Sodium etidronate (Didronel) is a synthetic therapeutic diphosphonate analog of endogenous pyrophosphate. As a member of the family of drugs known as bisphosphonates, Sodium etidronate differs from endogenous pyrophosphate in its resistance to enzymatic hydrolysis. This agent adsorbs to hydroxyapatite cells and reduces the number of osteoclasts, thereby inhibiting abnormal bone resorption. Etidronate may also directly stimulate bone formation by osteoblasts.

Etidronic acid (HEDP) is a diphosphonate which affects calcium metabolism. It inhibits ectopic calcification and slows down bone resorption and bone turnover.

Osteoprotegerin is a soluble secreted member of the tumor necrosis factor receptor superfamily, inhibiting osteoclastogenesis by interrupting the signaling between stromal cells and osteoclastic progenitor cells, leading to excess accumulation of bone and cartilage.