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

Tizanidine Dosage and Treatment Protocol for Muscle Spasms

The recommended dosage for tizanidine (Zanaflex) for muscle spasms is to start with 2-4 mg orally at night, gradually increasing by 2-4 mg daily as needed, up to 8 mg every 8 hours, with a maximum daily dose of 36 mg. 1, 2

Initial Dosing and Titration

• Starting dose: 4 mg orally as a single dose 1

  • Begin with lower doses (2 mg) in elderly patients or those with hepatic/renal impairment
  • Take initial doses at bedtime to minimize daytime sedation

• Titration schedule:

  • Increase gradually in 2-4 mg increments 1
  • Allow 1-4 days between dose increases to assess response and tolerance
  • Titrate over 2-4 weeks to find optimal dose for each patient 3

• Dosing frequency:

  • Can be repeated at 6-8 hour intervals as needed 1
  • Maximum of three doses in 24 hours
  • Total daily dose should not exceed 36 mg 1

Administration Considerations

• Timing with food: Food has complex effects on tizanidine pharmacokinetics 1

  • Maintain consistency in taking with or without food
  • Taking with food may reduce peak plasma concentrations

• Peak effect: Occurs approximately 1-2 hours after administration 1, 3

• Duration of action: Effects typically dissipate between 3-6 hours 1

Clinical Efficacy

• Tizanidine reduces muscle tone for several hours after a single dose 1
• Studies show 21-37% reduction in mean muscle tone scores versus 4-9% with placebo 3
• Improvement in muscle tone occurs in 60-82% of patients 3
• Effective for both cerebral and spinal spasticity 3
• Shows efficacy similar to baclofen but with a more favorable side effect profile 3

Monitoring and Adjustments

• Assess response 1-2 hours after dosing (at peak effect)
• Monitor for:
  • Effectiveness in reducing muscle spasm
  • Sedation and hypotension
  • Hepatic function (periodic liver function tests recommended)

Precautions and Contraindications

• Contraindicated with:

  • Concomitant use of CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) 2
  • When prescribed with methadone (increased risk of prolonged QTc) 2

• Use with caution in:

  • Hepatic or renal impairment (dose reduction required) 2
  • Elderly patients (increased risk of sedation and hypotension) 2
  • Pregnancy (class C) 2

Common Adverse Effects

• Sedation/drowsiness (most common) 3
• Dry mouth 3
• Dizziness 2
• Hypotension 2
• Asthenia 2
• Hepatotoxicity (monitor liver function) 2

Important Clinical Considerations

• Do not discontinue abruptly after long-term use due to risk of rebound hypertension, tachycardia, and hypertonia 2
• If discontinuation is necessary, taper slowly to prevent withdrawal symptoms 2
• Unlike baclofen and diazepam, tizanidine appears to cause less subjective muscle weakness 3
• Consider taking the medication primarily at bedtime if daytime sedation is problematic 4

Special Populations

• Pediatric patients: Limited data available; dosage of 0.1-0.2 mg/kg/day divided into 2-3 doses has been used for spasticity in children 4
• Elderly: Start with lower doses and titrate more slowly due to increased risk of adverse effects

Tizanidine is an effective muscle relaxant with alpha-2 adrenergic agonist properties that provides significant relief for muscle spasms while generally causing fewer instances of muscle weakness compared to other muscle relaxants 3.