methocarbamol

Absorption: Rapidly absorbed from the GI tract.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Metabolized by the liver.

Half-Life: 1–2 hr.

Time/Action Profile ⬆ ⬇

( skeletal muscle relaxation)

ROUTE	ONSET	PEAK	DURATION
PO	30 min	2 hr	unknown
IM	rapid	unknown	unknown
IV	immediate	end of infusion	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Hypersensitivity to polyethylene glycol (parenteral form);
Renal impairment (parenteral form).

Use Cautiously in:

Seizure disorders (parenteral form);
OB: Safety not established in pregnancy;
Lactation: Safety not established in breastfeeding;
Pedi: Safety and effectiveness not established in children;
Geri: Appears on Beers list. ↑ risk of anticholinergic adverse reactions, sedation, and fractures in older adults. Avoid use in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

CV: IVbradycardia, hypotension

Derm: flushing (IV), pruritus, rash, urticaria

EENT: blurred vision, nasal congestion

GI: anorexia, GI upset, nausea

GU: brown, black, or green urine.

Local: pain at IM site, phlebitis(IV)

Neuro: dizziness, drowsiness, light-headedness, SEIZURES (IV, IM)

Misc: fever, HYPERSENSITIVITY REACTIONS (IM, IV)(INCLUDING ANAPHYLAXIS)

Interactions ⬆ ⬇

Drug-drug:

Additive CNS depression with other CNS depressants, including alcohol, antihistamines, opioid analgesics, and sedative/hypnotics.

Drug-Natural Products:

Kava-kava, valerian, chamomile, or hops can ↑ risk of CNS depression.

Route/Dosage ⬆ ⬇

PO (Adults ): 1.5 g 4 times daily initially (up to 8 g/day) for 2–3 days, then 4–4.5 g/day in 3–6 divided doses; may be followed by maintenance dosing of 750 mg every 4 hr or 1 g 4 times daily or 1.5 g 3 times daily.
IM IV (Adults ): 1–3 g/day for not more than 3 days; course may be repeated after a 48-hr rest.

Availability ⬆ ⬇

(Generic available)

Tablets: 500 mg; 750 mg; 1000 mg
Solution for injection: 100 mg/mL

Assessment ⬆ ⬇

Assess pain, muscle stiffness, and range of motion before and periodically throughout therapy.
Monitor HR and BP every 15 min during parenteral administration.
Assess for hypersensitivity reactions (skin rash, asthma, hives, wheezing, hypotension) after parenteral administration. Implement emergent medical support (epinephrine, oxygen) if needed.
Monitor IV site. Injection is hypertonic and may cause thrombophlebitis. Avoid extravasation.
Monitor for seizure activity. Implement seizure precautions if needed.
Geri: Assess older adults for anticholinergic effects (sedation and weakness).

Lab Test Considerations:

Monitor renal function periodically during prolonged parenteral therapy (>3 days), because polyethylene glycol 300 vehicle is nephrotoxic.
- May falsely ↑ urinary 5-hydroxyindoleacetic acid and vanillylmandelic acid levels.

Implementation ⬆ ⬇

Provide safety measures as indicated. Supervise ambulation and transfer of patients.
PO: Administer with food to minimize GI irritation. Tablets may be crushed and mixed with food or liquids to facilitate swallowing. NG tube: Crush tablet and suspend in water or saline.
IM: Do not administer SUBQ. IM injections should contain no more than 5 mL (500 mg) at a time in the gluteal region.

IV Administration:

IV Push: Diluent: Administer undiluted.
Rate: Administer at a max rate of 180 mg/m²/min but not >3 mL (300 mg)/min.
Intermittent Infusion: Diluent: Dilute each dose in no more than 250 mL of 0.9% NaCl or D5W for injection.Concentration: 4 mg/mL for slower infusions. Do not refrigerate after dilution.
- Have patient remain recumbent during and for >10–15 min after infusion to avoid orthostatic hypotension.
Y-Site Incompatibility: Do not administer other drugs through same IV line.

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy. Advise to take as directed. Take missed doses within 1 hr; if not, return to regular dosing schedule. Do not double doses.
Advise patient to notify health care provider of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care provider before taking other medications.
Encourage patient to comply with additional therapies prescribed for muscle spasm (rest, physical therapy, heat).
May cause dizziness, drowsiness, and blurred vision. Advise patient to avoid driving and other activities requiring alertness until response to drug is known.
Instruct patient to change positions slowly to minimize orthostatic hypotension.
Advise patient to avoid concurrent use of alcohol and other CNS depressants.
Advise patient to contact health care provider immediately for new-onset seizures, premonitory symptoms, or change in seizure frequency.
Inform patient that urine may turn black, brown, or green, especially if left standing.
Instruct patient to notify health care provider immediately if skin rash, itching, fever, nasal congestion, or other signs of hypersensitivity reactions occur. Advise to seek immediate medical attention if needed.
Rep: Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or if breastfeeding.

section name header

Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇