First-order derivative ultraviolet spectrophotometry of imipenem–cilastatin formulations

ObjectiveImipenem–cilastatin is a well-established broad-spectrum intravenous antibiotic used for the treatment of life-threatening infections worldwide. The preparation has been studied by various methods but not by ultraviolet (UV) spectroscopy, although this technique remains one of the simplest, most accurate and precise validated quality control laboratory methods. The aim of this study was to validate a method for separating the intercalating peaks of the UV spectra of imipenem and cilastatin and to compare the purity and quantities of these two active ingredients in different marketed brands. No previous studies have been conducted to compare the generic product (Cilanem®) with the original (Tienam®).MethodsFirst-order derivative UV spectrophotometry was used to separate the intercalating peaks of imipenem and cilastatin by measuring absorbance at 243 nm and 300 nm, respectively.ResultsCilanem® had better physical characteristics and a higher cilastatin concentration, while the brand product Tienam® contained a higher concentration of imipenem.ConclusionThe generic product Cilanem® is at least non-inferior to the brand product Tienam®.