating machinery or driving).

• Serotonin syndrome: Potentially life-threatening serotonin syndrome has been reported; generally occurs when used concomitantly with serotonergic drugs (eg, tramadol, SSRIs), or when exceeding recommended doses.

Disease-related concerns:

• Hepatic impairment: Use with caution in patients with hepatic impairment; contraindicated in patients with significant hepatic impairment. Routine monitoring of transaminases is recommended.

• Renal impairment: Use with caution in patients with renal impairment; contraindicated in patients with significant impairment.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Pregnancy Considerations

Adverse events have not been observed in animal reproduction studies. Use during pregnancy (especially first trimester) only if benefits outweigh risks.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience fatigue, dizziness, headache, anxiety, vomiting, or nausea. Have patient report immediately to prescriber severe loss of strength and energy, chills, pharyngitis, severe abdominal pain, dark urine, jaundice, or signs of serotonin syndrome (dizziness, severe headache, agitation, hallucinations, tachycardia, arrhythmia, flushing, tremors, sweating a lot, change in balance, severe nausea, or severe diarrhea) (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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