Get your patient on Chlorzoxazone - Chlorzoxazone tablet (Chlorzoxazone)

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.

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.

Chlorzoxazone is contraindicated in patients with known intolerance to the drug.

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.

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

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.

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