tenofovir interacts with didanosine and hiv-1 protease inhibitors. tenofovir increases didanosine concentrations and can result in adverse effects such as pancreatitis and neuropathy. tenofovir also interacts with hiv-1 protease inhibitors such as atazanavir, by decreasing atazanavir concentrations while increasing tenofovir concentrations. in addition, since tenofovir is excreted by the kidney, medications that impair renal function can also cause problems.