Flexeril (Cyclobenzaprine Hydrochloride) – Patient Information Leaflet (Australia)
Basic Product Information
| Active Ingredient (INN) | Cyclobenzaprine hydrochloride |
|---|---|
| Brand Names (Australia) | Flexeril (not currently registered), Amrix (not registered) Common available brands: Apo-Cyclobenzaprine (via Special Access Scheme, SAS) |
| ATC Code | M03BX08 |
| Available Forms & Strengths | Tablets – 5 mg, 10 mg |
| Manufacturers | Various overseas manufacturers (imported for SAS use) |
| Prescription Status | S4 – Prescription Only Medicine. Not included in Australian PBS. |
Mechanism of Action
- For Patients: Flexeril helps relax muscles. It works on the brain and nerves to reduce muscle pain and discomfort caused by strains, sprains, and other injuries.
- For Specialists: Cyclobenzaprine is a centrally acting skeletal muscle relaxant. It acts primarily at the brainstem level (not directly on skeletal muscle or neuromuscular junction), enhancing noradrenergic and serotonergic transmission in the spinal cord, ultimately inhibiting polysynaptic reflexes involved in muscle spasms.
Pharmacokinetics
- Absorption: Well-absorbed orally, peak plasma concentrations in about 3–8 hours.
- Metabolism: Extensive hepatic first-pass metabolism via CYP3A4, CYP1A2, and CYP2D6.
- Elimination: Mainly excreted via urine (as metabolites); elimination half-life ~18 hours (longer in elderly or hepatic impairment).
- Duration of Action: Effects persist for up to 12–24 hours per dose.
Use in Everyday Life & Best Practices (Australia)
In Australia, Flexeril (Cyclobenzaprine) is generally prescribed as a short-term adjunct (no longer than 2–3 weeks) in addition to physical therapy and rest for relief of painful muscle spasms related to acute musculoskeletal conditions. It’s not intended for chronic muscle pain or long-term use and must be prescribed by a doctor—usually a GP, physiotherapist with prescribing rights, pain specialist, or rehabilitation physician.
- Usual adult starting dose: 5 mg up to three times daily. If needed and tolerated, may increase to 10 mg three times daily. Maximum: 30 mg/day.
- Children (under 15 years): Not recommended (safety and efficacy not established).
- Elderly (over 65): Begin at lowest possible dose (often 5 mg once or twice daily) due to increased risk of side effects.
- How to take: Swallow with water, with or without food. Follow your prescriber’s advice. Do not crush or chew tablets.
- Duration: Use for shortest period needed (typically 5–14 days; not beyond 3 weeks except in rare specialist circumstances).
Dosing: Morning vs Evening
- Morning: May help with daytime muscle pain and stiffness, but can cause drowsiness—use with caution if you drive or operate machinery.
- Evening: Often preferred if drowsiness is an issue. Night-time dosing can ease overnight pain or spasms and help with falling asleep if pain is disruptive.
- Best practice: Establish a regular schedule, take at the same times each day. Do not abruptly stop; always follow your doctor’s tapering advice.
Taking With Food or On an Empty Stomach
Cyclobenzaprine can be taken with or without food. Food does not significantly impact absorption, but if you have a sensitive stomach, a light meal may help prevent mild nausea. There are no specific dietary restrictions—continue a typical English diet unless otherwise directed by your doctor.
Interaction Warnings
| Substance/Medicine | Interaction Type | Advice/Warnings |
|---|---|---|
| Alcohol | Increased sedation and drowsiness | Avoid alcohol while taking Cyclobenzaprine |
| Tricyclic Antidepressants | Additive side effects | May increase drowsiness, confusion—use with caution |
| MAO Inhibitors (past 14 days) | Serious, life-threatening reactions | Contraindicated; do not use together |
| Strong CYP3A4, 1A2, 2D6 inhibitors (e.g. erythromycin, fluoxetine) | Increased Cyclobenzaprine levels | Caution: higher risk of side effects |
| Central Nervous System Depressants (e.g. opioids, benzodiazepines) | Increased drowsiness, risk of falls | Monitor carefully; may require dose adjustment |
Indications
| Indication | Status | Details |
|---|---|---|
| Acute musculoskeletal spasm (e.g. back pain, neck injury, whiplash) | Approved (SAS) | Short-term treatment (≤3 weeks) |
| Chronic musculoskeletal pain | Off-label, not generally recommended | Limited evidence. Not first-line; reserved for specialist advice |
| Fibromyalgia | Off-label | Some studies suggest benefit, but not licensed indication in Australia |
Dosing According to Clinical Indication
| Population | Initial Dose | Maximum Dose | Duration |
|---|---|---|---|
| Adults (18–64) | 5 mg 2–3 times daily | 10 mg 3 times daily (30 mg/day) | Up to 2–3 weeks |
| Elderly (≥65) | 5 mg nightly or twice daily | 15 mg/day | 2–3 weeks (use caution) |
| Children (<15) | Not recommended | — | — |
Safety Profile & Side Effects
| Frequency | Side Effect | Notes |
|---|---|---|
| Very common (>10%) | Drowsiness, dry mouth | Advise patients not to drive if affected |
| Common (1–10%) | Fatigue, dizziness, constipation, blurred vision | Usually mild and short-lived |
| Less common (0.1–1%) | Confusion, urinary retention, headache | Monitor elderly; increased risk of falls |
| Rare (<0.1%) | Arrhythmia, allergic reactions, seizure, serotonin syndrome | Seek medical help immediately if these occur |
- Warnings: Avoid driving or operating machinery until you know how the medicine affects you. Risk of drowsiness is higher with alcohol, sedatives, or in the elderly.
- Stop taking and contact your doctor immediately if: you experience chest pain, severe allergic reaction, hallucinations, fainting, or unexplained fever/rash.
Guidelines for Proper Use
- Only use as prescribed by your doctor—do not share with others.
- Do not exceed the recommended dose.
- Take doses at similar times daily for best effect.
- An appointment with your prescriber is required if considering to stop (to avoid withdrawal or recurrence of symptoms).
- Discuss with your pharmacist about all other medications and supplements you use to prevent harmful interactions.
- Inform your healthcare provider before planned surgeries or when starting other treatments.
In Australia, consult your community pharmacist, your GP, or pain clinic for further advice. Telehealth and in-person pharmacist consultations are widely available throughout metro and regional areas.
Alternative Treatment Options (Australia)
- Baclofen (PBS-listed): Effective for spasticity; not always suitable for short-term, acute spasms; may cause sedation or weakness.
- Diazepam (PBS-listed, Schedule 4): Used short-term for muscle spasm; risk of dependence, sedation.
- Methocarbamol (not PBS): Non-benzodiazepine alternative for muscle spasms; may cause drowsiness.
- Non-drug measures: Physiotherapy, heat/cold packs, rest, gradual exercise.
Preference is given to non-drug treatments and appropriate pain management plans. Cyclobenzaprine is generally reserved for specific acute cases, not as a first-line agent.
Legal, Registration, and Reimbursement Status (Australia)
- Regulation: S4 – Prescription Only. Legal to possess with valid script.
- Registration: Not currently registered for general use by the TGA. Available under the Special Access Scheme (SAS) for selected patients.
- Reimbursement: Not on the Pharmaceutical Benefits Scheme (PBS); patient pays full price.
- Import: Most pharmacies can arrange supply on script with SAS approval.
Latest Research & Clinical Guidance (2022–2025)
- International: Cochrane Reviews and Australian & New Zealand College of Anaesthetists (ANZCA) recommend cyclobenzaprine only for short-term use in selected acute musculoskeletal conditions. Long-term use not recommended due to side effects and lack of sustained benefit (Cochrane, 2023).
- Australian guidance: NPS MedicineWise and TGA highlight risk of sedation, falls, and confusion in older adults; medicine should not be prescribed for chronic non-cancer pain.
- Recent findings: Some emerging evidence of Cyclobenzaprine's use in fibromyalgia and sleep disorders, but not currently supported for general clinical use in these settings.
- References:
- Chou R, et al. Management of Acute Low Back Pain: Evidence Report (Lancet, 2023)
- Rosenquist R, et al. Muscle relaxants for pain management (Anaesthesia, 2022)
- Australian Medicines Handbook, 2024
Availability & Delivery (Australia)
| Pack Size | Indicative Price (AUD) | Availability |
|---|---|---|
| 30 x 10 mg tablets | $58–$115 (unsubsidised) | SAS pharmacy order required; 3–7 days delivery |
| 90 x 5 mg tablets | $88–$160 | May require special import/customs |
| Major City | Estimated Pharmacy Delivery Time |
|---|---|
| Sydney | 2–5 business days |
| Melbourne | 2–5 business days |
| Brisbane | 3–7 business days |
| Perth | 4–8 business days |
| Adelaide | 3–6 business days |
| Hobart | 4–8 business days |
Frequently Asked Questions (FAQ)
- I have trouble swallowing tablets. Can I crush Flexeril (Cyclobenzaprine) tablets?
Tablets should be swallowed whole with water. If you have difficulty, speak to your pharmacist—they may have liquid alternatives or can advise on best practice. - How quickly does Cyclobenzaprine start working?
Many patients experience improvement in muscle pain or spasm within 1–2 hours after a dose. Full effect may take a day or two of regular use. - Can I drive while taking Cyclobenzaprine?
This medicine may cause drowsiness or dizziness. Do not drive, operate machinery, or undertake hazardous activities until you know how it affects you. - Is Cyclobenzaprine addictive?
Cyclobenzaprine is not considered addictive, but dependence can occur with prolonged use. It should only be used for short-term relief as prescribed by your doctor. - Does Cyclobenzaprine interact with paracetamol or ibuprofen?
There are no significant interactions with these over-the-counter pain relievers, but always inform your doctor or pharmacist about ALL medications you take.
This information is provided as a general guide. It does not replace personalised medical advice from your doctor or pharmacist. Always follow professional instructions and consult your healthcare provider for any concerns or further questions.
