Gilead Sciences, United States of America. The manufacturer of the HIV protease inhibitor, cidofovir (Vistide: Gilead), has again stressed the importance of adhering to specific treatment guidelines when administering cidofovir after further reports were received of renal failure associated with its use. Cidofovir is indicated for the treatment of cytomegalovirus retinitis in patients with AIDS.

Pre-dose monitoring of creatinine and urinalysis within 48 hours prior to each infusion of cidofovir is essential. Properly timed intravenous prehydration with normal (0.9%) saline and probenecid must be used with each infusion of cidofovir. The importance of appropriate patient selection is stressed, as well as treatment administration and monitoring to ensure that cidofovir is used safely.

Most of the reports relate to patients with identifiable risk factors, including:

non-compliance with dose modification criteria;

omission of probenecid prior to administration of cidofovir;

failure to carefully monitor serum creatinine and/or urine protein prior to each infusion of cidofovir;

dehydration during therapy;

recent/concomitant use of other agents with nephrotoxic potential.

Uveitis/Iritis. Cases of anterior uveitis occurred during therapy with cidofovir, including some patients who also experienced varying degrees of hypotony (decrease in ocular pressure).

Hearing loss. Three cases of hearing loss, with or without tinnitus, have been reported in association with administration of cidofovir. In 2 patients, symptoms were reported within 24 to 48 hours of the infusion and declined over time until the next dose. Hearing impairment and tinnitus abated following discontinuation of therapy with cidofovir.

[See Pharmaceuticals Newsletter Nos. 9&10, September & October 1997]

Reference: Letter to Health Care Professionals from Gilead Sciences, Inc., August 1998. [http://www.fda.gov/medwatch/safety/1998/vistid.htm]