The effect of gender on the pharmacokinetics of metaxalone was assessed in an open label study, in which 48 healthy adult volunteers (24 males, 24 females) were administered two metaxalone 400 mg tablets (800 mg) under fasted conditions. The bioavailability of metaxalone was significantly higher in females compared to males as evidenced by Cmax (2115 ng/mL versus 1335 ng/mL) and AUC∞ (17884 ng· h/mL versus 10328 ng· h/mL). The mean half-life was 11.1 hours in females and 7.6 hours in males. The apparent volume of distribution of metaxalone was approximately 22% higher in males than in females, but not significantly different when adjusted for body weight. Similar findings were also seen when the previously described combined dataset was used in the analysis.
The impact of hepatic and renal disease on the pharmacokinetics of metaxalone has not been determined. In the absence of such information, metaxalone tablets should be used with caution in patients with hepatic and/or renal impairment.
Metaxalone tablets are 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.
Known hypersensitivity to any components of this product.
Known tendency to drug induced, hemolytic or other anemias.
Significantly impaired renal or hepatic function.
Metaxalone tablets may enhance the effects of alcohol and other CNS depressants.
Metaxalone should be administered with great care to patients with pre-existing liver damage. Serial liver function studies should be performed in these patients.
False-positive Benedict’s tests, due to an unknown reducing substance, have been noted. A glucose-specific test will differentiate findings.
Taking metaxalone tablets with food may enhance general CNS depression; elderly patients may be especially susceptible to this CNS effect. (See CLINICAL PHARMACOLOGY, Pharmacokinetics and PRECAUTIONS, Information for Patients).
Metaxalone tablets may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle, especially when used with alcohol or other CNS depressants.
The sedative effects of metaxalone tablets and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may be additive. Therefore, caution should be exercised with patients who take more than one of these CNS depressants simultaneously.
The carcinogenic potential of metaxalone has not been determined.
Reproduction studies in rats have not revealed evidence of impaired fertility or harm to the fetus due to metaxalone. Post marketing experience has not revealed evidence of fetal injury, but such experience cannot exclude the possibility of infrequent or subtle damage to the human fetus. Safe use of metaxalone has not been established with regard to possible adverse effects upon fetal development. Therefore, metaxalone tablets should not be used in women who are or may become pregnant and particularly during early pregnancy unless, in the judgement of the physician, the potential benefits outweigh the possible hazards.
It is not known whether this drug is secreted in human milk. As a general rule, nursing should not be undertaken while a patient is on a drug since many drugs are excreted in human milk.
Safety and effectiveness in children 12 years of age and below have not been established.
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: hypersensitivity reaction, rash with or without pruritus;
Hematologic: leukopenia, hemolytic anemia;
Though rare, anaphylactoid reactions have been reported with metaxalone.
Deaths by deliberate or accidental overdose have occurred with metaxalone, particularly in combination with antidepressants and have been reported with this class of drug in combination with alcohol.
When determining the LD50 in rats and mice, progressive sedation, hypnosis and finally respiratory failure were noted as the dosage increased. In dogs, no LD50 could be determined as the higher doses produced an emetic action in 15 to 30 minutes.
Gastric lavage and supportive therapy. Consultation with a regional poison control center is recommended.
The recommended dose for adults and children over 12 years of age is one 800 mg tablet three to four times a day.
Metaxalone Tablets are supplied as follows:
800 mg Tablets: rose-colored, capsule-shaped tablets, debossed “E 448” on one side and scored on the other side and supplied as:
|Bottles of 5Bottles of 10||NDC 54868-6102-5NDC 54868-6102-0|
|Bottles of 15||NDC 54868-6102-4|
|Bottles of 30||NDC 54868-6102-2|
|Bottles of 60||NDC 54868-6102-3|
|Bottles of 90||NDC 54868-6102-1|
Dispense contents in a tight, light-resistant container as defined in the USP with a child-resistant closure, as required.
Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].
To report SUSPECTED ADVERSE REACTIONS, contact Sandoz Inc. at 1-800-525-8747 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Princeton, NJ 08540
Repackaging and Relabeling by:
Physicians Total Care, Inc. Tulsa, OK 74146
Metaxalone 800 mg x 100 Tablets — Label
|METAXALONE metaxalone tablet|
|Labeler — Physicians Total Care, Inc. (194123980)|
|Physicians Total Care, Inc.||194123980||RELABEL, REPACK|
Revised: 03/2010 Physicians Total Care, Inc.
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