Optimization of the manufacturing process of a complex amphotericin B liposomal formulation using quality by design approach

In this work, the manufacturing process of a complex liposomal amphotericin B (AmB) product was optimized using quality by design (QbD) approach. A comprehensive QbD-based process understanding and design space (DS) to the critical process parameters (CPPs) is essential to the drug development and consistent quality control. The process was based on the acid-aided formation of drug-lipid complexes in a methanol-chloroform mixture (step I) followed by spray drying (step II), hydration and liposome formation by microfluidization (step III), and lyophilization (step IV). Firstly, the risk assessment was conducted to identify the critical process parameters among the four key steps. Nine CPPs and five CQAs (API Monomer identity (absorbance main peak at 321 nm), API Aggregation identity (absorbance peak ratio, OD 415 nm/321 nm), particle size, in-vitro toxicity, and the cake quality) were determined based on their severity and occurrences with their contribution to the quality target product profile (QTPP). Based on the risk assessment results, the final screening design of experiments (DoE) was developed using fractional factorial design. Secondly, the empirical equation was developed for each CQA based on experimental data. The impact of CPPs on the CQAs was analyzed using the coefficient plot and contour plot. In addition to the effect of individual formulation parameters and process parameters, the effects of the four key separate steps were also evaluated and compared. In general, the curing temperature during microfluidization has been identified as the most significant CPP. Finally, design space exploration was carried out to demonstrate how the critical process parameters can be varied to consistently produce a drug product with desired characteristics. The design space size increased at the higher value of the curing temperature, the API to phospholipid ratio (API:PL), and the lower value of the DSPG to phospholipid ratio (PG:PL) and aspirator rate.