Potential application of low molecular weight excipients for amorphization and dissolution enhancement of carvedilol

In this study, four low molecular weight (LMW) excipients, tryptophan (TRY), phenylalanine (PHE), lysine (LYS) and saccharin (SAC) were evaluated as co-formers to generate co-amorphous systems (CAMS) by ball milling with carvedilol (CRV). Mixtures of CRV and LMW excipient in 1:0.5, 1:1 and 1:2 drug:excipient molar ratios were ball milled and analysed by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), Fourier transform (FT-IR) infrared spectroscopy and dissolution testing. CAMS were formed by milling of a mixture of CRV with TRY in 1:2 M ratio and SAC in 1:1 M ratio, while amorphization of only CRV was achieved in other mixtures with SAC. In other samples containing TRY and PHE, milling resulted in partial amorphization, while LYS was the least suitable excipient for the amorphization of CRV. Unexpectedly, the highest supersaturation of CRV was achieved from samples containing CRV and LYS in 1:1 and 1:2 M ratios, despite the absence of a significant reduction in CRV crystallinity upon milling of these samples. Increase of hydrophobic surface area caused by milling of samples with TRY and PHE and agglomeration during dissolution testing of samples containing SAC are likely causes of poor dissolution performance of mixtures containing fully or partially amorphous CRV

Preparation of floating polymer-valsartan delivery systems using supercritical CO2

This study investigates pharmaceutical polymers (Soluplus((R)), HPMCAS, and Eudragit((R)) E100) and supercritical CO2-assisted process for preparation of floating valsartan delivery systems. Tested process (at pressure of 30 MPa and temperature of 100 degrees C during 2 h) enabled preparation of stable porous valsartan formulations which was confirmed with FESEM and mercury intrusion porosimetry analysis. The bulk density of obtained formulations was lower than 550 kg/m(3). FTIR, DSC, and PXRD analysis indicated that there was no chemical interaction between the drug and polymers and that amorphous solid dispersions were obtained. Formulations with Soluplus((R)) and HPMCAS retained its buoyancy in 0.1 M HCl for longer than 24 h, while formulation with Eudragit((R)) E100 retained its buoyancy up to 2 h. Controlled valsartan release was influenced by solubility of polymers in the tested release medium, which was confirmed by UV/VIS spectroscopy. The obtained results provided framework for further development of floating drug delivery system using an environmental friendly process