Tizanidine

Tizanidine is an alpha2-adrenoceptor agonist which is indicated for spasticity management due to multiple sclerosis, spinal cord injury, stroke, amyotrophic lateral sclerosis, and traumatic brain injury. (1)

Dosage begins at 2 mg once per day. The dose is increased according to response by 2 mg per day every 3-4 days until a maximum dose of 24 mg per day in 4 divided doses is reached.

The main side-effects include:

• drowsiness
• dry mouth
• GI upset

Tizanidine use requires caution in patients with hepatic impairment. Review articles on tizanidine report cases of severe hepatotoxicity, acute liver failure, and death. Creatinine and liver function tests require measurement at baseline, then one month after the maintenance dose is achieved. Periodically monitor liver function tests in patients managed with tizanidine chronically and in higher doses. (2)

Concomitant use of tizanidine with fluvoxamine or ciprofloxacin is contraindicated due to significant hypotension and increased psychomotor impairment. (3)

The summary of product characteristics must be consulted before prescribing this drug.

Reference

1. Kamen L, Henney HR, Runyan JD. A practical overview of tizanidine use for spasticity secondary to multiple sclerosis, stroke, and spinal cord injury. Curr Med Res Opin. 2008 Feb;24(2):425-39
2. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases; Jan 30, 2017. Tizanidine
3. Granfors MT et al. Ciprofloxacin greatly increases concentrations and hypotensive effect of tizanidine by inhibiting its cytochrome P450 1A2-mediated presystemic metabolism. Clin Pharmacol Ther. 2004 Dec;76(6):598-606.