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December 17, 2025
Brand Name :
Zanaflex
Synonyms :
tizanidine
Class :
Alpha2 Adrenergic Agonists
Dosage Forms & Strengths
Capsule
2mg
4mg
6mg
Tablet
2mg
4mg
Indicated for Muscle Spasticity:
Initial dose: 2mg orally thrice a day whenever necessary. Do not exceed three doses per day
Maintenance dose: Adjust dosage in increments of 2 to 4 mg daily, with a minimum interval of 1 to 4 days between dose adjustments, until the desired effect is achieved.
Do not exceed 36mg/day.
To gradually discontinue, reduce by 2-4 mg daily.
Dose Adjustments
Renal Impairment
CrCl <25 mL/min: Clearance decreased >50%
Creatinine Clearance Rate (CrCl) >25 mL/min: Not Studied; Caution Is Advised
Safety and Efficacy not established.
Refer adult dosing
may increase the hypotensive effect of blood pressure-lowering agents
may increase the AV blocking effect of alpha2 agonists
may increase the CNS depressant effect of CNS depressants
may increase the bradycardic effect of bradycardia causing agents
may increase the CNS depressant effect of CNS depressants
may enhance the serum concentration
may enhance the serum concentration
may enhance the serum concentration
may enhance the serum concentration
may enhance the serum concentration
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the bradycardic effect of bradycardia causing agents
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may decrease the hypertensive effect of alpha two agonists
may increase the hypotensive effect of blood pressure-lowering agents
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the bradycardic effect of bradycardia causing agents
may increase the toxic effect of CNS depressants
may increase the bradycardic effect of bradycardia, causing agents
may have an increased AV-blocking effect when combined with beta-blockers
may have an increased AV-blocking effect when combined with beta-blockers
may have an increased AV-blocking effect when combined with beta-blockers
may have an increased AV-blocking effect when combined with beta-blockers
may have an increased AV-blocking effect when combined with beta-blockers
may have an increased Av-blocking effect when combined with beta-blockers
may enhance the serum concentration of CYP3A4 inhibitors
may enhance the serum concentration of CYP1A2 inhibitors
may increase the AV-blocking effect of beta blockers
They may increase the vasopressor effect when combined with Alpha-/Beta-Agonists
It may increase the vasoconstricting effect when combined with Alpha-/Beta-Agonists
It may increase the hypertensive effect when combined with Alpha-/Beta-Agonists
may decrease the antihypertensive effect when combined with alpha2-agonists
cyproterone and ethinyl estradiol
may enhance the serum concentration of CYP1A2 Inhibitors
linezolid: they may increase the hypertensive effect of Alpha2-Agonists
may increase the CNS depressant effect of CNS depressants
may increase the hypotensive effect of blood pressure-lowering agents
may increase the arrhythmogenic effect of bradycardia-causing agents
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may enhance the serum concentration of CYP1A2 substrates
may increase the CNS depressant effect of CNS depressants
tizanidine: they may enhance the serum concentration of amiodarone
may increase the hypertensive effect
ciprofloxacin inhaled (Pending FDA approval)
may diminish the serum concentration of ciprofloxacin
may have an increased vasoconstricting effect when combined with alpha1-agonists
may have an increased vasoconstricting effect when combined with alpha1-agonists
may have an increased vasoconstricting effect when combined with alpha1-agonists
may have an increased vasoconstricting effect when combined with alpha1-agonists
may have an increased vasoconstricting effect when combined with alpha1-agonists
may increase the av-blocking effect of beta-blockers
may increase the av-blocking effect of beta-blockers
may increase the av-blocking effect of beta-blockers
may increase the av-blocking effect of beta-blockers
may increase the av-blocking effect of beta-blockers
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the CNS depressant effect of CNS depressants
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the hypotensive effect of blood pressure-lowering agents
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the hypotensive effect of blood pressure-lowering agents
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
may increase the CNS depressant effect of CNS depressants
tizanidine: they may enhance the serum concentration of CYP3A4 Inhibitors
tizanidine: they may enhance the serum concentration of CYP3A4 Inhibitors
tizanidine: they may enhance the serum concentration of CYP3A4 Inhibitors
tizanidine: they may enhance the serum concentration of CYP3A4 Inhibitors
tizanidine: they may enhance the serum concentration of CYP3A4 Inhibitors
may enhance the QTc-prolonging effect of Moxifloxacin
may enhance the Qtc prolonging effect
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
they increase the QTc prolongation effect of other QT-prolonging agents
amiodarone: they may enhance the serum concentration of tizanidine
may decrease the therapeutic effect when combined with Alpha2-Agonists
may decrease the therapeutic effect when combined with Alpha2-Agonists
may decrease the therapeutic effect when combined with Alpha2-Agonists
may decrease the therapeutic effect when combined with Alpha2-Agonists
may decrease the therapeutic effect when combined with Alpha2-Agonists
zavegepant: they may increase the hypertensive effect of Alpha2-Agonists
pergolide: they may increase the hypertensive effect of Alpha2-Agonists
fentanyl: they may increase the hypertensive effect of Alpha2-Agonists
May enhances the effects of the other by pharmacodynamic synergism
Actions and Spectrum:
Frequency defined
>10%
Somnolence (46-50%)
Asthenia (10-45%)
Dry mouth (46-50%)
Dizziness (16-20%)
1-10%
Constipation (4%)
LFT abnormalities (3-5%)
Vomiting (3%)
UTI (10%)
Blurred vision (3%)
Infection (6%)
Speech disorder (3%)
Urinary frequency (3%)
Frequency not defined
Bradycardia
Orthostatic hypotension
Syncope (rare)
Asthenia
Hypotension
Contraindications/caution:
Contraindications:
Caution:
Pregnancy consideration: Insufficient data available
Lactation:
Pregnancy category:
Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.
Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women.
Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.
Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.
Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.
Category N: There is no data available for the drug under this category
Pharmacology:
tizanidine is a centrally acting muscle relaxant that acts on alpha-2 adrenergic receptors in the brain and spinal cord. It reduces muscle spasticity by inhibiting the release of excitatory neurotransmitters, such as glutamate, and enhancing the activity of inhibitory neurotransmitters, such as gamma-aminobutyric acid (GABA)
Pharmacodynamics:
Pharmacokinetics:
Absorption
tizanidine is well absorbed after oral administration, with a bioavailability of approximately 40%. Taking the drug with food can increase its bioavailability.
Distribution
tizanidine is distributed throughout the body, with a volume of distribution of approximately 2.4 L/kg. It is highly protein-bound (approximately 30%) and can cross the blood-brain barrier.
Metabolism
tizanidine is extensively metabolized in the liver, primarily by the CYP1A2 enzyme system. The primary metabolites are inactive, and the drug is eliminated primarily in the urine (about 60%) and feces (about 20%).
Elimination and Excretion
The elimination half-life of tizanidine is approximately 2.5 hours. The drug is primarily eliminated in the urine as metabolites, with only a small amount of unchanged drugs excreted in the urine.
Administration:
tizanidine is a medication that is used to treat muscle spasticity. It is usually taken by mouth, and the dosage and frequency depend on the patient’s condition and response to the drug. Here are some general guidelines for the administration of tizanidine:
Patient information leaflet
Generic Name: tizanidine
Pronunciation: [ tye-ZAN-i-deen ]
Why do we use tizanidine?
tizanidine is a medication that is primarily used to treat muscle spasticity. Here are some common uses of tizanidine: