Preparation and evaluation of sustained release formulation of PLGA using a new injection system based on ink-jet injection technology.

We developed a method for the preparation of PLGA particles exhibiting long-term sustained-release of entrapped drugs. The fine droplet drying (FDD) technology using a new injection system based on ink-jet injection technology was adapted as the preparation method. PLGA microspheres containing TRITC-dextran, acetaminophen, and albumin as model drugs were prepared by the FDD technology. The resultant microspheres were uniform in size, with average particle sizes ranging from 16.3 to 33.0 μm and SPAN factors ranging from 0.49 to 0.77. The encapsulation efficiency of drugs showed high values ranging from 75 to 99 wt% of the total amount of water-soluble drug contained in the particles. In an investigation of the optimal operation conditions of the FDD technology, the dew point temperature of the dryer air stream was found to be an important factor for controlling the initial burst of the prepared particles. The TRITC-dextran-containing PLGA microspheres were confirmed to exhibit long-term sustained release for about 90 days, and the mechanism was found to be PLGA degradation rate-limiting. Based on these results, we concluded that long-term sustained-released PLGA particles can be prepared by using FDD technology under a suitable drying condition for controlling the initial burst.