Application of quality by design concept to develop a dual gradient elution stability-indicating method for...

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis
• Chromatography

Background:

• Penicillins present analytical challenges due to numerous degradation-related impurities (DRIs) with diverse properties.
• Developing selective and robust high performance liquid chromatography (HPLC) methods for these complex ionic samples is difficult.

Purpose of the Study:

• To develop a stability-indicating HPLC method for cloxacillin using an analytical quality by design (AQbD) approach.
• To improve the separation of cloxacillin DRIs by optimizing critical process parameters.

Main Methods:

• Utilized prior knowledge of penicillin structures, retention, and UV characteristics.
• Conducted quality risk assessment and screen design to identify critical process parameters (CPPs).
• Employed a combined mixture-process variable (MPV) design with response surface methodology (RSM) and dual gradient elution.
• Evaluated design spaces (DSs) using Monte Carlo simulation and tested robustness with Plackett-Burman design.

Main Results:

• Identified 3 CPPs (2 mixture variables, 1 process variable) influencing separation.
• Optimized experimental parameters using RSM and dual gradient elution for simultaneous control of buffer pH, mobile phase type, and strength.
• Established design spaces and normal operating ranges for a robust method.

Conclusions:

• This study presents the first application of MPV design and dual gradient elution for HPLC method development in complex ionic samples.
• The developed AQbD approach provides a selective, robust, and stability-indicating method for cloxacillin analysis.
• The findings offer a novel strategy for improving the separation of DRIs in challenging pharmaceutical samples.