Several studies presented at the 2010 International AIDS Conference found that treatment regimens containing Viread or Norvir are linked to kidney disease in people with HIV.

People with HIV are more prone to kidney disease, both because of the HIV virus, which can infect and kill kidney cells, and from damage caused by the antiretrovirals used to treat it. Viread (tenofovir), in particular, has been associated with loss of kidney function.

Viread is commonly used in combination with other antiretroviral medications and is an ingredient in Atripla (efavirenz/emtricitabine/tenofovir) and Truvada (emtricitabine/tenofovir).

Norvir (ritonavir) has also been linked to kidney problems, though less frequently than Viread. Norvir is commonly used as a “booster” to enhance the effectiveness of protease inhibitor treatment regimens. Norvir is also an ingredient in Kaletra (lopinavir/ritonavir).

In these studies, researchers continued to look for risk factors, including the use of antiretrovirals, that are associated with development of kidney disease in people with HIV.

Treatment With Viread Alone And In Combination With Other Drugs Is Associated With Decreased Kidney Function

A large study that reviewed medical records for over 5,600 HIV-positive patients confirmed that taking Viread is associated with a significant risk of kidney disease.

Researchers found that about 6 percent of the patients taking Viread developed kidney impairment, with 60 percent of those patients experiencing a 50 percent or greater loss of kidney function.

The researchers also found that the greatest predictor of decreasing kidney function was the number of months taking Viread, with longer Viread treatment associated with greater risk of kidney problems.

A second study found that treatment with Viread was associated with a greater decrease in kidney function compared to regimens without Viread.

The study measured kidney function in 474 HIV-positive adults treated with a variety of antiretroviral regimens, some with Viread and some without. Prior to the study, none of the participants had received treatment for their HIV.

Changes in kidney function were observed over a period of 96 weeks.

Combined, participants treated with Viread-containing regimens had declines in kidney function that were about three-fold larger than patients on non-Viread antiretroviral regimens.

Additionally, a greater decline in kidney function was observed in participants treated with Viread plus Kaletra compared to patients treated with Viread plus Sustiva (efavirenz).

Kaletra inhibits the breakdown of Viread in the body, which means people taking Kaletra plus Viread may have higher amounts of Viread in their system for a longer period of time. Sustiva does not affect the rate of Viread breakdown in the body.

Results of both studies emphasize the importance of carefully monitoring kidney function in patients receiving Viread therapy.

Advancing Age And Treatment With Norvir Are Associated With Kidney Disease

An ongoing Brazilian study has found that the use of Norvir, with or without Viread, is also associated with kidney disease.

The study has included 196 participants so far, all of whom have taken antiretroviral therapy for at least a year and have achieved viral suppression, 50 copies of HIV per milliliter or less.

Researchers classified each participant as having either normal kidney function (62 percent) or mild, moderate, or severe kidney impairment (29 percent, 8 percent, and 1 percent, respectively).

Results showed that moderate or severe kidney impairment was associated with taking Norvir (with or without Viread) and increasing age. European ancestry was also related to poorer kidney function.

However, the researchers noted that the results were still preliminary and more study participants would be needed to confirm these results.

In another study, Italian researchers found that older age, treatment with protease inhibitors boosted with Norvir, and smaller gains in CD4 (white blood cell) count after starting antiretroviral therapy are risk factors for kidney disease in people with HIV.

The study included 590 HIV-positive participants who were starting antiretroviral therapy for the first time.

Results showed that being more than 55 years old and having a more advanced HIV infection were also linked to a greater risk of kidney problems.

Unlike in previous studies, the researchers did not find treatment with Viread to be associated with a greater risk of kidney failure.

For more information, please see the AIDS 2010 conference website.