Simvastatin is a member of the statin drug class, used to reduce cholesterol levels in the bloodstream. The current research work emphases on the synthesis, characterization, and optimization of RP-HPLC method for determination of simvastatin and its synthesized metabolite β-hydroxy acid as an impurity simultaneously with high accuracy, precision, and sensitivity. In the present paper properties such as ADME and toxicity of the BHA were predicted through different ADME database like SWISS ADME and molesoft. The metabolite BHA of simvastatin was synthesized in the laboratory and characterized by UV, MS, NMR and FT-IR spectroscopy. The method was developed using Kinetex C18, 4.6 mm x 250 mm, 5 µm as the stationary phase, flow rate 1.0 mL/min, volume 20 µL with a run time of 10 minutes at 244 nm wavelength using Methanol (80%) : Phosphate buffer 20mM pH 3 (20%) as mobile phase. The HPLC analytical method, which includes the detection of the simvastatin metabolite, underwent validation according to the ICH Q2B (R1) guidelines. Analysis revealed that the findings were in the region of 98.57% to 101.86% for all analytes with satisfactory accuracy and precision. The developed method can be used for detection and quantification of metabolite in bulk or formulations of simvastatin. Further optimization of the method for quantification of BHA in biological fluids could make it useful for clinical and bioequivalence studies. Assessment of toxicity by using computational tools like Swiss tool is reported with the hope of reducing threats.