Urolithiasis and the protease inhibitor indinavir

To evaluate specific urological abnormalities in patients treated with the protease inhibitor indinavir.

A series of 155 consecutive human immunodeficiency virus-positive patients were treated with indinavir 800 mg p.o. three times a day. Of these, 14 (9%) treated for 1-321 (average 110) days experienced severe flank pain and were subjected to clinical and laboratory examinations.

Abdominal X-ray was consistently negative for stones. Ultrasonography showed upper-tract dilatation in 12 patients. Intravenous urography showed obstruction above a radiolucent obstacle in 7 patients; in 2 cases, there was a marked delay in urine excretion on the obstructed side. The mean urine pH was 6. Urine culture was negative. Serum uric acid, phosphorus, and calcium levels were normal. In 8 patients there was slight renal insufficiency, and 4 patients required ureteral stenting. In all cases, hyperhydration and oral analgesia led to a favorable outcome. In 3 patients, chemical analysis of the stone demonstrated monohydrate indinavir crystals.

In our experience, indinavir therapy is associated with urolithiasis in 9% of the cases. Hydration, analgesia, and acidification of the urine usually lead to a favorable clinical outcome. Prophylactic hydration and acidification of the urine are extremely important.