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1. causing relaxation.
2. an agent that causes relaxation.
muscle relaxant an agent that specifically aids in reducing muscle tension.


PMS-Methocarbamol (CA), Robaxin

Pharmacologic class: Autonomic nervous system agent

Therapeutic class: Skeletal muscle relaxant (centrally acting)

Pregnancy risk category C


Unknown. Thought to depress central perception of pain without directly relaxing skeletal muscles or directly affecting motor endplate or motor nerves.


Injection: 100 mg/ml in 10-ml ampules, 100 mg/ml in 10-ml vials

Tablets: 500 mg, 750 mg

Indications and dosages

Adjunct in muscle spasms caused by acute, painful musculoskeletal conditions

Adults: Initially, 1.5 g P.O. q.i.d. (up to 8 g/day) for 2 to 3 days, then 4 to 4.5 g/day P.O. in three to six divided doses; or 750 mg P.O. q 4 hours or 1 g P.O. q.i.d. or 1.5 g P.O. t.i.d. If oral dosing isn't feasible or if condition is severe, give 1 to 3 g/day I.M. or I.V. for maximum of 3 days.

Off-label uses

• Tetanus


• Hypersensitivity to drug, its components, or polyethylene glycol (with parenteral form)

• Renal impairment (with parenteral form)


Use cautiously in:

• seizure disorders (with parenteral use)

• pregnant or breastfeeding patients

• children (safety not established).


• For direct I.V. injection, administer slowly. Keep patient supine for 10 to 15 minutes afterward.

• For I.V. infusion, dilute 1 g with up to 250 ml 5% dextrose or 0.9% sodium chloride injection.

• Avoid extravasation; drug is hypertonic.

• Don't give subcutaneously.

• For I.M. use, inject no more than 500 mg (5 ml of 10% injection) into each gluteal area.

• Don't use parenteral form in patients with renal impairment. Polyethylene glycol vehicle may irritate kidneys.

• When giving for tetanus, crush and suspend tablets in water or saline solution, and give via nasogastric tube, if necessary.

• Be aware that drug is usually given as part of regimen that includes rest and physical therapy.

Adverse reactions

CNS: dizziness, light-headedness, drowsiness, syncope, seizures (with I.V. use)

CV: bradycardia or hypotension (with I.V. use)

EENT: blurred vision, conjunctivitis, nasal congestion

GI: nausea, GI upset, anorexia

GU: brown, black, or green urine

Musculoskeletal: mild muscle incoordination (with I.V. or I.M. use)

Skin: flushing (with I.V. use), pruritus, rash, urticaria

Other: fever, pain at I.M. injection site, phlebitis at I.V. site, allergic reactions including anaphylaxis (with I.M. or I.V. use)


Drug-drug. Antihistamines, CNS depressants (such as opioids, sedative-hypnotics): additive CNS depression

Drug-diagnostic tests. Urinary 5-hydroxyindoleacetic acid, urine vanillylmandelic acid: false elevations

Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Drug-behaviors. Alcohol use: increased CNS depression

Patient monitoring

• Assess for orthostatic hypotension, especially with parenteral use. Keep patient supine for 10 to 15 minutes after I.V. administration.

Watch for anaphylaxis after I.M. or I.V. administration.

Stay alert for bradycardia and syncope after I.V. or I.M. dose. As needed and prescribed, give epinephrine, corticosteroids, or antihistamines.

• Monitor I.V. site frequently to prevent sloughing and thrombophlebitis.

Patient teaching

• Tell patient that drug may turn urine brown, black, or green.

• Caution patient to avoid driving and other hazardous activities, because drug may cause drowsiness or dizziness.

• Instruct patient to move slowly when changing position, to avoid dizziness from sudden blood pressure decrease.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.


/meth·o·car·ba·mol/ (meth″o-kahr´bah-mol) a skeletal muscle relaxant used in the treatment of painful musculoskeletal conditions.


A drug that is a central nervous system depressant and is used for the relief of discomfort associated with painful musculoskeletal conditions.


a skeletal muscle relaxant.
indication It is prescribed in the relief of skeletal muscle spasm.
contraindications Renal dysfunction, central nervous system depression, or known hypersensitivity to this drug prohibits its use. Propylthiouracil is a better choice than methimazole for thyrotoxic crisis.
adverse effects Among the more serious adverse effects are hypotension and tachycardia. Drowsiness, dizziness, vertigo, and nausea may occur.


A centrally-acting muscle relaxant drug used to treat conditions of severe muscle spasm. A brand name is Robaxin.


a compound used as a skeletal muscle relaxant, particularly in dogs with intervertebral disk disease.
References in periodicals archive ?
The company has received final approval from the US Food and Drug Administration for its Abbreviated New Drug Application for Methocarbamol Injection, which is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions.
It shall terminate independently, automatically upon the entry into force of the exclusive contract for methocarbamol, ATC M03BA03, with one or more contracting parties pursuant to the regulations of Part Four of the GWB.
The company has received the US Food and Drug Administration's (FDA) final approval to market the Abbreviated New Drug Application (ANDA) for Methocarbamol Injection as adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions.
Additionally, health-care professionals should first evaluate patients who have used Reumofan Plus for drug and disease interactions involving methocarbamol, diclofenac, and corticosteroids, and then make a judgment as to whether a corticosteroid taper regimen may be appropriate in those who have used Reumofan Plus.
Worcester, charged with drug violation near a school or park, sentenced to 120 days in the House of Correction, $90 victim witness fee; possession of methocarbamol and cyclobenzaprine
baclofen, cyclobenzaprine, dantrolene, methocarbamol, tizanidine), and similar to the duration of CNS medication, the use encompassed the entire FY.
Guaifenesin and methocarbamol can be differentiated with p-dimethylaminobenzaldehyde, because methocarbamol is a carbamate and guaifenesin is not.
com/news/stories/op/storiesView/sid/52022/) laboratory analysis of Reumofan Plus found that it contains methocarbamol which is a prescription muscle relaxant that can cause sedation, dizziness, low blood pressure, and impair mental or physical abilities to perform tasks such as driving a motor vehicle or operating machinery.
Worcester, charged with possession of methocarbamol and cyclobenzaprine, possession of cocaine with intent to distribute, and drug violation near a school or park, continued to Aug.