Tizanidine
Skeletal muscle relaxants and spasmolytics
Skeletal muscle relaxants and spasmolytics
A short-acting alpha-2 agonist, related to clonidine, that relieves spasticity; it lowers blood pressure, sedates and depends on CYP1A2.
Quick facts
- Group
- Skeletal muscle relaxants and spasmolytics
- Target
- Alpha-2A adrenergic receptor
- Used for
- Spasticity from multiple sclerosis
- Key effects
- Sedation · Dry mouth · Low blood pressure
- Monitor
- Liver aminotransferases at baseline · Blood pressure
- ATC
- M03BX02
No doses: the clinician sets them by the current guideline.
Mechanism of action
Tizanidine stimulates alpha-2 adrenergic receptors in the spinal cord and increases presynaptic inhibition of motor neurons. It acts mostly on polysynaptic pathways, reducing facilitation of spinal motor neurons, and has no direct action on muscle fibres or the neuromuscular junction. Like clonidine, it can lower blood pressure, but much less.
- Tizanidine stimulates spinal alpha-2 receptors
- Presynaptic inhibition of motor neurons increases
- Polysynaptic reflexes drive less tone
- Spasticity eases for a few hours
Indications
- Spasticity from multiple sclerosis Multiple sclerosis →
- Spasticity from spinal cord injury Spinal cord injury →
Adverse effects
Common
- Sedation (common, dose-related)
- Dry mouth, dizziness and weakness
- Low blood pressure, orthostatic hypotension and slow heart rate
Contraindications
- Fluvoxamine or ciprofloxacin (potent CYP1A2 inhibitors)
- Hypersensitivity
- Generally avoided in liver impairment
Key interactions
- Fluvoxamine, ciprofloxacin
- Tizanidine levels rise many times over, with marked hypotension and sedation; contraindicated
- Other CYP1A2 inhibitors (other fluoroquinolones, amiodarone, verapamil, cimetidine, oral contraceptives, acyclovir)
- Higher tizanidine levels; ordinarily avoided
- Antihypertensives and other alpha-2 agonists (clonidine)
- Additive hypotension
- Alcohol and CNS depressants
- Additive sedation; alcohol also raises tizanidine levels
What is monitored
- Liver aminotransferases at baseline and during the first months, then periodically
- Blood pressure (including standing) and heart rate
- Sedation and hallucinations
- Kidney function
Administration and safety
- Tablets and capsules are not equivalent with food: the form and relation to meals are kept the same
- Timed for the activities when relief matters most, because the effect is short
- Withdrawn gradually, never stopped suddenly
Pregnancy and breastfeeding
Animal studies did not show malformations, but there are no adequate studies in pregnant women; it is used only if the benefit justifies the risk.
Nursing care
- Check the medication list for ciprofloxacin, fluvoxamine and other CYP1A2 inhibitors
- Measure blood pressure lying and standing; teach slow position changes
- Warn about drowsiness, alcohol and driving
- Teach not to stop it suddenly (fast heartbeat, high blood pressure)
Pharmacokinetics
- Absorption
- Well absorbed, but bioavailability is about 40% because of first-pass metabolism; food changes absorption
- Metabolism
- Liver, mainly CYP1A2
- Elimination
- Clearance falls sharply in severe kidney impairment
- Half-life
- About 2.5 hours (short-acting)
Test yourself
Think of the answer, then tap the question to see it.
Which receptor does tizanidine stimulate?
The alpha-2 adrenergic receptor (like clonidine).
Why is ciprofloxacin contraindicated with tizanidine?
It inhibits CYP1A2 and raises tizanidine levels many times, causing severe hypotension and sedation.
Which laboratory test is monitored on tizanidine?
Liver aminotransferases.
What happens if tizanidine is stopped abruptly?
Rebound high blood pressure, fast heartbeat and increased tone.
Connections
← Back to the class: Skeletal muscle relaxants and spasmolytics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TIZANIDINE HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); Tizanidine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.