Professor Ian R. Reid
MD FRSNZ
Endocrinologist and Distinguished Professor, The University of Auckland, NZ Ian Reid is an endocrinologist and Distinguished Professor at the University of Auckland. His research interests include calcium metabolism, vitamin D, osteoporosis and Paget’s disease. He has worked extensively in the development of the bisphosphonates for use in osteoporosis and Paget’s disease, and also on the safety and efficacy of calcium supplements, vitamin D deficiency and supplementation, and has been involved in development of most new osteoporosis treatments in the last 30 years. He is a past-president of the International Bone and Mineral Society (IBMS) and the Australian & New Zealand Bone & Mineral Society (ANZBMS), and recipient of research awards from the European Calcified Tissue Society, the American Society of Bone and Mineral Research, the ANZBMS and the New Zealand Prime Minister’s Science Prize.
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Zoledronate and Denosumab
Zoledronate and denosumab are the two most potent anti-resorptive drugs used in the treatment of osteoporosis. Their chemical structures and modes of action are quite distinct, zoledronate being a bisphosphonate and denosumab a monoclonal antibody. Zoledronate has a duration of action of up to a decade whereas denosumab acts for about six months before having a rapid offset. In the doses used clinically, denosumab is a much more potent inhibitor of bone resorption than zoledronate, but their anti-fracture efficacies are similar. Zoledronate cannot be used in patients with an eGFR <30 mL/min, and it causes an acute phase response in about 30% of treatment-naïve patients. Denosumab does not adversely impact on renal function but can cause severe hypocalcaemia in those with low eGFR. The most concerning adverse effect of denosumab is its rapid offset anti-resorptive effect after six months after the last injection, which can result in clusters of vertebral fractures. denosumab is associated with low frequencies of ONJ and AFFs, and these seem to be even lower in zoledronate users. Both are now available as generics, with the cost of zoledronate now about $30. Patterns of use of both agents are evolving, with zoledronate showing great promise in long-term maintenance of fracture prevention.