Nightmares and hallucinations with aprepitant and opium powder: a suspected drug-drug interaction.

Polypharmacy of elderly oncology patients and fragmented medication management are well-known risk factors for drug-drug interactions (DDIs). These interactions can occur among antineoplastic, ongoing chronic treatment(s) and chemotherapy-associated treatments, like antiemetics. Clinically relevant interactions based on enzyme- or transporter-inhibition phenomena of active drugs can increase the frequency of their DDIs. We describe a strongly suspected elderly cancer patient's DDI between aprepitant and opium powder in the context of an irinotecan-based regimen manifested by nightmares and visual hallucinations. We discuss this DDI's hypothetical pharmacological mechanisms and management.