Aprepitant and fosaprepitant decrease the effectiveness of hormonal contraceptives

We read with interest the recent article entitled Aprepitant and fosaprepitant drug interactions: a systematic review 1 and would like to identify another very important but perhaps under‐appreciated drug interaction: administration of aprepitant/fosaprepitant has been found to decrease significantly the area under the concentration–time curve of ethinylestradiol by 43% while decreasing that of norethindrone (norethisterone) by 8% 2. If patients are not counselled appropriately, unintended pregnancy could result. The UK package leaflet for aprepitant recommends to patients using oral or nonoral hormonal contraceptives that “Another or additional non‐hormonal form of birth control should be used during treatment with [aprepitant] and for up to 2 months after using [aprepitant]” 3. This is echoed by the package leaflet for fosaprepitant 4. Additionally, in some countries outside the UK, aprepitant has been approved for the prevention of postoperative nausea and vomiting as well as chemotherapy‐induced nausea and vomiting; education about the need for backup contraception may be required for healthcare workers in settings far removed from the chemotherapy infusion centre. A recent practice audit at our own institution found that of 13 905 doses of aprepitant and fosaprepitant administered over a 12‐month span, 1606 doses (12%) were given during the perioperative period. To help protect patients from the risk of unintended pregnancy, the hospital system's electronic medical record has been programmed to automatically insert the relevant precautions into the printed discharge instructions given to patients who have received these medications. Nurses have also been encouraged to counsel verbally these patients upon discharge. The same precautions have been instituted for the anaesthetic medication sugammadex, which has a similar (although shorter‐lived) interference with hormonal contraceptives. If these precautions are not followed, aprepitant/fosaprepitant may have longer‐lasting side effects than are commonly appreciated 5.

Nomenclature of targets and ligands

Key protein targets and ligands in this article are hyperlinked to corresponding entries in http://www.guidetopharmacology.org, the common portal for data from the IUPHAR/BPS Guide to PHARMACOLOGY 6, and are permanently archived in the Concise Guide to PHARMACOLOGY 2017/18 7.

Competing Interests

There are no competing interests to declare.

Bailard, N. , and Rebello, E. (2018) Aprepitant and fosaprepitant decrease the effectiveness of hormonal contraceptives. Br J Clin Pharmacol, 84: 602–603. doi: 10.1111/bcp.13472.