ANTIHISTAMINES AND APREPITANT

Aprepitant can increase the levels of CYP3A4 substrates in the short-term, then reduce them within 2 weeks of concurrent use. Terfenadine and astemizole are metabolised by CYP3A4 and therefore their levels would be expected to be increased by aprepitant. This may increase the risk of life-threatening arrhythmias. Fosaprepitant, a prodrug of aprepitant, would be expected to interact similarly.
The manufacturers of aprepitant contraindicate concurrent use, and advise caution for the 2 weeks following the use of aprepitant.