drug by chitosan the chitosan phosphonate salt could be embedded in chitosan for further delay of drug release the treatment with the controlled release delivery system is utilized by subdermal implantation as was done in fig1 or by site specific implantation with the aim being optimization of therapy using lower dosage minimizing systemic side effects and effective prolonged treatment with better patient compliance the novel bisphosphonates according to the present invention prevent calcium precipitation from metastable calcium and phosphate solution profound inhibition of rat subdermal bioprosthetic heart valve tissue calcification was achieved by coimplantion of alzet osmotic pumps releasing the drug and tissue cusps therapy was achieved without side effects as exhibited by the normal somatic growth these in vivo results are summarized in fig1 the novel bisphosphonates according to the present invention are useful in the treatment of the following diseases osteoporosis including disuse and postmenopausal osteoporosis hypercalcemia of malignancy direct anticancer effect heterotopic ossification hip arthroplasty spinal cord injury myositis ossificans paget 39 s disease hyperphosphatemia e g diabetes it can be seen that said compounds are useful not only for direct treatment of various diseases but also for treatment of the symptoms of the diseases e g hyperphosphatemia or hypercalcemia the compounds according to the present invention are also useful as diagnostics e g nuclear medicine the compounds according to the present invention may possess also industrial applications which are listed below r l hilderbrand the role of phosphonates in living systems chapter 7 page 172 crc press adhesives agents for extraction concentration and purification of uranium thorium and plutonium antioxidants antistatic agents blowing agents catalysts corrosion inhibitors coupling agents crystallization inhibitors dentifrice compositions deodorants detergent additives detergents for cleaning metal surfaces.