ACE and chronic kidney disease: In Germany, metamizole, requiring monitoring for its potentially myelosuppressive effect, has remained the alternative agent for postoperative analgesia [89] in vulnerable elderly patients, who are already often prescribed ACE inhibitors or sartans and diuretics or even suffering from CKD, to prevent further renal injury or acute renal failure, particularly in high-risk conditions of the “triple whammy” with add-on NSAIDs [41].