Overview
DESCRIPTION Metaxalone is available as an 800 mg pink, capsule shaped, scored tablet. Chemically, metaxalone is 5-[(3,5-dimethylphenoxy)methyl]-2-oxazolidinone. The empirical formula is C 12 H 15 NO 3 , which corresponds to a molecular weight of 221.25. The structural formula is: Metaxalone is a white to almost white, odorless crystalline powder freely soluble in chloroform, soluble in methanol...
Mechanism of Action
CLINICAL PHARMACOLOGY Mechanism of Action The mechanism of action of metaxalone in humans has not been established, but may be due to general central nervous system (CNS) depression. Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber. Pharmacokinetics The pharmacokinetics of metaxalone have been evaluated in healthy adult volunteers after single dose administration of metaxalone under fasted and fed conditions at doses ranging from 400 mg to 800 mg. Absorption Peak plasma concentrations of metaxalone occur approximately 3 hours after a 400 mg oral dose under fasted conditions. Thereafter, metaxalone concentrations decline log-linearly with a terminal half-life of 9.0 ± 4.8 hours.
Indications
- INDICATIONS AND USAGE Metaxalone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Metaxalone does not directly relax tense skeletal muscles in man.
Common Doses
- 800 mg
Dosage
DOSAGE AND ADMINISTRATION The recommended dose for adults and children over 12 years of age is one 800 mg tablet three to four times a day.
Contraindications
- CONTRAINDICATIONS Known hypersensitivity to any components of this product. Known tendency to drug induced, hemolytic, or other anemias. Significantly impaired renal or hepatic function.
Side Effects
- ADVERSE REACTIONS The most frequent reactions to metaxalone include: CNS : drowsiness, dizziness, headache, and nervousness or “irritability”; Digestive : nausea, vomiting, gastrointestinal upset. Other adverse reactions are: Immune System : anaphylaxis, hypersensitivity reaction, rash with or without pruritus; Hematologic : leukopenia; hemolytic anemia; Hepatobiliary : jaundice; CNS : cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of serotonergic drugs with metaxalone used within the recommended dosage range and with...
Interactions
- Drug Interactions CNS Depressants : The sedative effects of Metaxalone and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants (TCAs)) may be additive. Exercise caution with patients who take more than one of these CNS depressants simultaneously. Follow patients closely for signs and symptoms of respiratory depression and sedation (see WARNINGS ). Serotonergic Drugs : Serotonin syndrome has resulted from concomitant use of serotonergic drugs with Metaxalone used within the recommended dosage range (see WARNINGS ).