urinary retention
Cyclobenzaprine Contraindications and Precautions
Cyclobenzaprine is structurally related to the tricyclic antidepressant amitriptyline. In addition to the listed precautions for cyclobenzaprine, precautions relevant to the tricyclic antidepressants should be considered. Tricyclic drugs are known to produce an allergic response in some patients. There appears to be cross-sensitivity, and caution should be used when changing from one of these chemically-related agents to another. Alternative therapy to cyclobenzaprine should be considered in those patients with tricyclic antidepressant hypersensitivity.
Because of a potential risk of cardiac events, the manufacturer contraindicates the use of cyclobenzaprine in patients with hyperthyroidism.
Cyclobenzaprine, like the tricyclic antidepressants, should not be given to patients who are in the acute recovery phase following acute myocardial infarction; this could cause re-infarction or sudden death. Do not administer cyclobenzaprine to patients with QT prolongation or familial histories of long-QT syndromes or in those patients with cardiac conduction defects (e.g., cardiac arrhythmias, AV block, bundle-branch block or congestive heart failure). Use cyclobenzaprine with caution in patients with any other cardiac disease (past history of myocardial infarction), because of the alterations in ECG patterns or heart rhythm that may occur. Although the risk of cardiovascular adverse events is higher after acute overdose, patients with cardiovascular disease should be closely monitored. Many adverse cardiovascular effects are associated with the use of tricyclic-related drugs.
Because of the drug’s chemical similarity to tricyclic antidepressants (TCAs), use cyclobenzaprine with caution in patients being treated for psychological illness. Cyclobenzaprine is not an effective treatment for depression. Cyclobenzaprine is contraindicated for concomitant use in patients receiving MAOI therapy (see Drug Interactions). It is unclear if cyclobenzaprine, like the TCAs, can transform depression into mania or hypomania in predisposed individuals (e.g., some patients with bipolar disorder). Also use cyclobenzaprine with caution in patients with psychotic disorders (e.g., schizophrenia).
Use cyclobenzaprine with caution in patients with a seizure disorder. Tricyclic drugs can lower the seizure threshold. If seizures occur during therapy with cyclobenzaprine, discontinue the drug.
Cyclobenzaprine can induce significant sedation, particularly during the initiation of treatment. Patients should use caution when driving or operating machinery until they are aware of the effects of the medication. Use with caution in patients with a history of alcoholism or who may use alcohol or other sedative medications because the depressant effects on the CNS can be potentiated. Decreased mental alertness can occur.
Cyclobenzaprine possesses anticholinergic activity, which may cause GI and other side effects. This drug should not be used in patients with paralytic ileus. Patients with increased intraocular pressure, closed-angle glaucoma, prostatic hypertrophy, or urinary retention should receive cyclobenzaprine with caution. The anticholinergic effects of cyclobenzaprine may make the eyes dry, which may cause discomfort for wearers of contact lenses. The use of lubricating drops may be necessary. The anticholinergic effects of cyclobenzaprine may be additive with other anticholinergic medications. Anticholinergic effects appear most frequently and cause the greatest morbidity in elderly patients. Cyclobenzaprine is generally not recommended for use in patients 65 years of age and older. The manufacturer recommends that cyclobenzaprine be used in the elderly only if clearly needed. If needed, initiate cyclobenzaprine therapy with 5 mg doses and titrate cautiously in the elderly (see Dosage); less frequent dosing may be needed. The plasma concentrations of cyclobenzaprine are elevated 1.7-fold in elderly patients relative to younger patients. In addition, elderly patients are at higher risk for adverse CNS (e.g. hallucinations, confusion) and cardiac events, potentially leading to falls or other sequelae.
Like other tricyclic drugs, cyclobenzaprine may rarely cause liver dysfunction. Cyclobenzaprine should be used with caution in patients with hepatic disease. Cyclobenzaprine is extensive metabolized by the liver to glucuronides. Peak plasma concentrations and AUC of cyclobenzaprine are nearly doubled in patients with hepatic impairment (15 of 16 patients studied had mild hepatic impairment). Cyclobenzaprine is not recommended for patients with moderate to severe hepatic impairment due to insufficient data. In patients with mild hepatic impairment, initiate therapy with 5 mg doses and titrate cautiously (see Dosage); less frequent dosing may be needed.
Cyclobenzaprine has not been found effective in the treatment of spasticity associated with cerebral or spinal cord disease, or in children with cerebral palsy. Safety and efficacy of cyclobenzaprine in children under the age of 15 years have not been established.
Studies for determining safe use of cyclobenzaprine during pregnancy have not been performed. Although the drug is classed as FDA pregnancy risk category B, it is closely chemically related to the tricyclic antidepressants. Animal studies of cyclobenzaprine have not noted an increased incidence of harm to the fetus. Patients should be told about the potential risks to the neonate; cyclobenzaprine therapy should be used during pregnancy only when clearly needed.
Use caution when administering cyclobenzaprine during breast-feeding. Cyclobenzaprine is closely chemically related to the tricyclic antidepressants (e.g., amitriptyline). Distribution of the drug into breast milk has not been established, but tricyclic drugs are known to be found in breast milk. Tricyclic drugs are generally listed by the American Academy of Pediatrics as drugs whose effect on the nursing infants are not known but may be of concern, particularly with prolonged exposure.
Cyclobenzaprine lowers the seizure threshold. Because of a potential increased risk of seizures, cyclobenzaprine should not be used during intrathecal radiographic contrast administration. Cyclobenzaprine therapy should be discontinued 48 hours before and not restarted until at least 24 hours after myelography.
Patients may be more prone to sunburn during therapy with cyclobenzaprine. Suitable precautions should be taken prior to sunlight (UV) exposure, such as using sunscreens and protective clothing.
[ Last revised: 10/7/2004 5:12:00 PM ]
References
. Beers MH. Explicit criteria for determining potential inappropriate medication use by the elderly: an update. Arch Intern Med 1997;157:1531 - 6.
. Fick DM, Cooper JW, Wade WE, et al. Updating the Beers criteria for potentially inappropriate medication use in older adults: results of a US consensus panel of experts. Arch Intern Med 2003;163:2716 - 24.
. Douglass MA, Levine DP. Hallucinations in an elderly patient taking recommended doses of cyclobenzaprine. Arch Intern Med 2000; 160:1373.
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