Berberine With Femara Interaction Details

Answer

Hello, and thanks for reaching out!

Our HelloPharmacist Drug-Herbal Interaction Checker lists a potential interaction between berberine and letrozole, so it's important to be cautious.

The interaction is classified as Moderate in severity. You can find more details here: Berberine - Letrozole Interaction Details | HelloPharmacist.

Details

Femara (letrozole) is partially metabolized in the body by an enzyme called CYP3A4, as described in the drug's prescribing information:

In human microsomes with specific CYP isozyme activity, CYP3A4 metabolized letrozole to the carbinol metabolite, while CYP2A6 formed both this metabolite and its ketone analog.

Laboratory and clinical research suggest that berberine may moderately inhibit CYP3A4. This inhibition may slow down the metabolism of letrozole, potentially leading to higher levels of the drug. Elevated levels can increase the risk of side effects without necessarily enhancing the drug's effectiveness.

One study referenced on our interaction page (Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study - PubMed) investigated berberine's effect on the concentrations of cyclosporin A, an immunosuppressant also metabolized by CYP3A4.

The study found that berberine can significantly elevate cyclosporin A blood levels, likely due to CYP3A4 inhibition in the liver and/or small intestine.

While I could find no specific studies on the combined use of berberine and letrozole, considering how letrozole is metabolized and berberine's potential effects, it's best to avoid their combined use. At a minimum, discuss this combination with your doctor.

Final Words

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