Tizanidine

Tizanidine
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vignesh Ponnusamy, M.B.B.S. [2]

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Overview

Tizanidine is a central alpha-2-adrenergic agonist that is FDA approved for the {{{indicationType}}} of spasticity. Common adverse reactions include dry mouth, somnolence, asthenia, dizziness, urinary tract infection, constipation, liver function tests abnormal, vomiting, speech disorder, amblyopia, urinary frequency, flu syndrome, SGPT/ALT increased, dyskinesia, nervousness, pharyngitis, and rhinitis.

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

Spasticity

• Dosing Information

• Tizanidine hydrochloride capsules may be prescribed with or without food. Once the formulation has been selected and the decision to take with or without food has been made, this regimen should not be altered.
• Food has complex effects on tizanidine pharmacokinetics, which differ with the different formulations. Tizanidine hydrochloride capsules and tizanidine hydrochloride tablets are bioequivalent to each other under fasting conditions (more than 3 hours after a meal), but not under fed conditions (within 30 minutes of a meal). These pharmacokinetic differences may result in clinically significant differences when switching administration of tablet and capsules and when switching administration between the fed or fasted state. These changes may result in increased adverse events, or delayed or more rapid onset of activity, depending upon the nature of the switch. For this reason, the prescriber should be thoroughly familiar with the changes in kinetics associated with these different conditions.
• The recommended starting dose is 2 mg (base). Because the effect of tizanidine hydrochloride capsules peaks at approximately 1 to 2 hours post-dose and dissipates between 3 to 6 hours post-dose, treatment can be repeated at 6 to 8 hour intervals, as needed, to a maximum of three doses in 24 hours.
• Dosage can be gradually increased by 2 mg (base) to 4 mg (base) at each dose, with 1 to 4 days between dosage increases, until a satisfactory reduction of muscle tone is achieved. The total daily dose should not exceed 36 mg (base). Single doses greater than 16 mg (base) have not been studied.

Off-Label Use and Dosage (Adult)

Guideline-Supported Use

Condition1

• Developed by:

• Class of Recommendation:

• Strength of Evidence:

• Dosing Information

• Dosage

Condition2

There is limited information regarding Off-Label Guideline-Supported Use of Tizanidine in adult patients.

Non–Guideline-Supported Use

Condition1

• Dosing Information

• Dosage

Condition2

There is limited information regarding Off-Label Non–Guideline-Supported Use of Tizanidine in adult patients.

Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

Condition1

• Dosing Information

• Dosage

Condition2

There is limited information regarding FDA-Labeled Use of Tizanidine in pediatric patients.

Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

Condition1

• Developed by:

• Class of Recommendation:

• Strength of Evidence:

• Dosing Information

• Dosage

Condition2

There is limited information regarding Off-Label Guideline-Supported Use of Tizanidine in pediatric patients.

Non–Guideline-Supported Use

Condition1

• Dosing Information

• Dosage

Condition2

There is limited information regarding Off-Label Non–Guideline-Supported Use of Tizanidine in pediatric patients.

Contraindications

• Tizanidine hydrochloride capsules are contraindicated in patients taking potent inhibitors of CYP1A2, such as fluvoxamine or ciprofloxacin.

Warnings

Precautions

• Hypotension

• Tizanidine is an α2-adrenergic agonist that can produce hypotension. Syncope has been reported in the post marketing setting. The chance of significant hypotension may possibly be minimized by titration of the dose and by focusing attention on signs and symptoms of hypotension prior to dose advancement. In addition, patients moving from a supine to fixed upright position may be at increased risk for hypotension and orthostatic effects.
• Monitor for hypotension when tizanidine is used in patients receiving concurrent antihypertensive therapy. It is not recommended that tizanidine be used with other α2-adrenergic agonists. Clinically significant hypotension (decreases in both systolic and diastolic pressure) has been reported with concomitant administration of either fluvoxamine or ciprofloxacin and single doses of 4 mg (base) of tizanidine. Therefore, concomitant use of tizanidine with fluvoxamine or with ciprofloxacin, potent inhibitors of CYP1A2, is contraindicated.

• Risk of Liver Injury

• Tizanidine may cause hepatocellular liver injury. Tizanidine should be used with caution in patients with any hepatic impairment. Monitoring of aminotransferase levels is recommended for baseline and 1 month after maximum dose is achieved, or if hepatic injury is suspected.

• Sedation

• Tizanidine can cause sedation, which may interfere with everyday activity. In the multiple dose studies, the prevalence of patients with sedation peaked following the first week of titration and then remained stable for the duration of the maintenance phase of the study. The CNS depressant effects of tizanidine with alcohol and other CNS depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants) may be additive. Monitor patients who take tizanidine with another CNS depressant for symptoms of excess sedation.

• Hallucinosis/Psychotic-like Symptoms

• Tizanidine use has been associated with hallucinations. Formed, visual hallucinations or delusions have been reported in 5 of 170 patients (3%) in two North American controlled clinical studies. Most of the patients were aware that the events were unreal. One patient developed psychosis in association with the hallucinations. One FDA approved labeling dated October 4, 2013 patient among these five continued to have problems for at least 2 weeks following discontinuation of tizanidine. Consider discontinuing tizanidine in patients who develop hallucinations.

• Interaction with CYP1A2 Inhibitors

• Because of potential drug interactions, tizanidine is contraindicated in patients taking potent CYP1A2 inhibitors, such as fluvoxamine or ciprofloxacin. Adverse reactions such as hypotension, bradycardia, or excessive drowsiness can occur when tizanidine is taken with other CYP1A2 inhibitors, such as zileuton, fluoroquinolones other than ciprofloxacin (which is contraindicated), antiarrythmics (amiodarone, mexiletine, propafenone), cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine). Concomitant use should be avoided unless the necessity for tizanidine therapy is clinically evident. In such a case, use with caution.

• Hypersensitivity Reactions

• Tizanidine can cause anaphylaxis. Signs and symptoms including respiratory compromise, urticaria, and angioedema of the throat and tongue have been reported. Patients should be informed of the signs and symptoms of severe allergic reactions and instructed to discontinue tizanidine and seek immediate medical care should these signs and symptoms occur.

• Increased Risk of Adverse Reactions in Patients with Renal Impairment

• Tizanidine should be used with caution in patients with renal insufficiency (creatinine clearance < 25 mL/min), as clearance is reduced by more than 50%. In these patients, during titration, the individual doses should be reduced. If higher doses are required, individual doses rather than dosing frequency should be increased. These patients should be monitored closely for the onset or increase in severity of the common adverse events (dry mouth, somnolence, asthenia and dizziness) as indicators of potential overdose.

• Withdrawal Adverse Reactions

• Withdrawal adverse reactions include rebound hypertension, tachycardia, and hypertonia. To minimize the risk of these reactions, particularly in patients who have been receiving high doses (20 mg (base) to 28 mg (base) daily) for long periods of time (9 weeks or more) or who may be on concomitant treatment with narcotics, the dose should be decreased slowly (2 mg (base) to 4 mg (base) per day).

Adverse Reactions

Clinical Trials Experience

• Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in clinical practice.

• Three double-blind, randomized, placebo controlled -clinical studies were conducted to evaluate the effect of tizanidine on spasticity control. Two studies were conducted in patients with multiple sclerosis and one in patients with spinal cord injury. Each study had a 13-week active treatment period which included a 3-week titration phase to the maximum tolerated dose up to 36 mg (base)/day in three divided doses, a 9-week plateau phase where the dose of tizanidine was held constant and a 1-week dose tapering. In all, 264 patients received tizanidine and 261 patients received placebo. Across the three studies patient ages ranged from 15 to 69 years and 51.4 percent were women. The median dose during the plateau phase ranged from 20 mg (base)/day to 28 mg (base)/day.

• The most frequent adverse reactions reported in multiple dose, placebo-controlled clinical studies involving 264 patients with spasticity were dry mouth, somnolence/sedation, asthenia (weakness, fatigue and/or tiredness) and dizziness. Three-quarters of the patients rated the events as mild to moderate and one-quarter of the patients rated the events as being severe. These events appeared to be dose related.

• Table 1 lists signs and symptoms that were reported in greater than 2% of patients in three multiple dose, placebo-controlled studies who received tizanidine where the frequency in the tizanidine group was greater than the placebo group. For comparison purposes, the corresponding frequency of the event (per 100 patients) among placebo treated patients is also provided.

T1

• In the single dose, placebo-controlled study involving 142 patients with spasticity due to multiple sclerosis (Study 1) [see Clinical Studies (14)], the patients were specifically asked if they had experienced any of the four most common adverse reactions: dry mouth, somnolence (drowsiness), asthenia (weakness, fatigue and/or tiredness) and dizziness. In addition, hypotension and bradycardia were observed. The occurrence of these reactions is summarized in Table 2. Other events were, in general, reported at a rate of 2% or less.

T2

Postmarketing Experience

• The following adverse reactions have been identified during post approval use of tizanidine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

• Certain events, such as somnolence, dry mouth, hypotension, decreased blood pressure, bradycardia, dizziness, weakness or asthenia, muscle spasms, hallucinations, fatigue, liver function test abnormality and hepatotoxicity, have been observed in post marketing and clinical trials and are discussed in previous sections of this document.

• The following adverse reactions have been identified as occurring in the post marketing experience of tizanidine. Based on the information provided regarding these reactions, a causal relationship with tizanidine cannot be entirely excluded. The events are listed in order of decreasing clinical significance; severity in the post marketing setting is not reported.

• Stevens Johnson Syndrome
• Anaphylactic Reaction
• Exfoliative Dermatitis
• Ventricular Tachycardia
• Hepatitis
• Convulsion
• Depression
• Arthralgia
• Paresthesia
• Rash
• Tremor

Drug Interactions

• Fluvoxamine

• Concomitant use of fluvoxamine and tizanidine is contraindicated. Changes in pharmacokinetics of tizanidine when administered with fluvoxamine resulted in significantly decreased blood pressure, increased drowsiness, and increased psychomotor impairment.

• Ciprofloxacin

• Concomitant use of ciprofloxacin and tizanidine is contraindicated. Changes in pharmacokinetics of tizanidine when administered with ciprofloxacin resulted in significantly decreased blood pressure, increased drowsiness, and increased psychomotor impairment.

• CYP1A2 Inhibitors other than Fluvoxamine and Ciprofloxacin

• Because of potential drug interactions, concomitant use of tizanidine with other CYP1A2 inhibitors, such as zileuton, fluoroquinolones other than strong CYP1A2 inhibitors (which are contraindicated), antiarrythmics (amiodarone, mexiletine, propafenone, and verapamil), cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine) should be avoided. If their use is clinically necessary, therapy should be initiated with 2 mg (base) dose and increased in 2 mg (base) to 4 mg (base) steps daily based on patient response to therapy. If adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce or discontinue tizanidine therapy.

• Oral Contraceptives

• Concomitant use of tizanidine with oral contraceptives is not recommended. However, if concomitant use is clinically necessary, initiate tizanidine with a single 2 mg (base) dose and increase in 2 mg (base) to 4 mg (base) steps daily based on patient response to therapy. If adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce or discontinue tizanidine therapy.

• Alcohol

• Alcohol increases the overall amount of drug in the bloodstream after a dose of tizanidine hydrochloride. This was associated with an increase in adverse reactions of tizanidine. The CNS depressant effects of tizanidine and alcohol are additive.

• Other CNS Depressants

• The sedative effects of tizanidine with CNS depressants (e.g., benzodiazepines, opioids, tricyclic antidepressants) may be additive. Monitor patients who take tizanidine with another CNS depressant for symptoms of excess sedation.

• α2-adrenergic Agonists

• Because hypotensive effects may be cumulative, it is not recommended that tizanidine be used with other α2-adrenergic agonists.

Use in Specific Populations

Pregnancy

Pregnancy Category (FDA):

• Pregnancy Category C

• Tizanidine has not been studied in pregnant women. Tizanidine should be given to pregnant women only if the benefit outweighs the risk to the unborn fetus. Reproduction studies performed in rats at a dose of 3 mg (base)/kg, equal to the maximum recommended human dose on a mg/m2 basis, and in rabbits at 30 mg (base)/kg, 16 times the maximum recommended human dose on a mg/m2 basis, did not show evidence of teratogenicity. Tizanidine at doses that are equal to and up to 8 times the maximum recommended human dose on a mg/m2 basis increased gestation duration in rats. Prenatal and postnatal pup loss was increased and developmental retardation occurred. Post-implantation loss was increased in rabbits at doses of 1 mg (base)/kg or greater, equal to or greater than 0.5 times the maximum recommended human dose on a mg/m2 basis.

Pregnancy Category (AUS):

• Australian Drug Evaluation Committee (ADEC) Pregnancy Category

There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Tizanidine in women who are pregnant.

Labor and Delivery

There is no FDA guidance on use of Tizanidine during labor and delivery.

Nursing Mothers

• It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when tizanidine is administered to a nursing woman.

Pediatric Use

• Safety and effectiveness in pediatric patients have not been established.

Geriatic Use

• Tizanidine is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. Clinical studies of tizanidine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. Cross-study comparison of pharmacokinetic data following single dose administration of 6 mg (base) tizanidine showed that younger subjects cleared the drug four times faster than the elderly subjects. In elderly patients with renal insufficiency (creatinine clearance < 25 mL/min), tizanidine clearance is reduced by more than 50% compared to healthy elderly subjects; this would be expected to lead to a longer duration of clinical effect. During titration, the individual doses should be reduced. If higher doses are required, individual doses rather than dosing frequency should be increased. Monitor elderly patients because they may have an increased risk for adverse reactions associated with tizanidine.

Gender

There is no FDA guidance on the use of Tizanidine with respect to specific gender populations.

Race

There is no FDA guidance on the use of Tizanidine with respect to specific racial populations.

Renal Impairment

• Tizanidine is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. In patients with renal insufficiency (creatinine clearance < 25 mL/min) clearance was reduced by more than 50%. In these patients, during titration, the individual doses should be reduced. If higher doses are required, individual doses rather than dosing frequency should be increased. These patients should be monitored closely for the onset or increase in severity of the common adverse events (dry mouth, somnolence, asthenia and dizziness) as indicators of potential overdose.

Hepatic Impairment

• The influence of hepatic impairment on the pharmacokinetics of tizanidine has not been evaluated. Because tizanidine is extensively metabolized in the liver, hepatic impairment would be expected to have significant effects on pharmacokinetics of tizanidine.

Females of Reproductive Potential and Males

There is no FDA guidance on the use of Tizanidine in women of reproductive potentials and males.

Immunocompromised Patients

There is no FDA guidance one the use of Tizanidine in patients who are immunocompromised.

Administration and Monitoring

Administration

• Oral

• Intravenous

Monitoring

There is limited information regarding Monitoring of Tizanidine in the drug label.

• Description

IV Compatibility

There is limited information regarding IV Compatibility of Tizanidine in the drug label.

Overdosage

Acute Overdose

Signs and Symptoms

• Description

Management

• Description

Chronic Overdose

There is limited information regarding Chronic Overdose of Tizanidine in the drug label.

Pharmacology

There is limited information regarding Tizanidine Pharmacology in the drug label.

Mechanism of Action

Structure

This image is provided by the National Library of Medicine.

Pharmacodynamics

There is limited information regarding Pharmacodynamics of Tizanidine in the drug label.

Pharmacokinetics

There is limited information regarding Pharmacokinetics of Tizanidine in the drug label.

Nonclinical Toxicology

There is limited information regarding Nonclinical Toxicology of Tizanidine in the drug label.

Clinical Studies

There is limited information regarding Clinical Studies of Tizanidine in the drug label.

How Supplied

Storage

There is limited information regarding Tizanidine Storage in the drug label.

Images

Drug Images

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Package and Label Display Panel

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Patient Counseling Information

There is limited information regarding Patient Counseling Information of Tizanidine in the drug label.

Precautions with Alcohol

• Alcohol-Tizanidine interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

• ®

Look-Alike Drug Names

• A® — B®

Drug Shortage Status

Price

References

The contents of this FDA label are provided by the National Library of Medicine.

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