Aprepitant reduces the levels of ethinylestradiol and norethisterone (given as a combined hormonal contraceptive). Greater effects were seen in another study when
dexamethasone was also given with
aprepitant. The hormones in
HRT are similar to those used in hormonal
contraceptives, and so may be affected by enzyme-inducing drugs in the same way. Note that fosaprepitant, a prodrug of
aprepitant, would also be expected to reduce
HRT levels.
Consider the possibility of reduced
HRT efficacy.