Cilastatin is primarily used in combination with imipenem to enhance its effectiveness as an antibiotic. It works by inhibiting the enzyme dehydropeptidase-I in the kidneys, which prevents the breakdown of imipenem, thereby increasing its concentration and activity in the body. This combination is particularly effective in treating severe infections caused by multidrug-resistant bacteria, including those affecting the respiratory tract, urinary tract, abdominal area, and skin. Additionally, it is utilized in managing infections in patients with compromised immune systems, such as those undergoing chemotherapy or organ transplants. The use of cilastatin helps reduce the nephrotoxic side effects of imipenem, making it a safer option for patients with kidney-related concerns.