Interactions between anti‐infective agents and immunosuppressants—Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

Abstract These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation provide an update on potential drug‐drug interactions between anti‐infectives and immunosuppressants, which are most notable with calcineurin and mTOR inhibitors. Drug‐drug interactions may occur through pharmacokinetic mechanisms leading to altered drug concentrations of either the anti‐infective or immunosuppressive drug, or by pharmacodynamic interactions increasing or decreasing the efficacy or toxicity of the medications. Many of the significant pharmacokinetic interactions occur through inhibition or induction of the cytochrome 3A4 system by anti‐infective agents leading to increased or decreased immunosuppressive agent levels, respectively. The membrane transporter P‐glycoprotein is also often involved in drug interactions. Since the last iteration of these guidelines, multiple new hepatitis C virus direct‐acting antivirals have become available for use in SOT recipients. Of these agents, some are substrates of cytochrome and drug transporter systems, while others inhibit these systems and may affect immunosuppressive agents. Due to the high risk for drug‐drug interactions in the solid organ transplant population, practitioners must be aware of potential interactions and be vigilant in monitoring and adjusting drug dosing when appropriate.