XOLNIC 4mg Injection belongs to the class of medicines called 'bisphosphonates' used to treat osteoporosis (weak and brittle bones) caused by menopause or long-term steroid use. XOLNIC 4mg Injection also treats Paget?s bone and high calcium levels caused by cancer. Osteoporosis is a bone disease that weakens and thins bones by decreasing bone density, common in post-menopausal women. As the density of bones decreases, they weaken and are more likely to break. This Injection contains Zoledronic acid that works by binding to the bone tightly and preventing the removal of calcium by osteoclasts (a type of bone cell that destroys bone tissue). This prevents osteoclasts from breaking down the bone and keeps the bones strong and minimizes the risk of bones breaking.