Cilastatin is a chemical compound which inhibits the human enzyme dehydropeptidase. Dehydropeptidase is found in the kidney and is responsible for degrading the antibiotic imipenem. Cilastatin is therefore given intravenously with imipenem in order to protect imipenem from dehydropeptidase and allow it to kill bacteria. However, cilastatin itself does not have any antibiotic activity.
An example of an Imipenem and Cilastatin combination therapy is the Merck drug Primaxin (also known as Tienam).