Drate plus D

At the cellular level, alendronate shows preferential localization to sites of bone resorption, specifically under osteoclasts. The osteoclasts adhere normally to the bone surface but lack the ruffled border that is indicative of active resorption. Alendronate does not interfere with osteoclast recruitment or attachment, but it does inhibit osteoclast activity. While incorporated in bone matrix, alendronate is not pharmacologically active. Thus, alendronate must be continuously administered to suppress osteoclasts on newly formed resorption surfaces. Cholecalciferol (vitamin D3) is formed in the skin under influence of UV rays and metabolized in two hydroxylation steps at first in the liver and then in the kidney tissue into the biological active metabolite 1,25-dihydroxy-cholecalciferol. 1,25-dihydroxy-cholecalciferol is involved fundamentally in the regulation of the calcium and phosphate balance together with parathyroid hormone and calcitonin.