A calculator has been added to provide a decision support tool to optimize the efficacy and limit the toxicity of colistin. The advantage of the calculator is its availability from a patient's review screen and the importation of the demographic and clinical data necessary for the calculations. The calculator is harmonized with the recommendations of the latest international consensus guidelines. (Pharmacotherapy 2019; 39 (1): 10–39).

Since its reintroduction, significant confusion remains regarding colistin use due to differences in the available formulations and the different conventions used to describe the dosage [milligrams (mg) or international units (IU) of colistin base (CBA) or colistin methanesulfonate (CMS)].  As a reminder, colistin is administered as an inactive prodrug, colistimethate, also known as colistin methanesulfonate [CMS]. A lack of clarity remained about how optimally to utilize and dose colistin, a highly nephrotoxic and neurotoxic agent. Given the narrow therapeutic windows of colistin, the calculator and the dosages included in the knowledge base should provide a practical framework for clinicians who use colistin in the treatment of infections caused by multidrug-resistant (MDR) gram-negative pathogens.