Cilastatin is given in combination with Imipenem because

* Cilastatin is a renal dipeptidase (or dehydropeptidase) enzyme inhibitor, used in conjunction with Imipenem antibiotic to prevent degradation of Imipenem by the renal tubular dipeptidase. * Imipenem is a carbapenem class of Beta-Lactam antibiotic. It has poor absorption following oral administration. Given IV, the drug is rapidly catabolized by the dipeptidase enzyme expressed by the brush border cells of proximal tubules in kidney. * Both Imipenem and Cilastatin have identical pharmacokinetic profile - so ideal for combination. * Following concurrent administration, Imipenem degradation is blocked significantly, biovailability and duration of action is enhanced, around 70% active drug is recovered from urine (When Imipenem is used alone, only about 5.5-42.5% of unchanged drug is recovered from urine). Ref:- Goodman & Gilman Pharmacological Basis of Therapeutics 13th Ed; Pg num:- 1035