Effects of long term treatment with high doses of odanacatib on bone mass, bone strength, and remodeling/modeling in newly ovariectomized monkeys

The objectives here were to evaluate the effects of odanacatib (ODN) at doses exceeding the clinical exposure on biomechanical properties of lumbar vertebrae (LV), hip and central femur (CF), and compare ODN to alendronate (ALN) on bone remodeling/modeling in ovariectomized (OVX) monkeys. Ten days post-surgery, animals were treated with vehicle (VEH), ODN-L (2mg/kg/day, p.o.), ODN-H (8/4mg/kg/day), or ALN (30μg/kg/week, s.c.) for 20months. An intact group was also included. ODN-L provided systemic exposures of 1.8-fold of clinical exposure. ODN-H started at 20-fold for 5.5months, and then reduced to 7.8-fold of clinical exposure, compared to ALN at approximated clinical exposure. From cross sectional analyses, LV density and peak load in ODN at both doses or ALN were not different from VEH or Intact. However, cortical thickness of femoral neck (FN) and CF in ODN were higher (21-34%, p<0.05) than VEH, due to smaller endocortical (Ec) perimeter of FN (10-11%; p<0.05) and CF (9-12%; ODN-L, p<0.05), and larger CF periosteal (Ps) perimeter (2-12%; ODN-H, p<0.001) versus VEH. ODN groups also showed slightly higher cortical porosity and Ps non-lamellar bone in CF. ODN-H treatment resulted in higher CF peak load (p<0.05) versus VEH. For all bone sites analyzed, a positive, linear relationship (r(2)=0.46-0.69, p<0.0001) of peak load to density or structural parameters was demonstrated. No treatment-related differences in the derived intrinsic strength properties were evidenced as compared between groups. ALN reduced all remodeling surfaces without affecting Ps modeling. Trabecular and intracortical remodeling were reduced in ODN groups, similar to ALN. Ec mineralizing surface in ODN-H trended to be lower than VEH by month 20, but Ec bone formation indices in ODN groups generally were not different from VEH. Ps modeling in ODN groups was significantly higher than other treatment groups. This study overall demonstrated the bone safety profile of ODN and its unique mechanism on cortical bone supporting the clinical application for osteoporosis treatment.

Contribution of B(2) receptors for bradykinin in arthus reaction-induced plasma extravasation in wild-type or B(2) transgenic knockout mice

The aim of the present study was to investigate the contribution of bradykinin (BK) B(1) and B(2) receptors in a model of type III hypersensitivity, the reverse passive Arthus reaction (RPA), in wild-type mice and transgenic B(2) knockout littermates. BK (10 microg mouse(-1)) or bovine serum albumin (0.5 mg mouse(-1)) induced a sustained Evans blue extravasation for more than 80 min in naive or rabbit anti-bovine serum albumin-treated mice (RPA model), respectively. The response to the two stimuli was prevented by the B(2) receptor antagonist, HOE-140, but not by [Leu(8)]desArg(9)-BK (B(1) receptor antagonist). In contrast to the wild-type littermates, RPA and bradykinin were unable to trigger an increase in plasma extravasation in B(2) knockout mice. Furthermore, endothelin-1 (5 microg mouse(-1)) and a selective NK-1 receptor agonist [Sar(9),Met (O(2))(11)]-SP (20 microg mouse(-1)), triggered a significant increase in peritoneal plasma extravasation in both wild-type and B(2) knockout animals. A pretreatment with indomethacin (200 microg mouse(-1)) significantly reduced the RPA-induced but not the BK-induced increase in Evans blue extravasation. Furthermore, RPA, but not BK, triggered a significant indomethacin-sensitive increase in peritoneal prostaglandin E(2) content. Our results suggest a pivotal role for B(2) receptors in the mechanism of plasma extravasation which occurs during the reverse passive Arthus reaction in the mouse. Moreover, our results suggest an important contribution of prostanoids in the plasma leakage mechanisms triggered by RPA but not by bradykinin.