CHLORZOXAZONE 375 mg Tablet, 100-count
🆔 Identity & classification
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🏭 Manufacturer & labeler
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🩺 Clinical
Chlorzoxazone is used to relieve pain and stiffness caused by muscle strains and sprains. It is used in combination with physical therapy, analgesics (such as aspirin or acetaminophen), and rest.
Read the full MedlinePlus article ↗- Chlorzoxazone is a muscle relaxant used to help with short-term muscle pain and spasms — the kind that comes on suddenly from an injury or strain. It's meant to be used together wi...
- Yes, drowsiness and dizziness are real possibilities with chlorzoxazone. Until you know how it affects you, it's best to avoid driving or operating machinery. Alcohol makes the dro...
- Will this make me drowsy? Is it safe to drive?
- This is actually a known and harmless side effect. Chlorzoxazone breaks down into a substance that can temporarily color your urine orange or reddish-brown. It has no known clinica...
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Chlorzoxazone — 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 M28OL1HH48
Croscarmellose sodium is a plant-based substance derived from cellulose. It acts as a disintegrant, helping tablets and capsules break down quickly in the digestive system so the medicine can be absorbed.
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UNII 656HXR6YXN
A combination of two additives: docusate sodium softens the medicine's texture to help it break apart, while sodium benzoate acts as a preservative to prevent spoilage and maintain shelf life.
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UNII EWQ57Q8I5X
Lactose monohydrate is a natural sugar derived from milk. It serves as a filler and binder in tablets and capsules, helping create the proper size, texture, and consistency of the medicine.
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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 OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
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UNII ETJ7Z6XBU4
Silicon dioxide is a naturally occurring mineral used as a glidant and anti-caking agent. It helps powder ingredients flow smoothly and prevents clumping during manufacturing and storage.
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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
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💲 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 | $0.667 | $66.65 / 100 tablets |
| Medicaid paysCMS SDUD · 12 mo | $1.04 | $104.13 / 100 tablets |
| Medicare drug plans payPart D · Q2 2026 | $0.2693 | $26.93 / 100 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Chlorzoxazone 375 mg 00254-2053-01 | Par | 100 tablets | $0.667 | AB | Availability likely | — |
| Chlorzoxazone 375 mg 16571-0725-01 | Rising | 100 tablets | $0.667 | AB | Availability likely | — |
| Chlorzoxazone 375 mgthis 59651-0305-01 | Aurobindo | 100 tablets | $0.667 | — | Availability likely | — |
| Chlorzoxazone 375 mg 80425-0525-01 | Advanced | 30 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
FDA-approved generic versions are listed, and recent pricing/market data suggests they may be available — see Therapeutic equivalents.
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
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📦 Packaging — all sizes for this product
| Package NDC | Description | Per unit | Per pack | Marketing start | Status |
|---|---|---|---|---|---|
| 59651-0305-01 You're viewing this | 100 TABLET in 1 BOTTLE (59651-305-01) | $0.6665 / ea | $66.65 | 2023-08-17 | Active |
| 59651-0305-13 | 14000 TABLET in 1 BAG (59651-305-13) | — | — | — | Active |
You're viewing the smallest of 2 pack sizes for this product.
In Medicaid, this is the most-dispensed pack of this product — about 100% of fills over the last four reported quarters. See all packs ↓
Pack size FAQ
What quantity is in NDC 59651-0305-01?
What is the difference between NDC 59651-0305-01 and NDC 59651-0305-13?
What NDC number is used to bill for this package of CHLORZOXAZONE 375 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.
🧭 About this NDC listing & data coverage
What "drug for further processing" means
FDA lists this package under the "drug for further processing" marketing category: Aurobindo Pharma Limited supplies it to other companies for further processing or repackaging (blister cards that are later repackaged or co-packaged are a common example). The units themselves are a finished dosage form — which is why pricing or Medicaid data can still appear — but this exact package code may not be the presentation a retail pharmacy dispenses.
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) | ✓ Available |
| Orange Book / therapeutic-equivalence data | — Not published for this NDC Applies only to products approved under an NDA/ANDA; many listings are out of scope. |
| 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) | ✓ Available |
Questions about this listing
Is this NDC FDA-approved?
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📄 Full FDA label FDA SPL
🎯 Indications and Usage ▾
INDICATIONS AND USAGE Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort 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. Chlorzoxazone does not directly relax tense skeletal muscles in man.
⏱️ Dosage and Administration ▾
DOSAGE AND ADMINISTRATION Usual Adult Dosage Chlorzoxazone tablets USP, 375 mg: One tablet three or four times daily. If adequate response is not obtained with this dose, the 375 mg tablets may be increased to two tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Chlorzoxazone tablets USP, 500 mg: One tablet three or four times daily. If adequate response is not obtained with this dose, it may be increased to one and one-half tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Chlorzoxazone tablets USP, 750 mg: 1/3 tablet (250 mg) three or four times daily. Initial dosage for painful musculoskeletal conditions should be 2/3 tablet (500 mg) three or four times daily. If adequate response is not obtained with this dose, it may be increased to one tablet (750 mg) three or four times daily.
As improvement occurs dosage can usually be reduced.
⛔ Contraindications ▾
CONTRAINDICATIONS Chlorzoxazone is contraindicated in patients with known intolerance to the drug.
⚠️ Warnings ▾
WARNINGS Serious (including fatal) hepatocellular toxicity has been reported rarely in patients receiving chlorzoxazone. The mechanism is unknown but appears to be idiosyncratic and unpredictable. Factors predisposing patients to this rare event are not known.
Patients should be instructed to report early signs and/or symptoms of hepatotoxicity such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, or jaundice. Chlorzoxazone should be discontinued immediately and a physician consulted if any of these signs or symptoms develop. Chlorzoxazone use should also be discontinued if a patient develops abnormal liver enzymes (e.g., AST, ALT, alkaline phosphatase and bilirubin.) The concomitant use of alcohol or other central nervous system depressants may have an additive effect.
Usage in Pregnancy: The safe use of chlorzoxazone has not been established with respect to the possible adverse effects upon fetal development. Therefore, it should be used in women of childbearing potential only when, in the judgment of the physician, the potential benefits outweigh the possible risks.
🤒 Adverse Reactions ▾
ADVERSE REACTIONS Chlorzoxazone containing products are usually well tolerated. It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, lightheadedness, malaise, or over-stimulation may be noted by an occasional patient.
Rarely, allergic type skin rashes, petechiae, or ecchymoses may develop during treatment. Angioneurotic edema or anaphylactic reactions are extremely rare. There is no evidence that the drug will cause renal damage.
Rarely, a patient may note discoloration of the urine resulting from a phenolic metabolite of chlorzoxazone. This finding is of no known clinical significance. To report SUSPECTED ADVERSE EVENTS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800- FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.
🆘 Overdosage ▾
OVERDOSAGE Symptoms: Initially, gastrointestinal disturbances such as nausea, vomiting, or diarrhea together with drowsiness, dizziness, lightheadedness or headache may occur. Early in the course there may be malaise or sluggishness followed by marked loss of muscle tone, making voluntary movement impossible. The deep tendon reflexes may be decreased or absent.
The sensorium remains intact, and there is no peripheral loss of sensation. Respiratory depression may occur with rapid, irregular respiration and intercostal and substernal retraction. The blood pressure is lowered, but shock has not been observed.
Treatment: Gastric lavage or induction of emesis should be carried out, followed by administration of activated charcoal. Thereafter, treatment is entirely supportive. If respirations are depressed, oxygen and artificial respiration should be employed and a patent airway assured by use of an oropharyngeal airway or endotracheal tube.
Hypotension may be counteracted by use of dextran, plasma, concentrated albumin or a vasopressor agent such as norepinephrine. Cholinergic drugs or analeptic drugs are of no value and should not be used.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY Chlorzoxazone is a centrally-acting agent for painful musculoskeletal conditions. Data available from animal experiments as well as human study indicate that chlorzoxazone acts primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles.
Blood levels of chlorzoxazone can be detected in people during the first 30 minutes and peak levels may be reached, in the majority of the subjects, in about 1 to 2 hours after oral administration of chlorzoxazone. Chlorzoxazone is rapidly metabolized and is excreted in the urine, primarily in a conjugated form as the glucuronide. Less than one percent of a dose of chlorzoxazone is excreted unchanged in the urine in 24 hours.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED Chlorzoxazone tablets USP are supplied as follows: 375 mg A white to off-white capsule shaped tablet debossed with “N” on one side and “375” on other side. Bottles of 100 NDC 59651-305-01 500 mg A light orange to orange round shaped, flat hexagonal, beveled debossed with “N” on one side of break line and “500” on other side of break line and plain on other side. Bottles of 100 with child-resistant closure NDC 59651-306-01 Bottles of 500 NDC 59651-306-05 750 mg A white to off-white capsule shaped tablet debossed with “N” on one side with trisect and “750” on other side with bisect.
Bottles of 100 NDC 59651- 307-01 Dispense in tight container as defined in the official compendium. Store at 20° to 25° C (68° to 77° F) [see USP Controlled Room Temperature]. Distributed by: Aurobindo Pharma USA, Inc.
279 Princeton-Hightstown Road East Windsor, NJ 08520 Manufactured by: Aurobindo Pharma Limited Hyderabad-500 032, India Revised: 09/2023
📋 Description ▾
DESCRIPTION Each 375 mg chlorzoxazone tablet contains: Chlorzoxazone USP 375 mg. Each 500 mg chlorzoxazone tablet contains: Chlorzoxazone USP 500 mg. Each 750 mg chlorzoxazone tablet contains: Chlorzoxazone USP 750 mg.
Chemical Name: 5-Chloro-2-benzoxazolinone. Structural Formula: Molecular Formula: C 7 H 4 ClNO 2 Molecular Weight: 169.56 Chlorzoxazone, USP is a white or practically white, practically odorless, crystalline powder. Chlorzoxazone USP is slightly soluble in water; sparingly soluble in alcohol, in isopropyl alcohol, and in methanol; soluble in solutions of alkali hydroxides and ammonia.
Inactive ingredients: 375 mg contains colloidal silicon dioxide, corn starch, croscarmellose sodium, docusate sodium with sodium benzoate, lactose monohydrate, magnesium stearate and microcrystalline cellulose. 500 mg contains D&C Red 27/Phloxine Aluminium lake, FD&C Yellow 6/Sunset Yellow FCF Aluminium lake, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polysorbate 80, pregelatinized starch, sodium starch glycolate. 750 mg contains colloidal silicon dioxide, corn starch, croscarmellose sodium, docusate sodium with sodium benzoate, lactose monohydrate, magnesium stearate and microcrystalline cellulose.
Meets USP dissolution test 5 for 500 mg. FDA approved dissolution method differs from that of the USP for 375 mg and 750 mg. str