Patent ID: 7179490

Claim:
A method of spherifying a sustained release ionic conjugate comprising a biodegradable polymer containing a free carboxyl group containing biodegradable polymer and a free amino group-containing drug which are ionically bonded to each other, said method comprising: mixing said conjugate with a first liquid to form a first dispersion, wherein said conjugate has the shape of a microparticle having an average diameter of between 5 μm to 200 μm and is not soluble in said first liquid; heating said first dispersion to a temperature greater than the Tg or Tm of said conjugate; cooling said first dispersion below the Tg or Tm of said conjugate; mixing said first dispersion with a second liquid to form a second dispersion, wherein said second liquid is miscible with said first liquid and said conjugate is not soluble in said second liquid; and isolating said conjugate from said second dispersion.