IN VITRO STUDIES INDICATE THAT TILUDRONIC ACID ACTS PRIMARILY ON BONE THROUGH A MECHANISM THAT INVOLVES INHIBITION OF OSTEOCLASTIC ACTIVITY WITH A PROBABLE REDUCTION IN THE ENZYMATIC AND TRANSPORT PROCESSES THAT LEAD TO RESORPTION OF THE MINERALIZED MATRIX.
BONE RESORPTION OCCURS FOLLOWING RECRUITMENT, ACTIVATION, AND POLARIZATION OF OSTEOCLASTS. TILUDRONIC ACID APPEARS TO INHIBIT OSTEOCLASTS THROUGH AT LEAST TWO MECHANISMS: DISRUPTION OF THE CYTOSKELETAL RING STRUCTURE, POSSIBLY BY INHIBITION OF PROTEIN-TYROSINE-PHOSPHATASE, THUS LEADING TO DETACHMENT OF OSTEOCLASTS FROM THE BONE SURFACE AND THE INHIBITION OF THE OSTEOCLASTIC PROTON PUMP.