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Centrally Acting Muscle Relaxant (Alpha-2 Agonist)

Tizanidine

Brand names: Zanaflex

Tizanidine is a centrally acting alpha-2 adrenergic agonist used as a skeletal muscle relaxant for painful muscle spasm and spasticity.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

By stimulating central alpha-2 adrenoceptors it reduces excitatory neurotransmitter release at spinal interneurons, decreasing motor neuron firing and muscle tone.

Prescribing in practice

  • Contraindicated with potent CYP1A2 inhibitors such as fluvoxamine and ciprofloxacin, which markedly raise tizanidine levels and can cause profound hypotension and sedation.
  • Titrate gradually and avoid abrupt withdrawal, which can cause rebound hypertension, tachycardia and increased spasticity.
  • Causes dose-related hypotension, sedation and dry mouth, and requires caution with other antihypertensives or CNS depressants.

Monitoring

Monitor liver function and blood pressure, particularly during dose titration and with interacting medicines.

Counselling the patient

  • May cause drowsiness and dizziness, especially on standing; take care driving until you know how it affects you.
  • Do not stop the medicine suddenly without advice.
  • Report yellowing of the skin or eyes or persistent nausea.

Evidence & guidelines

Tizanidine is recognised in UK references for muscle spasticity, with prescribing shaped by its CYP1A2 interactions and hepatic monitoring requirements.

Reference: MHRA Drug Safety Update (Tizanidine hepatotoxicity); SPC Zanaflex; Cochrane Review (Muscle relaxants for acute low back pain); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways