Integrated physicochemical and therapeutic assessment of bovine hydroxyapatite–gelatin–vitamin D₃–chondroitin sulfate capsules in a rabbit osteochondral defect model with OA-like changes

Osteoarthritis (OA) is a degenerative joint disease marked by cartilage degradation and subchondral bone remodeling, while most nutraceuticals focus on cartilage and overlook bone health. We developed a capsule containing bovine hydroxyapatite (BHA), gelatin, vitamin D₃, and chondroitin sulfate and evaluated its physicochemical quality and in vivo effectiveness. Formulations were tested for organoleptic properties, moisture, weight uniformity, disintegration time, microbial contamination, heavy metals, and active-ingredient identification in accordance with Indonesian Food and Drug Agency regulations; all specifications were met. Efficacy was assessed in a rabbit osteochondral defect model (post-traumatic degeneration/repair model) with negative control, positive control, and test groups treated for 28 days, followed by radiography, histology (H&E quantification of osteoblasts, osteoclasts, osteocytes, and chondrocytes), and immunohistochemistry (type II collagen and MMP-13). Compared with untreated controls, the test group showed improved cartilage architecture, higher osteoblast, osteocyte, and chondrocyte counts, fewer osteoclasts, increased type II collagen expression, and reduced MMP-13, with outcomes comparable or superior to the positive control. These findings indicate the formulated nutraceutical supports both cartilage and subchondral bone and may serve as a complementary strategy for OA management, warranting confirmation in longer, dose-responsive, and translational studies.