Drug Facts
Composition & Profile
Identifiers & Packaging
HOW SUPPLIED Chlorzoxazone tablets, USP, 250 mg are supplied as white, Capsule shaped tablet, debossed "A26" on one side and "250" on the other side. They are available as: Bottles of 60 with child-resistant closure: NDC 24470-923-60 Bottles of 100 with child-resistant closure: NDC 24470-923-10 Dispense contents with a child-resistant closure (as required) and in a tight container as defined in the USP/NF. Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Manufactured for: Cintex Services, LLC Dallas, TX 75243 855-899-4237 Rev. 03/2023 L7039/01; label1 label2
- HOW SUPPLIED Chlorzoxazone tablets, USP, 250 mg are supplied as white, Capsule shaped tablet, debossed "A26" on one side and "250" on the other side. They are available as: Bottles of 60 with child-resistant closure: NDC 24470-923-60 Bottles of 100 with child-resistant closure: NDC 24470-923-10 Dispense contents with a child-resistant closure (as required) and in a tight container as defined in the USP/NF. Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Manufactured for: Cintex Services, LLC Dallas, TX 75243 855-899-4237 Rev. 03/2023 L7039/01
- label1 label2
Overview
Each tablet contains: Chlorzoxazone* .................................. 250 mg * 5-Chloro-2-benzoxazolinone Structural Formula: Molecular Formula: C 7 H 4 CINO 2 Molecular Weight: 169.57 Chlorzoxazone, USP is a white or practically white, practically odorless, crystalline powder. Chlorzoxazone 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: colloidal silicon dioxide, croscarmellose sodium, docusate sodium, sodium benzoate, lactose monohydrate, magnesium stearate and microcrystalline cellulose. Meets USP Dissolution Test 4 structure
Indications & 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 & Administration
Usual Adult Dosage: One tablet (250 mg) three or four times daily. Initial dosage for painful musculoskeletal conditions should be two tablets (500 mg) three or four times daily. If adequate response is not obtained with this dose, it may be increased to three tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Warnings & Precautions
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.
Contraindications
Chlorzoxazone is contraindicated in patients with known intolerance to the drug.
Adverse Reactions
After extensive clinical use of chlorzoxazone-containing products, it is apparent that the product is well tolerated and seldom produces undesirable side effects. Occasional patients may develop gastrointestinal disturbances. It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, lightheadedness, malaise, or overstimulation 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.
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