[Urinary calculi and crystalluria in HIV+ patients treated with indinavir sulfate]

Anti-proteases, a new class of anti-HIV drugs used in combination with reverse transcriptase inhibitors have led to spectacular improvement in the patients' clinical status. Since April 1996, indinavir is the most widely prescribed anti-protease in France.

From July 1996 to July 1997, we analyzed 46 spontaneously expulsed stones in 45 HIV+ patients (35 men and 10 women; age range 25 to 64 years) given indinavir in combination with other drugs since one week to ten months. Only six patients were known to have a past history of renal lithiasis.

Forty-one calculi contained indinavir monohydrate (INDM) identified by mass spectrometry and infrared spectrophotometry. INDM was the only component excepting proteins in 39/45 calculi. In the 12 others, other compounds were also identified. Among the 114 urine samples collected 2 to 3 hours after an 800 mg dose of indinavir, 38 (33%) monohydrate indinavir crystals, identified by infrared microscopy. Mean urinary pH was significantly higher than in samples without INDM crystals (6.53 +/- 0.68 versus 5.96 +/- 0.71, p < 0.001).

Two measures could possibly reduce the risk of crystalization: administration of urine acidifiers and increased fluid intake to raise diuresis. Alkalinisation is not indicated. Long-term increased fluid intake should be preferred over acidification which could be reserved solely for the treatment of drug-induced lithiasis.