With Zolidd®, a tiny dose of a bisphosphonate is given locally. Local administration of a drug is generally advantageous because it greatly reduces the amount of drug needed for a good effect. It is particularly so for bisphosphonates and the bisphosphonates high affinity for bone ensures that it preferentially targets the site of interest, i.e. the immediate vicinity of the implant, thereby avoiding systemic exposure.
Bisphosphonates are a class of drugs used in a group of patients to strengthen their bone, and so reduce the risk of bone fractures. They are used in various metabolic bone disorders, including hypercalcemia of malignancy, tumor osteolysis, Paget’s disease and postmenopausal osteoporosis. These drugs are derivatives of inorganic pyrophosphate and strongly bind to hydroxyapatite crystals in the skeleton. They have a long half-life in the skeleton and are preferentially incorporated and accumulated at sites of accelerated bone turnover. Bisphosponate act in an inhibitory action of osteoclast cells in bone, which are responsible for the breakdown and turnover of bone, with possible stimulatory activity to enhance osteoblast activity involved in bone synthesis. The overall effect is to enhance formation of new bone in areas of weakness.
Accordingly, there is a consequent improvement in the mechanical properties of bone as well as a reduced risk of fracture. Second- and third-generation bisphosphonates have nitrogen-containing side chains and are actually the agents most commonly used for treatment of osteoporosis. In Europe, the bisphosphonates approved for osteoporosis treatment and prevention includes oral alendronate, risedronate and ibandronate and intravenous (IV) ibandronate and zoledronic acid.