Drugs used in paediatric bone and calcium disorders. Calcium and bone disorders in paediatrics are treated with a variety of drugs, many of which, although licensed for use in adults, are not so in children but are nevertheless used on the basis of accepted practice. The mainstay of drug treatment for osteoporosis is the bisphosphonates which alter the balance between bone accretion and reabsorption mainly by temporarily reducing the activity of osteoclasts. Vitamin D and its metabolites are used for the treatment of various forms of rickets and vitamin D deficiency and the active metabolites are also employed when hypoparathyroidism causes hypocalcaemia. Phosphate supplements may also be required in some forms of rickets. Hypercalcaemia is treated initially with hyperhydration and diuretics but may require more specific treatment with either calcitonin or bisphosphonates. Several newer drugs have either recently been introduced or are under consideration. These include the calcimimetics (cinacalcet), rank ligand inhibitors (osteoprotegerin and denusomab), cathepsin K inhibitor, sclerostin, bone morphogenic protein 2, and calciolytic drugs. More recently, recombinant alkaline phosphatase and PTH have been used to treat hypophosphatasia and hypoparathyroidism respectively. These developments promise to direct treatment more specifically to targeting individual conditions as our understanding of these conditions increases.