BACKGROUNDAntihypertensives bisoprolol fumarate (BIS) and perindopril arginine (PER) were simultaneously determined in their pure, bulk, and combined tablet dosage form.OBJECTIVEThis study develops a novel, reproducible, and accurate Reversed phase high-performance liquid chromatography (RP-HPLC) and Reversed phase ultra-performance liquid chromatography (RP-UPLC) with photodiode array detection techniques, which were then applied to in vitro dissolution studies.METHODSThe first RP-HPLC method relied on isocratic elution using a mobile phase of methanol-0.05 M phosphate buffer pH 2.6 (1 + 1, by volume), and separation was performed using a Thermo Hypersil C8 column (150 mm × 4.6 mm, 5 μm). Ion-pair UPLC was the second method. An acceptable resolution was achieved using an RP-C18 chromatographic column, Agilent Eclipse (100 × 2.1 mm, 1.7 μm), with a mobile phase containing 0.005 M sodium 1-heptane sulfonate-triethylamine (64 + 1 + 35, by volume), adjusted with phosphoric acid to a pH of 2.0. RP-HPLC used a 1.0 mL/min flow rate, while UPLC used 0.5 mL/min, and the two methods used detection at 210 nm.RESULTSCalibration curves of BIS and PER were linear for RP-HPLC and RP-UPLC methods at 0.5-15 and 0.5-40 μg/mL, respectively. BIS and PER had RP-UPLC LODs of 0.22 and 0.10 μg/mL, respectively, and LOQs of 0.68 and 0.31 μg/mL, respectively. As a result, the approach has been effectively applied to in vitro dissolution testing for drugs in generic and reference products, showing that the two products are comparable. The Six Sigma approach was implemented to compare the recommended and United States Pharmacopeia (USP) procedures, which both exhibited process capability index (Cpk) >1.33. A content uniformity test demonstrated that the drugs in their dosage form met the acceptance limit (85-115%). The degradation products were reliably distinguished from pure drugs for a range of retention times.CONCLUSIONIn their commercial drug product, the proposed method could be used in QC laboratories for concurrent testing, content uniformity, and in vitro dissolution investigations of BIS and PER. The methods were successfully validated per International Council for Harmonisation (ICH) guidelines.HIGHLIGHTSThis study is innovative since it is the first to establish and validate specific and reproducible UPLC and HPLC methods for the concurrent quantitation of the studied drugs in their binary mixture and application to lean Six Sigma, content uniformity, and comparative dissolution approaches.