ABSTRACT
Allergens extracts encapsulated with an aqueous coating system of a polymethacrylic acid copolymer over a core of allergen-coated nonpareil microsphera were found effective in achieving immunologic effects when given orally to allergic patients, however, the spray coating manufacturing process used to encapsulate the allergens always resulted in allergen loss and low percentage allergen load onto the spheres. The purpose of this study was to develop a coating formulation to increase the percentage short ragweed pollen extract [SRW] load on sugar spheres using a fluid-bed bottom spray [Wurster] coaling process. In this work the use of a solution made of lactose and a film-forming agent such as hydroxypropyl methyl cellulose [HPMC] to coat the allergen was found to significantly [p= 0.018] increase the percentage allergen load on sugar spheres [80%] when compared to a coating solution made of PVP and lactose [68%]. The processing time was also significantly decreased from about 7 hours when using the PVP-lactose coating solution to only 2 hours when using the HPMC-lactose coating solution. When a precoat made of HPMC alone was first coated on the sugar spheres before coating the allergen layer the percentage allergen load was further significantly increased from 80% to 92% [p=0.015]. The coating technique did not alter the allergenic epitopes and released the SRW allergen in their native form as indicated by an ELISA inhibition test. The use of trehalose, a non-reducing sugar, instead of lactose was also found to increase the percentage allergen load from 92% to 96%, however this increase was not significant [p =0.16]. An HPMC coat between the allergen layer and the enteric layer, on the other hand, was found unnecessary and had no significant effect on the allergen percentage load [p= 0.3]