Probenecid is given before and after administration of cidofovir to help prevent kidney damage. Probenecid hypersensitivity is a frequent cause for discontinuing cidofovir therapy. They were most often treated with granulocyte colony-stimulating factor to increase their white blood cell counts. See Blood Cell Deficiencies , this issue, for more information. In such cases, the drug should be stopped.
Metabolic acidosis means that the blood is more acidic and the urine is less acidic than usual.
If the acid balance is not corrected, excess acid may cause softening of the bones, kidney stones, hardening of the kidneys and low levels of blood potassium. Hospitalization is usually required to manage this side effect. Finally, when cidofovir is given intravenously, there is a small increased risk of infection at the infusion site if the skin, needle and dressings are not sterile. Because cidofovir must be preceded and followed by the drug probenecid, physicians must guard against many possible drug interactions with probenecid. Mark Bowers is Managing Editor of treatment publications at the San Francisco AIDS Foundation.