Zofran and CYP2D6 drugs

Zofran (Ondansetron) is used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery. It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.

Zofran is broken down in the liver by on of the Cytochrome P450 enzymes, CYP2D6 - which metabolizes approximately 25% of current drugs.
Certain versions of CYP2D6 result in the poor metabolizer phenotype, characterized by a decreased ability to metabolize the enzyme's substrates.

Related to:
Zuplenz, Ondansetron