Enteric coating of drug loaded aerogel particles in a wurster fluidized bed and its effect on release behaviour

Ibuprofen loaded and unloaded alginate aerogel particles were successfully coated with methacrylic acid-ethyl acrylate copolymer in a Wurster fluidized bed. Pores of both aerogels were well-preserved during the coating process. Effects of drug loading, polymer rheology, and atomizing pressure on coating thickness and coating layer surface morphology were investigated. Coatings were conducted at circulatory particle motion regime. Due to low weight of unloaded aerogels, this regime was achieved at lower air flow rates than ibuprofen loaded aer-ogels. Coatings of ibuprofen loaded aerogels were conducted between 1.3 and 1.5 bar atomizing pressures and at 60 degrees C. Unloaded aerogels were coated at a constant and high atomizing pressure of 1.7 bar and at 60 degrees C. At this condition, coating thickness of unloaded aerogels increased linearly from 25.6 mu m to 53.4 mu m with increasing coating time from 10 to 50 min. For ibuprofen loaded aerogels, coating thickness increased non-linearly from 15.9 mu m to 84.1 mu m with increasing coating time from 10 to 180 min. Ibuprofen release from aerogels in acidic medium was prevented via coating. In the basic medium, the fastest release was obtained from uncoated aerogels and 57% of ibuprofen was released in 30 min while 44% of crystalline ibuprofen dissolved at the same time. The slowest release rate was achieved via coating and 13% of the drug was released from coated aerogels in 30 min.