Vitamin ad refers to a large class of substances containing cyclopentadienyl phenanthrene ring structure and with calciferol biological activity. Yikexin is a compound preparation containing vitamin A and vitamin D2.

2. Yikexin is involved in maintaining intracellular and extracellular calcium concentration and regulating calcium and phosphorus metabolism. Compared with Yikexin, vitamin AD drops contain more vitamin A in the main components, which is used to prevent and treat vitamin A and D deficiency.