Structural and thermal properties of spray-dried methotrexate-loaded biodegradable microparticles

Physicochemical aspects involved in methotrexate release kinetics from biodegradable spray-dried chitosan microparticles

“…4 shows XRD analysis for different samples. Unprocessed methotrexate occurred in a crystalline state, which was attributed to well-defined diffraction peaks at 2θ of 7.6 and 9.2, characteristic of its trihydrate form [10,19]. In accordance with some reported studies, in the XRD of chitosan diffraction peaks were observed at 10°or 20°corresponding to hydrated and anhydrous crystals respectively [20,21].…”

“…The non-similarity among XRD patterns of MTX-loaded CH microparticles and physical mixtures confirmed the absence of crystalline MTX into particles, which indicated total dissolution of drug into polymeric matrix or amorphization during drying [10,23]. Anterior studies with biodegradable spray dried microparticles containing ciprofloxacin or triamcinolone also demonstrated the preparation of amorphous particles even for drug ratio about 50% [8,9].…”

“…However, the presence aggregate or agglomerates of particles were observed, mainly for particles with higher amount of drug loading. This was attributed to particles' composition because biodegradable polyesters exhibit low Tg, which make it prone to aggregation during spray drying [10]. Thus, the selected parameters and composition were fundamental to obtain small droplets during drying to produce regular spherical chitosan microparticles, which also showed a dependence on used drug ratio.…”

“…The "burst effect" occurred for all formulations according to the used drug-polymer ratio, which is characteristic of spray dried particles [9,10]. At the moment of drying of molecular dispersions, during self-assembly of compounds, a faster diffusion of small molecules into polymeric matrix can occur by capillary flow, with co-precipitation of drug near the surface of particles [6,30].…”

“…Other advantages include total solvent removal, easy scale up and mainly a small and narrow size distribution [5][6][7]. Some important encapsulation parameters like rate of spraying, the feed rate of drug/polymer solution, nozzle size, inlet and outlet temperatures have previously studied and standardized in our research group to produce efficient drug loaded-spray dried particles which impacted directly on the presence of residual solvent size, shape and surface of particles, as well as the crystallinity, thermal behavior and drug-polymer distribution in particles [8][9][10]. In this work, different MTX/CH ratios were used to produce spray dried microparticles containing a considerable drug amount in particles.…”