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 the 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 end fibers generated with core/shell feeding rates of 0.5/1 and 5/10 mL/h. The 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 hours at 37 °C. After storage under ambient conditions (19-21°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 electrospinning for fabricating a sustained-release floating gastro-retentive drug delivery system for captopril.