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

• Methotrexate was loaded in chitosan microparticles to sustained drug release.
• Particles exhibit spherical shape according MTX/CH ratio (9%, 18%, 27%, 45% w/w).
• Even particles with higher drug loading presented a sustained drug release profile.
• Drug release profiles were mathematically modeled using adjusted Higuchi model.

Spray dried methotrexate (MTX) loaded chitosan microparticles were prepared using different drug/copolymer ratios (9%, 18%, 27% and 45% w/w). The physicochemical aspects were assessed in order to select particles that were able to induce a sustained drug release effect. Particles were successfully produced which exhibited desired physicochemical aspects such as spherical shape and high drug loading. XRD and FT-IR analysis demonstrated that drug is not bound to copolymer and is only homogeneously dispersed in an amorphous state into polymeric matrix. Even the particles with higher drug loading levels presented a sustained drug release profile, which were mathematically modeled using adjusted Higuchi model. The drug release occurred predominantly with drug dissolution and diffusion through swollen polymeric matrix, with the slowest release occurring with particles containing 9% of drug, demonstrating an interesting and promising drug delivery system for MTX.