Eldecalcitol

Eldecalcitol is an active vitamin D analogue used for osteoporosis in Japan. Its usual dose is 0.75 μg/day, but calcium-related adverse effects can become clinically important when reduced kidney reserve, frailty, low body weight, poor intake, dehydration risk, interacting medicines, or unreliable follow-up coexist. This narrative review synthesizes trial, post-marketing, pharmacovigilance, and real-world monitoring evidence to define a practical safety framework. Eldecalcitol reduces vertebral fractures compared with alfacalcidol, whereas hip-fracture protection has not been established; therefore, its role should be determined by the patient's fracture pattern, treatment objective, kidney function, and availability of alternatives with established hip-fracture efficacy. Before treatment, clinicians should confirm osteoporosis, measure total serum calcium with albumin (and use albumin-adjusted calcium where appropriate), and assess serum creatinine with reported eGFR. Primary hyperparathyroidism and other metabolic bone disorders should be considered when baseline findings are atypical. Creatinine-based eGFR is the pragmatic minimum standard; cystatin C is most useful when low muscle mass or discordance makes kidney reserve uncertain. A lower dose of 0.5 μg/day is a dose-adjustment or re-challenge option after calcium normalization; it does not remove the need for calcium surveillance and clinical reassessment, and long-term fracture-prevention efficacy at that dose is not established. Eldecalcitol should be withheld during poor intake, dehydration, or acute illness and reconsidered when calcium rises or kidney function deteriorates. Safe use therefore requires risk-based selection rather than passive routine-dose prescribing, planned biochemical follow-up, and explicit treatment reassessment.