cyclobenzaprine, Flexeril, Amrix

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GENERIC NAME: cyclobenzaprine

BRAND NAME: Flexeril, Amrix

DRUG CLASS AND MECHANISM: Cyclobenzaprine is a muscle relaxant. Specifically, cyclobenzaprine relieves muscle spasm when the spasm is due to local problems, that is, in the muscle itself and not in the nerves controlling the muscles. Cyclobenzaprine has no effect on muscle function. Cyclobenzaprine seems to accomplish its beneficial effect through a complex mechanism within the nervous system, probably in the brainstem. The FDA approved cyclobenzaprine in August 1977.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 5 and 10 mg. Capsules (Extended Release): 15 and 30 mg.

STORAGE: Tablets should be stored between 15-30 C (59-86 F).

PRESCRIBED FOR: Cyclobenzaprine is used with rest and physical therapy for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. It is only for short-term use, up to two or three weeks.

DOSING: The recommended dose of cyclobenzaprine dose is 5 or 10 mg three times daily using immediate release tablets or 15 or 30 mg once daily using extended release tablets.

DRUG INTERACTIONS: Cyclobenzaprine is chemically related to the tricyclic class of antidepressants (for example, amitriptyline [ Elavil, Endep], nortriptyline [ Pamelor]). As such, it should not be taken with or within two weeks of any monoamine oxidase (MAO) inhibitor, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane). High fever, convulsions, and even death can occur when these drugs are used together. Additionally, cyclobenzaprine interacts with other medications and drugs that slow the brain's processes, such as alcohol, barbiturates, benzodiazepines (for example, diazepam [Valium], lorazepam [ Ativan]), and narcotics.

PREGNANCY: There are no adequate studies of cyclobenzaprine in pregnant women. However, studies in animals suggest no important effects on the fetus. Cyclobenzaprine therefore can be used in pregnancy if the physician feels that it is necessary.

NURSING MOTHERS: It is not known whether cyclobenzaprine is secreted in milk. However, since it is related to the tricyclic antidepressants, some of which are excreted in breast milk, caution is advised in using this medication in women who are breastfeeding.

SIDE EFFECTS: Common side effects of cyclobenzaprine include drowsiness, dry mouth, fatigue, headaches, and dizziness. Other reported side effects include nausea, constipation, blurred vision, unpleasant taste, nervousness, confusion, acid reflux, and abdominal pain or discomfort. Abrupt cessation after prolonged therapy may cause withdrawal symptoms such as headaches, nausea, and weakness.

Reference: FDA Prescribing Information


Last Editorial Review: 7/28/2010




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