Analytical Quality-by-Design Based Method Development for the Analysis of Formoterol, Budesonide, and Related Compounds Using UHPLC-MS

Importance of the Topic

Analytical methods that reliably quantify active pharmaceutical ingredients and impurities are essential to ensure drug quality and regulatory compliance. Quality-by-Design (QbD) frameworks support systematic method development by defining a method operable design region (MODR) and building robust understanding of critical factors. In the context of respiratory therapeutics such as formoterol and budesonide, a well-characterized UHPLC-MS assay enables precise monitoring of potency and impurity profiles across the product lifecycle.

Objectives and Study Overview

The study aimed to apply an analytical QbD approach, facilitated by Fusion QbD software and the ACQUITY™ Arc™ UHPLC system, to develop a fit-for-purpose assay for formoterol, budesonide, and their related compounds. Key goals included minimizing development time, maximizing method robustness, and establishing a multi-dimensional design space for routine application.

Methodology

A design of experiments (DOE) strategy was implemented using Fusion QbD. Phase 1 involved low pH screening (pH 2.0–4.2) across five reversed-phase chemistries (BEH C18, BEH Shield RP18, CORTECS T3, CORTECS Phenyl, HSS PFP) with gradient times of 10–20 min. Phase 2 focused on high pH screening (pH 6.7–10.7) on the selected BEH C18 column to optimize formoterol peak shape. Phase 3 optimization fine-tuned flow rates (0.35–0.50 mL/min), temperatures (30–50 °C), and buffer pH (8.0–9.0) to define the acceptable performance region (APR) and proven acceptable ranges (PAR). Final verification runs under best overall conditions validated predicted responses.

Used Instrumentation

• Waters ACQUITY Arc UHPLC System with column heater and solvent select valve
• ACQUITY QDa Mass Detector (ESI+)
• CORTECS and BEH C18 columns (3.0 × 100 mm, 2.5 µm)
• Empower 3 Chromatography Data System with Fusion QbD software

Main Results and Discussion

Low pH screening identified BEH C18 at pH 2.0 with a 20 min gradient as the best initial conditions. High pH screening improved formoterol tailing (T<1.5) and established pH 9.6 with a 25 min run as the best overall answer. Optimization studies demonstrated a robust design space where all seven analytes achieved resolution ≥2.0 and tailing ≤1.3 over wide parameter ranges. Verification experiments confirmed the accuracy of software predictions, matching peak counts, resolutions, and tailing factors within 3% of predicted values.

Benefits and Practical Applications

• Reduction in experimental runs and development time through DOE automation
• Enhanced method robustness and understanding of critical factors
• Defined design space allowing independent post-approval adjustments
• Regulatory alignment with ICH Q8(R2) and risk-based development principles

Future Trends and Potential Applications

The integration of advanced chemometric tools, machine learning-driven QbD approaches, and in silico modeling is expected to further streamline method development. Expansion to other drug classes and incorporation of real-time quality monitoring will enhance control strategies throughout the pharmaceutical lifecycle.

Conclusion

Software-assisted analytical QbD using Fusion QbD and the ACQUITY Arc platform enabled the development of a robust UHPLC-MS method for formoterol, budesonide, and related compounds. The defined design space and verified performance support reliable method transfer and lifecycle management.

References

1. ICH Q8(R2): Pharmaceutical Development, 2009.
2. Reid G.L. et al., American Pharmaceutical Review 2013.
3. Chatfield M.A.K.B.M. et al., Pharmaceutical Technology 2017;41(4):52-59.
4. Alkhateeb F.L., Rainville P., Application Note, Waters Corporation, 2019.