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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.