A Cremophor solvent reaction is a hypersensitivity reaction (HSR) triggered by Cremophor EL, the polyoxyethylated castor oil used as a vehicle for drugs like paclitaxel.
These reactions are primarily attributed to the excipient (solvent) rather than the chemotherapy agent itself. They typically occur within the first few cycles—often the very first dose—and can range from mild flushing to severe anaphylaxis. To mitigate this risk, clinical protocols mandate a mandatory premedication triplet of dexamethasone, an H1-antagonist (diphenhydramine), and an H2-antagonist (like famotidine) administered prior to the infusion.
