Drug encapsulation, coaxial

Martin et al. precipitated budesonide and budesonide-PLA microparticles by a PCA technique. Utilizing SC CO2 as an antisolvent at various temperatures (35°C and 40°C) and pressures (78.9, 85.8, 92.7, and 138 bar), the drug solution and antisolvent were passed coaxially, as drug solution was introduced through a 100-pm capillary tube. Typical experiments involved two 20-1- —sec sprays of budesonide-PLA solution at 1.4mL/min, followed by CO2 equivalent volume purging to remove the residual solvent (methylene chloride). The mean diameters of processed budesonide and budesonide-PLA particles were 1-2 pm. The budesonide-PLA microparticles had a loading of 7.94%, which was equivalent to an 80% encapsulation efficiency. The in vitro release studies indicated a 50% budesonide release from the microparticles at the end of 28 days. The unprocessed budesonide, SCF-processed budesonide, and SCF-processed budesonide-PLA particles are shown in Fig. 5. 

A coaxial electrospray process was also developed to encapsulate protein-based drugs in biodegradable polymeric microparticles, eliminating the key problem of protein denaturation and aggregation faced by other conventional methods of... 

As reported in other chapters in this volume, PLA is one of the most used materials for biomedical applications due to biocompatibility and biodegradability, but hydrophobic properties require the encapsulation of water-soluble agents to avoid decomposition and failure of the polymer as a drug-carrier substrate. One of the advantages of coaxial electrospinning is that solid or liquid drugs can be incorporated into electrospun nanofibres and it is possible to encapsulate drugs into a structural shell. 

Wu, Q. S. Encapsulating drugs in biodegradable ultrafine fibers through coaxial electrospinning. 77A, 169-179. 

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