Robaxin

Methocarbamol may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• drowsiness
• dizziness
• upset stomach
• blurred vision
• fever
• black, blue, or green discoloration of urine

If you experience either of the following symptoms, call your doctor immediately:

• rash
• itching

Methocarbamol may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Common side effects include:

• drowsiness
• dizziness
• headache
• nausea
• vomiting
• blurred vision
• fever
• changes in urine color

​This is not a complete list of Robaxin side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Specific Drugs and Laboratory Tests

Absorption

Bioavailability

Rapidly and almost completely absorbed following oral administration.b

Onset

Usually within 30 minutes following oral administration.b

Almost immediate after IV administration.b

Distribution

Extent

Widely distributed in dogs, with highest concentrations in the kidney and liver.b

Methocarbamol and/or its metabolites cross the placenta in dogs.b

Distributed into milk in dogs; not known whether distributed into human milk.a b c

Plasma Protein Binding

46–50%.a c

Elimination

Metabolism

Extensively metabolized, presumably in the liver, by dealkylation and hydroxylation.b

Elimination Route

Eliminated principally in urine as metabolites (40–50% as glucuronide and sulfate conjugates, remainder as unidentified metabolites); small amount (10–15%) eliminated unchanged in urine.b Very small amounts excreted in feces.b

Half-life

0.9–1.8 hours.b

Special Populations

In geriatric patients, half-life slightly prolonged.a c

In patients with renal impairment on maintenance dialysis, clearance decreased by 40% but no apparent increase in half-life.a c

In patients with cirrhosis secondary to alcohol abuse, clearance decreased by 70% and half-life increased to about 3.4 hours.a c

Storage

Oral

Tight containers at 20–25°C.a

Parenteral

20–25°C (may be exposed to 15–30°C).b c Do not freeze.b

Do not refrigerate after dilution (see Compatibility under Stability).b c

Compatibility

For information on systemic interactions resulting from concomitant use, see Interactions.

Parenteral

Precipitation and haze formation may occur if diluted solution is refrigerated.b c

Haze formation in diluted solutions may be unpredictable; visually inspect all diluted solutions prior to administration regardless of storage conditions.b

• CNS depressant with sedative and skeletal muscle relaxant effects.a b c

• Precise mechanism of action is not known; does not directly relax skeletal muscle and has minimal skeletal muscle relaxant effects.a b c Beneficial effect probably is related to the drug’s sedative effect.a b c

• Unlike neuromuscular blocking agents, does not depress neuronal conduction, neuromuscular transmission, or muscle excitability.b

Robaxin (methocarbamol injection, USP) Injectable, a carbamate derivative of guaifenesin, is a central nervous system (CNS) depressant with sedative and musculoskeletal relaxant properties. It is a sterile, pyrogen-free solution intended for intramuscular or intravenous administration.

Each mL contains: methocarbamol, USP 100 mg, polyethylene glycol 300, NF 0.5 mL, Water for Injection, USP q.s. The pH is adjusted, when necessary, with hydrochloric acid and/or sodium hydroxide. The chemical name of methocarbamol is 3‑(2‑methoxyphenoxy)‑1,2-propanediol 1‑carbamate and has the empirical formula of 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 Injectable has a pH between 3.5 and 6.0.

AFTER MIXING WITH I.V. INFUSION FLUIDS, DO NOT REFRIGERATE.

For Intravenous and Intramuscular Use Only. Total adult dosage should not exceed 30 mL (3 vials) a day for more than 3 consecutive days except in the treatment of tetanus. If the condition persists, a like course may be repeated after a drug-free interval of 48 hours. Dosage and frequency of injection should be based on the severity of the condition being treated and therapeutic response noted.

For the relief of symptoms of moderate degree, one dose of 1 gram (one 10 mL vial) may be adequate. Ordinarily this injection need not be repeated, as the administration of the oral form will usually sustain the relief initiated by the injection. For the severest cases or in postoperative conditions in which oral administration is not feasible, additional doses of 1 gram may be repeated every 8 hours up to a maximum of 3 g/day for no more than 3 consecutive days.

Directions for Intravenous Use

Robaxin Injectable may be administered undiluted directly into the vein at a maximum rate of three mL per minute. It may also be added to an intravenous drip of Sodium Chloride Injection (Sterile Isotonic Sodium Chloride Solution for Parenteral Use) or five percent Dextrose Injection (Sterile 5 percent Dextrose Solution); one vial given as a single dose should not be diluted to more than 250 mL for I.V. infusion. AFTER MIXING WITH I.V. INFUSION FLUIDS, DO NOT REFRIGERATE. Care should be exercised to avoid vascular extravasation of this hypertonic solution, which may result in thrombophlebitis. It is preferable that the patient be in a recumbent position during and for at least 10 to 15 minutes following the injection.

Directions for Intramuscular Use

When the intramuscular route is indicated, not more than five mL (one-half vial) should be injected into each gluteal region. The injections may be repeated at eight hour intervals, if necessary. When satisfactory relief of symptoms is achieved, it can usually be maintained with tablets.

Not Recommended for Subcutaneous Administration.

Special Directions for Use in Tetanus

There is clinical evidence which suggests that methocarbamol may have a beneficial effect in the control of the neuromuscular manifestations of tetanus. It does not, however, replace the usual procedure of debridement, tetanus antitoxin, penicillin, tracheotomy, attention to fluid balance, and supportive care. Robaxin Injectable should be added to the regimen as soon as possible.

For adults: Inject one or two vials directly into the tubing of the previously inserted indwelling needle. An additional 10 mL or 20 mL may be added to the infusion bottle so that a total of up to 30 mL (three vials) is given as the initial dose (see PRECAUTIONS). This procedure should be repeated every six hours until conditions allow for the insertion of a nasogastric tube. Crushed methocarbamol tablets suspended in water or saline may then be given through this tube. Total daily oral doses up to 24 grams may be required as judged by patient response.
For pediatric patients: A minimum initial dose of 15 mg/kg or 500 mg/m2 is recommended. This dosage may be repeated every six hours, if required. The total dose should not exceed 1.8 g/m2 for 3 consecutive days. The maintenance dosage may be given by injection into tubing or by I.V. infusion with an appropriate quantity of fluid. See directions for I.V. use.

Robaxin (methocarbamol) is a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain.

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

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

Applies to methocarbamol: oral tablet

Other dosage forms:

• injection solution

Along with its needed effects, methocarbamol (the active ingredient contained in Robaxin) 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 methocarbamol:

• Black, tarry stools
• changes in skin color
• chest pain or discomfort
• chills
• clay-colored stools
• cough
• dark urine
• diarrhea
• difficulty in swallowing
• dizziness
• fast heartbeat
• feeling of warmth
• fever
• headache
• joint or muscle pain
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• lightheadedness, dizziness, or fainting
• loss of appetite
• loss of bladder control
• loss or problems with memory
• nausea
• numbness or tingling of face, hands, or feet
• pain, tenderness, or swelling of foot or leg
• painful or difficult urination
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• redness and soreness of the eyes
• redness of the face, neck, arms, and occasionally, upper chest
• skin rash
• sleepiness
• slow or irregular heartbeat
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• stomach pain
• sweating
• swollen glands
• tightness in the chest
• total body jerking
• unpleasant breath odor
• unusual bleeding or bruising
• unusual tiredness or weakness
• vomiting of blood
• yellow eyes or skin

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

• Loss of consciousness
• shaking or jerking of one area or side of the body

Some side effects of methocarbamol 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:

• Belching
• double vision
• drowsiness
• feeling of constant movement of self or surroundings
• heartburn
• indigestion
• mood or mental changes
• sensation of spinning
• stomach discomfort, upset, or pain
• trouble sleeping
• uncontrolled eye movements

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.

You should not use methocarbamol if you are allergic to it.

To make sure methocarbamol is safe for you, tell your doctor if you have:

• myasthenia gravis; or

• if you also use a narcotic (opioid) medication.

Using methocarbamol during early pregnancy may cause birth defects. Tell your doctor if you are pregnant or if you become pregnant while using this medicine.

It is not known whether methocarbamol passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

Methocarbamol is not approved for use by anyone younger than 16 years old.

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Drinking alcohol with this medicine can cause side effects.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2018 Cerner Multum, Inc. Version: 6.01.

Medical Disclaimer