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Fluvoxamine Drug Interactions

Fluvoxamine drug interactions can be clinically significant in clinical practice. It is a major reason why this medication is not used very often. If you ever see it on a medication list of one of your patients, you must do a drug interaction screen. According to the package insert, fluvoxamine can inhibit CYP1A2, CYP2C9, CYP3A4, and CYP2C19. Let’s breakdown fluvoxamine drug interactions by covering the specific enzymes that the drug can inhibit.

Fluvoxamine Drug Interactions: CYP1A2

Clozapine, an antipsychotic, can have its concentrations significantly increased by a CYP1A2 inhibitor like fluvoxamine. In addition, propranolol and olanzapine are two drugs that I see used on occasion. Similar to clozapine, concentrations of propranolol and olanzapine would likely go up when we start or increase fluvoxamine.

CYP2C9

When I think of CYP2C9 inhibition, I can’t help but think about warfarin. The s-enantiomer is broken down by CYP2C9 and if we block the action of 2C9, we are likely to increase warfarin concentrations. Keep an eye out for bleeding and bruising risks.

CYP3A4

Numerous drugs are impacted by alterations in the CYP3A4 pathway. Of highest concern is often the group of anticoagulants. Many are broken down via CYP3A4 and fluvoxamine can potentially raise their concentrations.

CYP2C19

The most common CYP2C19 related interactions could potentially involve citalopram and (more likely) clopidogrel. Citalopram uses the CYP2C19 pathway for breakdown while clopidogrel requires 2C19 for activation. While we wouldn’t likely use two SSRIs together, there may be a situation where a cross taper from one to the other is tried. If that is the case, we need to recognize that elevated citalopram concentrations are possible.

Looking for more information on drug interactions? Check out my latest book: Clinician’s Guide to Common Drug Interactions in Primary Care (if you have never tried an Audible book, get the 10-hour book for free right here). It is also available as a Paperback and eBook.

Written By Eric Christianson

March 25, 2020

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