The official analytical method for assay and impurities in enalapril maleate tablets, as described in pharmacopoeial monographs, relies on HPLC-UV with a C8 column (250 × 4.6 mm; 5 µm) and a mobile phase consisting of acetonitrile and phosphate buffer pH 2.2 (25:75 v/v). In order to reduce analysis time, cost, and environmental impact, an optimised method was developed. The chromatographic column was replaced by a C18 (100 × 4.6 mm; 3.5 µm), as the reduced particle size and shorter column length allowed for faster separations while maintaining efficiency. In addition, the mobile phase was modified to ethanol and phosphate buffer pH 2.2 (30:70 v/v), since ethanol has a lower environmental impact compared with acetonitrile. Relative to the official method, the optimised procedure shortened the chromatographic run by approximately 8 minutes, reduced organic solvent consumption by 17.1 mL (equivalent to US$ 0.40) per run, and achieved better scores in the NEMI, GAPI, Eco-Scale (84 vs. 89), and AGREE (0.57 vs. 0.78) assessment tools. During validation, the linear range for enalapril was established at 140–260 µg mL⁻¹, and the method proved capable of simultaneously quantifying enalapril, enalaprilat, and diketopiperazine with 80.0 and 67.5 score for BAGI and RAPI metric, respectively.