Tizanidine (Zanaflex) Dosing for Muscle Relaxation
The recommended starting dose of tizanidine for muscle relaxation is 2 mg up to three times daily, with gradual titration to achieve optimal effect while monitoring for side effects. 1
Initial Dosing and Titration
- Start with 4 mg as a single dose, as effects are dose-related and common adverse events make it prudent to begin with lower doses 2
- Gradually increase the dose in 2-4 mg steps to achieve optimal effect (satisfactory reduction of muscle tone at a tolerated dose) 2
- The dose can be repeated at 6-8 hour intervals, as needed, up to three times daily 2
- Maximum single dose: 8 mg reduces muscle tone for several hours, with peak effect at 1-2 hours and dissipation between 3-6 hours 2
- Maximum daily dose: Should not exceed 36 mg total per day, though daily doses exceeding 24 mg have limited clinical experience 2
Special Population Considerations
- Older adults: Starting dose of 2 mg up to three times daily is recommended, with older persons rarely tolerating doses greater than 30-40 mg per day 3, 1
- Patients with hepatic or renal dysfunction: Use with caution due to reduced clearance 4, 1
Monitoring and Side Effects
- Monitor for muscle weakness, urinary function issues, cognitive effects, sedation, and orthostatic hypotension 3, 1
- Most common adverse effects include dry mouth and somnolence/drowsiness 5
- Be aware of potential hypotensive effects, especially when combining with other medications that lower blood pressure, such as opioids 4
- Potential for many drug-drug interactions, particularly with CYP1A2 inhibitors 3, 1
Important Clinical Considerations
- Food has complex effects on tizanidine pharmacokinetics which may result in clinically significant differences when switching administration between fed and fasted states 2
- Avoid abrupt discontinuation in long-term users; the dose should be tapered slowly to prevent withdrawal symptoms and rebound effects such as tachycardia, hypertension, and hypertonia 4, 1
- Wide interpatient variability in effective plasma concentrations means that optimal dosage must be individualized through careful titration over 2-4 weeks 5
- Tizanidine is specifically for treating spasticity (increased muscle tone), not hypotonia (reduced muscle tone) 6
Efficacy
- Tizanidine has been shown to reduce mean muscle tone scores by 21-37% versus 4-9% for patients receiving placebo 5
- Improvement in muscle tone occurs in 60-82% of tizanidine recipients, comparable to baclofen and diazepam 5
- Global tolerability is assessed as good to excellent in 44-100% of patients receiving tizanidine, compared with 38-90% of baclofen and 20-54% of diazepam recipients 5