Tizanidine
ZANAFLEX
Pronunciation: tye-ZAN-i-deen
“Zany flex in a Tizzy”
orange plus signs → alpha-2 agonist
What it isAlpha-2 and imidazoline agonist that reduces central motor drive; treatment of spasticity.
Why this oneIt causes less muscle weakness than baclofen, and its short action can be timed to when spasticity matters.
What limits itCiprofloxacin or fluvoxamine can cause extreme exposure and hypotension; avoid the combinations. Sedation and liver injury also matter.
FDA-approved for
- spasticity (1996)
Off-label
- tension headache
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Spasticity | Adults | 2 mg, may repeat q6-8h PRN (max 3 doses/24h) | increase by 2-4 mg per dose | 36 mg/day |
Titration 1 to 4 days between dose increases
Renal Use with caution if CrCl <25 mL/min (clearance reduced >50%); reduce individual doses during titration
Hepatic Use with caution in any hepatic impairment; reduce individual doses; monitor aminotransferases
Repeat doses at 6-8 hour intervals; max 3 doses per 24 hours
Instructions
- May take with or without food, but keep the chosen regimen (with vs without food) consistent
- Do not exceed 3 doses in 24 hours
- Discontinue by tapering slowly (2-4 mg/day) to avoid rebound hypertension, tachycardia, hypertonia
- Single doses greater than 16 mg not studied
Available strengths
- cap 2, 4, 6, 8 mg
- tab 2, 4 mg
- sol 2 mg/5 mL
Contraindications
- Concomitant use with potent CYP1A2 inhibitors such as fluvoxamine or ciprofloxacin
Cautions
- Hypotension, including syncope; caution with antihypertensives and other alpha-2 agonists
- Hepatocellular liver injury; monitor ALT
- Sedation, additive with alcohol/CNS depressants
- Hallucinations/psychotic-like symptoms
- Anaphylaxis
- Withdrawal reactions (rebound hypertension, tachycardia, hypertonia)
Adverse reactions
- Dry mouth
- Somnolence
- Asthenia (weakness/fatigue)
- Dizziness
- Hypotension, bradycardia
Pregnancy Not studied in pregnant women; animal data show fetal harm; use only if benefit outweighs risk
Lactation Undefined
Cost
Generic entry2002
NO BOXED WARNINGS
Principal riskHypotension and sedation; exposure multiplied by CYP1A2 inhibitors
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
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