RESUMO
OBJECTIVE: To investigate the applicability of carboxymethyl starch (CMS) as a carrier to prepare solid dispersions (SDs) of piperine (PIP) and 18ß-glycyrrhetinic acid (ß-GA) (PIP-CMS and ß-GA-CMS SDs) and to explore the influence of drug properties on carrier selection. SIGNIFICANCE: The low oral bioavailability of natural therapeutic molecules, including PIP and ß-GA, severely restricts their pharmaceutical applications. Moreover, CMS, a natural polymer, is rarely reported as a carrier for SDs. METHODS: PIP-CMS and ß-GA-CMS SDs were prepared using the solvent evaporation method. Differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) were used for formulation characterization. Additionally, drug release characteristics were investigated. RESULTS: In vitro dissolution studies showed that the dissolutions of PIP-CMS and ß-GA-CMS SDs were 1.90-2.04 and 1.97-2.22 times higher than pure PIP and ß-GA, respectively, at a drug:polymer ratio of 1:6. DSC, XRPD, FT-IR, and SEM analyses confirmed the formation of SDs in their amorphous states. Significant improvements in Cmax and AUC0-24 h of PIP-CMS and ß-GA-CMS SDs (17.51 ± 8.15 µg/mL and 210.28 ± 117.13 µg·h/mL, respectively) and (32.17 ± 9.45 µg/mL and 165.36 ± 38.75 µg·h/mL, respectively) were observed in the pharmacokinetic study. Compared with weakly acidic ß-GA, loading weakly basic PIP seemed to have a profound effect on stability through intermolecular forces. CONCLUSIONS: Our findings showed CMS could be a promising carrier for SDs, and loading weakly basic drug may be more suitable, especially in binary SDs system.