What is the recommended dosage and treatment protocol for Tizanidine (Zanaflex) for muscle spasms?

Tizanidine Dosage and Treatment Protocol for Muscle Spasms

For muscle spasms, tizanidine treatment should begin with 4 mg single oral doses, gradually increasing in 2-4 mg steps to an optimal dose, with a maximum of three doses per 24 hours not exceeding 36 mg total daily dose. 1

Initial Dosing and Titration

• Start with 4 mg single oral doses (although the FDA notes that single doses of less than 8 mg have not been demonstrated effective in controlled clinical studies, the dose-related adverse events make it prudent to begin with 4 mg) 1
• Gradually increase the dose in 2-4 mg steps to achieve optimal effect (satisfactory reduction of muscle tone at a tolerated dose) 1
• Doses can be repeated at 6-8 hour intervals, up to three times daily 1
• The optimal dosage must be individually titrated over 2-4 weeks due to wide interpatient variability in effective plasma concentrations 2
• Maximum effects occur within 1-2 hours of administration and dissipate between 3-6 hours 1

Maximum Dosing

• Maximum single dose: 8-12 mg (experience with single doses exceeding 8 mg is limited) 1
• Maximum daily dose: 36 mg (total daily dose should not exceed 36 mg, with limited experience for daily doses exceeding 24 mg) 1
• Optimal daily doses in clinical practice typically range from 8-36 mg 2

Special Considerations

• Food has complex effects on tizanidine pharmacokinetics, which may result in clinically significant differences when switching administration between fed and fasted states 1
• These pharmacokinetic changes may result in increased adverse events or delayed/more rapid onset of activity 1
• Tizanidine is preferred over diazepam or other benzodiazepines during stroke recovery due to possible deleterious effects of benzodiazepines on recovery 3
• Tizanidine has been shown to have efficacy in chronic stroke patients with improvement in spasticity and pain without loss of motor strength 3

Monitoring and Adverse Effects

• Monitor for common adverse effects including dry mouth and somnolence/drowsiness 2
• Watch for hypotension, particularly when tizanidine is used concomitantly with opioids like oxycodone due to additive hypotensive effects 4
• Patients with hepatic or renal dysfunction are at higher risk of adverse effects due to reduced clearance 4
• Avoid abrupt discontinuation in long-term users; taper slowly to prevent withdrawal and rebound tachycardia, hypertension, and hypertonia 4

Efficacy and Advantages

• Tizanidine reduces mean muscle tone scores by 21-37% compared to 4-9% with placebo 2
• Improvement in muscle tone occurs in 60-82% of tizanidine recipients 2
• Spasm frequency and clonus are also reduced by tizanidine 2
• Muscle strength appears not to be adversely affected by tizanidine, with subjective muscle weakness reported less often than with baclofen or diazepam 2
• Global tolerability is assessed as good to excellent in 44-100% of patients receiving tizanidine 2

Treatment Duration

• For acute paravertebral muscle spasm, a 7-day treatment course has shown efficacy 5
• For chronic spasticity (such as in multiple sclerosis or spinal cord injury), longer-term treatment may be necessary 6
• In back pain treatment, initial pain relief typically occurs by the 2nd day of treatment, with complete relief after approximately 4 days 7