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Pharmacologic class: Alpha-adrenergic agonist (centrally acting)
Therapeutic class: Skeletal muscle relaxant
Pregnancy risk category C
Stimulates alpha2-adrenergic agonist receptor sites and reduces spasticity by inhibiting presynaptic motor neurons
Tablets: 2 mg, 4 mg
Indications and dosages
➣ Increased muscle tone associated with spasticity
Adults: Initially, 4 mg P.O. q 6 to 8 hours (no more than three doses in 24 hours). Increase in increments of 2 to 4 mg, up to 8 mg/dose or 24 mg/day (not to exceed 36 mg/day), as needed.
• Hypersensitivity to drug or its components
Use cautiously in:
• renal or hepatic impairment
• elderly patients
• pregnant or breastfeeding patients
• children (safety not established).
• Give with or without food.
CNS: drowsiness, asthenia, dizziness, speech disorder, dyskinesia, nervousness, anxiety, depression, hallucinations, sedation, paresthesia
CV: hypotension, bradycardia
EENT: blurred vision, pharyngitis, rhinitis
GI: vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth
GU: urinary frequency, urinary tract infection
Musculoskeletal: back pain, myasthenia
Skin: rash, skin ulcers, sweating
Other: fever, infection, flulike symptoms
Drug-drug. Alpha2-adrenergic agonist antihypertensives: increased risk of hypotension
CNS depressants (such as antihistamines, opioids, sedative-hypnotics): additive CNS depression
Hormonal contraceptives: increased tizanidine blood level, greater risk of adverse reactions
Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, glucose: increased levels
Drug-food. Any food: increased drug bioavailability, shorter time to peak concentration (with no effect on absorption)
Drug-behaviors. Alcohol use: additive CNS depression
• Monitor temperature and vital signs. Watch for orthostatic hypotension, bradycardia, and fever or other signs and symptoms of infection.
• Assess liver function tests.
• Advise patient he may take with or without food.
• Tell patient to report signs or symptoms of infection or depression.
• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure decrease.
Tell patient to immediately report unusual tiredness or yellowing of skin or eyes.
• Caution patient not to drink alcohol.
• Instruct patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and behaviors mentioned above.
ClassificationTherapeutic: antispasticity agents
Time/action profile (reduced muscle tone)
|PO||unknown||1–2 hr||3–6 hr|
Adverse Reactions/Side Effects
Central nervous system
- anxiety (most frequent)
- depression (most frequent)
- dizziness (most frequent)
- sedation (most frequent)
- weakness (most frequent)
Ear, Eye, Nose, Throat
- blurred vision
- hypotension (most frequent)
- abdominal pain (most frequent)
- diarrhea (most frequent)
- dry mouth (most frequent)
- dyspepsia (most frequent)
- hepatocellular injury
- ↑ liver enzymes
- urinary frequency
- rash (most frequent)
- skin ulcers (most frequent)
- sweating (most frequent)
- back pain (most frequent)
- myasthenia (most frequent)
- paresthesia (most frequent)
- fever (most frequent)
- speech disorder
Drug-Drug interactionLevels and effects ↑ by concurrent use of hormonal contraceptives or alcohol.↑ risk of hypotension with alpha2-adrenergic agonist antihypertensives (avoid concurrent use).↑ CNS depression may occur with alcohol or other CNS depressants including some antidepressants, sedative/hypnotics, antihistamines, and opioid analgesics.Concurrent CYP1A2 inhibitors (ciprofloxacin, fluvoxamine and others) may ↑ levels and risk of hypotension and excessive sedation.
Route/DosageTablets are not interchangeable with capsules
Availability (generic available)
- Assess muscle spasticity before and periodically during therapy.
- Monitor BP and pulse, especially during dose titration. May cause orthostatic hypotension, bradycardia, dizziness, and, rarely, syncope. Effects are usually dose related.
- Observe patient for drowsiness, dizziness, and asthenia. A change in dose may alleviate these problems.
- Lab Test Considerations: Monitor liver function tests before and at 1, 3, and 6 mo of therapy. May cause ↑ in serum glucose, alkaline phosphatase, AST, and ALT levels.
Potential Nursing DiagnosesImpaired physical mobility (Indications)
Risk for injury (Adverse Reactions)
- Do not confuse tizanidine with tiagabine.
- Doses should be titrated carefully to prevent side effects.
- Oral: May be taken without regard to meals.
- Instruct patient to take tizanidine as directed. Tizanidine may need to be discontinued gradually.
- May cause dizziness and drowsiness. Advise patient to avoid driving or 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 or other CNS depressants while taking this medication.
- Decrease in muscle spasticity with an increased ability to perform activities of daily living.