Tizanidine


Concise Prescribing Info
Indications/Uses
Spasticity in patient with multiple sclerosis or spinal cord injury or disease.
Dosage/Direction for Use
Adult : PO Initial: 2 mg as a single dose, increase according to patient’s requirement and response in increments of 2-4 mg daily at 3-4 days interval. Dose should be taken in 3-4 divided doses. Usual dose: 24 mg/day. Max: 36 mg/day.
Dosage Details
Oral
Spasticity
Adult: In patient with multiple sclerosis or spinal cord injury or disease: Initially, 2 mg as a single dose, increase according to patient’s requirement and response in increments of 2-4 mg daily at 3-4 days interval. Dose should be taken in 3-4 divided doses. Usual dose: 24 mg daily. Max: 36 mg daily.
Renal Impairment
CrCl (mL/min) Dosage
<25 Initially, 2 mg once daily, increase in increments of no more than 2 mg, according to patient’s tolerability and response.
Hepatic Impairment
Contraindicated.
Contraindications
Concomitant use with potent CYP1A2 inhibitors (e.g. fluvoxamine, ciprofloxacin). Hepatic impairment.
Special Precautions
Patient with psychiatric disorder, CV disorder, coronary artery disease. Renal impairment. Elderly. Pregnancy and lactation. Avoid abrupt dose reduction and withdrawal.
Adverse Reactions
Significant: Hepatotoxicity, hypersensitivity reactions, hypotension, sedation, hallucinations.
Gastrointestinal disorders: Xerostomia.
General disorders and administration site conditions: Weakness, fatigue, withdrawal hypertension.
Infections and infestations: Infection.
Investigations: Increased liver enzymes.
Nervous system disorders: Dizziness, drowsiness.
Cardiac disorders: Bradycardia, tachycardia.
Patient Counseling Information
This drug may cause drowsiness, dizziness, and hypotension, if affected, do not drive or operate machinery.
MonitoringParameters
Monitor LFT at baseline and monthly for the first 4 months of therapy; blood pressure, renal function, and ECG periodically.
Overdosage
Symptoms: Nausea, vomiting, hypotension, bradycardia, QT prolongation, dizziness, miosis, respiratory distress, coma, restlessness, somnolence. Management: Symptomatic and supportive treatment. Employ gastric lavage or administer high doses of activated charcoal. Maintain adequate hydration.
Drug Interactions
Enhanced CNS effects with sedatives and other CNS depressants (e.g. benzodiazepines, opioids, TCA). Increased hypotensive effects, rebound hypertension and tachycardia with β-adrenoceptor blockers, digoxin. Increased plasma concentration with oral contraceptives.
Potentially Fatal: Increased serum concentration with potent CYP1A2 inhibitors (e.g. fluvoxamine, ciprofloxacin).
Food Interaction
Enhanced CNS effects with alcohol.
Action
Description: Tizanidine is an α2-adrenergic agonist that acts on the spinal and supraspinal levels to block excitatory interneurons. It reduces spasticity by increasing presynaptic inhibition and has great effects in the polysynaptic pathways. It also possesses a moderate central analgesic effect.
Onset: 1-2 hours.
Duration: 3-6 hours.
Pharmacokinetics:
Absorption: Well absorbed from the gastrointestinal tract. Food alters absorption and bioequivalence. Bioavailability: Approx 40% (oral). Time to peak plasma concentration: Approx 1 hour.
Distribution: Volume of distribution: 2.4 L/kg. Plasma protein binding: Approx 30%.
Metabolism: Undergoes extensive first-pass hepatic metabolism by CYP1A2 to inactive metabolites.
Excretion: Mainly via urine (60%); faeces (20%). Elimination half-life: Approx 2.5 hours.
Chemical Structure

Chemical Structure Image
Tizanidine

Source: National Center for Biotechnology Information. PubChem Database. Tizanidine, CID=5487, https://pubchem.ncbi.nlm.nih.gov/compound/Tizanidine (accessed on Jan. 23, 2020)

Storage
Store at 25°C.
MIMS Class
ATC Classification
M03BX02 - tizanidine ; Belongs to the class of other centrally-acting muscle relaxants.
References
Anon. Tizanidine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 20/11/2017.

Buckingham R (ed). Tizanidine Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/11/2017.

Joint Formulary Committee. Tizanidine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 20/11/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Tizanidine Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 18/01/2018.

Tizanidine Hydrochloride (Par Pharmaceutical, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 20/11/2017.

Disclaimer: This information is independently developed by MIMS based on Tizanidine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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