Clinical study of cinacalcet in Japan.

For the approval of cinacalcet hydrochloride, five clinical trials have been performed excluding pharmacokinetic studies for healthy volunteers and hemodialysis patients. An early phase II dose-finding study was started for regular hemodialysis patients with secondary hyperparathyroidism from a daily dose of 12.5 mg cinacalcet and increasing 25 mg up to 50 mg for 9 weeks. A placebo-controlled double-blind three dose-finding study (late phase II study) was then conducted. By this trial, an adequate initial dose of cinacalcet was determined as 25 mg daily, and the placebo-controlled double-blind study (phase III study) was started using this initial dose. Two long-term (1 year) phase III open trials were also conducted during and after these phase II and III studies. The results of two double-blind trials (phase II and phase III) and safety profiles of cinacalcet in all Japanese clinical trials for approval are summarized in this article.