Tizanidine Flashcards

Tizanidine Overview

• Brand name: Zanaflex
• Generic name: Tizanidine
• Indicated for short-term management of spasticity

Dosing Information

• Initial dose: 4 mg every 6-8 hours, maximum three doses per 24 hours
• Dosing increments: Increase by 2 mg to 4 mg as needed for therapeutic response
• Maximum daily dose: 36 mg
• Adjustments required for renal impairment: decrease frequency of dosing

Strengths and Dosage Forms

• Available as tablets: 2 mg and 4 mg
• Available as capsules: 2 mg, 4 mg, and 6 mg

Medication Classification

• Classified as a muscle relaxant

Pharmacology and Mechanism of Action

• Acts as an agonist at α2-adrenergic receptor sites
• Reduces spasticity by increasing presynaptic inhibition of motor neurons
• Minimal impact on skeletal muscle fibers or neuromuscular junction
• Primarily affects polysynaptic pathways

Drug Interactions

• Oral contraceptives may reduce clearance of tizanidine
• Potential for increased CNS adverse effects when combined with alcohol and other CNS depressants
• No reported risk X or D interactions

Side Effects and Adverse Reactions

• Common side effects: dry mouth, drowsiness, asthenia, bradycardia, hypotension, dizziness
• Other possible effects: constipation, abnormal liver function tests, blurred vision, rhinitis, nervousness, vomiting, speech disorder, pharyngitis

Contraindications

• Use with caution in those on antihypertensive treatment or other α2-adrenergic agonists due to risk of hypotension
• Occasional reports of liver injury
• Caution advised for patients with renal impairment
• Classified as Pregnancy Category C

Patient Counseling Points

• Can be taken with food/milk to mitigate GI upset
• Causes drowsiness; caution advised when operating machinery
• Store in a cool, dry place away from sunlight and children
• If a dose is missed, take as soon as possible unless close to the next dose; do not double doses
• Contact a physician for unusual muscle weakness, tenderness, pain, or blurred vision