CHLORZOXAZONE- chlorzoxazone tablet 
Bryant Ranch Prepack

----------

CHLORZOXAZONE TABLETS, USP 500 mg

DESCRIPTION

Chlorzoxazone USP is a centrally acting skeletal muscle relaxant, available as tablets of 500 mg for oral administration. Its chemical name is 5-Chloro-2-benzoxazolinone, and its structural formula is: 

Chlorzoxazone Structural Formula

Chlorzoxazone Structural Formula

C7H4CINO2 MW 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.

Chlorzoxazone tablets contain the inactive ingredients Docusate Sodium, Lactose (hydrous), Magnesium Stearate, Microcrystalline Cellulose, Pregelatinized Starch, Sodium Benzoate, and Sodium Starch Glycolate.

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.   

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.  

CONTRAINDICATIONS

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

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 judgement of the physician, the potential benefits outweigh the possible risks.  

PRECAUTIONS

Chlorzoxazone should be used with caution in patients with known allergies or with a history of allergic reactions to drugs. If a sensitivity reaction occurs such as urticaria, redness, or itching of the skin, the drug should be stopped.

If any symptoms suggestive of liver dysfunction are observed, the drug should be discontinued.  

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.  

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.      

DOSAGE AND ADMINISTRATION

Usual Adult Dosage

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 500mg

Image File
CHLORZOXAZONE 
chlorzoxazone tablet
Product Information
Product Type HUMAN PRESCRIPTION DRUG Item Code (Source) NDC:63629-1586(NDC:0591-3968)
Route of Administration ORAL DEA Schedule     
Active Ingredient/Active Moiety
Ingredient Name Basis of Strength Strength
CHLORZOXAZONE (UNII: H0DE420U8G) (CHLORZOXAZONE - UNII:H0DE420U8G) CHLORZOXAZONE 500 mg
Inactive Ingredients
Ingredient Name Strength
DOCUSATE SODIUM (UNII: F05Q2T2JA0)  
LACTOSE MONOHYDRATE (UNII: EWQ57Q8I5X)  
MAGNESIUM STEARATE (UNII: 70097M6I30)  
CELLULOSE, MICROCRYSTALLINE (UNII: OP1R32D61U)  
STARCH, CORN (UNII: O8232NY3SJ)  
SODIUM BENZOATE (UNII: OJ245FE5EU)  
SODIUM STARCH GLYCOLATE TYPE A POTATO (UNII: 5856J3G2A2)  
Product Characteristics
Color WHITE Score 2 pieces
Shape OVAL (oblong) Size 17mm
Flavor Imprint Code 93;542
Contains     
Packaging
# Item Code Package Description Marketing Start Date Marketing End Date
1 NDC:63629-1586-1 20 in 1 BOTTLE
2 NDC:63629-1586-2 30 in 1 BOTTLE
3 NDC:63629-1586-3 40 in 1 BOTTLE
4 NDC:63629-1586-4 90 in 1 BOTTLE
5 NDC:63629-1586-5 60 in 1 BOTTLE
6 NDC:63629-1586-6 100 in 1 BOTTLE
7 NDC:63629-1586-7 14 in 1 BOTTLE
8 NDC:63629-1586-8 7 in 1 BOTTLE
9 NDC:63629-1586-9 120 in 1 BOTTLE
Marketing Information
Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date
ANDA ANDA089859 12/23/2008
Labeler - Bryant Ranch Prepack (171714327)
Registrant - Bryant Ranch Prepack (171714327)
Establishment
Name Address ID/FEI Business Operations
TEVA Pharmaceuticals USA Inc 118234421 MANUFACTURE(63629-1586)
Establishment
Name Address ID/FEI Business Operations
Bryant Ranch Prepack 171714327 REPACK(63629-1586) , RELABEL(63629-1586)

Revised: 12/2008
Document Id: 1ff481d5-133f-441f-9634-65b48eb2d23a
Set id: 5e6889c9-a091-4622-0a00-ad0fc1830f78
Version: 2
Effective Time: 20081223
 
Bryant Ranch Prepack