Objectives were to evaluate correlates, and economic outcomes of proton pump inhibitor (PPI) use by route in the intensive care unit from an institutional-payer perspective. A 13-month retrospective study of electronic medical records was conducted of 534 adult (≥19 year-old) intensive care unit patients receiving a PPI (39% enteral-only, 34% parenteral-only, 27% both-route) in a Midwest USA academic medical center. Possible cost-savings with sensitivity analysis were estimated as differences in drug costs (US dollars) between switch eligible parenteral and alternate enteral-PPI medication doses. In multivariate logistic-regression of switch criteria (any oral-medication, orogastric-tube, nothing by oral route), significant correlate for enteral versus parenteral PPI-use was any oral-medication use but not orogastric-tube. Using enteral esomeprazole/lansoprazole instead of parenteral (esomeprazole/pantoprazole) PPI (in 37% i.e. 696 of 1895 switch-eligible doses) would have saved US$2384.17 or US$3564.86, respectively. By switching eligible patients on oral-medications or on orogastric-tube from parenteral- to enteral-PPI, institutions can realize significant drug cost-savings.