Piroxicam cocrystals with phenolic coformers: preparation, characterization, and dissolution properties

<p>This study explores the preparation and investigation of dissolution properties of piroxicam cocrystals. Differential scanning calorimetry (DSC) was used to determine the capability of resorcinol (RES), methylparaben (MPB), and vanillin (VAN) to form cocrystals with piroxicam (PRX). Generation of cocrystals was attempted by liquid assisted grinding and slurry methods. Cocrystals were characterized by thermal methods, powder X-ray diffraction, and Fourier-transform infrared spectroscopy. Apparent solubility, intrinsic dissolution rate (IDR), and powder dissolution profile of cocrystals were compared with anhydrous piroxicam, piroxicam monohydrate (PRXMH), and previously reported piroxicam-succinic acid cocrystal. Contact angles and particle sizes of the studied solids were also measured. Based on the DSC screening results, we prepared and characterized PRX-RES and PRX-MPB cocrystals. Interestingly, the cocrystals not only failed to improve apparent solubility and IDR of PRX but also showed lower values than PRX that were attributed to induction of phase transformation of PRX to PRXMH. In contrary, cocrystals performed better than PRX in powder dissolution studies. The higher dissolution rates of cocrystals were explained by improved wettability and reduced sizes. This study has highlighted the complexity of solid state properties of cocrystals and has provided new evidence for the in-solution stability issues of cocrystals.</p

Piroxicam nanoparticles for ocular delivery: Physicochemical characterization and implementation in endotoxin-induced uveitis

To investigate the anti-inflammatory impacts of piroxicam nanosuspension, in the current investigation, piroxicam:Eudragit RS100 nanoformulations were used to control inflammatory symptoms in the rabbits with endotoxin-induced uveitis (EIU). The nanoparticles of piroxicam:Eudragit RS100 was formulated using the solvent evaporation/extraction technique. The morphological and physicochemical characteristics of nanoparticles were studied using particle size analysis, X-ray crystallography, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Drug release profiles were examined by fitting the data to the most common kinetic models. Selected nanosuspensions were used to assess the anti-inflammatory impacts of piroxicam nanoparticles in the rabbits with EIU. The major symptoms of EIU (i.e. inflammation and leukocytes numbers in the aqueous humor) were examined. All the prepared piroxicam formulations using Eudragit RS100 resulted in a nano-range size particles and displayed spherical smooth morphology with positively charged surface, however, the formulated particles of drug alone using same methodology failed to manifest such characteristics. The Eudragit RS100 containing nanoparticles displayed lower crystallinity than piroxicam with no chemical interactions between the drug and polymer molecules. Kinetically, the release profiles of piroxicam from nanoparticles appeared to fit best with the Weibull model and diffusion was the superior phenomenon. The in vivo examinations revealed that the inflammation can be inhibited by the drug:polymer nanosuspension more significantly than the microsuspension of drug alone in the rabbits with EIU. Upon these findings, we propose that the piroxicam:Eudragit RS100 nanosuspensions may be considered as an improved ocular delivery system for locally inhibition of inflammation