Which of the following medications is NOT used for arthritis due to its anti-inflammatory effects?

Sulfisoxazole (Gantrisin) and nitrofurantoin (Macrodantin) are antibiotics. They are primarily used to treat bacterial infections and do not possess anti-inflammatory properties that would typically be beneficial for conditions like arthritis. In contrast, the other medications listed, such as ibuprofen, naproxen, sulindac, fenoprofen, and acetylsalicylic acid, all function as nonsteroidal anti-inflammatory drugs (NSAIDs). These medications reduce inflammation and relieve pain, making them common choices for treating arthritis. Therefore, the correct answer identifies medications that are not used for arthritis treatment due to their lack of anti-inflammatory effects.