selpercatinib + ranitidine

This is a combination of **selpercatinib**, a selective small molecule RET tyrosine kinase inhibitor used for RET-driven cancers, and **ranitidine**, a histamine H2-receptor antagonist used primarily for reducing gastric acid secretion. Selpercatinib inhibits RET and other kinases to prevent tumor growth; ranitidine acts by reversibly inhibiting the histamine H2-receptors of gastric parietal cells, thereby suppressing gastric acid production. This combination is not marketed as a fixed-dose product but refers to co-administration of both drugs, which is clinically relevant because ranitidine (an H2 antagonist) can reduce selpercatinib's serum concentration, likely by raising gastric pH and altering selpercatinib absorption[2][3]. Selpercatinib is developed for RET fusion-positive cancers (e.g., non-small cell lung cancer, medullary thyroid cancer, other RET fusion solid tumors)[1][2]. Ranitidine is developed and marketed for treatment of peptic ulcer disease and gastroesophageal reflux disease.