Vandetanib is a chemotherapy drug that is prescribed to thyroid cancer patients. It is generally used in patients who have inoperable cancer of the thyroid gland or whose cancer has spread to other parts of the body. This medication works by inhibiting a protein that signals cancer cells to multiply so that cancer cells stop growing.
This medication can cause a serious irregularity in the heartbeat called QT prolongation. This heart problem causes fainting and seizures; it can also cause sudden death. Patients who have a history of heart disease, heart failure or heart arrhythmias should not take this medication. In addition, patients who have an inherited condition called long QT syndrome are more likely to have QT prolongation if they take this medication.