A 67-year-old female with osteoarthritis has worsening knee pain and reduced renal function. Which medication is most appropriate for long-term pain management?

• A. Naproxen
• B. Prednisone
• C. Acetaminophen
• D. Methotrexate

Answer: (C)

For long-term pain control in an older patient with osteoarthritis and reduced kidney function, prioritize a medication that relieves pain without harming renal function or causing serious systemic side effects. Acetaminophen fits this need because it provides analgesia through central mechanisms and does not impair renal blood flow or increase the risk of renal injury, which makes it safer for chronic use when kidney function is limited. It also avoids the gastrointestinal bleeding and blood pressure effects commonly associated with NSAIDs.

In contrast, NSAIDs like naproxen can worsen kidney function by reducing prostaglandin-mediated renal perfusion and carry higher risks of GI ulcers, particularly in older adults with CKD. Prednisone, while it can reduce inflammation and pain, has significant long-term risks such as osteoporosis, hyperglycemia, hypertension, mood changes, and increased infection risk, making it a poor choice for chronic OA management. Methotrexate targets inflammatory arthritis and has its own potential hepatotoxicity and bone marrow suppression; it’s not a standard treatment for osteoarthritis pain.

Thus, acetaminophen emerges as the best long-term option in this scenario, with careful dosing to protect the liver (and avoidance in significant liver disease or heavy alcohol use) and consideration of non-pharmacologic therapy or other options if pain persists.