Tizanidine HCl

A to Z Drug Facts

 Actions Unknown; may increase presynaptic inhibition of motor neurons.

 Indications Acute and intermittent management of increased muscle tone associated with spasticity.

 Contraindications Standard considerations.

 Route/Dosage

ADULTS: PO Initiate therapy with a 4 mg dose, increasing the dose gradually in 2 to 4 mg increments to optimum effect. The dose can be repeated at 6- to 8-hr intervals as needed (max 3 doses in 24 hr not to exceed 36 mg/day).

 Interactions

Alcohol: Plasma levels of tizanidine may be elevated, increasing the side effects. Antihypertensive agents: Use with caution; do not administer with other alpha₂ -adrenergic agonists (eg, clonidine). Oral contraceptives: Clearance of tizanidine may be reduced; decrease the dosage requirement.

 Lab Test Interferences None well documented.

 Adverse Reactions

CNS: Somnolence; dizziness; dyskinesia; nervousness; depression; anxiety; paresthesia. CARDIOVASCULAR: Vasodilation; postural hypotension; syncope; arrhythmia; migraine. DERMATOLOGIC: Rash; sweating; skin ulcer. EENT: Pharyngitis; amblyopia; rhinitis; ear pain; tinnitus; deafness; glaucoma; conjunctivitis; eye pain; optic neuritis; otitis media; retinal hemorrhage; visual field defect. GI: Dry mouth; constipation; vomiting; abdominal pain; diarrhea; dyspepsia. GU: Urinary frequency; urinary tract infection; urinary urgency; cystitis; menorrhagia; pyelonephritis; urinary retention; kidney calculus; enlarged uterine fibroids; vaginal moniliasis; vaginitis. HEMATOLOGIC: Ecchymosis; hypercholesterolemia; anemia; hyperlipemia; leukopenia; leukocytosis; sepsis. HEPATIC: Increased ALT and liver function tests. RESPIRATORY: Sinusitis; pneumonia; bronchitis. OTHER: Asthenia; increased spasm or tone; flu-like syndrome; infection; speech disorder; myasthenia; back pain; fever; allergic reaction; malaise; abscess; neck pain; cellulitis.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Elderly: Use with caution because clearance may be decreased 4-fold. Hypotension: Hypotension may occur; patients are at increased risk for orthostatic effects. Hepatotoxicity: Hepatocellular liver injury may occur. Hepatic and renal impairment: Use with caution. Psychotic-like symptoms: Hallucinations or delusions may occur. Sedation: Sedation severe enough to interfere with every day activities may occur.

 Administration/Storage

• Administer prescribed dose at 6- to 8-hr intervals as needed for spasticity, to max of 3 doses in 24-hr period.
• Administer without regard to meals. Administer with food if GI upset occurs.
• Store at controlled room temperature (59° to 86°F).

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note history of liver disease, renal disease, and concurrent use of antihypertensive drugs.
• Ensure that LFTs are determined before starting therapy and periodically during treatment.
• Assess effect of medication on spasticity.
• Monitor BP when starting therapy or changing dose. Inform health care provider if hypotension occurs.
• Initiate safety precautions if orthostatic hypotension occurs.
• Monitor patient for CV, CNS, GI, and general body side effects.
• Inform health care provider if any of the following are noted: bradycardia, orthostatic hypotension; lightheadedness; dizziness; excessive sedation; fainting; jaundice; dark urine; right upper quadrant abdominal pain.

 Patient/Family Education

• Explain name, dose, action, and potential side effects of drug.
• Instruct patient to take prescribed dose at 6- to 8-hr intervals as needed for spasticity, to a max of 3 doses in 24-hr period.
• Advise patient that medication can be taken without regard to meals but to take with food if GI upset occurs.
• Advise patient that medication is started at a low dose and gradually increased as tolerated until maximum benefit is achieved.
• Instruct patient to avoid alcohol and other CNS depressant medications.
• Instruct patient to get up slowly from lying or sitting position and to avoid sudden position changes to prevent postural hypotension. Advise patient to report dizziness with position changes to health care provider. Caution patient that hot tubs and hot showers or baths may make dizziness worse.
• Instruct patient to lie or sit down if experiencing dizziness or lightheadedness when standing.
• Advise patient to take sips of water, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct women to notify health care provider if they become pregnant, plan on becoming pregnant, or are breastfeeding.
• Advise patient to notify health care provider of the following: excessive drowsiness, yellowing of skin or eyes, dark urine, right upper abdominal pain.
• Instruct patient not to take any prescription or otc medications or dietary supplements unless advised to do so by health care provider.
• Advise patient that follow-up visits and lab tests will be required to monitor therapy and to be sure and keep appointments.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts