Drugs eliminated by tubular secretion include cimetidine and procainamide.
It is obvious that dose adjustments are necessary for those drugs that are eliminated renally. A creatinine clearance must be calculated for each patient. It is important to note that many of the equations used to predict renal function are much less accurate in predicting renal function in the elderly. This is due primarily to an age-related decline in creatinine production and loss of lean body mass that produces lower than expected serum creatinine levels. In many cases, over-estimation of renal function occurs.