The not-so-secret ingredients: nephrocaps consist of vitamins B1 (thiamine), B2 (riboflavin), B6, B12, folic acid, niacin, pantothenic acid, biotin, and a small dose of vitamin C.
You will note that these are all water-soluble vitamins. The fat-soluble vitamins (A,D,E, & K) are generally not a problem in ESRD patients (with the obvious exception of vitamin D, whose activated form is produced in the kidney) as the body has adequate stores of these and in fact supplementation with vitamin A, for instance, can cause toxicity. ESRD patients are often deficient in water-soluble vitamins for a number of reasons: poor oral intake, restricted protein diet, and the fact that many of these are dialyzed off during treatment. Nephrocaps are designed with these losses in mind.