Since thienamycin decomposes in the presence of water, it is impractical for the clinical treatment of bacterial infections, so stable derivatives were created for medicinal consumption.  One such derivative, imipenem, was formulated in 1985.  Imipenem, an N-formimidoyl derivative of thienamycin, is rapidly metabolized by a renal dipeptidase enzyme found in the human body.  To prevent its rapid degradation, imipenem is normally coadministered with cilastatin, an inhibitor of this enzyme.