Fendiline hydrochloride is primarily used in research settings to study calcium channel blocking mechanisms. It has been investigated for its potential effects on smooth muscle relaxation, which could be relevant in conditions like hypertension or angina. Additionally, it has been explored for its role in inhibiting cancer cell proliferation, particularly in leukemia, due to its ability to interfere with calcium signaling pathways. Its application in cardiovascular and oncological research highlights its potential therapeutic value, though it is not widely used in clinical practice.