Imipenem + Cilastatin is a combination of two medicines: Imipenem + Cilastatin1 and Imipenem + Cilastatin2. Imipenem + Cilastatin1 is an antibiotic. It works by preventing the formation of the bacterial protective covering which is essential for the survival of bacteria in the human body. Imipenem + Cilastatin2 is dehydropeptidase I inhibitor which blocks the activity of an enzyme (dehydropeptidase I) that causes breakdown of Imipenem + Cilastatin1. Hence, it helps Imipenem + Cilastatin1 stay active in your body for a longer period of time.