digoxin + vandetanib

This is a **combination of two small-molecule pharmaceuticals: digoxin and vandetanib**. Digoxin is a cardiac glycoside used to treat various heart conditions, including atrial fibrillation and heart failure, by inhibiting the sodium-potassium ATPase and thereby increasing intracellular calcium in cardiac cells. Vandetanib is an oral antineoplastic agent, characterized as a tyrosine kinase inhibitor, indicated for the treatment of medullary thyroid cancer and targets vascular endothelial growth factor receptor 2 (VEGFR-2), epidermal growth factor receptor (EGFR), and rearranged during transfection (RET) tyrosine kinases. While this combination is not marketed as a fixed-dose product, drug-drug interaction studies in healthy volunteers show that vandetanib increases plasma concentrations of digoxin due to inhibition of P-glycoprotein (P-gp), possibly increasing the risk of adverse cardiovascular effects such as QTc prolongation and bradycardia. Patients receiving both agents may require additional clinical and ECG monitoring, and dose adjustments of digoxin are recommended due to this interaction[1][2][6].