Drug interactions between Flexeril and Prozac
| Results for the following 2 drugs: |
|---|
| Flexeril (cyclobenzaprine) |
| Prozac (fluoxetine) |
Interactions between your selected drugs
fluoxetine ↔ cyclobenzaprine
Applies to:Prozac (fluoxetine) and Flexeril (cyclobenzaprine)
MONITOR: A case report suggests that coadministration of cyclobenzaprine and fluoxetine may prolong QT interval of the electrocardiogram. The authors theorize that fluoxetine may inhibit the CYP450 3A4 metabolism of cyclobenzaprine, resulting in increased plasma concentrations of cyclobenzaprine and its dose-related cardiac effects. In the report, a 59-year-old woman who had been receiving long-term fluoxetine (30 mg daily) and cyclobenzaprine (10 mg daily) therapy demonstrated a prolonged baseline QTc (i.e., QT interval corrected for heart rate) of 497 msec five days prior to admission for surgery. Her other medications included amlodipine, diclofenac, and triamterene/HCTZ. During surgery, the patient developed torsade de pointes and then ventricular fibrillation presumably induced by the preoperative administration of droperidol, a drug with well-known QT prolonging and proarrhythmic effects. The patient had no known history of cardiac problems except for hypertension, and other potential causes such as congenital long QT syndrome and electrolyte abnormalities were ruled out. She received defibrillation and cardiopulmonary resuscitation, and QT interval returned to normal after the discontinuation of cyclobenzaprine and droperidol.
MANAGEMENT: Until further data are available, caution is advised when cyclobenzaprine is used concomitantly with fluoxetine. Any drug that can prolong the QT interval should be avoided with this combination. Patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, palpitations, or syncope.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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