A statistical analysis to assess the most critical bioequivalence parameters for generic liposomal products

OBJECTIVES: The purpose of the study was to identify the most sensitive analyte (i.e., encapsulated, free, and total forms) for assessing the bioequivalence (BE) of liposome drug products using Monte Carlo simulation. METHODS: We proposed a liposome classification system that divided liposome drug products into four classes according to the extent of reticuloendothelial system uptake and in vivo release rate: class I: low reticuloendothelial system uptake-rapid release rate; class II: low reticuloendothelial system uptake-slow release rate; class III: high reticuloendothelial system uptake-rapid release rate; Class IV: high reticuloendothelial system uptake-slow release rate. In conjunction with the proposed classification scheme, a variety of drug classes were simulated to determine which analyte provides the most sensitive measure of BE. All drug classes were investigated in single and multiple dose studies. The sensitivity of analytes for measuring BE was evaluated using the power curve. RESULTS AND CONCLUSIONS: Our simulations indicated the encapsulated form provides the most accurate assessment BE for liposome drug products with low reticuloendothelial system uptake (i.e., class I and II). For liposome drug products with high reticuloendothelial system uptake (i.e., class III and IV), the free form provides the best indication BE. Measurement of total drug form to assess BE was preferred only for liposome drug products with low reticuloendothelial system uptake and slow release rates (i.e., class II liposomal drug product). In general, a single dose form is sufficient for demonstrating the BE of liposome drug products.