Metaxalone 800 mg Tablet, 500-count
🆔 Identity & classification
Where does this data come from?
🏷️ RxNorm drug class
This medicine belongs to the Muscle Relaxant class.
Where does this data come from?
🏭 Manufacturer & labeler
Where does this data come from?
🩺 Clinical
- Metaxalone is a muscle relaxant used to help ease pain and discomfort from short-term musculoskeletal conditions — things like muscle strains or injuries. It's not meant to be used...
- Drowsiness is one of the most common side effects, yes. Dizziness, headache, and feeling irritable or nervous can also happen. You should not drive, operate heavy machinery, or do...
- Will metaxalone make me too drowsy to function?
- It does matter — and you should be consistent. Taking metaxalone with a high-fat meal significantly increases the amount of drug absorbed into your body compared to taking it on an...
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Metaxalone — tap one for details:
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💊 What it looks like
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
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UNII 8C3Z4148WZ
Alginic acid is a natural polymer extracted from brown seaweed. In medicines, it acts as a thickener, binder, and disintegrant to help form tablets and control how quickly the medicine dissolves.
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UNII D9C330MD8B
Copovidone is a synthetic polymer made by combining two types of plastic-like molecules. It acts as a binder and film-former to help hold tablet ingredients together and improve how the medicine dissolves in your body.
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UNII 1K09F3G675
Ferric oxide red is an inorganic iron compound used as a colorant in medicines. It gives tablets, capsules, or other dosage forms a red or reddish tint for identification and appearance.
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UNII 70097M6I30
Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
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UNII FZ989GH94E
Povidone is a synthetic polymer made from a plastic-like material. It acts as a binder to hold tablet ingredients together and as a disintegrant to help the tablet break apart in your stomach so the medicine can be absorbed.
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UNII C269C4G2ZQ
Sodium alginate is a natural thickener and gelling agent derived from seaweed. In medicines, it acts as a binder to hold ingredients together, a thickener to adjust texture, and a disintegrant to help the tablet or capsule break apart for absorption.
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UNII O8232NY3SJ
A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.
7 inactive ingredients listed in the exact product block matched to this NDC.
Where does this data come from?
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
Are inactive ingredients the same for every manufacturer?
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Can inactive ingredients matter?
💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per ea | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | $0.402 | $200.90 / 500 tablets |
| Medicaid paysCMS SDUD · 12 mo | $0.6894 | $344.70 / 500 tablets |
| Medicare drug plans payPart D · Q2 2026 | $1.73 | $865.35 / 500 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Metaxalone 800 mg 00527-1435-01 | Lannett | 100 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 00591-2341-01 | Actavis | 100 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 00904-6831-04 | Major | 30 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mgthis 50228-0323-05 | ScieGen | 500 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 50268-0530-15 | AvPAK | 50 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 55111-0650-01 | Dr. | 100 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 60687-0663-21 | American | 30 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 65162-0553-10 | Amneal | 100 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 68001-0485-00 | BluePoint | 100 tablets | $0.402 | AB | Availability likely | — |
| Metaxalone 800 mg 42291-0985-50 | AvKARE | 500 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 50090-3650-00 | A-S | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 50090-3670-00 | A-S | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 51655-0171-20 | Northwind | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 51655-0792-20 | Northwind | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 53746-0553-01 | Amneal | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 55700-0494-30 | Quality | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 60760-0093-06 | St. | 6 tablets | — | AB | Discontinued | — |
| Metaxalone 800 mg 60760-0289-06 | St. | 6 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 61919-0832-90 | DIRECT | 90 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 63187-0490-10 | Proficient | 10 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 63629-2097-01 | Bryant | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 63629-8014-01 | Bryant | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 68788-7675-00 | Preferred | 15 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 68788-8678-01 | Preferred | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 69306-0100-01 | Doc | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 69306-0311-20 | Doc | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 70518-0771-00 | REMEDYREPACK | 90 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 70518-4559-00 | REMEDYREPACK | 90 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71205-0016-10 | Proficient | 10 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71205-0326-20 | Proficient | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71205-0426-14 | Proficient | 14 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71335-0375-00 | Bryant | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71335-0958-00 | Bryant | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 71335-2066-01 | Bryant | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 72162-1083-01 | Bryant | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 72189-0645-30 | Direct_Rx | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 72789-0028-15 | PD-Rx | 15 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 76420-0232-20 | Asclemed | 20 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 76420-0898-01 | Asclemed | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 80425-0084-02 | Advanced | 60 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 80425-0122-02 | Advanced | 60 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 80425-0131-02 | Advanced | 60 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 80425-0524-01 | Advanced | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 80425-0580-01 | Advanced | 30 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 85509-1435-01 | PHOENIX | 120 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 85509-2341-01 | PHOENIX | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 85766-0011-01 | Sportpharm | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 85766-0143-01 | Sportpharm | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 68788-4168-01 | Preferred | 100 tablets | — | AB | FDA listed | — |
| Metaxalone 800 mg 72789-0592-30 | PD-Rx | 30 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
Where does this data come from?
🗺️ Medicaid utilization & spend
💊 Medicaid utilization by pack size
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Age at onset
Reporter sex
Serious outcomes
Where does this data come from?
📦 Packaging — all sizes for this product
| Package NDC | Description | Per unit | Per pack | Marketing start | Status |
|---|---|---|---|---|---|
| 50228-0323-01 | 100 TABLET in 1 BOTTLE (50228-323-01) | $0.4018 / ea | $40.18 | 2017-08-31 | Active |
| 50228-0323-05 You're viewing this | 500 TABLET in 1 BOTTLE (50228-323-05) | $0.4018 / ea | $200.89 | 2017-08-31 | Active |
| 50228-0323-30 | 30 TABLET in 1 BOTTLE (50228-323-30) | — | — | 2017-08-31 | Active |
You're viewing the largest of 3 pack sizes for this product.
This pack effectively ties for the lowest per-ea cost of the 2 priced pack sizes ($0.4018 NADAC).
This pack accounts for about 3.3% of this product's recent Medicaid fills; most go to the 100 tablets pack. See all packs ↓
Pack size FAQ
What quantity is in NDC 50228-0323-05?
What is the difference between NDC 50228-0323-05 and NDC 50228-0323-30?
What NDC number is used to bill for this package of Metaxalone 800 mg Tablet?
Prices are the latest CMS NADAC pharmacy acquisition cost per NDC; per-pack figures are per-unit × pack quantity, shown only when the pack is denominated in the same measure NADAC prices.
📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
1 INDICATIONS AND USAGE Metaxalone tablets are indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions in adults and pediatric patients 13 years of age and older. Metaxalone tablet is a muscle relaxant indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions in adults and pediatric patients 13 years of age and older. ( 1 )
⏱️ Dosage and Administration ▾
2 DOSAGE AND ADMINISTRATION The recommended dosage of metaxalone tablets in adults and pediatric patients 13 years of age and older is two 400 mg tablets (800 mg) or one 800 mg tablet orally three to four times a day [see Use in Specific Populations (8) ] . Metaxalone tablets, 400 mg and 800 mg are not substitutable on a mg to mg basis with Metaxalone Tablets, 640 mg [see Clinical Pharmacology (12.3) ] . When it is appropriate to switch: Switch only in patients who have been taking metaxalone tablets, 640 mg on an empty stomach.
Stop metaxalone tablets, 640 mg three times a day and start metaxalone tablets, 800 mg or two 400 mg tablets three times a day on an empty stomach, OR stop metaxalone tablets 640 mg four times a day and start metaxalone tablets, 800 mg or two 400 mg tablets four times a day on an empty stomach. Do not switch from metaxalone tablets, 640 mg to metaxalone tablets, 800 mg or two 400 mg tablets when the patient is taking food during administration. Recommended dosage of metaxalone tablets in adults and pediatric patients 13 years of age and older is two 400 mg tablets (800 mg) or one 800 mg tablet orally three to four times a day.
( 2 ) Metaxalone tablets, 400 mg and 800 mg are not substitutable on a mg to mg basis with Metaxalone Tablets, 640 mg. When it is appropriate to switch, see the Full Prescribing Information on switching instructions. ( 2 )
💊 Dosage Forms and Strengths ▾
3 DOSAGE FORMS AND STRENGTHS Tablets: 400 mg: round, light pink debossed with ‘SG 474’ on one side and plain on the other. 800 mg: capsule shape scored, pink debossed with ‘SG’ on scored side and ‘323’ on the other. Tablets: 400 mg: round, light pink debossed with ‘SG 474’ on one side and plain on the other. 800 mg: capsule shape scored, pink debossed with ‘SG’ on scored side and ‘323’ on the other.
⛔ Contraindications ▾
4 CONTRAINDICATIONS Metaxalone tablets are contraindicated in patients with: Known hypersensitivity to any component of metaxalone tablets. Known tendency to drug induced, hemolytic, or other anemias. Severe renal or hepatic impairment. Known hypersensitivity to any components of this product. ( 4 ) Known tendency to drug induced, hemolytic, or other anemias. ( 4 ) Severe renal or hepatic impairment. ( 4 )
⚠️ Warnings and Cautions ▾
5 WARNINGS AND PRECAUTIONS Serotonin Syndrome : Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of metaxalone tablets (within the recommended dosage range) and other serotonergic drugs and with the use of metaxalone tablets as the only serotonergic drug taken at a dosage higher than the recommended dosage. If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dosage increases. Discontinue metaxalone tablets if serotonin syndrome is suspected or it occurs.
( 5.1 , 7.1 ) Central Nervous System (CNS) Depression : Metaxalone tablets may impair mental and/or physical abilities required for the performance of hazardous tasks, such as operating machinery or driving a motor vehicle, especially when used with other CNS depressants including alcohol. Follow patients closely for signs and symptoms of respiratory depression and sedation. If concomitant use is warranted, closely monitor for signs of respiratory depression and sedation, particularly during treatment initiation and dosage increases.
( 5.2 , 7.2 )
5.1Serotonin Syndrome Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of metaxalone tablets (within the recommended dosage range) and other serotonergic drugs [see Drug Interactions (7) ] and with the use of Metaxalone tablets as the only serotonergic drug taken at a dosage higher than the recommended dosage [see Overdosage (10) ] . Serotonin syndrome symptoms may include mental status changes (e.g., agitation, hallucinations, coma), autonomic instability (e.g., tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (e.g., hyperreflexia, incoordination, rigidity), and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea).
The onset of symptoms generally occurs within several hours to a few days after initiation of a serotonergic drug, but may occur later than that. If concomitant use of metaxalone tablets and another serotoneric drug is warranted, reassess the patient, particularly during treatment initiation and dosage increases. Discontinue metaxalone tablets if serotonin syndrome is suspected or it occurs.
5.2Central Nervous System Depression Because of its central nervous system (CNS) depressant effects, 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 other CNS depressants including alcohol. Geriatric patients may be especially susceptible to CNS depression associated with metaxalone tablets use. When used concomitantly, the sedative effects of metaxalone tablets and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may be additive [see Drug Interactions (7) ] .
Follow metaxalone tablets-treated patients closely for signs and symptoms of respiratory depression and sedation. If concomitant use of metaxalone tablets and another CNS depressant is warranted, closely monitor for signs of respiratory depression and sedation, particularly during treatment initiation and dosage increases.
🤒 Adverse Reactions ▾
6 ADVERSE REACTIONS The following adverse reactions associated with the use of metaxalone tablets were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The most frequent reactions to metaxalone were: CNS : drowsiness, dizziness, headache, and nervousness or "irritability".
Digestive : nausea, vomiting, gastrointestinal upset. Other adverse reactions were: CNS : cases of serotonin syndrome have been reported during concomitant use of metaxalone tablets (within the recommended dosage range) and other serotonergic drugs and with the use of metaxalone tablets as the only serotonergic drug at a dosage higher than the recommended dosage [see Warnings and Precautions (5.1) , Drug Interactions (7.1) and Overdosage (10) ] . Hematologic : leukopenia; hemolytic anemia; Hepatobiliary : jaundice; Immune System : anaphylaxis, hypersensitivity reaction, rash with or without pruritus.
Most common adverse reactions (incidence >5%) are nausea and vomiting. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact ScieGen Pharmaceuticals, Inc. at toll-free phone 1-855-724-3436 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .
🔄 Drug Interactions ▾
7 DRUG INTERACTIONS
7.1Serotonergic Drugs If concomitant use of metaxalone tablets and another serotoneric drug is warranted, carefully observe the patient, particularly during treatment initiation and dosage modification. Discontinue metaxalone tablets if serotonin syndrome is suspected or if it occurs. Serotonin syndrome has resulted from concomitant use of metaxalone tablets (within the recommended dosage range) with other serotonergic drugs [see Warnings and Precautions (5.1) and Adverse Reactions (6) ] .
Serotonergic drugs include 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 (e.g., 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).
7.2CNS Depressants If concomitant use of metaxalone tablets and another CNS depressant is warranted, closely monitor for signs of respiratory depression and sedation, particularly during treatment initiation and dosage increases. Due to the additive pharmacologic effect, concomitant use of metaxalone tablets with other CNS depressants may increase the risk of sedation and respiratory depression [see Warnings and Precautions (5.2) ] .
7.3Interaction of Metaxalone with Benedict’s Tests False-positive Benedict’s tests, due to an unknown reducing substance, have been noted in metaxalone-treated patients. A glucose-specific test will differentiate findings.
👥 Use in Specific Populations ▾
8 USE IN SPECIFIC POPULATIONS Geriatric Use : Metaxalone tablets-treated geriatric patients may be especially susceptible to CNS depression. ( 8.5 )
8.1Pregnancy Risk Summary There are no available data on metaxalone use in pregnant patients to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes despite decades of metaxalone use. Reproduction studies in rats have not revealed effects on the fetus due to metaxalone. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown.
All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
8.2Lactation Risk Summary There are no data available to evaluate the presence of metaxalone or its metabolite in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for metaxalone and any potential adverse effects on the breastfed infant from metaxalone or from the underlying maternal condition.
8.4Pediatric Use 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 in pediatric patients 13 years of age and older. The safety and effectiveness of metaxalone tablets in pediatric patients 12 years of age or younger have not been established.
8.5Geriatric Use Clinical studies of metaxalone tablets did not include sufficient numbers of patients 65 years of age and older to determine whether they respond differently from younger adult patients. Geriatric patients may be especially susceptible to CNS depression associated with metaxalone tablets use [see Warnings and Precautions (5.2) ] . The recommended metaxalone tablets dosage in patients 65 years of age and older is the same as in younger adult patients.
Metaxalone peak plasma concentrations (C max ) and area under the curve (AUC) were higher in patients 65 years of age and older in the fasted state; however, a clinically significant difference was not observed when metaxolone was administered in the fed state [see Clinical Pharmacology (12.3) ] .
8.6Hepatic Impairment Metaxalone is contraindicated in patients with severe hepatic impairment. Metaxalone tablets should be used with caution and additional follow-up should be considered in patients with mild to moderate hepatic impairment. The effect of hepatic impairment on metaxalone pharmacokinetics is unknown; however, metaxalone undergoes expensive hepatic metabolism [see Clinical Pharmacology (12.3) ] .
8.7Renal Impairment Metaxalone is contraindicated in patients with severe renal impairment. Metaxalone tablets should be used with caution and additional follow-up should be considered in patients with mild to moderate renal impairment. The effect of renal impairment on metaxalone pharmacokinetics is unknown; however, metaxalone undergoes renal excretion as unidentified metabolites [see Clinical Pharmacology (12.3) ] .
🤰 Pregnancy ▾
8.1Pregnancy Risk Summary There are no available data on metaxalone use in pregnant patients to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes despite decades of metaxalone use. Reproduction studies in rats have not revealed effects on the fetus due to metaxalone. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown.
All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
🧓 Geriatric Use ▾
8.5Geriatric Use Clinical studies of metaxalone tablets did not include sufficient numbers of patients 65 years of age and older to determine whether they respond differently from younger adult patients. Geriatric patients may be especially susceptible to CNS depression associated with metaxalone tablets use [see Warnings and Precautions (5.2) ] . The recommended metaxalone tablets dosage in patients 65 years of age and older is the same as in younger adult patients.
Metaxalone peak plasma concentrations (C max ) and area under the curve (AUC) were higher in patients 65 years of age and older in the fasted state; however, a clinically significant difference was not observed when metaxolone was administered in the fed state [see Clinical Pharmacology (12.3) ] .
🆘 Overdosage ▾
10 OVERDOSAGE Clinical Presentation of Metaxalone Overdose Deaths by deliberate or accidental overdose have occurred with metaxalone, particularly in combination with other CNS depressants (including alcohol). CNS manifestations may include CNS depression, agitation, hallucinations, delusions, seizures, respiratory depression, and coma. Cardiovascular effects may include tachycardia and hypertension; hypotension has also been reported.
Serotonin syndrome, leading to muscle rigidity, tremor, and hyperthermia, has been reported [see Warnings and Precautions (5.1) , Drug Interactions (7.1 , 7.2) ] . Treatment of Metaxalone Overdose The standard of treatment is supportive care. Monitor for CNS and respiratory depression and manage airway with oxygen as needed.
Gastrointestinal decontamination procedures (including emesis) should generally be avoided because aspiration may result from CNS depression and seizures. Extracorporeal elimination such as hemodialysis or plasmapheresis have no proven clinical benefit. Consider contacting the Poison Help line (1-800-222-1222) or a medical toxicologist for additional overdose management recommendations.
🧬 Clinical Pharmacology ▾
12 CLINICAL PHARMACOLOGY
12.1Mechanism of Action Metaxalone’s mechanism of action has not been fully characterized, but may be related to its sedative properties. Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber.
12.2Pharmacodynamics The exposure-response relationship and time course of pharmacodynamic response for the safety and effectiveness of metaxalone not been fully characterized.
12.3Pharmacokinetics Metaxalone pharmacokinetics were evaluated in two groups of healthy volunteers that received a single oral dose of 800 mg of metaxalone tablets or 400 mg of metaxalone tablets (0.5 times the approved recommended dose). Metaxalone pharmacokinetic parameters are presented below as mean (% CV) unless otherwise specified. Observed metaxalone peak plasma concentrations (C max ) and area under the curve (AUC) are shown in Table 1.
Doubling the dose of metaxalone tablets from 400 mg (0.5 times the approved recommended dose) to 800 mg resulted in a proportional increase in metaxalone C max and AUC. Table 1: Metaxalone Exposure after a Single-Dose of Metaxalone Tablets Under Fasting Conditions Dose Dose C max 2 AUC ∞ 2 400 mg 1 983 (53) ng/mL 7,479 (51) ng∙h/mL 800 mg 1,816 (43) ng/mL 15,044 (46) ng∙h/mL 1 0.5 times the approved recommended dose 2 Mean (% CV) Absorption The absolute bioavailability of metaxalone is not known. Peak plasma metaxalone concentrations occurred at a mean T max of 3.3 hours (1.5 hours to 5 hours) of metaxalone under fasted conditions.
The single-dose pharmacokinetic parameters of metaxalone in two groups of healthy volunteers who received 400 mg or 800 mg of metaxalone tablets are shown in Table 1. Effect of Food: Peak plasma metaxalone concentrations were noted at a mean T max of 4.3 hours (1.5 hours to 12 hours) under fed conditions. The mean T max under fasting and fed conditions was 3.3 hours and 4.3 hours, respectively.
Metaxalone exposure was increased and the half-life (t 1/2 ) was decreased following metaxalone tablets administration with a high fat meal as shown in Table 2. The increase in metaxalone exposure coinciding with a reduction in half-life may be attributed to more complete absorption of metaxalone in the presence of a high fat meal. Table 2: Relative Changes in Metaxalone Exposure, T max , and t 1/2 Following Metaxalone Tablets Administration with a High Fat Meal Compared to Fasting Dose (mg) C max (ng/mL) AUC 0-t (ng∙h/mL) AUC 0-INF (ng∙h/mL) T max (hrs) t 1/2 (hrs) 400 mg 0.5 times the approved recommended dose. ↑ 78% ↑ 24% ↑ 15% ↑ 30% ↓ 73% 800 mg ↑ 94% ↑ 46% ↑ 42% ↑ 63% ↓ 48% Distribution Metaxalone apparent volume of distribution is approximately 800 Liters; however, plasma protein binding is unknown.
Elimination Metaxalone mean ± SD terminal t 1/2 is 9 ± 4.8 hours and apparent clearance is approximately 67 ± 34 L/h under fasted conditions. Metabolism: Metaxalone is primarily metabolized by CYP1A2, CYP2D6, CYP2E1, and CYP3A4 and, to a lesser extent, CYP2C8, CYP2C9, and CYP2C19. Excretion: Metaxalone is metabolized by the liver and excreted in the urine as unidentified metabolites.
Specific Populations The effect of renal impairment and hepatic impairment on metaxalone pharmacokinetics is unknown [see Use in Specific Populations (8.6 , 8.7) ] . Geriatric Patients: The effects of age on the pharmacokinetics of metaxalone were determined following administration of 800 mg of metaxalone tablets under fasted and fed conditions. Age had a significantly greater effect on metaxalone pharmacokinetics under fasted conditions than under fed conditions.
Bioavailability under fasted conditions increased with age. Metaxalone bioavailability under fasted and fed conditions in the three groups of healthy volunteers of varying age is shown in Table 3. Table 3: Metaxalone Pharmacokinetic Parameters under Fasted and Fed Conditions in Three Age Groups Following Oral Administration of 800 mg of Metaxalone Tablets Mean Age in Yea…
🧬 Mechanism of Action ▾
12.1Mechanism of Action Metaxalone’s mechanism of action has not been fully characterized, but may be related to its sedative properties. Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber.
📦 How Supplied / Storage and Handling ▾
16 HOW SUPPLIED/STORAGE AND HANDLING Metaxalone Tablets, USP 400 mg are available as light pink, round shaped tablet debossed with ‘SG 474’ on one side and plain on the other. NDC 50228-474-30: Bottles of 30 Tablets NDC 50228-474-10: Bottles of 1,000 Tablets Metaxalone Tablets, USP 800 mg are available as pink, capsule shape scored tablet debossed with ‘SG’ on scored side and ‘323’ on the other. NDC 50228-323-30: Bottles of 30 Tablets NDC 50228-323-01: Bottles of 100 Tablets NDC 50228-323-05: Bottles of 500 Tablets Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].
Dispense in well-closed, light-resistant containers.
📋 Description ▾
11 DESCRIPTION Metaxalone tablets , USP contain 400 mg and 800 mg of metaxalone and the following inactive ingredients: alginic acid, corn starch, ferric oxide red, copovidone, magnesium stearate, povidone, pregelatinized starch, sodium alginate. Metaxalone tablet is a muscle relaxant for oral administration. 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, USP is a white to almost white, crystalline powder freely soluble in dichloromethane, soluble in methanol, sparingly soluble in ethanol and ethyl acetate, slightly soluble in toluene and isopropanol, insoluble in water and n-hexane. image
💬 Information for Patients ▾
17 PATIENT COUNSELING INFORMATION Serotonin Syndrome Inform patients that metaxalone tablets could cause a rare but potentially life-threatening condition called serotonin syndrome. Warn patients of the symptoms of serotonin syndrome and to seek medical attention right away if symptoms develop. Instruct patients to inform their healthcare providers if they are taking, or plan to take, serotonergic drugs [see Warnings and Precautions (5.1) and Drugs Interactions (7.1) ] .
Central Nervous System Depression Advise patients that 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 and other CNS depressants [see Drug Interactions (7.2) ] . Rx Only Manufactured by: ScieGen Pharmaceuticals, Inc. Hauppauge, NY 11788 Rev: 7/2024