Chlorzoxazone

Each caplet (capsule shaped tablet) contains:

Chlorzoxazone* 500 mg

Inactive ingredients: FD&C Blue No. 1, microcrystalline cellulose, docusate sodium, lactose (hydrous), magnesium stearate, sodium benzoate, sodium starch glycolate, pregelatinized corn starch, D&C Yellow No. 10.

*5-chlorobenzoxazolinone

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.

Pregnancy Category: C

Lactation: not known if excreted in breast milk

Pregnancy Categories

A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA:Information not available.

Chlorzoxazone is a muscle relaxer that blocks pain sensations between the nerves and the brain.

Chlorzoxazone is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.

Chlorzoxazone may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Taking carisoprodol with other drugs that make you sleepy or slow your breathing can cause dangerous side effects or death. Ask your doctor before taking a sleeping pill, narcotic pain medicine, prescription cough medicine, a muscle relaxer, or medicine for anxiety, depression, or seizures.

Other drugs may interact with chlorzoxazone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Centrally acting skeletal muscle relaxant.b

It is very important that your doctor check your progress at regular visits to make sure that chlorzoxazone is working properly and to check for unwanted effects.

Liver problems may occur while you are using chlorzoxazone. Stop using chlorzoxazone and check with your doctor right away if you are having more than one of these symptoms: abdominal pain or tenderness; clay-colored stools; dark urine; decreased appetite; fever; headache; itching; loss of appetite; nausea and vomiting; skin rash; swelling of the feet or lower legs; unusual tiredness or weakness; or yellow eyes or skin.

chlorzoxazone will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of these medicines while you are taking chlorzoxazone.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Throwing up blood or throw up that looks like coffee grounds.
• Black, tarry, or bloody stools.
• Very bad belly pain.
• Very bad and sometimes deadly liver problems have happened with this medicine. Call your doctor right away if you have signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

(klor ZOKS a zone)

Consult your pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Applies to chlorzoxazone: oral capsule, oral tablet

Along with its needed effects, chlorzoxazone may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking chlorzoxazone:

• Bloody or black, tarry stools
• clay-colored stools
• constipation
• cough
• dark urine
• decreased appetite
• difficulty swallowing
• dizziness
• fast heartbeat
• fever
• headache
• hives
• itching
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• loss of appetite
• nausea and vomiting
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• severe stomach pain
• shortness of breath
• skin rash
• swelling of the feet or lower legs
• tightness in the chest
• unusual tiredness or weakness
• vomiting of blood or material that looks like coffee grounds
• wheezing
• yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking chlorzoxazone:

• Diarrhea
• difficult or troubled breathing
• drowsiness
• general feeling of discomfort or illness
• headache
• irregular, fast or slow, or shallow breathing
• lightheadedness
• nausea
• pale or blue lips, fingernails, or skin
• sluggishness
• vomiting

Some side effects of chlorzoxazone may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Bruising
• large, flat, blue, or purplish patches in the skin
• small red or purple spots on the skin

Chlorzoxazone is contraindicated in patients with liver dysfunction.

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

Serious (including fatal) hepatocellular toxicity has been reported rarely in patients receiving chlorzoxazone. 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.