UHPLC Method Development for Simultaneous Determination of Antihypertensive Combination Agents

Significance of the Topic

Combination therapy for hypertension is a widely accepted approach to enhance therapeutic efficacy, improve patient compliance, and reduce adverse effects by targeting multiple physiological pathways simultaneously.

Objectives and Overview

This study aimed to develop a robust, rapid, and generic UHPLC method capable of separating six commonly used antihypertensive drugs—amlodipine besylate, hydrochlorothiazide, chlorthalidone, azilsartan, telmisartan, and valsartan—in under one minute. The method development leveraged advanced UHPLC instrumentation, automated method scouting, and method transfer tools.

Methodology and Instrumentation

Used Instrumentation

• Thermo Scientific Vanquish UHPLC System (Binary Pump H, Split Sampler HT, Column Compartment H, Diode Array Detector HL)
• Thermo Scientific Accucore Vanquish C18+ column (1.5 µm, 2.1 × 100 mm)
• Thermo Scientific Chromeleon CDS 7.2 with Automated Method Scouting and Method Transfer tools

Gradient elution was performed using combinations of water (with or without formic acid or ammonium acetate) and organic solvents (acetonitrile, methanol) at flow rates of 0.4 mL/min and an accelerated 0.8 mL/min, at 50 °C. Sample preparation involved preparing single stock solutions in methanol and mixing to yield a standard mixture reflective of typical dosage ratios.

Main Results and Discussion

Automated solvent scouting identified 0.1% formic acid in water and 0.1% formic acid in acetonitrile as the optimal mobile phase pair, achieving baseline separation of all six drugs within 1.80 minutes at pressures below 700 bar. Method acceleration doubled the flow rate without compromising resolution, maintaining critical peak separations and reducing total analysis time to under one minute at 1290 bar.
The UHPLC system exhibited excellent injection reproducibility down to 10 nL injections, with peak area and retention time RSDs below 5%. Calibration curves over injection volumes of 0.01–1 µL delivered correlation coefficients above 0.996 for all analytes.

Benefits and Practical Applications

• High throughput screening with sub-minute run times enhances laboratory productivity.
• Generic method applicability across multiple antihypertensive combinations reduces method development time.
• Wide injection volume linearity supports both trace analysis and routine QC requirements.
• Automated scouting and method transfer streamline method optimization and transfer between instruments.

Future Trends and Opportunities

The integration of advanced software-driven method optimization with next-generation UHPLC hardware paves the way for fully automated workflows in pharmaceutical analysis. Future developments may include real-time method adaptation, further reduction in analysis times through higher pressure systems or novel stationary phases, and expanded multiplexed detection for broader drug panels.

Conclusion

A fast, robust, and generic UHPLC method was successfully developed for simultaneous analysis of six antihypertensive agents. Leveraging automated scouting and method transfer tools enabled a sub-minute separation without compromising resolution, while the UHPLC system delivered exceptional reproducibility and linearity across a wide injection volume range. This approach supports high-throughput pharmaceutical screening and quality control applications.

Reference

1. Jones JD, Jackson SH, Agboton C, Martin TS. Pharmacy and Therapeutics. 2011;36(10):634–640.
2. Thermo Fisher Scientific. Vanquish UHPLC System; 2014.
3. Thermo Scientific Technical Note 161: LC Method Development by an Automated Method Scouting System; 2015.
4. Thermo Scientific Technical Note 75: A Universal Tool for Method Transfer From HPLC to UHPLC; 2014.