ROBAXIN

(methocarbamol) Tablet, Film Coated
DRUG DESCRIPTION
What are the possible side effects of methocarbamol (Robaxin, Robaxin-750)?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using methocarbamol and call your doctor at once if you have any of these serious side effects:
slow heart rate;
feeling like you might pass out;
jaundice (yellowing of your skin or eyes);
confusion, spinning sensation, loss of balance; or
seizure…
Read All Potential Side Effects and See Pictures of Robaxin »
robaxin®/robaxin®-750 (methocarbamol tablets, USP), a carbamate derivative of guaifenesin, is a central nervous system (CNS) depressant with sedative and musculoskeletal relaxant properties.
The chemical name of methocarbamol is 3-(2-methoxyphenoxy)-l,2-propanediol 1-carbamate and has the empirical formula C11H15NO5. Its molecular weight is 241.24. The structural formula is shown below.

Methocarbamol is a white powder, sparingly soluble in water and chloroform, soluble in alcohol (only with heating) and propylene glycol, and insoluble in benzene and n-hexane.
robaxin® is available as a light orange, round, film-coated tablet containing 500 mg of methocarbamol, USP for oral administration. The inactive ingredients present are corn starch, FD&C Yellow 6, hydroxypropyl cellulose, hypromellose, magnesium stearate, polysorbate 20, povidone, propylene glycol, saccharin sodium, sodium lauryl sulfate, sodium starch glycolate, stearic acid, titanium dioxide.
robaxin®-750 is available as an orange capsule-shaped, film-coated tablet containing 750 mg of methocarbamol, USP for oral administration. In addition to the inactive ingredients present in robaxin®, robaxin®-750 also contains D&C Yellow 10.
Last reviewed on RxList: 11/1/2010
Robaxin Indications & Dosage

INDICATIONS
robaxin® and robaxin®-750 are 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 methocarbamol has not been clearly identified, but may be related to its sedative properties. Methocarbamol does not directly relax tense skeletal muscles in man.
DOSAGE AND ADMINISTRATION
robaxin® (methocarbamol), 500 mg – Adults:
Initial dosage: 3 tablets q.i.d.
Maintenance dosage: 2 tablets q.i.d.
robaxin®-750 (methocarbamol): 750 mg – Adults:
Initial dosage: 2 tablets q.i.d.
Maintenance dosage: 1 tablet q.4h. or 2 tablets ti.d.
Six grams a day are recommended for the first 48 to 72 hours of treatment. (For severe conditions 8 grams a day may be administered). Thereafter, the dosage can usually be reduced to approximately 4 grams a day.
HOW SUPPLIED
robaxin® (methocarbamol tablets, USP)
500 mg tablets are light orange, round, film-coated tablets engraved with ROBAXIN 500 on the unscored side and SP above the score on the other side. They are supplied as follows:
Bottles of 100 NDC 0091-7429-63
robaxin®-750 (methocarbamol tablets, USP)
750 mg tablets are orange, capsule-shaped, film-coated tablets engraved with ROBAXIN 750 on one side and SP on the other. They are supplied as follows:
Bottles of 100 NDC 0091-7449-63
Bottles of 500 NDC 0091-7449-70
Store at controlled room temperature, between 20°C and 25°C (68°F and 77°F).
Dispense in tight container.
Schwarz Pharma.
Last reviewed on RxList: 11/1/2010
Robaxin Side Effects & Drug Interactions

SIDE EFFECTS
Adverse reactions reported coincident with the administration of methocarbamol include:
Body as a whole: Anaphylactic reaction, angioneurotic edema, fever, headache
Cardiovascular system: Bradycardia, flushing, hypotension, syncope, thrombophlebitis
Digestive system: Dyspepsia, jaundice (including cholestatic jaundice), nausea and vomiting
Hemic and lymphatic system: Leukopenia
Immune system: Hypersensitivity reactions
Nervous system: Amnesia, confusion, diplopia, dizziness or lightheadedness, drowsiness, insomnia, mild muscular incoordination, nystagmus, sedation, seizures (including grand mal), vertigo
Skin and special senses: Blurred vision, conjunctivitis, nasal congestion, metallic taste, pruritus, rash, urticaria
DRUG INTERACTIONS
See WARNINGS and PRECAUTIONS for interaction with CNS drugs and alcohol.
Methocarbamol may inhibit the effect of pyridostigmine bromide. Therefore, methocarbamol should be used with caution in patients with myasthenia gravis receiving anticholinesterase agents.
Drug/laboratory test interactions
Methocarbamol may cause a color interference in certain screening tests for 5-hydroxyindoleacetic acid (5-HIAA) using nitrosonaphthol reagent and in screening tests for urinary vanillylmandelic acid (VMA) using the Gitlow method.
Last reviewed on RxList: 11/1/2010
Robaxin Warnings & Precautions

WARNINGS
Since methocarbamol may possess a general CNS depressant effect, patients receiving robaxin® or robaxin®-750 should be cautioned about combined effects with alcohol and other CNS depressants.
Safe use of robaxin® and robaxin®-750 has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congenital abnormalities following in utero exposure to methocarbamol. Therefore, robaxin® and
robaxin®-750 should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgment of the physician the potential benefits outweigh the possible hazards (see PRECAUTIONS, Pregnancy).
Use In Activities Requiring Mental Alertness
Methocarbamol may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle. Patients should be cautioned about operating machinery, including automobiles, until they are reasonably certain that methocarbamol therapy does not adversely affect their ability to engage in such activities.
PRECAUTIONS
Included as part of the PATIENT INFORMATION section.
Carcinogenesis, mutagenesis, impairment of fertility
Long-term studies to evaluate the carcinogenic potential of methocarbamol have not been performed. No studies have been conducted to assess the effect of methocarbamol on mutagenesis or its potential to impair fertility.
Pregnancy
Teratogenic effects – Pregnancy Category C
Animal reproduction studies have not been conducted with methocarbamol. It is also not known whether methocarbamol can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity, robaxin® and robaxin®-750 should be given to a pregnant woman only if clearly needed.
Safe use of robaxin® and robaxin®-750 has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congenital abnormalities following in utero exposure to methocarbamol. Therefore, robaxin® and
robaxin®-750 should not be used in women who are or may become pregnant and particularly during early pregnancy unless in the judgment of the physician the potential benefits outweigh the possible hazards (see WARNINGS).
Nursing mothers
Methocarbamol and/or its metabolites are excreted in the milk of dogs; however, it is not known whether methocarbamol or its metabolites are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when robaxin® or robaxin®-750 is administered to a nursing woman.
Pediatric use
Safety and effectiveness of robaxin® and robaxin®-750 in pediatric patients below the age of 16 have not been established.
Last reviewed on RxList: 11/1/2010
Robaxin Overdosage & Contraindications

OVERDOSE
Limited information is available on the acute toxicity of methocarbamol. Overdose of methocarbamol is frequently in conjunction with alcohol or other CNS depressants and includes the following symptoms: nausea, drowsiness, blurred vision, hypotension, seizures, and coma.
In post-marketing experience, deaths have been reported with an overdose of methocarbamol alone or in the presence of other CNS depressants, alcohol or psychotropic drugs.
Treatment
Management of overdose includes symptomatic and supportive treatment. Supportive measures include maintenance of an adequate airway, monitoring urinary output and vital signs, and administration of intravenous fluids if necessary. The usefulness of hemodialysis in managing overdose is unknown.
CONTRAINDICATIONS
robaxin® and robaxin®-750 are contraindicated in patients hypersensitive to methocarbamol or to any of the tablet components.
Last reviewed on RxList: 11/1/2010
Robaxin Clinical Pharmacology

CLINICAL PHARMACOLOGY
The mechanism of action of methocarbamol in humans has not been established, but may be due to general central nervous system (CNS) depression. It has no direct action on the contractile mechanism of striated muscle, the motor end plate or the nerve fiber.
Pharmacokinetics
In healthy volunteers, the plasma clearance of methocarbamol ranges between 0.20 and 0.80 L/h/kg, the mean plasma elimination half-life ranges between 1 and 2 hours, and the plasma protein binding ranges between 46% and 50%.
Methocarbamol is metabolized via dealkylation and hydroxylation. Conjugation of methocarbamol also is likely. Essentially all methocarbamol metabolites are eliminated in the urine. Small amounts of unchanged methocarbamol also are excreted in the urine.
Special populations
Elderly
The mean (+ SD) elimination half-life of methocarbamol in elderly healthy volunteers (mean (+ SD) age, 69 (+ 4) years) was slightly prolonged compared to a younger (mean (+ SD) age, 53.3 (+ 8.8) years), healthy population (1.5 (+ 0.4) hours versus 1.1 (+0.27) hours, respectively). The fraction of bound methocarbamol was slightly decreased in the elderly versus younger volunteers (41 to 43% versus 46 to 50%, respectively).
Renally impaired
The clearance of methocarbamol in 8 renally-impaired patients on maintenance hemodialysis was reduced about 40% compared to 17 normal subjects, although the mean (+ SD) elimination half-life in these two groups was similar: 1.2 (+ 0.6) versus 1.1 (+0.3) hours, respectively.
Hepatically impaired
In 8 patients with cirrhosis secondary to alcohol abuse, the mean total clearance of methocarbamol was reduced approximately 70% compared to that obtained in 8 age- and weight-matched normal subjects. The mean (+ SD) elimination half-life in the cirrhotic patients and the normal subjects was 3.38 (+ 1.62) hours and 1.11 (+ 0.27) hours, respectively. The percent of methocarbamol bound to plasma proteins was decreased to approximately 40 to 45% compared to 46 to 50% in the normal subjects.
Last reviewed on RxList: 11/1/2010
Robaxin Medication Guide

PATIENT INFORMATION
Patients should be cautioned that methocarbamol may cause drowsiness or dizziness, which may impair their ability to operate motor vehicles or machinery.
Because methocarbamol may possess a general CNS-depressant effect, patients should be cautioned about combined effects with alcohol and other CNS depressants.
Last reviewed on RxList: 11/1/2010

Robaxin Consumer
IMPORTANT NOTE: This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your health care professional. Always seek the advice of your health care professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your health care professional. This information does not contain any assurances that this product is safe, effective, or appropriate for you.
METHOCARBAMOL – ORAL
(meth-oh-KAR-ba-mole)
COMMON BRAND NAME(S): Robaxin
USES: This medication relaxes muscles. It is used along with rest and physical therapy to decrease muscle pain and spasms associated with strains, sprains or other muscle injuries.
HOW TO USE: Take this medication by mouth usually 3 or 4 times a day, or as directed by your doctor. It may be taken with food or immediately after meals to prevent stomach upset.
Dosage is based on your medical condition and response to therapy. Do not increase your dose or take it more often than prescribed because the risk of side effects may increase.
This medication is intended for short-term use, usually no longer than 3 weeks, unless otherwise directed by your doctor. If your condition does not improve in 2-3 weeks, contact your doctor.

Robaxin Consumer (continued)
SIDE EFFECTS: Stomach upset, nausea, flushing, constipation, headache, blurred vision, lightheadedness, dizziness or drowsiness may occur during the first few days as your body adjusts to this medication. If these symptoms persist or become severe, notify your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor immediately if any of these unlikely but serious side effects occur: fast/slow heartbeat, fainting, yellowing eyes or skin, persistent nausea/vomiting, stomach/abdominal pain, mental/mood changes, clumsiness, trouble urinating, signs of infection (e.g., persistent sore throat, fever).
This medication may cause your urine to turn green-black in color. This harmless effect is temporary and will disappear when the medication is stopped.
A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or 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 begin_of_the_skype_highlighting 1-800-FDA-1088 end_of_the_skype_highlighting.
In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345 begin_of_the_skype_highlighting 1-866-234-2345 end_of_the_skype_highlighting.
PRECAUTIONS: Before taking methocarbamol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, severe difficulty urinating (urinary retention).
This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.
To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position.
Caution is advised when using this drug in the elderly because they may be more sensitive to its side effects, especially dizziness and drowsiness.
This medication should be used during pregnancy only when clearly needed. Discuss the risks and benefits with your doctor.
It is not known if this drug passes into breast milk. Consult your doctor before breast-feeding.

Robaxin Consumer (continued)
DRUG INTERACTIONS: Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with them first.
Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of drugs that cause drowsiness such as: certain antihistamines (e.g., diphenhydramine), anti-anxiety drugs (e.g., diazepam), anti-seizure drugs (e.g., carbamazepine), medicine for sleep (e.g., sedatives), narcotic pain relievers (e.g., codeine), psychiatric medicines (e.g., phenothiazines such as chlorpromazine, or tricyclic anti-depressants such as amitriptyline), tranquilizers.
Check the labels on all your medicines (e.g., cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about the safe use of those products.
This product can affect the results of certain urine lab tests. Make sure laboratory personnel and your doctors know you use this drug.
This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.
OVERDOSE: If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222 begin_of_the_skype_highlighting 1-800-222-1222 end_of_the_skype_highlighting. Canadian residents should call their local poison control center directly. Symptoms of overdose may include severe drowsiness or unconsciousness.
NOTES: Do not share this medication with others.
MISSED DOSE: If you miss a dose, take it as soon as you remember within 1 hour. Otherwise, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.
STORAGE: Store at room temperature between 59-86 degrees F (15-30 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.