Abstract
Background/Objectives: This study investigated how selected functionality-related characteristics (FRCs) of hypromellose (HPMC)-namely viscosity, hydroxypropoxy substitution, particle size, and the ratio of water-soluble (FlowLac(®) 100) to water-insoluble (Avicel(®) PH-102) fillers- affect the release of carvedilol from matrix tablets. Methods: Using a Central Composite Design (CCD) Design of Experiments (DoE), mixtures of HPMC QbD samples were prepared to achieve target HPMC FRC levels. Within the CCD, levels of FlowLac(®) 100 and Avicel(®) PH-102 were also varied. The mean and standard deviation of carvedilol release at each analyzed time point of the release profile were used as target variables for individual multiple linear regression (MLR) models. Results: Lactose, the water-soluble filler, significantly accelerated carvedilol release, whereas the water-insoluble MCC slowed and stabilized release by improving gel integrity. Among the HPMC FRCs, particle size had the strongest influence during the early release phase, while HPMC viscosity and hydroxypropoxy substitution degree became more important in later phases. Analysis of the results using optimized multiple linear regression (MLR) models revealed key interaction effects, particularly between HPMC viscosity and lactose content, and between viscosity and particle size, demonstrating their combined role in modulating release kinetics. Conclusions: These findings provide valuable insight into how controlling HPMC's FRCs and filler composition can reduce interbatch variability in drug release and support the rational design of robust controlled release formulations.