Transient increase in international normalized ratio (INR) and bleeding risk following Alendronate sodium in elderly patients on warfarin: Two case reports

INTRODUCTION: Alendronate sodium is used to reduce the risk of bone fracture in aged osteoporosis patients. However, its side effects should be recognized, especially for those aged patients with one or more basic cardiovascular diseases. PATIENT CONCERNS: A 90-year-old and a 75-year-old male patient were admitted to our department. These 2 patients were examined by dual energy X-ray absorptiometry (DXA). DIAGNOSIS: Both patients were diagnosed with osteoporosis, they also had history of atrial fibrillation (AF) and had long term use of warfarin. INTERVENTIONS: Alendronate sodium was prescribed to the two patients at 70 mg once a week. OUTCOMES: The 2 patients had experienced dramatic increase of international normalized ratio (INR) to 4.69∼4.86 within 24 hours and gradual decrease in the next 5 days. Both patients experienced spontaneous ecchymoses and petechiae in the skin at the first 72 hours. CONCLUSION: Alendronate sodium can transiently increase the INR over 50%, induce spontaneous ecchymoses and petechiae in the skin of aged male osteoporosis patients with AF who took warfarin. Clinicians should pay enough attention when using alendronate sodium on these kinds of patients and be aware of the consequent potential bleeding risk.