Drug-polymer miscibility, interactions, and precipitation inhibition studies for the development of amorphous solid dispersions for the poorly soluble anticancer drug flutamide.

The major goal of this research was to successfully formulate solid dispersion (SD) of the poorly soluble anticancer drug flutamide (FLT) using various hydrophilic polymers. Furthermore, to get more insight into SD, solid-state studies (miscibility and molecular interaction) were correlated with solution study (precipitation inhibition, dissolution). Hydrophilic polymers like PVP K90, HPMC, Eudragit EPO, and PEG 8000 were used at different drug-to-polymer w/w ratios. Solid-state miscibility studies were carried out using modulated differential scanning calorimetry (MDSC). SDs were prepared using solvent-evaporation technique and characterized by powder X-ray diffraction (PXRD) and MDSC. Infrared, Raman spectroscopy and molecular modeling were used to investigate drug-polymer interactions in the dispersions. Precipitation inhibition studies were carried out at various FLT-hydrophilic polymer ratios. Precipitation inhibition studies showed that PEG 8000 has the highest efficiency, followed by PVP K90, while HPMC and EPO showed no effect on precipitation inhibition. In the solid-state, MDSC of the physical mixture (PM) suggested that FLT is miscible to a greater extent with EPO and PEG 8000. Characterization of the amorphous dispersions using MDSC and PXRD concluded that FLT transformed from crystalline to amorphous form in the presence of PVP K90 and PEG 8000. Spectroscopic results confirmed stronger interaction of FLT with PVP K90 and PEG 8000, thereby confirming the in-solution precipitation and molecular modeling binding energy results. Amorphous dispersions formulated with PVP and PEG were stable and showed higher dissolution, an important property necessary to improve the physicochemical properties and drug delivery of poorly soluble anticancer drug FLT.

Drug-Lipid-Surfactant Miscibility for the Development of Solid Lipid Nanoparticles.

This research aimed to study the correlation between miscibility of flutamide (FLT), lipids and surfactant on the particle size of solid lipid nanoparticles (SLNs). Physical mixtures (PMs) of lipids-glyceryl monooleate (GMO), Precirol® (glyceryl palmitostearate, PRE), glyceryl monostearate (GMS), and Compritol® (glyceryl dibehenate, COM) were prepared with surfactant-Gelucire® (stearoyl polyoxyl-32 glycerides, GEL) 50/13 and 44/14. PMs were prepared in 5:2 w/w ratio (lipid:surfactant) and 2:1 w/w (Flutamide (FLT):lipids/GEL 50/13) by co-melting. Miscibility of PMs was investigated using modulated differential scanning calorimetry (MDSC). SLNs with and without drug were prepared using GEL 50/13 by the ultra-sonication method and particle size analysis was conducted. PMs of GMO, GMS, and PRE with both surfactants showed a decrease in the melting temperature, no change in melting and crystallization peak was observed with COM-GELs, indicating immiscibility. Similarly, MDSC data suggests good miscibility of FLT in GMO, GMS, and GEL 50/13 but not in PRE and COM. The particle size of drug-loaded SLNs prepared from GMO and GMS with GEL 50/13 was found to be 70.2 ± 5.4 and 92.6 ± 8.5 compared to > 200-nm particles obtained from PRE and COM. On lyophilization, an increase in particles size was observed with COM only. The particle size of SLNs with PRE and COM was prominently increased during stability studies indicating SLNs prepared with GMO and GMS are more stable due to miscibility and ability to reduce the crystallinity of FLT. The results established a good correlation between drug, lipids, and surfactants miscibility to the obtained particle size of SLNs before and after lyophilization. Graphical Abstract ᅟ.

Investigation and correlation of drug polymer miscibility and molecular interactions by various approaches for the preparation of amorphous solid dispersions.

Curcumin (CUR) was used as a poorly soluble drug whereas polyvinyl pyrrolidone K90 (PVP), Eudragit EPO (EPO), hydroxypropyl methylcellulose E5 (HPMC) and polyethylene glycol 8000 (PEG) were used as hydrophilic polymers. CUR polymer miscibility was evaluated by solubility parameter, melting point depression and glass transition temperature (Tg) measurements. Molecular interactions between CUR and polymers were determined by Fourier-transform infrared spectroscopy (FTIR) and Raman. Amorphous solid dispersions were prepared with CUR-polymer ratio of 70:30 (w/w) by solvent evaporation technique and were evaluated for dissolution enhancement using USP II method. Physical states of solid dispersions were characterized by X-ray diffraction (XRD) whereas thermal behaviors were investigated using modulated differential scanning calorimetry (MDSC). CUR-EPO system showed good miscibility through all the approaches, whereas immiscibility was found in other CUR-polymer systems. CUR-EPO and CUR-HPMC systems showed significant molecular interactions whereas CUR-PVP and CUR-PEG showed no molecular interactions. All solid dispersions showed significant dissolution enhancement with CUR-EPO showing highest dissolution rate during first 1h whereas CUR-HPMC was effective in maintaining high CUR concentrations for 6h. The study highlights the importance of investigating and correlating drug polymer miscibility and molecular interactions by various approaches for successful formulation of amorphous solid dispersions.