Flexeril Disease Interactions

The manufacturers consider the use of cyclobenzaprine to be contraindicated in the acute recovery phase following myocardial infarction and in patients with hyperthyroidism, congestive heart failure, arrhythmias, heart block, and/or conduction disturbances. Cyclobenzaprine is structurally related to the tricyclic antidepressants, which have been reported to cause tachycardia, arrhythmias, heart block, hypertension, hypotension (particularly orthostatic hypotension), thrombosis, thrombophlebitis, myocardial infarction, strokes, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation. Therapy with cyclobenzaprine should be administered cautiously in patients with a history of cardiovascular or cerebrovascular disease or a predisposition to hypotension, particularly if the intended dosage exceeds those normally used for musculoskeletal conditions. Tachycardia, arrhythmia, palpitation, and hypotension have been reported with the use of cyclobenzaprine in less than 1% of patients.

Cyclobenzaprine has anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with cyclobenzaprine should be administered cautiously in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Glaucoma should be treated and under control prior to initiation of cyclobenzaprine therapy, and intraocular pressure monitored during therapy.