cyclobenzaprine

Action and Spectrum

Actions and spectrum:

cyclobenzaprine is a skeletal muscle relaxant used to relieve muscle spasms and associated pain. It is a centrally acting muscle relaxant, which means that it works by acting on the central nervous system (CNS) rather than directly on the muscles themselves. cyclobenzaprine acts by blocking nerve impulses.

cyclobenzaprine is primarily used to treat muscle spasms and associated pain, including those caused by musculoskeletal conditions such as low back pain, fibromyalgia, and myofascial pain syndrome. It is often prescribed as a short-term treatment, usually no more than 2-3 weeks, to relieve acute symptoms.

cyclobenzaprine has a relatively narrow spectrum of activity and is primarily used for its muscle relaxant effects. It does not have significant anti-inflammatory or analgesic (pain-relieving) effects and is not effective for treating other types of pain.

Drug Interaction

Adverse Reaction

Frequency defined:

>10%

Dizziness (3-11%)

Drowsiness 39%

Dry mouth (21-32%)

1-10%

Pharyngitis (1-3%)

Constipation (1-3%)

Confusion (1-3%)

Nervousness (1-3%)

Asthenia (1-3%)

Nausea (1-3%)

Headache (1-5%)

Bad taste in mouth (1-6%)

Blurred vision (3%)

Indigestion (4%)

Palpitations (6%)

Fatigue (6%)

<1%

Hypotension

Syncope

Vasodilation

Cholestasis

Jaundice

Immune hypersensitivity reaction

Arrhythmia

Palpitation

Tachycardia

Cardiac dysrhythmia

Hepatitis

Anaphylaxis

Post-marketing Reports

Serotonin syndrome

Stroke

Myocardial infarction

Hypertension

Heart block

Black Box Warning

Contraindication / Caution

Contraindication /Caution

Contraindication

cyclobenzaprine is contraindicated in patients with a hypersensitivity to the drug, as well as in patients with an acute recovery phase of myocardial infarction, heart block, and arrhythmias. It is also contraindicated in patients with hyperthyroidism, congestive heart failure and in those who have taken monoamine oxidase inhibitors (MAOIs) within the past 14 days.

Caution

• Hypersensitivity: Patients who have had an allergic reaction to cyclobenzaprine should not take it.
• Cardiovascular disease: cyclobenzaprine can cause changes in heart rate and rhythm, especially in patients with preexisting cardiovascular disease, such as arrhythmias, heart block, or heart failure.
• Glaucoma: cyclobenzaprine can cause an increase in intraocular pressure and may worsen glaucoma.
• Hepatic impairment: cyclobenzaprine is metabolized by the liver, and patients with hepatic impairment may have a slower metabolism and an increased risk of side effects.
• Renal impairment: cyclobenzaprine is primarily excreted in the urine, and patients with renal impairment may have a slower excretion and an increased risk of side effects.
• CNS depression: cyclobenzaprine can cause drowsiness and sedation, and patients should use caution when driving or operating heavy machinery.
• Alcohol use: Alcohol can enhance the sedative effects of cyclobenzaprine and increase the risk of side effects.

comorbidities

• Severe liver disease: cyclobenzaprine is metabolized by the liver, and its use is not recommended in individuals with severe liver disease or liver failure.
• Cardiovascular disease: cyclobenzaprine may cause cardiovascular side effects, such as arrhythmias and tachycardia, and caution should be used in individuals with pre-existing cardiovascular disease.
• Glaucoma: cyclobenzaprine may cause increased intraocular pressure, and it should be avoided in patients with uncontrolled angle-closure glaucoma.
• Urinary retention: cyclobenzaprine may worsen urinary retention, and it should be avoided in patients with urinary retention or bladder obstruction.
• Hyperthyroidism: cyclobenzaprine may worsen symptoms in individuals with hyperthyroidism, and its use should be avoided in these individuals.

Pregnancy / Lactation

Pregnancy consideration: pregnancy category B

Lactation: safety and efficacy not established 

Pregnancy category:

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester.
• Category B: There is no evidence of risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women.
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits.
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women.
• Category N: There is no data available for the drug under this category.

Pharmacology

Pharmacology

cyclobenzaprine is a centrally acting skeletal muscle relaxant. It works by inhibiting the motor neuron activity in the spinal cord, resulting in skeletal muscle relaxation. cyclobenzaprine is structurally like tricyclic antidepressants, which are known to have analgesic properties. While the exact mechanism of action of cyclobenzaprine is believed to work through its effects on the noradrenergic and serotonergic pathways in the brain and spinal cord.

Pharmacodynamics

cyclobenzaprine is a centrally acting muscle relaxant with pharmacological properties like those of tricyclic antidepressants. It works by decreasing the excitability of alpha-motor neurons, which results in reduced muscle spasms.

cyclobenzaprine acts on the brainstem, where it inhibits the reflexes responsible for muscle contraction. It also increases muscle tone, reduces muscle spasms, and decreases pain perception. Additionally, it has some anticholinergic effects, which contribute to its muscle relaxant and sedative properties.

Pharmacokinetics

• Absorption: cyclobenzaprine is rapidly absorbed from the gastrointestinal tract after oral administration.
• Distribution: cyclobenzaprine is widely distributed in the body, with a volume of distribution of about 20 L/kg. It crosses the blood-brain barrier and the placenta and is distributed into breast milk.
• Metabolism: cyclobenzaprine undergoes extensive first-pass metabolism in the liver, with the main metabolite being norcyclobenzaprine.
• Elimination: The elimination half-life of cyclobenzaprine is about 18 hours. cyclobenzaprine and its metabolites are primarily excreted in the urine, with less than 1% being excreted in the feces. The pharmacokinetics of cyclobenzaprine are affected by age, liver function, and renal function.

Adminstartion

Administration

cyclobenzaprine is available in tablet form and is taken orally, usually 3 times a day. The tablets are typically available in 5 mg, 7.5 mg, and 10 mg doses. The dosage and duration of treatment should be based on the patient’s individual needs and response to treatment.

cyclobenzaprine should be taken with food or a glass of milk to reduce the risk of stomach upset. Patients should not crush or chew the tablets, as this can affect the way the medication is released and absorbed by the body. It is important to follow the instructions provided by the healthcare provider or pharmacist when taking cyclobenzaprine.

Patient Information Leaflet

Patient information leaflet

Generic Name: cyclobenzaprine

Pronounced: (sye-kloe-ben-za-preen)

Why do we use cyclobenzaprine?

cyclobenzaprine is a muscle relaxant that is used to relieve muscle spasms and associated pain. It is commonly prescribed for the short-term treatment of muscle pain, muscle spasms, and stiffness that is caused by musculoskeletal conditions such as back pain, neck pain, and fibromyalgia. cyclobenzaprine is not recommended for long-term use, as it has the