Pronunciation:

(meth oh KAR ba mole)

U.S. Brand Names:

Generic Available:

Canadian Brand Names:

Use:

Use - Dental:

Pregnancy Risk Factor:

Pregnancy Implications:

Lactation:

Contraindications:

Warnings/Precautions:

Oral: Use caution with renal or hepatic impairment.

Injection: Rate of injection should not exceed 3 mL/minute; solution is hypertonic; avoid extravasation. Use with caution in patients with a history of seizures. Use caution with hepatic impairment.

Adverse Reactions:

Cardiovascular: Flushing of face, bradycardia, hypotension, syncope

Central nervous system: Drowsiness, dizziness, lightheadedness, convulsion, vertigo, headache, fever, amnesia, confusion, insomnia, sedation, coordination impaired (mild)

Dermatologic: Allergic dermatitis, urticaria, pruritus, rash, angioneurotic edema

Gastrointestinal: Nausea, vomiting, metallic taste, dyspepsia

Hematologic: Leukopenia

Hepatic: Jaundice

Local: Pain at injection site, thrombophlebitis

Ocular: Nystagmus, blurred vision, diplopia, conjunctivitis

Renal: Renal impairment

Respiratory: Nasal congestion

Miscellaneous: Allergic manifestations, anaphylactic reaction

Overdosage/Toxicology:

Drug Interactions:

Ethanol/Nutrition/Herb Interactions:

Ethanol: Avoid ethanol (may increase CNS depression).

Herb/Nutraceutical: Avoid valerian, St John's wort, kava kava, gotu kola (may increase CNS depression).

Stability:

Injection: Prior to dilution, store at controlled room temperature of 20°C to 25°C (68°F to 77°F). Injection when diluted to 4 mg/mL in sterile water, 5% dextrose, or 0.9% saline is stable for 6 days at room temperature; do not refrigerate after dilution

Tablet: Store at controlled room temperature of 20°C to 25°C (68°F to 77°F).

Mechanism of Action:

Pharmacodynamics/Kinetics:

Onset of action: Muscle relaxation: Oral: ~30 minutes

Protein binding: 46% to 50%

Metabolism: Hepatic via dealkylation and hydroxylation

Half-life elimination: 1-2 hours

Time to peak, serum: ~2 hours

Excretion: Urine (as metabolites)

Dosage:

Tetanus: I.V.:

Children: Recommended only for use in tetanus: 15 mg/kg/dose or 500 mg/m²/dose, may repeat every 6 hours if needed; maximum dose: 1.8 g/m²/day for 3 days only

Adults: Initial dose: 1-3 g; may repeat dose every 6 hours until oral dosing is possible; injection should not be used for more than 3 consecutive days

Muscle spasm: Children 16 years and Adults:

Oral: 1.5 g 4 times/day for 2-3 days (up to 8 g/day may be given in severe conditions), then decrease to 4-4.5 g/day in 3-6 divided doses

I.M., I.V.: 1 g every 8 hours if oral not possible; injection should not be used for more than 3 consecutive days. If condition persists, may repeat course of therapy after a drug-free interval of 48 hours.

Elderly: Muscle spasm: Oral: Initial: 500 mg 4 times/day; titrate to response

Dosing adjustment/comments in renal impairment: Do not administer parenteral formulation to patients with renal dysfunction.

Dosing adjustment in hepatic impairment: Specific dosing guidelines are not available; plasma protein binding and clearance are decreased; half-life is increased

Administration:

Injection:

I.M.: A maximum of 5 mL can be administered into each gluteal region.

I.V.: Maximum rate: 3 mL/minute; should not be used for more than 3 consecutive days; may be administered undiluted. Monitor closely for extravasation. Administer I.V. while in recumbent position. Maintain position 15-30 minutes following infusion.

Tablet: May be crushed and mixed with food or liquid if needed. Avoid alcohol.

Test Interactions:

Patient Education:

Dental Health: Effects on Dental Treatment:

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

Mental Health: Effects on Mental Status:

Mental Health: Effects on Psychiatric Treatment:

Dosage Forms:

Injection, solution: 100 mg/mL (10 mL) [in polyethylene glycol; vial stopper contains latex]

Tablet: 500 mg, 750 mg

International Brand Names: