The thioether resulting from the formal oxidative coupling of the thiol group of L-cysteine with the 7-position of (2Z)-2-({[(1S)-2,2-dimethylcyclopropyl]carbonyl}amino)hept-2-enoic acid. It is an inhibitor of dehydropeptidase I (membrane dipeptidase, 3.4.13.19), an enzyme found in the brush border of renal tubes and responsible for degrading the antibiotic imipenem. Cilastatin is therefore administered (as the sodium salt) with imipenem to prolong the antibacterial effect of the latter by preventing its renal metabolism to inactive and potentially nephrotoxic products. Cilastatin also acts as a leukotriene D4 dipeptidase inhibitor, preventing the metabolism of leukotriene D4 to leukotriene E4.