| 摘要 |
Particles of acetylsalicylic acid, which have first been coated with an acid buffering salt, are encapsulated in hydrophobic polymeric material by dispersing the particles in a hot solution, in cyclohexane, of ethyl cellulose and a phase separation agent, and then cooling while maintaining dispersion by agitation, whereon the ethyl cellulose deposits on the particles as a liquid phase which solidifies by desolvation as cooling progresses; after cooling the coated particles are separated, and washed with a solvent for the phase separation agent. Preferred such agent may be polyethylene of molecular weight about 7000, melting point 100-101 DEG C. Suitable acid buffering salts are the monobasic phosphates of sodium, potassium, or ammonium. The phase separation temperature of the ethyl cellulose may be lowered by inclusion of an acetylated monoglyceride in the dispersion.ALSO:Particles of acetylsalicylic acid are encapsulated in hydrophobic polymeric material by dispersing the particles, which are first coated with an acid buffering salt, in a hot cyclohexane solution of ethyl cellulose and a phase separation agent and then cooling the dispersion while agitating it, until the ethyl cellulose separates out on the acetylsalicylic acid particles, when the coated particles are separated off, washed in a solvent for the phase separation agent, and then dried. The preferred phase separation agent is a suitable polyethylene (e.g. Mol. Wt. CA. 7, 000, softening point: 100 to 101 DEG C). Suitable acid buffering salts are the mono basic phosphates of sodium, potassium, or ammonium. The process may be modified by addition of an acetylated monoglyceride to the bispersion to lower the temperature at which phase separation of the ethyl cellulose takes place. |
