Two new medications called Bosaya and Aukelso just became available across the United States, offering more affordable options for the estimated 10 million American adults living with osteoporosis and over 330,000 patients annually dealing with bone loss from advanced cancer. These drugs work by blocking a protein that causes bone breakdown, helping patients maintain stronger bones and reduce fracture risk. The medications received FDA approval in September 2025 with an interchangeable designation, meaning pharmacists can substitute them for the original brand-name versions at the pharmacy level.

What Are These New Medications and How Do They Work?

Bosaya and Aukelso are biosimilars, which means they're highly similar copies of existing bone-health medications that have been on the market for years. The original versions generated approximately 5 billion dollars in U.S. sales in 2024, reflecting just how common bone loss has become. Both new drugs contain denosumab, a human monoclonal antibody that targets a protein called RANKL . RANKL is essential for the formation and function of osteoclasts, which are the cells responsible for breaking down bone. By blocking RANKL, these medications reduce bone resorption, allowing bone mass and strength to increase over time.

Bosaya comes as a 60 mg injection in a prefilled syringe for subcutaneous use, while Aukelso is available as a 120 mg injection in a single-dose vial. Both are now available by prescription through specialty pharmacies and healthcare providers nationwide .

Who Needs These Medications and Why Does It Matter?

The scale of bone disease in America is substantial. One in two women and up to one in four men over age 50 will break a bone in their lifetime due to osteoporosis . Beyond osteoporosis, these medications address bone complications from advanced cancer. Bone metastases, which occur when cancer spreads to the bones, affect more than 330,000 patients annually in the United States and can significantly impair quality of life and increase healthcare burden . The medications also treat giant cell tumor of bone, a rare but locally aggressive benign tumor that primarily affects young adults and can cause severe pain, fractures, and disability.

The arrival of biosimilar versions matters because they typically cost less than brand-name medications, potentially expanding access to treatment for patients who might otherwise struggle with affordability. With 44 million Americans at risk due to low bone density in addition to the 10 million already diagnosed with osteoporosis, the need for accessible treatment options is urgent .

Important Safety Information and Monitoring Requirements

While these medications are effective, they do come with important safety considerations that patients and healthcare providers need to understand. The most significant concern involves patients with advanced chronic kidney disease, who face a greater risk of severe hypocalcemia, a dangerous drop in blood calcium levels. Severe hypocalcemia can result in hospitalization, life-threatening events, and in rare cases, fatal outcomes . Patients with chronic kidney disease-mineral bone disorder face markedly increased risk and should receive treatment only under supervision by a healthcare provider with expertise in managing this condition.

Before starting either medication, healthcare providers must correct any existing low calcium levels and ensure patients receive adequate calcium and vitamin D supplementation throughout treatment. Patients should not receive other denosumab products at the same time, and those taking calcimimetic drugs may face increased hypocalcemia risk .

Steps to Take If You're Considering These Medications

• Schedule a Bone Density Test: If you're over 50 or have risk factors for osteoporosis, ask your doctor about a bone density scan to determine if treatment is appropriate for your situation.
• Discuss Your Kidney Function: Inform your healthcare provider about any kidney disease or kidney-related conditions, as this significantly affects whether these medications are safe for you.
• Ensure Adequate Calcium and Vitamin D: Before starting treatment, work with your doctor to establish baseline calcium and vitamin D levels and commit to supplementation as recommended during therapy.
• Monitor for Side Effects: Report any signs of infection, severe bone or joint pain, jaw problems, or unusual thigh or groin pain to your healthcare provider immediately, as these can indicate serious complications.
• Plan for Ongoing Supervision: If you discontinue the medication, your doctor should transition you to another bone-protective medication to prevent multiple vertebral fractures that can occur after treatment stops.

Other reported side effects vary depending on the condition being treated. For postmenopausal osteoporosis, the most common adverse reactions occurring in more than 5 percent of patients included back pain, pain in the extremities, high cholesterol, musculoskeletal pain, and urinary tract infections . For male osteoporosis, back pain, joint pain, and upper respiratory infections were most common. Patients receiving these medications for bone loss due to cancer hormone therapy most frequently experienced joint pain and back pain .

"The U.S. introduction of Bosaya and Aukelso marks a strategic expansion of our biosimilars portfolio, building on our established leadership in oncology and immunology. These therapies broaden access to high-quality, affordable treatment options for patients living with serious bone conditions," said Shreehas Tambe, CEO and Managing Director at Biocon Limited.

Shreehas Tambe, CEO and Managing Director, Biocon Limited

What This Means for the Future of Bone Health Treatment

The launch of these biosimilar medications represents a significant shift in bone health treatment accessibility. With denosumab products generating 5 billion dollars in annual U.S. sales, the introduction of more affordable alternatives could help millions of patients who currently cannot afford or access these life-changing therapies. The interchangeable designation means patients may not even need to request the biosimilar version; their pharmacist can automatically provide it unless their doctor specifically requires the brand-name product .

For the estimated 10 million Americans with osteoporosis and the hundreds of thousands facing bone loss from cancer, these new options offer hope for better fracture prevention and improved quality of life. However, treatment decisions should always be made in consultation with a healthcare provider who understands your individual health situation, particularly if you have kidney disease or other complicating factors. The key takeaway is that effective bone-building treatment is becoming more accessible, but it requires careful medical supervision to ensure safety and effectiveness.