| Summary: | The aim of this study is to develop a novel drug delivery system for biologics i.e. proteins and peptides using a solid core drug delivery system (SCDDS). Both, 0.5 μm and 1.0 μm silica particles were used as a model core material and were coated with different ratios of fatty acid. A proportional increase in particle size was observed with increasing ratio of fatty acid in the formulation. Coating of silica particles with smaller chain fatty acids (lauric and myristic acid) resulted in a higher increase in particle size compared to the longer chain fatty acids i.e. palmitic acid and stearic acid. Bovine serum albumin was used as a model drug. SCDDS preparation included absorption of BSA on silica (BSA-Si) followed by coating of the BSA-Si particles with fatty acid via supercritical processing. In order to determine the best system to achieve maximum absorption of BSA, isotherms were obtained in different media i.e. water, 0.15 M NaCI solution and a citrate-phosphate buffer at pH 4.0, 4.7, 5.0, and 7.0. Results showed an increase in the amount of BSA absorbed was observed with the increasing specific surface area of silica particles. Isotherms demonstrated that maximum absorption of BSA can be achieved at or close to the iso-electric point (IEP) of the protein. A SCDDS was prepared by absorbing BSA on silica at pH 5.0 in citrate/phosphate buffer and coating these particles with fatty acid in the ratio (fatty acid:silica) of 0.1:1, 0.25:1 and 0.5:1. Release studies were conducted in phosphate buffer saline at pH 7.4. The release of BSA was fastest and highest from SCDDs prepared using 0.5 μm silica with a specific surface area of 4.4 m2/g. SCDDS prepared using 1.0 μm silica with a specific surface area of 2.2 m2/g provided slowest BSA release. BSA release from the SCDDS was also dependent on the chain length of fatty acid used and its ratio in the formulation. The release of BSA from SCDDS prepared with lauric acid was fastest and highest whilst stearic acid formulations showed the slowest release amongst all systems.
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