Application of acid-treated yeast cell wall (AYC) as a pharmaceutical additive I. AYC as a novel coating material

Acid-treated yeast cell wall (AYC) was newly prepared by acidifying the cel l wall of brewer's yeast and the potential to use AYC as a novel coating ma terial was studied. AYC had an oval shape with the diameter of several mu m . The rheogram of AYC aqueous dispersion showed the plastic fluid property that is generally observed in the suspension. Core tablets containing 3% of acetaminophen (AAP) were coated with the AYC aqueous dispersion containing 5% (w/v) of AYC and 0.35% (w/v) of glycerol at various coating percents. T he AAP release profile from the AYC-coated tablets was studied by the JP13 paddle method using solutions at various pH. Tensile strength and permeabil ity of oxygen and water vapor of AYC cast film were measured. The AAP relea se from the AYC-coated tablets showed sigmoidal release profile with an ini tial lag time and the duration of the lag time depended on the coating perc ent of AYC. The pH of the dissolution fluid or the storage at room temperat ure for 120 days had little affect on AAP release from the AYC-coated table ts. These results suggest that it is possible to control the start time of medicine release independent of the pH by coating of AYC, that is the time- controlled release. The AYC cast film showed a large tensile strength and a n extremely small oxygen permeability coefficient and a sufficient level of water permeability coefficient in order to protect from moisture. These re sults present that AYC has the high utility as a novel aqueous coating mate rial for DDS preparations. (C) 2000 Elsevier Science B.V. All rights reserv ed.