Formulation and characterization of liposomal spray dried powders intended for inhalation

Abstract: This master thesis has evaluated the possible use of a spray dryer to produce powders suitable for use as inhalants and whether the addition of liposomes to the solution to be spray dried would improve the properties of the powder. The powders created consisted of Lysozyme as model drug, Lactose as filler and stabilizer, and different types of phospholipids to create liposomes using an ethanol injection method. It was shown that powders suitable for use as inhalants were possible to create. By adjusting the parameters of both the spray dryer and by changing the proportions of the ingredients it was possible to achieve various powders, some of which displayed strong signs of having the proper parameters for use for inhalation. The quality parameter deemed most important for the powders was the fine particle fraction, which corresponds to the fraction of powder that reaches the target area of the lungs. The fine particle fraction was tested using a cascade impactor and it was discovered that this fraction was dependent on the concentration of both lysozyme and liposomes as well as the inlet temperature and feed flow rate of the spray dryer. The detected fine particle fraction varied between just a few percent for some of the powders without liposomes up to more than 50 % for one of the powders created using liposomes. Other investigated parameters were the water activity (important for the stability of the powder), the liposome size distribution (to see how this affected the particles), the yield and the outlet temperature from the spray dryer.