Zanaflex

Basic Zanaflex information

• INN (international nonproprietary name): Tizanidine
• Brand names available in the United Kingdom: Zanaflex, generic tizanidine
• ATC code: M03BX02
• Forms and dosages: Tablets 2 mg and 4 mg. Administration route: oral.
• Manufacturers in the United Kingdom: Accord Healthcare, Teva, Mylan, Apotex
• Registration status in the United Kingdom: Prescription-only medicine (POM)
• OTC / Rx classification: Prescription-only medicine (POM)

Legal status and availability in the UK

Zanaflex (tizanidine) is a prescription-only medicine (POM) in the UK.

In our online pharmacy, Zanaflex is available without a prescription, with discreet delivery to the United Kingdom in 9–21 days.

Forms and strengths

Tizanidine is supplied as 2 mg and 4 mg tablets. Pack sizes and excipients vary by brand, so check the patient information leaflet for the details of the product you receive.

Indications and uses

Tizanidine is licensed for the symptomatic management of spasticity, including in multiple sclerosis and spinal cord injury, where reduced muscle tone improves function.

Standard adult dosing for spasticity starts at 2 mg up to three times daily with cautious up-titration. The maximum daily dose is 36 mg. Some clinicians trial tizanidine for other muscle-spasm states, but evidence is variable.

Short-term use is appropriate when relief is needed for physiotherapy or activity periods; chronic use requires specialist review and monitoring.

• Spasticity: increased muscle tone due to upper motor neurone lesions causing stiffness and involuntary spasms.
• Short-term therapy: intermittent courses around activity or rehabilitation.
• Chronic therapy: ongoing daily treatment for persistent spasticity, under specialist follow-up.

How tizanidine (Zanaflex) works

Tizanidine is a centrally acting alpha-2 adrenergic agonist that reduces spinal cord excitability and interrupts nerve-mediated muscle spasms, without acting directly on the muscle. The result is decreased involuntary muscle tone and fewer painful spasms, which can aid physiotherapy and function.

Onset of action is relatively quick, but sedative effects may coincide with peak action, which influences dose scheduling around daily activities.

Compared with baclofen, which acts on GABA-B receptors, and benzodiazepines, which enhance GABA-A activity, tizanidine’s alpha-2 mechanism gives a different side-effect and monitoring profile.

Safety profile, contraindications and monitoring

Absolute contraindications include concomitant use with fluvoxamine or ciprofloxacin, known allergy to tizanidine or its excipients, and severe hepatic impairment.

Relative cautions include hypotension, bradycardia and concomitant use of CNS depressants or multiple antihypertensive agents.

Tizanidine is metabolised in the liver, so dose adjustments and increased monitoring are required in hepatic impairment. Blood pressure, heart rate and, where clinically indicated, liver function should be monitored.

Pregnancy and breastfeeding: discuss with your prescriber, as safety is not established. Counsel about sedation risk when driving or working with machinery.

New fainting, profound dizziness, unexplained jaundice or a slow heart rate require immediate contact with the prescriber.

Side effects

The most frequently reported effects are drowsiness, dry mouth and dizziness. Other common effects include asthenia, muscle weakness, hypotension and bradycardia. Side effects most often arise early in titration and often improve with dose adjustment.

Ways to reduce them include taking the first doses at night, starting at the lowest dose, spacing doses to avoid midday sedation and avoiding alcohol or other CNS depressants. A dry mouth can be eased with sips of water or sugar-free lozenges.

Serious reactions such as severe bradycardia, respiratory depression or coma are rare but may occur in overdose and require emergency care. Report fainting, chest pain, severe dizziness or yellowing of the skin immediately, and stop the medicine and seek urgent medical advice if you feel very sleepy, faint, or have a racing or slow heart.

Drug interactions

Fluvoxamine and ciprofloxacin are contraindicated: they are CYP1A2 inhibitors and markedly increase tizanidine levels with a risk of severe hypotension and sedation. Other CYP1A2 inhibitors also increase tizanidine levels.

Other important interactions include other CNS depressants (opioids, benzodiazepines) and additive blood-pressure-lowering effects with antihypertensives. When an interacting antibiotic or SSRI is started, tizanidine therapy needs to be reviewed immediately.

Tell your prescriber or pharmacist about recent antibiotics, non-prescription medicines and herbal remedies such as St John’s wort, and avoid alcohol.

Dosing and titration

Treatment typically starts at 2 mg up to three times daily, with increases of 2-4 mg every 4-7 days as tolerated. The maximum daily dose is 36 mg, and escalation beyond this should not occur without specialist input.

Elderly patients should start at lower doses and titrate more slowly because of the increased risk of hypotension and sedation. Patients with hepatic impairment require lower starting doses and close monitoring.

For missed doses, take the dose as soon as remembered unless it is near the next dose; do not double doses. On discontinuation, taper gradually to avoid rebound hypertension and withdrawal symptoms.

Overdose: seek immediate medical help (NHS 111, or 999 in an emergency) for severe drowsiness, a slow heart rate or breathing difficulty.

Brands and generics

Zanaflex is available alongside generic tizanidine from manufacturers such as Accord Healthcare, Apotex, Teva and Mylan. Products may differ in bioequivalence, so do not switch between brands without discussing it with your prescriber or pharmacist, and report new or worsening side effects after a switch.

Storage

Store tizanidine at room temperature, approximately 20-25°C, protected from moisture and light and in the original packaging. Avoid freezing and excessive heat, and do not store it in bathrooms or near radiators. Keep out of reach of children.

Dispose of expired or unwanted medicines through NHS pharmacy disposal schemes.

Frequently asked questions

Can I drive on tizanidine?

Avoid driving until you know how it affects you; drowsiness is common early on, especially during titration.

What if I miss a dose?

Take it as soon as remembered unless it is close to the next dose; do not double up.

Can I drink alcohol?

Avoid alcohol while taking tizanidine because of the increased sedation risk.

When should I contact my GP or specialist?

For severe hypotension, significant bradycardia, jaundice or suspected overdose.

Alternatives

Baclofen and diazepam are commonly used alternatives for spasticity, with different side-effect profiles and monitoring needs. Tizanidine is chosen when a centrally acting alpha-2 agent is preferred or baclofen is not tolerated, and should be avoided with ciprofloxacin or fluvoxamine or in severe hepatic impairment.

Delivery across the United Kingdom