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Metaxalone 800 mg Tablet, 90-count — NDC 85509-2341-09 package photo
Label image from the product's FDA listing (DailyMed) — may show a different pack size or an older label revision.

Metaxalone 800 mg Tablet, 90-count — NDC 85509-2341-9 (Billing 85509-2341-09)

by PHOENIX RX LLC · 90 TABLET in 1 BOTTLE

This is a package of 90 tablets of Metaxalone 800 mg Tablet from PHOENIX RX LLC, marketed since Jun 2017 and currently FDA-listed.

NDC 85509-2341-09
🏷️ FDA NDC (as labeled) 85509-2341-9 billing pads the package segment with a zero
This package
Contains90-count Pack sizes5 compare ↓
Also priced by: Part D plans $1.73/unit — full pricing hub ↓
Product page 85509-2341-01 Also comes in: 30 tablets 85509-2341-3 60 tablets 85509-2341-6 100 tablets 85509-2341-1 120 tablets 85509-2341-2
Rx only Generic On market Non-controlled ⇄ Compare with another NDC
🗂️ FDA directory synced Oct 1, 2026 · this listing last changed Jul 24, 2026 · sources: openFDA · FDA label (DailyMed) · FDA Orange & Purple Book · First Databank · CMS NADAC, ASP, Medicare & Medicaid · RxNorm
📋 All sources & update times →

This page is curated, coded, and maintained by

Compiled from public FDA, CMS, DailyMed, NADAC, and related drug data sources. Editorial policy

Identity & classification

Regulatory identifiers FDA, NLM and CMS codes for this package

FDA NDC (as labeled) 85509-2341-9
Product NDC 85509-2341
11-digit billing NDC 85509234109
NCPDP billing unit EA — each (per item)
RxCUI 351254
UNII 1NMA9J598Y
Application # ANDA203695
SPL Set ID 3a7c8b4d-7add-cb31-e063-6294a90a37f8
Established class (EPC) Muscle Relaxant
Physiologic effect Centrally-mediated Muscle Relaxation
DEA schedule Non-controlled
Marketing category ANDA
Marketing status On market
FDA listing status Listed (active directory)
Marketing start 2017-06-19
Route ORAL
Dosage form TABLET
Substance METAXALONE
TE code (Orange Book) AB · RLD · RS

Drug-database identifiers Medi-Span GPI and First Databank GCN / HICL / AHFS classification

GCN Seq No 051112
GCN 91765
HICL code 001945
Ingredient (HICL) Metaxalone
HIC1 code H
Therapeutic class — broad (HIC1) Nervous System (Except Autonomic)
HIC2 code H6
Therapeutic class — intermediate (HIC2) Drugs Acting Principally On The Midbrain
HIC3 code H6H
Therapeutic class — specific (HIC3) Skeletal Muscle Relaxants
AHFS code 12:20.04.00
AHFS class Centrally Acting Skeletal Muscle Relaxnt
FDB label name METAXALONE 800 MG TABLET
FDB brand name Metaxalone
Legend status F — Federal legend — prescription drug or device
Quick answers
  • GSN (GCN sequence number): 051112
  • GCN: 91765
  • HICL (First Databank): 001945
  • AHFS class code: 12:20.04.00
  • RxCUI (RxNorm): 351254
Why two NDCs? The FDA registers this code as 85509-2341-9 — a 5-4-1 layout, and that's what's printed on the package and shown on DailyMed. For insurance claims, every NDC is standardized to a uniform 11-digit 5-4-2 format by adding a zero to the package segment → 85509-2341-09. Same drug, same package — only the format differs.
Where does this data come from?
Identifiers from the FDA openFDA NDC Directory and Structured Product Labeling; RxCUI from RxNorm (NLM); GPI from Medi-Span; GCN / HIC / AHFS / legend from First Databank.

RxNorm drug class

This medicine belongs to the Muscle Relaxant class.

Pharmacologic class Muscle Relaxant
Where does this data come from?
Therapeutic classes from RxNorm RxClass (U.S. National Library of Medicine) — Established Pharmacologic Class (FDA), ATC drug family (WHO) and mechanism of action, matched by this product’s RxCUI.

Clinical

Label name METAXALONE 800 MG TABLET Ingredient Metaxalone
📖 What it is MedlinePlus · NLM

Metaxalone, a muscle relaxant, is used with rest, physical therapy, and other measures to relax muscles and relieve pain and discomfort caused by strains, sprains, and other muscle injuries. Metaxalone is in a class of medications called skeletal muscle relaxants. It works by slowing activity in the nervous system to allow the body to relax.

Read the full MedlinePlus article ↗
📗 Our plain-language guide HelloPharmacist
  • It helps relieve discomfort from sudden, painful muscle and bone conditions. It is meant to be used along with rest and physical therapy, not by itself. It is for adults and teens...
  • Take it by mouth, with or without food, usually three to four times a day as your prescriber directs. Don't take more than prescribed. If you were on Skelaxin 800 mg, don't switch...
  • The most common are drowsiness, dizziness, headache, feeling nervous or irritable, nausea, vomiting and stomach upset. Be careful driving until you know how it affects you.
  • It's best to avoid it. Alcohol and other sedating medicines can add to the sleepiness and may slow your breathing.
📖 Read our full Metaxalone guide →
Where does this data come from?
Plain-language summary from MedlinePlus (U.S. National Library of Medicine); supplement & herbal interactions and nutrient depletion data from the Natural Medicines database; our full guide is HelloPharmacist editorial content.

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 systemPer eachPer package
Retail pharmacies payNADAC · weekly Not in the retail survey — common for institutional, discontinued, or low-volume packs.
Medicaid paysCMS SDUD · 12 mo No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data.
Medicare drug plans payPart D · Q2 2026 $1.73 $155.76 / 90 tablets
Where does this data come from?
NADAC (National Average Drug Acquisition Cost) is the CMS weekly pharmacy-acquisition-cost survey — what pharmacies pay. ASP (Average Sales Price) is the CMS Medicare Part B drug-payment file, published quarterly. Medicaid pays is computed by us from CMS State Drug Utilization Data (total reimbursed ÷ units, trailing 12 months) — gross of rebates and inclusive of dispensing fees, so it reflects what Medicaid paid, not an acquisition cost. Medicare drug plans pay is the median negotiated point-of-sale unit cost across plans listing this NDC in the CMS quarterly Prescription Drug Plan pricing files, before rebates. The VA pays is the federal contract price (FSS, and the statutory Big 4 ceiling where listed) from the VA National Acquisition Center pharmaceutical price file. All are free public government data; each measures a different payer, so the figures are not directly comparable.

Packaging — all sizes for this product

Package NDCDescription Marketing startMarketing endStatus
85509-2341-01 85509-2341-1 Main listing 100 TABLET in 1 BOTTLE 2025-07-31 — Active
85509-2341-02 85509-2341-2 120 TABLET in 1 BOTTLE 2025-07-31 — Active
85509-2341-03 85509-2341-3 30 TABLET in 1 BOTTLE 2025-07-31 — Active
85509-2341-06 85509-2341-6 60 TABLET in 1 BOTTLE 2025-07-31 — Active
85509-2341-09 You're viewing this 90 TABLET in 1 BOTTLE 2025-07-31 — Active

You're viewing one of 5 pack sizes for this product.

Pack size FAQ

What quantity is in this package?
This is a 90-count package — 90 tablet in 1 bottle.
How does this package differ from NDC 85509-2341-03?
Both are Metaxalone 800 mg Tablet — the drug itself is identical. This page's package is the 90-count one, while NDC 85509-2341-03 is the 30 tablets package.
What NDC number is used to bill for this package of Metaxalone 800 mg Tablet?
Use the 11-digit billing form listed in the identifiers section of this page. Pharmacy and medical claims use the 11-digit form; the FDA label may print a shorter form of the same code.

Therapeutic equivalents

ProductLabelerPackNADAC/unitTEStatusPrice vs. this
Metaxalone 800 mg 00527-1435-01 Lannett 100 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 00591-2341-01 Actavis 100 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 00904-6831-04 Major 30 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 50228-0323-01 ScieGen 100 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 50268-0530-15 AvPAK 50 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 55111-0650-01 Dr. 100 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 60687-0663-21 American 30 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 65162-0553-10 Amneal 100 tablets $0.452 AB Availability likely —
Metaxalone 800 mg 68001-0485-00 BluePoint 100 tablets $0.452 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 mgthis 85509-2341-09 PHOENIX 90 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 —
About this product: this is a generic version of the medicine. FDA equivalence ratings are shown when available, and other versions are listed above, least expensive first.
Where does this data come from?
Equivalents are other NDCs of the same ingredient, form and route from the openFDA NDC Directory, ranked least-expensive-first by NADAC. Therapeutic-equivalence (AB) ratings come from the FDA Orange Book; biologics use the FDA Purple Book for biosimilar & interchangeable status.

Availability & generic status

🏛️
2017
On the market since
Jun 2017
📍
2026
Currently FDA-listed
9 years listed
🔓
·
Generic on the market
this product is a generic
✅This is a generic drug

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?
Patents and exclusivity from the FDA Orange Book (small-molecule drugs), refreshed from public FDA data. Generic launch timing is an estimate, not a guarantee.

What it looks like

Color white
ShapeOval
Imprint31;90;WPI
Size19 mm
ScoringScored — splits in 2
One label can cover several strengths, so colors may be combined — always confirm a loose pill against the dispensed prescription label or a pharmacist.
Where does this data come from?
Physical description (imprint, shape, color, scoring, coating) from this product’s FDA Structured Product Labeling (SPL), mirrored from DailyMed / openFDA.

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.

  • 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.
  • UNII Q9QKJ39Q3X
    Ammonium alginate is a natural thickening agent derived from brown seaweed. It's used in medicines as a binder to hold ingredients together and as a gelling agent to control how quickly the medicine dissolves or releases.
  • UNII 8P20S56HZI
    Calcium alginate is a natural substance derived from seaweed that acts as a thickener, binder, and disintegrant in medicines. It helps hold ingredients together and allows tablets or capsules to break apart properly for absorption.
  • 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.
  • 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.

5 inactive ingredients listed in the exact product block matched to this NDC.

Where does this data come from?
Data sourced from official FDA Structured Product Labeling (SPL) via DailyMed — 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?
No. Inactive ingredients can differ by manufacturer, dosage form, strength, and package / product version.
Why might an inactive ingredient be missing?
Some SPLs do not provide a complete structured inactive-ingredient list, and older or unusual labels may only include the information in narrative text.
Can inactive ingredients matter?
Yes. They can matter for allergies, intolerances, dyes, gluten / lactose concerns, preservatives, and formulation differences — but confirm with a pharmacist or the manufacturer when it’s clinically important.

Manufacturer & labeler

LabelerPHOENIX RX LLC
Application holderACTAVIS LABORATORIES FL INC
FDA applicationANDA203695 (ANDA)
Labeler code85509
First marketedJun 2017
Product typeHuman Prescription Drug
Portfolio61 products on file
The labeler markets the product; the application holder owns the FDA approval. They’re often the same company but can differ (e.g. a repackager or an authorized generic). A mailing address / phone appears here when the manufacturer includes it in the product’s FDA label (not all do).
Where does this data come from?
Labeler, application holder and registered establishment from the FDA openFDA NDC Directory and Drugs@FDA; address/contact from the product’s FDA label.

Full prescribing information FDA SPL

The complete FDA label for this product — the official prescribing information, verbatim, section by section. Very long sections are excerpted here and marked; the full text is on DailyMed (linked in the sources below). Jump with a chip, search within the label, or expand everything.
🎯 Indications and Usage ⏱️ Dosage and Administration 💊 Dosage Forms and Strengths ⛔ Contraindications ⚠️ Warnings and Cautions 🤒 Adverse Reactions 🔄 Drug Interactions 👥 Use in Specific Populations 🤰 Pregnancy 🧒 Pediatric Use 🧓 Geriatric Use 🆘 Overdosage 🧬 Clinical Pharmacology 🧬 Mechanism of Action 📦 How Supplied / Storage and Handling 📋 Description 💬 Information for Patients 🧬 Pharmacokinetics 🧬 Pharmacodynamics 🧪 Nonclinical Toxicology 📄 Carcinogenesis, Mutagenesis, Impairment of Fertility 📄 Recent Major Changes 📄 Package Label / Principal Display Panel
🎯 Indications and Usage 82 words ▾

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 tablets are 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 215 words ▾

2 DOSAGE AND ADMINISTRATION The recommended dosage of metaxalone tablets in adults and pediatric patients 13 years of age and older is 800 mg orally three to four times a day [see Use in Specific Populations ( 8 )]. Metaxalone tablets 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 three times a day on an empty stomach, OR stop metaxalone tablets 640 mg four times a day and start metaxalone tablets 800 mg four times a day on an empty stomach. Do not switch from metaxalone tablets, 640 mg to metaxalone 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 800 mg orally three to four times a day.

( 2 ) Metaxalone tablets 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 62 words ▾

3 DOSAGE FORMS AND STRENGTHS Tablets: 800 mg capsule-shaped, scored white to off-white tablet, inscribed with “ 31 90 ” on the scored side and “ WPI ” on the other side. Tablets: 800 mg capsule-shaped, scored white to off-white tablet, inscribed with “ 31 90 ” on the scored side and “ WPI ” on the other side. ( 3 )

⛔ Contraindications 62 words ▾

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 ~2 min read ▾

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 serotonergic 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 188 words ▾

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 Actavis at 1-888-838-2872 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

🔄 Drug Interactions ~1 min read ▾

7 DRUG INTERACTIONS

7.1Serotonergic Drugs If concomitant use of metaxalone tablets and another serotonergic 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 Tablets with Benedict’s Tests False-positive Benedict's tests, due to an unknown reducing substance, have been noted in metaxalone tablets-treated patients. A glucose-specific test will differentiate findings.

👥 Use in Specific Populations ~2 min read ▾

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 tablets 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 tablets and any potential adverse effects on the breastfed infant from metaxalone tablets 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 metaxalone was administered in the fed state [see Clinical Pharmacology ( 12.3 )].

8.6Hepatic Impairment Metaxalone tablets are 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 tablets are 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 110 words ▾

8.1Pregnancy Risk Summary There are no available data on metaxalone tablets 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.

🧒 Pediatric Use 57 words ▾

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.

🧓 Geriatric Use 122 words ▾

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 metaxalone was administered in the fed state [see Clinical Pharmacology ( 12.3 )].

🆘 Overdosage 148 words ▾

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 ~3 min read ▾

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 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 – 5 hours) of metaxalone tablets 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 – 12 hours) under fed conditions. The mean T max under fasting and fed conditions was 3.3 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* ↑ 78% ↑ 24% ↑ 15% ↑ 30% ↓ 73% 800 mg ↑ 94% ↑ 46% ↑ 42% ↑ 63% ↓ 48% *0.5 times the approved recommended dose.

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 Years (± SD) 26 ±… [Excerpted — this section continues on DailyMed.]

🧬 Mechanism of Action 41 words ▾

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 101 words ▾

16 HOW SUPPLIED/STORAGE AND HANDLING Metaxalone tablets, USP are available as 800 mg capsule-shaped, scored white to off-white tablet, inscribed with “ 31 90 ” on the scored side and “ WPI ” on the other side. Available in the below sizes: Bottles of 100 tablets NDC 85509-2341-1 Bottles of 120 tablets NDC 85509-2341-2 Bottles of 30 tablets NDC 85509-2341-3 Bottles of 60 tablets NDC 85509-2341-6 Bottles of 90 tablets NDC 85509-2341-9 Metaxalone tablets USP, 800 mg has functional scoring. Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].

Repackaged/Relabeled by: PHOENIX RX LLC Hatboro, PA 19040

📋 Description 108 words ▾

11 DESCRIPTION Metaxalone tablets, USP contain 800 mg of metaxalone, USP and the following inactive ingredients: alginic acid, ammonium alginate, calcium alginate, corn starch, magnesium stearate and pregelatinized starch (starch 1500 partially pregelatinized maize starch). Metaxalone tablets, USP is a muscle relaxant for oral administration. Chemically, metaxalone is 5-[(3,5-dimethylphenoxy) methyl]-2-oxazolidinone.

The molecular 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, odorless crystalline powder freely soluble in chloroform, soluble in methanol and in 96% ethanol, but practically insoluble in ether or water. Meets USP dissolution test 2.

1

💬 Information for Patients 138 words ▾

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 )]. Manufactured by: Actavis Laboratories FL, Inc. Fort Lauderdale, FL 33314 USA Distributed by: Actavis Pharma, Inc.

Parsippany, NJ 07054 USA Rev. B 7/2024

🧬 Pharmacokinetics ~3 min read ▾

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 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 – 5 hours) of metaxalone tablets 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 – 12 hours) under fed conditions. The mean T max under fasting and fed conditions was 3.3 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* ↑ 78% ↑ 24% ↑ 15% ↑ 30% ↓ 73% 800 mg ↑ 94% ↑ 46% ↑ 42% ↑ 63% ↓ 48% *0.5 times the approved recommended dose.

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 Years (± SD) 26 ± 9 Years Old 39 ± 11 Years Old 72 ± 5 Years Old Fasted vs. Fed State Fasted Fed Fasted Fed Fasted Fed C max (ng/mL) 1 1816 (43) 3510 (41) 2719 (46) 2915 (55) 3168 (43) 3680 (59) T max (hours) 1 3 (39) 4.9 (4.8) 3 (40) 8.7 (91) 2.6 (30) 6.5 (67) AUC 0-t (ng∙h/mL) 1 14531 (47) 20683 (41) 19836 (40) 20482 (37) 23797 (45) 24340 (48) AUC ∞ (ng∙h/mL) 1 15045 (46) 20833 (41) 20490 (39) 20815 (37) 24194 (44) 24704 (47) 1 Mean values (% CV) Male and Female Patients: Th… [Excerpted — this section continues on DailyMed.]

🧬 Pharmacodynamics 22 words ▾

12.2Pharmacodynamics The exposure-response relationship and time course of pharmacodynamic response for the safety and effectiveness of metaxalone not been fully characterized.

🧪 Nonclinical Toxicology 44 words ▾

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies to evaluate the carcinogenic potential of metaxalone have not been conducted. Studies to evaluate the mutagenic potential of metaxalone have not been conducted. No effects on fertility were observed in rats administered metaxalone.

📄 Carcinogenesis, Mutagenesis, Impairment of Fertility 41 words ▾

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies to evaluate the carcinogenic potential of metaxalone have not been conducted. Studies to evaluate the mutagenic potential of metaxalone have not been conducted. No effects on fertility were observed in rats administered metaxalone.

📄 Recent Major Changes 7 words ▾

Dosage and Administration ( 2 ) 6/2024

📄 Package Label / Principal Display Panel 9 words ▾

PRINCIPAL DISPLAY PANEL Metaxalone Tablets, USP 800 mg label

Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA. Prefer the government’s original formatting? View this label on DailyMed ↗

Medicare Part D spend CMS · PART D · 2026 (Q1)

Medicare Part D (outpatient prescription) spending for Metaxalone — the program that covers self-administered drugs. 8 manufacturers.
⚠️ Drug-level data: CMS publishes Part D spending by drug, not by NDC — these figures combine every manufacturer, strength and package size sold under the name Metaxalone. That’s a different level of aggregation than the Medicaid card above, which is specific to this exact 11-digit NDC (pack size included), so the two aren’t directly comparable.
Period
Total Part D spend
$1.81M
Claims incl. refills
18.6K
Beneficiaries
13K
Spend / beneficiary
$138.82
Spend / claim
$97.57
Trend by period
💵 About the dollar figures: spending is what Part D plans paid before confidential manufacturer rebates, so the program’s real net cost is lower. A blank patient count means fewer than 11 people — CMS hides counts that small to protect privacy. Source: CMS Medicare Quarterly Part D Spending by Drug (data.cms.gov), updated quarterly.

About this NDC listing & data coverage

Finished prescription product
What data is (and isn’t) available for this NDC — tap to expand
NDC identity (package / product / labeler codes) ✓ Available
Labeler ✓ Available
Product & package description ✓ Available
Marketing category & status ✓ Available
Active ingredient / dosage form / route ✓ Available
FDA label (SPL via DailyMed) ✓ Available
Package photos ✓ Available
Inactive ingredients (structured) ✓ Available
NADAC pharmacy acquisition price (CMS) — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey.
Orange Book / therapeutic-equivalence data ✓ Available
HCPCS J-code billing crosswalk — Not published for this NDC Most self-administered / retail products have no J-code — that is normal.
Medicaid utilization (CMS SDUD) — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold.
“Not published” reflects what the public FDA / CMS / NLM sources provide for this exact package code — it is a property of the data feeds, not a judgment about the product.

Questions about this listing

Why is there no price listed?
The pricing shown on our NDC pages comes from CMS NADAC, a voluntary survey of retail community pharmacy invoices. CMS does not publish a NADAC for every NDC — packages outside the retail survey (institutional and hospital products, bulk packages, discontinued items, and many OTC items) may never receive one. A missing price reflects the survey's scope, not this product's actual cost, and does not mean the product is free or unavailable.
Is the NDC printed on the package the same as the 11-digit billing NDC?
Yes, they identify this exact package in different formats. The form printed on the packaging and shown on DailyMed is the one the FDA registered. Insurance claims use a fixed 11-digit 5-4-2 format, so the short segment is padded with a leading zero and the dashes are dropped. The Identity section at the top of this page lists each form of this code.
Is this package still being marketed?
Yes, per the latest FDA NDC Directory data on this page: this package is listed as actively marketed, with no marketing end date reported by PHOENIX RX LLC. Listing status can change — the directory data on this page refreshes weekly.
Does this product come in other package sizes?
Yes — the FDA directory lists 4 other package presentations of this same product, including 30 tablets (85509-2341-03), 60 tablets (85509-2341-06), 100 tablets (85509-2341-01). Each has its own NDC and its own page — see the package list near the top of this page.
Who lists this product with the FDA?
PHOENIX RX LLC is the labeler of record for this NDC — the company under whose FDA-assigned code the package is listed. The labeler may be the manufacturer itself or a distributor marketing the product under its own code.
Do I need a prescription for this product?
This NDC is listed with FDA as a prescription product, so it is dispensed under a prescriber's order. Your pharmacist can tell you whether any over-the-counter forms of the same medication exist.
This page identifies an FDA-listed package (the NDC) and reports public regulatory and pricing data about the listing. It is reference information, not a medical recommendation — talk to your pharmacist or prescriber about your own medication.
Where does this data come from?
Listing facts (marketing category, packager status, marketing dates) from the FDA openFDA NDC Directory; label availability from DailyMed; pricing coverage from CMS NADAC; equivalence scope from the FDA Orange Book.
← 85509-2180-01 · PHOENIX 85509-2396-03 · PHOENIX →
For educational and professional reference only — not medical advice. Pricing reflects published NADAC and CMS ASP (free public data) and may differ from your acquisition cost; always verify before billing or dispensing.