Metaxalone

DAE Class; Rx

Common Brand Names; Skelaxin

• Skeletal Muscle Relaxants

Oral CNS depressant used for adjunct therapy of acute, painful musculoskeletal conditions
Classified as a skeletal muscle relaxant, but does not directly relax skeletal muscle
Beneficial effects may be due to sedative properties

Indicated for acute, painful musculoskeletal conditions

For the treatment of musculoskeletal pain associated with acute, painful musculoskeletal conditions, as an adjunct to rest, physical therapy, and other measures.

Hypersensitivity

History of drug-induced hemolytic anemia

Significant renal/hepatic impairment

Drug-induced gastrointestinal disturbance

Nausea

Vomiting

Dizziness

Headache

Somnolence

Nervousness

Hemolytic anemia (rare)

Leukopenia (rare)

Jaundice (rare)

Immune hypersensitivity reaction (rare)

Postmarketing Report

Serotonin syndrome (when used concomitantly with serotonergic drugs or doses higher than recommended)

CNS depression may occur

Sedative effects may be potentiated when used with other sedatives

Medication is poorly tolerated by the elderly

Bioavailability may increase in female patients

Use caution in renal and hepatic impairment

Safety and efficacy not established in children <12 years

May impair physical or mental abilities; caution patient against operating heavy machinery or performing tasks requiring mental alertness

Serotonin syndrome

• Cases of serotonin syndrome, a potentially life-threatening condition, reported during concomitant use of serotonergic drugs with this drug when used within recommended dosage range and with metaxalone as a single agent taken at doses higher than recommended dose (see drug interaction overview)
• Serotonin syndrome symptoms may include mental status changes (eg, agitation, hallucinations, coma), autonomic instability (eg, tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (eg, hyperreflexia, incoordination, rigidity), and/or gastrointestinal symptoms (eg, nausea, vomiting, diarrhea); the onset of symptoms generally occurs within several hours to a few days, but may occur later than that
• Discontinue therapy if serotonin syndrome suspected

Drug interaction overview

• Sedative effects of this drug and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may be additive; caution should be exercised with patients who take more than one of these CNS depressants simultaneously
• Serotonin syndrome have occurred with concomitant use of serotonergic drugs, including selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, opioids (particularly fentanyl, meperidine, and methadone), drugs that affect the serotonergic neurotransmitter system (eg, mirtazapine, trazodone, tramadol), and drugs that impair metabolism of serotonin (including monoamine oxidase (MAO) inhibitors, both those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue)

Pregnancy category: C

Lactation: Unknown if excreted in breast milk; not recommended

Adults

3200 mg/day PO.

Geriatric

Not advised for use in the elderly due to potential anticholinergic effects.

Adolescents

3200 mg/day PO.

Children

<= 12 years: Safety and efficacy have not been established.

Infants

Not indicated.

Metaxalone