Femara 2,5 mg Orifarm

Description

Overdose

Isolated cases of letrozole overdose have been reported.
No specific treatment for overdose is known. Symptomatic and supportive treatment is indicated. Letrozole is excreted from plasma by haemodialysis.

Interactions

Letrozole is mainly metabolised in the liver with the cytochrome P450 isoenzymes CYP3A4 and CYP2A6. Therefore, systemic excretion of letrozole may be affected by medicinal products that interact with these isoenzymes. The metabolism of letrozole is insensitive to the CYP3A4 isoenzyme, as saturation of this enzyme only occurs at a plasma concentration of letrozole 150 times higher than its equilibrium concentration when the drug is used in a standard clinical situation.

Drugs leading to increased serum letrozole concentrations:

Inhibitors of the CYP3A4 and CYP2A6 isoenzymes may inhibit the metabolism of letrozole, increasing its serum concentration. Concomitant use of potent inhibitors of these isoenzymes (for the CYP3A4 isoenzyme, these include e.g. ketoconazole, itraconazole, voriconazole, ritonavir, clarithromycin and telithromycin; for the CYP2A6 isoenzyme, methoxsalen) may lead to increased exposure to letrozole. Caution should be exercised when using letrozole concomitantly with potent inhibitors of the CYP3A4 and CYP2A6 isoenzymes.