Developing and scaling up captopril-loaded electrospun ethyl cellulose fibers for sustained-release floating drug delivery

In this work ethyl cellulose (EC) was used as a matrix polymer and loaded with captopril, with the goal to fabricate electrospun fibers as potential sustained-release floating gastro-retentive drug delivery systems. Fibers were prepared with monoaxial and coaxial electrospinning, and both bench-top and scaled-up (needle-based) methods were explored. With monoaxial electrospinning, EC-based fibers in the shape of cylinders and with smooth surfaces were obtained both at 1 and 20 mL/h. For coaxial electrospinning, the drug was encapsulated in the core and fibers generated with core/shell feeding rates of 0.5/1 and 5/10 mL/h. These fibers were cylindrical in shape with a wrinkled surface, and confocal microscopy suggested them to have a core/shell structure. X-ray diffraction and differential scanning calorimetry results showed that all the fibers were amorphous. The encapsulation efficiency of all the formulations was almost 100%. Release studies in simulated gastric fluid indicated that the monoaxial electrospun fibers gave slower release profiles compared with a physical mixture of captopril and EC, but there was still an initial "burst" of release at the start of the experiment. Fibers with low drug-loading (9.09% w/w) showed a slower release than fibers with high loading (23.08% w/w). The coaxial fibers exhibited sustained release profiles with reduced initial burst release. Both monoaxial and coaxial fibers could float on the surface of simulated gastric fluid for over 24 h at 37 degrees C. After storage under ambient conditions (19-21 degrees C, relative humidity 30-40%) for 8 weeks, all the fibers remained amorphous and the release profiles had no significant changes compared with fresh fibers. This work thus highlights the potential of coaxial elec-trospinning for fabricating a sustained-release floating gastro-retentive drug delivery system for captopril.