Drug Interaction Report

The use of vandetanib with proton pump inhibitors may theoretically reduce its gastrointestinal absorption. Vandetanib exhibits pH-dependent solubility, with increased solubility at lower pH. The clinical significance is unknown. In healthy subjects, no clinically significant changes in the Cmax and AUC of vandetanib occurred, after coadministration of a single dose of vandetanib with five daily doses of omeprazole, or after coadministration of a single dose of vandetanib and two doses of ranitidine 12 hours apart. Dose adjustments are not required when vandetanib is administered with omeprazole or ranitidine.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.