Hyopneumoniae Vaccine Research Articles

Preparation of enteric-coated microspheres ofMycoplasma hyopneumoniaevaccine with cellulose acetate phthalate: (II). Effect of temperature and pH on the stability and release behaviour of microspheres

The in vitro stability (temperature and pH) and dissolution study (pH 7.4 phosphate buffer solution and pH changed medium) of the enteric-coated microspheres containing Mycoplasma hyopneumoniae vaccine (MHV) were examined. The MHV microspheres were thermally more stable than the unencapsulated MHV. More than 90% of antigenicity was retained in the MHV microspheres for 3 weeks when stored at 4 degrees C. The MHV microspheres in pH 1.2 and pH 3.0 medium were more stable than the unencapsulated MHV. The MHV enteric-coated microspheres exhibited an excellent enteric function to prevent pH-related inactivation. The influence of particle size, CAP concentration and span 80 concentration on the MHV released from microspheres was also determined. The smaller the particle size, the higher the dissolution rate due to the larger surface area of the smaller particle. The higher the concentration of span 80 used, the more the greater the amount of MHV released. This was attributed to the more porous structure of microspheres prepared by the higher concentration of span 80. By increasing the CAP concentration, however, the release rate of MHV was decreased due to the larger amount of CAP and the more compact structure of microspheres.

Preparation of enteric-coated microspheres of Mycoplasma hyopneumoniae vaccine with cellulose acetate phthalate: I. Formation condition and micromeritic properties

The solvent evaporation method was employed to encapsulate Mycoplasma hyopneumoniae vaccine (MHV) using cellulose acetate phthalate (CAP) as an enteric coating material. Glucose was used as a diluent. The effect of some factors, such as encapsulating temperature, surfactant concentration, mechanical agitation and CAP concentration on the formation condition, particle size distribution, morphology, surface topography and antigen content of MHV microspheres, was investigated. The result indicates that the optimal operating conditions were: encapsulating temperatures, 20 degrees C; stirring speed, 400 rpm; span 80 concentration, 0.6; and 8 per cent of CAP concentration, 30 ml. The optimal condition can be used to prepare the desirable microspheres. The content uniformity of MHV microspheres was also indicated.