Generic Name: Methocarbamol
Class: Centrally Acting Skeletal Muscle Relaxants
VA Class: MS200
Chemical Name: 1-Carbamate-3-(2-methoxyphenoxy)-1,2-propanediol
Molecular Formula: C11H15NO5
CAS Number: 532-03-6
Introduction
Centrally acting skeletal muscle relaxant.b
Uses for Robaxin
Muscular Conditions
Adjunct to rest, physical therapy, analgesics, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions.a b c
For low back pain, generally reserve skeletal muscle relaxants for adjunctive treatment when pain is unresponsive to OTC analgesics (e.g., NSAIAs).h i j k l m
Skeletal muscle relaxants less well tolerated than NSAIAs, and clinical superiority to NSAIAs not established for low back pain.h i j k l m
Various skeletal muscle relaxants appear to have comparable efficacy for low back pain reliefg h and are more effective than placebo.h j l
Initially, symptomatic control of acute low back pain focuses on providing sufficient comfort to allow maximum possible activity while awaiting spontaneous recovery; later, as aid to overcome specific activity intolerance.l
Because of rapid spontaneous recovery rate, efficacy of various therapies may be difficult to establish;l improvement of low back pain usually occurs within 2 weeks, substantial improvement within 4 weeks.k
Ineffective in the treatment of skeletal muscle hyperactivity secondary to chronic neurologic disorders (e.g., cerebral palsy) and other dyskinesias.b
Tetanus
Has been used as an adjunct to debridement, tetanus antitoxin, penicillin, tracheotomy, fluid and electrolyte replacement, and supportive therapy in the management of tetanus.b However, most authorities prefer other sedatives or muscle relaxants (e.g., diazepam) and, in severe cases, neuromuscular blocking agents.b
Robaxin Dosage and Administration
Administration
Administer orally; may administer IV or IM when oral administration is not feasible or for severe musculoskeletal pain.a b c Do not administer sub-Q.b
Switch from parenteral to oral therapy as soon as possible.b
Oral Administration
NG Tube
For administration via NG tube, crush tablets and suspend in water or saline solution.b c
IV Administration
For solution compatibility information, see Compatibility under Stability.
Administer by direct IV injection or by IV infusion.b c
Patient should be recumbent during and for 10–15 minutes following IV administration.b
Avoid extravasation; solution is hypertonic.b c
For direct IV use, inject undiluted solution slowly to minimize adverse effects.b c
Blood aspirated into syringe does not mix with methocarbamol injection; either inject any blood in the syringe or stop the injection when the plunger reaches the blood.b c
Dilution
For IV infusion, dilute 1 g with up to 250 mL of 5% dextrose or 0.9% sodium chloride injection.b c
Visually inspect diluted solutions for haze prior to administration.b (See Stability.)
Rate of Administration
For direct IV injection, maximum rate of 300 mg (3 mL of 10% injection) per minute.b c Some clinicians have recommended injection at rate of 180 mg/m2 per minute in children.b
IM Administration
Administer no more than 500 mg (5 mL of 10% injection) into each gluteal region.b c
Dosage
Pediatric Patients
Tetanus
IV
Children ≥12 years of age: Recommended minimum initial dose is 15 mg/kg or 500 mg/m2; give additional doses of 15 mg/kg or 500 mg/m2 by direct IV injection or IV infusion every 6 hours, if necessary (maximum 1.8 g/m2 daily for 3 consecutive days).b c
Adults
Muscular Conditions
Oral
Usual initial dosage is 1.5 g 4 times daily for 2–3 days.a b For maintenance, decrease dosage to 4–4.5 g daily in 3–6 divided doses.a b
A few patients may require initial dosage of 8 g daily in divided doses.a b
IV or IM
Usually, 1 g as a single dose, followed by oral methocarbamol to maintain relief.b c
For more severe conditions or when oral administration is not feasible, 1 g every 8 hours (maximum 3 g daily for 3 consecutive days).b c If necessary, may readminister IV or IM after a 2-day drug-free interval.a c
Tetanus
IV, then Oral
Usual initial dose is 1–2 g by direct IV injection; may administer additional 1–2 g by IV infusion (for maximum total initial dose of 3 g).b c
Repeat IV infusion of 1–2 g every 6 hours until NG tube can be inserted.b c Up to 24 g daily (via NG tube) may be required.b c
Prescribing Limits
Pediatric Patients
Tetanus
IV
Maximum 1.8 g/m2 daily for 3 consecutive days.b c
Adults
Muscular Conditions
IV or IM
Maximum 3 g daily for 3 consecutive days.b c
Cautions for Robaxin
Contraindications
Warnings/Precautions
Warnings
CNS Depression
Performance of activities requiring mental alertness or physical coordination may be impaired.a b c
Possible additive effect with other CNS depressants and/or alcohol.a b c (See Specific Drugs and Laboratory Tests under Interactions.)
Sensitivity Reactions
Anaphylactic reactions, urticaria, pruritus, rash, skin eruptions, and conjunctivitis with nasal congestion have occurred.a b c
Latex Sensitivity
The stopper of the methocarbamol injection (Robaxin) vial contains dry natural rubber (latex).c Some individuals may be hypersensitive to natural latex proteins.c d e f Take appropriate precautions if injection is handled by or administered to individuals with a history of latex sensitivity.c
General Precautions
Epilepsy
Use IV or IM with caution, if at all, in patients with known or suspected epilepsy.b c
Specific Populations
Pregnancy
Category C.a b c
Lactation
Distributed into milk in dogs; not known whether distributed into human milk.a b c Use caution.a b c
Pediatric Use
Safety and efficacy (other than IV use in the management of tetanus) not established in children.a b c
Renal Impairment
Polyethylene glycol vehicle of methocarbamol injection may be irritating to the kidneys; may worsen preexisting acidosis and urea retention.b c Do not administer to patients with impaired renal function.b c
Common Adverse Effects
Drowsiness, dizziness, lightheadedness.a b c
Interactions for Robaxin
Specific Drugs and Laboratory Tests
Drug or Test
|
Interaction
|
Comments
|
|---|
Anticholinesterase agents (e.g., pyridostigmine)
|
Potential for severe weaknessa b c
|
Use with caution in patients with myasthenia gravisa b c
|
CNS depressants (e.g., alcohol)
|
Potential for additive CNS depressiona b c
|
Use caution to avoid overdosagea b c
|
Tests for 5-hydroxyindolacetic acid (5-HIAA) in urine (nitrosonaphthol reagent in quantitative method of Udenfriend)
|
False-positive results (color interference) a b c
|
|
Tests for vanillylmandelic acid (VMA) in urine by the screening method of Gitlow
|
False-positive results (color interference)a b c
|
|
Robaxin Pharmacokinetics
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
Stability
Storage
Oral
Tablets
Tight containers at 20–25°C.a
Parenteral
Injection
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
Solution Compatibility
Compatible
|
|---|
Dextrose 5% in waterc
|
Sodium chloride 0.9%c
|
ActionsActions
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
Advice to Patients
Potential to impair mental alertness or physical coordination, especially with concomitant use of alcohol or other CNS depressants; use caution when driving or operating machinery.a b c
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as concomitant illnesses.a b c
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.a b
Importance of informing patients of other important precautionary information. (See Cautions.)
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Methocarbamol
Routes
|
Dosage Forms
|
Strengths
|
Brand Names
|
Manufacturer
|
|---|
Oral
|
Tablets
|
500 mg*
|
Methocarbamol Tablets
|
Global, Sandoz, United Research, Watson, West-Ward
|
|
|
750 mg*
|
Methocarbamol Tablets
|
Global, Sandoz, United Research, Watson, West-Ward
|
|
Tablets, film-coated
|
500 mg
|
Robaxin (with povidone and propylene glycol)
|
Schwarz
|
|
|
750 mg
|
Robaxin (with povidone and propylene glycol)
|
Schwarz
|
Parenteral
|
Injection
|
100 mg/mL
|
Robaxin (with 50% polyethylene glycol 300)
|
Baxter
|
Comparative Pricing
This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 03/2011. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.
Methocarbamol 500MG Tablets (QUALITEST): 60/$14.97 or 120/$23.94
Robaxin 500MG Tablets (ACTIENT PHARMACEUTICALS): 30/$59.99 or 90/$149.96
Robaxin-750 750MG Tablets (ACTIENT PHARMACEUTICALS): 30/$75.99 or 90/$200.98
Disclaimer
This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.
The American Society of Health-System Pharmacists, Inc. and Drugs.com represent that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. and Drugs.com make no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. and Drugs.com do not endorse or recommend the use of any drug. The information is not a substitute for medical care.
AHFS Drug Information. © Copyright, 1959-2011, Selected Revisions April 2007. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.
References
a. Schwarz Pharma. Robaxin and Robaxin-750 tablets prescribing information. Milwaukee, WI; 2003 Apr.
b. AHFS Drug Information 2004. McEvoy GK, ed. Methocarbamol. Bethesda, MD: American Society of Health-System Pharmacists; 2004: 1336-7.
c. Baxter. Robaxin injection prescribing information. Deerfield, IL; 2003 Nov.
d. Food and Drug Administration. Amended economic impact analysis of final rule requiring use of labeling on natural rubber containing devices. 21 CFR Part 801. Final rule. (Docket No. 96N-0119) Fed Regist. 1998; 63:50660-704.
e. Food and Drug Administration. Latex-containing devices; user labeling. 21 CFR Part 801. Proposed rule. (Docket No. 96N-0119) Fed Regist. 1996; 61:32617-21.
f. Food and Drug Administration. Natural rubber-containing medical devices; user labeling. 21 CFR Part 801. Final rule. (Docket No. 96N-0119) Fed Regist. 1997; 62:51021-30.
g. McNeil. Cyclobenzaprine hydrochloride (Flexeril) tablets prescribing information. Fort Washington, PA: 2003 Feb.
h. van Tulder MW, Touray T, Furlan AD et al. Muscle relaxants for non-specific low back pain. The Cochrane Library. From their web site (). Accessed 11/10/2003.
i. van Tulder MW, Scholten RJPM, Kowes BW, et al. Non-steroidal anti-inflammatory drugs for low back pain. The Cochrane Library. From their web site (). Accessed 11/10/2003.
j. Department of Veterans Affairs Veterans Health Administration Office of Quality & Performance. Management of Person with Low Back Pain/Sciatica in Primary Care. From the web site (). Accessed 8/25/2003.
k. Agency for Healthcare Research and Quality. Adult low back pain. From the National Guideline Clearinghouse website. (). Accessed 8/25/2003.
l. U.S. Department of Health and Human Services. Public Health Service. Agency for Halath Care Policy and Research. Acute low back problems in adults. Clinical Practice Guideline.1994; No. 14
m. U.S. Department of Health and Human Services. Public Health Service. Agency for Health Care Policy and Research. Acute low back problems in adults: Assessment and treatment. Clinical Practice Guideline. Quick Reference Guide for Clinicians.1994; No. 14
More Robaxin resources
- Robaxin Side Effects (in more detail)
- Robaxin Use in Pregnancy & Breastfeeding
- Drug Images
- Robaxin Drug Interactions
- Robaxin Support Group
- 15 Reviews for Robaxin - Add your own review/rating
- Robaxin Prescribing Information (FDA)
- Robaxin Consumer Overview
- Robaxin Advanced Consumer (Micromedex) - Includes Dosage Information
- Robaxin MedFacts Consumer Leaflet (Wolters Kluwer)
- Methocarbamol Prescribing Information (FDA)
- Methocarbamol Professional Patient Advice (Wolters Kluwer)
Compare Robaxin with other medications
- Muscle Spasm
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