Effects of novel cathepsin K inhibitor ONO-5334 on bone resorption markers: a study of four sustained release formulations with different pharmacokinetic patterns

The purpose of the study was clarify the effect of the cathepsin K inhibitor ONO-5334 on bone resortion markers using sustained release (SR) formulations with different pharmacokinetic (PK) patterns, and identify the optimal SR formulation. The PK profiles and pharmacodynamic effect on bone resorption markers of 4 SR candidates formulations were evaluated in healthy postmenopausal women within a randomized, 2-part, open-label crossover study. In Part A, subject received a single dose of each formulation orally in the fed state. In Part B, two selected formulations were evaluated in the fasted state. From the results from Part A, C _max was reduced and plasma concentrations of ONO-5334 were sustained with all SR formulations compared with an immediate release tablet. In pharmacodynamics, the level of C-terminal telopeptide of type I collagen (CTX) in serum and urine were inhibited with SR tablets rather than with granules. C _max and area under the concentration–time curve from time 0 to the last measurable time point (AUC_0?t ) of SR tablets were higher than those of granules. From Part B, C _max in the fasted condition was lower than that in the fed condition with two SR tablets. In contrast, C _{24 h} in the fasted condition was slightly higher than that in the fed condition, but AUC_0?t was similar. The inhibitory effect on CTX in serum and urine may depend on the PK pattern of ONO-5334. The SR tablets was well tolerated in postmenopausal women and has the optimal SR profiles on pharmacodynamics effect on bone resortion markers and PK profile. These results suggest that SR tablets of ONO-5334 are an excellent drug candidate for osteoporosis.