Adjunct to rest and physical therapy for the relief of muscular spasm associated with acute, painful musculoskeletal conditions.
For low back pain, generally reserve skeletal muscle relaxants for adjunctive treatment when pain is unresponsive to OTC analgesics (e.g., NSAIAs).
Skeletal muscle relaxants less well tolerated than NSAIAs, and clinical superiority to NSAIAs not established for low back pain.
Various skeletal muscle relaxants appear to have comparable efficacy for low back pain relief and are more effective than placebo.
Initially, symptomatic control of acute low back pain focuses on providing sufficient comfort to allow maximum possible activity while awaiting spontaneous recovery; later, as aid to overcome specific activity intolerance.
Because of rapid spontaneous recovery rate, efficacy of various therapies may be difficult to establish; improvement of low back pain usually occurs within 2 weeks, substantial improvement within 4 weeks.
Insufficient evidence to indicate whether cyclobenzaprine enhances the effects of aspirin or other analgesics, or vice versa, in the management of painful musculoskeletal conditions.
Ineffective for the treatment of cerebral or spinal disease-associated spasticity or in children with cerebral palsy.
Shares the toxic potentials of tricyclic antidepressants; observe the usual precautions associated with tricyclic antidepressant therapy.
Cardiac Effects
Arrhythmias, sinus tachycardia, prolongation of the conduction time leading to MI, and stroke reported with tricyclic antidepressants.
CNS Effects
May cause serious CNS effects, especially when recommended dosage is exceeded.
Performance of activities requiring mental alertness or physical coordination may be impaired.
Concurrent use of other CNS depressants may potentiate CNS depression. (See Interactions: Specific Drugs.)
General Precautions
Anticholinergic Effects
Potential for adverse anticholinergic effects. Use with caution in patients with history of urinary retention, angle-closure glaucoma, or increased intraocular pressure or in patients receiving anticholinergic drugs.
Specific Populations
Pregnancy
Category B.
Lactation
Not known whether cyclobenzaprine is distributed into milk; however, distribution into milk is likely, since other tricyclic drugs distribute into milk. Use with caution.
Pediatric Use
Safety and efficacy not established in children <15 years of age.
Geriatric Use
Increased plasma concentrations.
Increased frequency and severity of adverse effects (with or without concomitant drug therapy). Increased risk of adverse CNS effects (e.g., hallucinations, confusion, sedation), adverse cardiovascular effects resulting in falls or other sequelae, and interactions with other drugs or diseases.
Use only if clearly needed. Cautious dosing recommended. (See Geriatric Patients under Dosage and Administration.)
Hepatic Impairment
Increased plasma concentrations and susceptibility to sedation.
Initiate with caution in patients with mild hepatic impairment. (See Hepatic Impairment under Dosage and Administration.)
Use not recommended in patients with moderate or severe hepatic impairment.
Well absorbed following oral administration but appears to undergo first-pass metabolism; mean oral bioavailability is 33–55%. Undergoes enterohepatic circulation.
Special Populations
In patients ≥65 years of age, mean steady-state AUC is about 1.7 times greater than AUC in younger adults.
In patients with mild to moderate hepatic impairment, peak plasma concentration and AUC are twice the values in healthy individuals.
Distribution
Extent
Widely distributed into most body tissues.
Plasma Protein Binding
About 93%.
Elimination
Metabolism
Extensively metabolized in the liver via oxidation and conjugation. Oxidative N-demethylation mediated by CYP3A4, 1A2, and (to a lesser extent) 2D6.
Elimination Route
Eliminated mainly in urine as inactive glucuronide metabolites; <1% eliminated as unchanged drug.
Half-life
About 18 hours (range: 8–37 hours).
Stability
Storage
Oral
Tablets
25°C (may be exposed to 15–30°C).
Actions
CNS depressant with sedative and skeletal muscle relaxant effects.
Precise mechanism of action not known. Does not directly relax skeletal muscle and, unlike neuromuscular blocking agents, does not depress neuronal conduction, neuromuscular transmission, or muscle excitability.
Like tricyclic antidepressants, potentiates the effects of norepinephrine and has anticholinergic effects.
Advice to Patients
Potential for drug to impair mental alertness and physical coordination, particularly when used with alcohol or other CNS depressants. Use caution when driving or operating machinery.
Potential for more frequent or severe adverse effects in geriatric patients.
Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs as well as any concomitant illnesses.
Importance of informing patients of other important precautionary information. (See Cautions.)
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Comparative Pricing
This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 09/2009. For the most current and up-to-date pricing information, please visit www.drugstore.com. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.
Remember, keep this and all other medicines out of the reach of children,
never share your medicines with others, and use this medication only for the indication prescribed.
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