No

Alpha₂ Agonist

Skeletal muscle relaxant used for treatment of muscle spasticity; although not approved for these indications it has been shown to be effective for tension headaches, low back pain and trigeminal neuralgia in a limited number of trials

C

Previous hypersensitivity to tizanidine

Reduce dose in patients with liver or renal disease; use with caution in patients with hypotension or cardiac disease. Tizanidine clearance is reduced by more than 50% in elderly patients with renal insufficiency (Cl_cr <25 mL/minute) compared to healthy elderly subjects; this may lead to a longer duration of effects and, therefore, should be used with caution in renally impaired patients.

>10%:

Cardiovascular: Hypotension

Central nervous system: Sedation, daytime drowsiness, somnolence

Gastrointestinal: Xerostomia

1% to 10%:

Cardiovascular: Bradycardia, syncope

Central nervous system: Fatigue, dizziness, anxiety, nervousness, insomnia

Dermatologic: Pruritus, skin rash

Gastrointestinal: Nausea, vomiting, dyspepsia, constipation, diarrhea

Hepatic: Elevation of liver enzymes

Neuromuscular & skeletal: Muscle weakness, tremor

<1%: Palpitations, ventricular extrasystoles, psychotic-like symptoms, visual hallucinations, delusions, hepatic failure

Symptoms of overdose include dry mouth, bradycardia, hypotension

Treatment: Lavage (within 2 hours of ingestion) with activated charcoal; benzodiazepines for seizure control; atropine can be given for treatment of bradycardia; flumazenil has been used to reverse coma successfully; forced diuresis is not helpful; multiple dosing of activated charcoal may be helpful. Following attempts to enhance drug elimination, hypotension should be treated with I.V. fluids and/or Trendelenburg positioning.

Increased effect: Oral contraceptives

Increased toxicity: Additive hypotensive effects may be seen with diuretics, other alpha adrenergic agonists, or antihypertensives; CNS depression with alcohol, baclofen or other CNS depressants

An alpha₂-adrenergic agonist agent which decreases excitatory input to alpha motor neurons; an imidazole derivative chemically-related to clonidine, which acts as a centrally acting muscle relaxant with alpha₂-adrenergic agonist properties; acts on the level of the spinal cord

Duration: 3-6 hours

Bioavailability: 40%

Half-life: 2.5 hours

Time to peak serum concentration: 1-5 hours

Adults: 2-4 mg 3 times/day

Usual initial dose: 4 mg, may increase by 2-4 mg as needed for satisfactory reduction of muscle tone every 6-8 hours to a maximum of three doses in any 24 hour period

Maximum dose: 36 mg/day

Dosing adjustment in renal/hepatic impairment: May require dose reductions or less frequent dosing

Monitor liver function (aminotransferases) at baseline, 1, 3, 6 months and then periodically thereafter; monitor ophthalmic function

Drowsiness is common; may cause dizziness, anxiety, nervousness, or insomnia; may rarely cause psychosis

Concurrent use with psychotropics may produce additive sedation and dry mouth

No information available to require special precautions

>10% of patients medicated with tizanidine will experience significant dry mouth; this will disappear with cessation of drug therapy

Take exactly as directed; do not miss doses. Do not use alcohol and prescription or OTC medications that may cause sedation (eg, antidepressants, anxiolytics, sleep medications, etc) without consulting prescriber. Change position slowly when rising from sitting or lying. May cause transient drowsiness, dizziness; avoid driving or engaging in tasks that require alertness until response to drug is known. Small frequent meals may help reduce any nausea or vomiting; frequent mouth care or sucking on lozenges may help reduce dry mouth. Report unusual weight gain or swelling of ankles and hands, yellowing of skin or eyes, fever, unusual bruising, extreme fatigue, rash, palpitations or chest pain. Consult prescriber if breast-feeding.

Tablet: 4 mg