Triamterene and renal lithiasis: a review.

A small number of patients taking products containing triamterene (TAT) develop renal calculi that contain TAT and its metabolites. Most TAT-containing calculi are composed of various crystalline materials, but a small number consist only of TAT, its metabolites, and a protein matrix. Calculi form as the drug binds to the protein matrix. In patients receiving TAT therapy, the incidence of calculi consisting of TAT and its metabolites ranges from 1 in 1,500 to 1 in 2,000 patients. No clear "dose-effect" relationship between TAT use and renal lithiasis has been established, and no correlation between the duration of TAT therapy and the formation of renal calculi has been found. Patients with a propensity for renal calculi formation, based on previous occurrence or family history, develop calculi at about the same rate in the presence or absence of TAT. Patients who form renal calculi containing TAT do not absorb or excrete abnormal quantities of TAT and do not metabolize the drug abnormally.