Tizanidine Dosing for Leg Spasticity
Start tizanidine at 2-4 mg as a single dose, then titrate upward in 2-4 mg increments every 3-7 days to achieve optimal spasticity control, with doses repeated every 6-8 hours as needed (maximum 3 doses per 24 hours, not exceeding 36 mg/day total). 1
Initial Dosing Strategy
Begin with 4 mg as a single oral dose 1. While 8 mg is the dose proven effective in controlled trials, the dose-related adverse events (particularly sedation, dizziness, and hypotension) make starting at 4 mg more prudent 2, 1.
- Timing consideration: The effect peaks at 1-2 hours and dissipates between 3-6 hours 1
- Frequency: Doses can be repeated at 6-8 hour intervals as needed, up to 3 times daily 1
- Reserve dosing for times when spasticity relief is most functionally important 1
Titration Protocol
Increase by 2-4 mg increments to reach the optimum effect—defined as satisfactory reduction of muscle tone at a tolerated dose 1. The evidence shows:
- Linear dose-response relationship exists between single doses and antispastic action 3
- Strong within-patient correlation between plasma concentrations and effect, but weak between-patient correlation 3
- This means effective doses must be determined individually through careful titration
Maximum dosing limits 1:
- Single dose: 8 mg (limited experience beyond 12 mg)
- Daily total: 36 mg (limited experience beyond 24 mg)
- Three doses per 24-hour period maximum
Evidence for Efficacy in Leg Spasticity
Tizanidine has demonstrated efficacy specifically for chronic stroke patients with leg spasticity 4. In an open-label dose-titration study of stroke patients (minimum 6 months post-stroke), tizanidine significantly improved spasticity while preserving muscle strength—a critical advantage for leg function 5.
For multiple sclerosis patients with extensor spasticity of the legs, tizanidine showed statistically significant linear dose-response relationships at 2,4, and 8 mg doses 3.
Critical Safety Considerations
Avoid or use extreme caution in 2:
- Hepatic or renal dysfunction
- Elderly patients (increased sedative and hypotensive effects)
- Concurrent use with CYP1A2 inhibitors (oral contraceptives, ciprofloxacin, fluvoxamine, cimetidine, famotidine, verapamil, amiodarone)
Absolute contraindication: Concurrent ciprofloxacin or fluvoxamine (significantly reduces tizanidine clearance) 2
Most common adverse events 5:
- Somnolence (62%)
- Dizziness (32%)
- Dry mouth
- Hypotension and bradycardia
Withdrawal Risk
Never discontinue abruptly in patients on long-term therapy 2. Withdrawal can cause:
- Rebound tachycardia
- Hypertension
- Rebound hypertonia (increased spasticity)
Taper slowly over several days to weeks if discontinuation is necessary 2.
Food Effects and Formulation Switching
Food has complex effects on tizanidine pharmacokinetics that can result in clinically significant differences when switching between fed and fasted states 1. This may cause:
- Increased adverse events
- Delayed or more rapid onset of activity
Recommendation: Maintain consistent administration relative to meals (always with food or always without food) 1.
Practical Dosing Example
For a patient with chronic stroke and leg spasticity:
- Week 1: Start 4 mg once daily, timed before the activity most impaired by spasticity
- Week 2: If tolerated but insufficient effect, increase to 4 mg twice daily (8 mg total)
- Week 3-4: Titrate upward by 2-4 mg increments based on response and tolerability
- Maintenance: Most patients in clinical trials required 12-24 mg/day divided into 2-3 doses 5, 6
- Note: Only 21% of stroke patients reached the maximum 36 mg/day dose 5
Guideline Context
The 2005 Stroke Rehabilitation guideline specifically recommends considering tizanidine for chronic stroke patients with spasticity causing pain, poor skin hygiene, or decreased function 4. This is part of a stepwise approach beginning with positioning, range of motion exercises, and stretching before advancing to oral medications.