The binding of metal ions by enalapril maleate and lisinopril

Abstract A number of side-effects have been observed in patients receiving the antihypertensive agents enalapril maleate and lisinopril. Many of the symptoms could be indicative of trace metal imbalances. Formation constants for the zinc(II) and copper(II) complexes of maleate, enalapril maleate and lisinopril have been measured potentiometrically at 37 °C and I = 150 mmol dm −3 chloride. The constants have been used in computer simulation models to assess the relative efficacy of the agents in mobilizing zinc and copper from the labile protein complexes in normal plasma. The study indicates that neither, enalapril nor lisinopril mobilize zinc and copper at normal pharmacological levels of the drug.