Cyrin

Indications

Cyclobenzaprine Hydrochloride is a muscle relaxant used for short-term relief of muscle spasm linked to sudden (acute), painful muscle and joint problems such as back strain, neck sprain and similar injuries. It is used together with rest and physical therapy.

How It Works

Cyclobenzaprine acts mainly in the brainstem, the part of the brain that controls muscle tone. It reduces the overactive nerve signals that keep a muscle tight, which eases spasm, pain and stiffness. It does not act directly on the muscle itself. It is chemically related to tricyclic antidepressants.

Dosage and Administration

Usual adult dose: 5 mg three times a day. The doctor may increase it to 10 mg three times a day if needed. Swallow with water, with or without food. Use for short periods only, usually no longer than 2 to 3 weeks. Older adults and people with liver problems usually need a lower dose or should avoid it. Not recommended for children under 15 years.

Interactions

• MAO inhibitors (such as Selegiline or Linezolid): do not use together or within 14 days.
• Antidepressants (SSRIs, SNRIs, tricyclics), Tramadol and Bupropion: risk of serotonin syndrome and seizures.
• Alcohol, sleeping tablets, opioids and other sedatives increase drowsiness.
• Anticholinergic medicines add to dry mouth, constipation and urine retention.
• It may weaken the effect of some blood pressure medicines such as Clonidine.

Contraindications

• Allergy to Cyclobenzaprine.
• Use of MAO inhibitors within the last 14 days.
• Recent heart attack, heart failure, heart block or irregular heartbeat.
• Overactive thyroid (hyperthyroidism).

Side Effects

Common: drowsiness, dry mouth, dizziness, tiredness, headache, constipation, nausea and blurred vision. Less common: confusion (especially in older people), fast heartbeat, difficulty passing urine and unpleasant taste.

Get urgent medical help for a fast or irregular heartbeat, chest pain, fainting, seizures, agitation with fever, sweating and muscle twitching (possible serotonin syndrome), hallucinations, inability to pass urine, or swelling of the face or throat.

Pregnancy and Lactation

Studies have not shown clear harm, but data in pregnancy are limited, so use only if your doctor thinks it is needed. It is not known how much passes into breast milk; ask your doctor before using it while breastfeeding.

Precautions and Warnings

• Causes drowsiness: do not drive or operate machines if affected, and avoid alcohol.
• Use with care in glaucoma (narrow angle), enlarged prostate, urine retention, liver disease and in older adults.
• Not for long-term use or for spasm caused by brain or spinal cord disease.

Overdose

Overdose can cause severe drowsiness, agitation, confusion, fast heartbeat, dangerous heart rhythm changes, seizures, low blood pressure and coma. Seek emergency medical help immediately.

Therapeutic Class

Centrally acting skeletal muscle relaxant.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.