Development and characterization of solid dispersion of rifampicin-polyethylene glycol 4000

Rifampicin is an antibiotic used for the treatment of tuberculosis caused by Mycobacterium tuberculosis. It is included in class II of the Biopharmaceutical Classification System (BCS) drug with high permeability but low solubility. Therefore, this study aims to determine the intrinsic dissolution rate and analyze the interactions in solid dispersions of rifampicin-polyethylene glycol (PEG) 4000. The solid dispersion system was created by dissolving rifampicin and PEG 4000in various weight ratios, including 1:0,5 (DPa),1:1 (DPb), and 1:1,5 (DPc). All solid dispersion formulas were formed into pellets and an intrinsic dissolution test was performed. Analysis of the intrinsic dissolution test results of rifampicin was performed using a UV-Vis spectrophotometer, while the statistical analysis was carried out with one-way ANOVA. The solid dispersion composition that produced the highest intrinsic dissolution rate was characterized using Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). The results of the intrinsic dissolution rate in mg.cm-2.minute-1 were rifampicin (3,33±0,54)×10-2, physical mixture rifampicin-PEG 4000 compositions a (CFa) (2,7±0,11)×10-2; CFb (3,27±0,28) ×10-2; CFc (4,12±0,48) ×10-2; DPa (6,09±0,40)×10-2; DPb (6,47±0,73)× 10-2; and DPc (6,82±0,04)×10-2. Furthermore, the FTIR spectra revealed that DPc formed a complex between rifampicin and PEG 4000. This was also observed in the thermogram of DPc, which showed a significant peak shift. Based on the results, rifampicin-PEG 4000 solid dispersion can increase the intrinsic dissolution rate of rifampicin on DPc 1:1,5 by 2,05 times (p<0,05) through electrostatic interactions (ionic bonds).