Alendronate is in the group of medicines called bisphosphonates (bis FOS fo nayts). It alters the cycle of bone formation and breakdown in the body. Alendronate slows bone loss while increasing bone mass, which may prevent bone fractures. Cholecalciferol is a form of vitamin D, and is important for the absorption of calcium from the stomach and for the functioning of calcium in the body. Alendronate and cholecalciferol is used to treat and prevent osteoporosis. Alendronate and cholecalciferol may also be used for purposes not listed in this medication guide. You should not take this medicine if you have low levels of calcium in your blood (hypocalcemia), or a problem with the movement of muscles in your esophagus.