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Methocarbamol Tablets 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.
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.
Off-Label Use and Dosage (Adult)
Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Methocarbamol (tablet) in adult patients.
Non–Guideline-Supported Use
There is limited information regarding Off-Label Non–Guideline-Supported Use of Methocarbamol (tablet) in adult patients.
Pediatric Indications and Dosage
FDA-Labeled Indications and Dosage (Pediatric)
There is limited information regarding FDA-Labeled Use of Methocarbamol (tablet) in pediatric patients.
Off-Label Use and Dosage (Pediatric)
Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Methocarbamol (tablet) in pediatric patients.
Non–Guideline-Supported Use
There is limited information regarding Off-Label Non–Guideline-Supported Use of Methocarbamol (tablet) in pediatric patients.
Contraindications
Methocarbamol Tablets are contraindicated in patients hypersensitive to methocarbamol or to any of the tablet components.
Warnings
Precautions
Since methocarbamol may possess a general CNS depressant effect, patients receiving Methocarbamol Tablets should be cautioned about combined effects with alcohol and other CNS depressants.
Safe use of Methocarbamol Tablets 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, Methocarbamol Tablets 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.
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.
Adverse Reactions
Clinical Trials Experience
Adverse reactions reported coincident with the administration of methocarbamol include:
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. Methocarbamol Tablets should be given to a pregnant woman only if clearly needed.
Safe use of Methocarbamol Tablets has not been established with regard to possible adverse effects upon fetal development. There have been reports of fetal and congential abnormalities following in utero exposure to methocarbamol. Therefore, Methocarbamol Tablets 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
Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Methocarbamol (tablet) in women who are pregnant.
Labor and Delivery
There is no FDA guidance on use of Methocarbamol (tablet) during labor and delivery.
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 Methocarbamol Tablets are administered to a nursing woman.
Pediatric Use
Safety and effectiveness of Methocarbamol Tablets in pediatric patients below the age of 16 have not been established.
Geriatic Use
There is no FDA guidance on the use of Methocarbamol (tablet) with respect to geriatric patients.
Gender
There is no FDA guidance on the use of Methocarbamol (tablet) with respect to specific gender populations.
Race
There is no FDA guidance on the use of Methocarbamol (tablet) with respect to specific racial populations.
Renal Impairment
There is no FDA guidance on the use of Methocarbamol (tablet) in patients with renal impairment.
Hepatic Impairment
There is no FDA guidance on the use of Methocarbamol (tablet) in patients with hepatic impairment.
Females of Reproductive Potential and Males
There is no FDA guidance on the use of Methocarbamol (tablet) in women of reproductive potentials and males.
Immunocompromised Patients
There is no FDA guidance one the use of Methocarbamol (tablet) in patients who are immunocompromised.
Administration and Monitoring
Administration
Oral
Monitoring
There is limited information regarding Monitoring of Methocarbamol (tablet) in the drug label.
IV Compatibility
There is limited information regarding IV Compatibility of Methocarbamol (tablet) in the drug label.
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.
Management
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.
Chronic Overdose
There is limited information regarding Chronic Overdose of Methocarbamol (tablet) in the drug label.
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.
Structure
Methocarbamol Tablets, USP, a carbamate derivative of guaifenesin, are a central nervous system (CNS) depressant with sedative and musculoskeletal relaxant properties. The structural formula is:
The chemical name for Methocarbamol is 3-(2-Methoxyphenoxy)-1,2-propanediol 1-carbamate and has the empirical formula C11H15NO5. Its molecular weight is 241.24.
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.
Each tablet, for oral administration, contains 500 mg or 750 mg of methocarbamol, USP. In addition each tablet contains the following inactive ingredients: Colloidal Silicon Dioxide, Lactose Monohydrate, Magnesium Stearate, Methylcellulose, Microcrystalline Cellulose, Pregelatinized Starch and Sodium Starch Glycolate.
Pharmacodynamics
There is limited information regarding Pharmacodynamics of Methocarbamol (tablet) in the drug label.
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.
Nonclinical Toxicology
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.
Clinical Studies
There is limited information regarding Clinical Studies of Methocarbamol (tablet) in the drug label.
How Supplied
Methocarbamol Tablets 500 mg: White, Round Tablets; Debossed “West-ward 290” on one side and Scored on the other side.
Bottles of 100 tablets
Bottles of 500 tablets
Bottles of 1000 tablets
Unit Dose Box of 100 tablets
Methocarbamol Tablets 750 mg: White, Capsule Shaped Tablets; Debossed “WEST-WARD 292” on one side and Scored on the other side.
Bottles of 100 tablets
Bottles of 500 tablets
Bottles of 1000 tablets
Unit Dose Box of 100 tablets
Store at 20-25oC (68-77oF). Protect from light and moisture.
Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.
Storage
There is limited information regarding Methocarbamol (tablet) Storage in the drug label.
Images
Drug Images
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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.
Precautions with Alcohol
Alcohol-Methocarbamol (tablet) interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.
The contents of this FDA label are provided by the National Library of Medicine.
↑Sica DA, Comstock TJ, Davis J, Manning L, Powell R, Melikian A, Wright G. (1990). "Pharmacokinetics and protein binding of methocarbamol in renal insufficiency and normals". European Journal of Clinical Pharmacology. 39 (2): 193–4. doi:10.1007/BF00280060. PMID2253675.CS1 maint: Multiple names: authors list (link)
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