Characterization, in vitro dissolution and release kinetics of salicylamide in capsule shells made from κ-carrageenan-hydroxypropyl methylcellulose

This study aimed to characterize, in vitro dissolution, and evaluate the release kinetics of salicylamide in capsule shells made from κ-carrageenan-HPMC. The capsule shell was prepared using the dipping method with CRG: HPMC (1:1, 1:2, 1:3) ratio, supplemented with sorbitol and antifoam silicone emulsion. Characterization was conducted using FTIR, SEM-EDX mapping, AFM, hardness, and swelling degree experiments. The results indicated that the optimal capsule shells were obtained at a CRG: HPMC ratio of 1:2, with a hardness of 7.04 N and a swelling degree of 299.79 % at 15 mins. FTIR analysis revealed the wavenumber of sulfate groups, and SEM-EDX mapping indicated evenly distributed elemental composition. AFM analysis of capsules showed that the surface texture was rough. The disintegration times at different pH levels were 55, 53, and 24 min at pH 1.2; 4.5 and 6.8, respectively. The in vitro dissolution test showed salicylamide release of 6.40, 8.51, and 11.51 % in 120 min at pH 1.2, 4.5, and 6.8, respectively. The release kinetics followed a zero-order model at pH 1.2 and 6.8 and the Ritger-Peppas model at pH 4.5. The CRG-HPMC/sorbitol capsule shells exhibited good physicochemical characteristics with a controlled drug release profile and thereby supporting SDGs 3 and 14.