DESIGN OF AMORPHOUS SOLID DISPERSIONS FOR THE SYNCHRONIZED RELEASE OF TWO DRUGS

Abstract

Purpose: To develop an amorphous solid dispersion (ASD) design strategy for poorly water soluble drug combinations.Methods: Using sulfamethoxazole (SMZ) and trimethoprim (TMP) as the model drugs, a mixture of SMZ and TMP at weight ratios of 5:1 and 1:5 were formulated into ternary ASDs with an aminoalkyl methacrylate copolymer, Eudragit® E (EDE), and polyacrylic acid (PAA), respectively. The ASDs were characterized by thermal (differential scanning calorimetry, DSC), spectroscopic (dielectric and infrared spectroscopies, DES and IR) and X-ray diffractometric (XRD) techniques. The dissolution performance was evaluated under non-sink conditions using USP dissolution apparatus II method. Results: Ternary ASDs were successfully prepared by solvent evaporation. Analyses of the glass transition temperature data of the binary (drug-drug) and ternary (drug-drug-polymer) systems implied strong drug-drug and drug-polymer interactions. The interactions resulted in a reduction in molecular mobility, evident from the increase in the structural (α-) relaxation time. The ionic SMZ-EDE and TMP-PAA interactions were characterized using IR. The ternary ASDs exhibited substantial enhancement in drug dissolution when compared with the crystalline mixtures. The ternary ASDs exhibited synchronized release. Conclusion: The drug-drug and drug-polymer interactions improved the physical stability of the ternary ASDs by reducing molecular mobility. The proposed ASD design strategy could be a potential approach for the solubility enhancement of drug combinations with poor aqueous solubility.