General Information

  • 1. Coward DM, Tizanidine: Neuropharmacology and Mechanism of Action, NEUROLOGY 1994;44 (suppl 9):S6-S11
  • 2. We Move, Worldwide Education and Awareness for Movement Disorders, Spasticity page. Available at: www.wemove.org/spa/. Last accessed 05/12/08.
  • 3. Nance PW, Bugaresti J, Shellenberger K, Sheremata W, Martinez-Arizala A, and the North American Tizanidine Study Group. Efficacy and safety of tizanidine in the treatment of spasticity in patients with spinal cord injury, NEUROLOGY 1994;44(suppl 9):S44-S52
  • 4. FDA, Approved Drug Products with Therapeutic Equivalence Evaluations, 28th Edition, 2008, Section 3.0, Prescription Drug Product List;p348. Available at http://www.fda.gov/cder/orange/obannual.pdf.
  • 5. Shah J et al, Effects of Food on the Single Dose Pharmacokinetics/Pharmacodynamics of Tizanidine Capsules and Tablets in Healthy Volunteers. Clin Ther 2006;28:1308-1317
  • 6. Zanaflex® (tizanidine hydrochloride) Prescribing Information. Hawthorne, NY. Acorda Therapeutics, Inc; Rev. 4/08

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Zanaflex Capsules® (tizanidine hydrochloride) is a short-acting drug indicated for the management of spasticity. Because of the short duration of effect, treatment with Zanaflex Capsules® (tizanidine hydrochloride) should be reserved for those daily activities and times when relief of spasticity is most important.

Important Safety Information:

  • Use with fluvoxamine or ciprofloxacin is contraindicated and results in significant increases in tizanidine plasma levels.
  • There is a limited data base for chronic use of single doses above 8 mg and multiple doses above 24 mg per day.
  • Tizanidine is an alpha2-adrenergic agonist and can produce hypotension. In a single-dose study where patients were not titrated, two-thirds of patients given 8 mg of Zanaflex experienced hypotension, which may be minimized by titration of dose. The hypotensive effect is dose related and has been measured following single doses of 2 mg or more.
  • Tizanidine occasionally causes liver injury, most often of the hepatocellular type.
  • Patients should be advised that sedation may interfere with daily activities. These effects appear to be dose related.
  • Visual hallucinations or delusions occurred in 3% (5/170) of study patients in two North American clinical trials.
  • Use with caution in hepatic or renally impaired patients.
  • Use with oral contraceptives results in 50% decrease in tizanidine clearance.
  • To discontinue therapy, taper the dose in patients receiving high doses over long time periods to reduce the risk of hypertension, tachycardia and hypertonia.
  • In vitro studies indicate that neither tizanidine nor the major metabolites are likely to affect the metabolism of other drugs metabolized by cytochrome P450 isoenzymes.
  • Most common adverse events with tizanidine include dry mouth (49%), somnolence (48%), asthenia [weakness, fatigue and/or tiredness] (41%), dizziness (16%) and increased ALT (5%). Other adverse events include UTI, infection and constipation.
  • Food has complex effects on tizanidine pharmacokinetics, which differ for the different formulations. These pharmacokinetic differences may result in clinically significant differences when switching formulations, or changing administration during a fed or fasted state. These changes may result in increased adverse events or a delayed/more rapid onset of activity, depending on the nature of the switch.
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