Cilastatin is a medication that is primarily used to prevent the breakdown of the antibiotic imipenem in the kidneys. It works by inhibiting an enzyme called dehydropeptidase, which can otherwise inactivate imipenem, allowing it to remain effective in treating bacterial infections. Cilastatin is often administered in combination with imipenem as part of a treatment regimen for serious infections caused by various bacteria. This combination helps to enhance the antibiotic's efficacy and ensures that it reaches the bloodstream in sufficient amounts to combat infections effectively.