Jon Campbell publishes a newsletter on alt. health and has researched vitamin c's ability to protect the liver and kidey from NSAIDS overdoses. (He has shared with me some remarkable antedotes .) His home page is
but I can't find the NSAIDS material. You might contact him.
In addition to high sustained bowel tolerance ascorbic acid, I'd be thinking CoQ10 (200 to 600 mg) and Unique-E (2000 iu) to improve kidney function, perhaps by regrowing "dead" tissue. Again, you can send me a private message and I can share more on stimulating stem cells to regrow tissue.