HIV patients who are underweight and/or have high blood pressure do have a higher risk of reduced kidney function when treated with tenofovir disoproxil fumarate (TDF) as compared to those who have been prescribed an AZT-based medication without protease inhibitors (medications that prevent viruses from replicating). However, this risk is “not significantly increased,” according to researchers who recently published their findings in the Journal of Infection – at least, in the short term.
The World Health Organization has recommended the use of TDF as part of an initial antiretroviral therapy (ART) in HIV patients. It is also prescribed for prophylactic reasons for people who may have been exposed to HIV and is used as monotherapy for patients suffering from hepatitis B.
Despite the high efficacy rate for ART in treating or preventing HIV infections, chronic kidney disease continues to be a common problem for HIV patients. When given in combination with a boosted protease inhibitor such as Reyataz (atazanavir), Prezista (darunavir), or Lexiva (fosamprenavir), the result can be a serious reduction in the rate of estimated glomerular filtration rate (eGFR), an important measure of renal health. This can put the patient at high long-term risk for chronic kidney disease.
The purpose of the study, which was conducted in Thailand, was to learn more about the long-term changes in eGFR in patients treated with TDF versus ATZ and how body weight affects kidney function. The study involved a total of 640 patients, 72 percent of whom had been on a TDF regimen and the remaining having been treated with ATZ over approximately six-and-half years. Results of the study found that patients with normal weight and blood pressure did not experience significant eGFR reduction. Those who were underweight and/or had hypertension were more prone to kidney problems.
The study did not address the risks of long-term TDF treatment.
An improved version of TDF, known as tenofovir alafenamide fumarate (TAF), has been available for at least a decade. Although TAF poses many of the same risks and side effects as TDF, it is more potent and can, therefore, be administered in smaller doses – thus mitigating the toxic effects. Currently, the drug's developer, Gilead Sciences, has come under fire for allegedly withholding TAF from the market in order to make the maximum amount of profit from the older formulation before its patent expired.
Other serious adverse effects associated with TDF include lactic acidosis, liver damage, and osteoporosis. Patients who experience kidney disease from long-term use of TDF can sometimes reverse the condition by discontinuing the medication.