Urolithiasis and the protease inhibitor indinavir

Objective: To evaluate specific urological abnormalities in patients treate d with the protease inhibitor indinavir. Methods: A series of 155 consecuti ve human immunodeficiency virus-positive patients were treated with indinav ir 800 mg p.o. three times a day. Of these, 14 (9%) treated for 1-321 (aver age 110) days experienced severe flank pain and were subjected to clinical and laboratory examinations. Results: Abdominal X-ray was consistently nega tive for stones. Ultrasonography showed upper-tract dilatation in 12 patien ts. Intravenous urography showed obstruction above a radiolucent obstacle i n 7 patients; in 2 cases, there was a marked delay in urine excretion on th e obstructed side. The mean urine pH was 6. Urine culture was negative. Ser um uric acid, phosphorus, and calcium levels were normal. In 8 patients the re was slight renal insufficiency, and 4 patients required ureteral stentin g. In all cases, hyperhydration and oral analgesia led to a favorable outco me. In 3 patients, chemical analysis of the stone demonstrated monohydrate indinavir crystals. Conclusions: In our experience, indinavir therapy is as sociated with urolithiasis in 9% of the cases. Hydration, analgesia, and ac idification of the urine usually lead to a favorable clinical outcome. Prop hylactic hydration and acidification of the urine are extremely important.