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Published on: March 23, 2021
Atomizing into a chilled extraction solvent eliminates liquid gas from a spray-freeze drying microencapsulation
Michael T Kennedy1, Alana Ali-Reynolds, Christina Farrier
1Department of Pharmaceutics, Amgen Inc., MS 8-2-D, Thousand Oaks, California 91320, USA.
Journal of Pharmaceutical Sciences
|February 8, 2008
Summary
A novel spray-freeze drying encapsulation method, atomization into chilled extraction solvent (ACES), was developed. Rapid freezing in ACES (<12 ms) yields high-quality encapsulated particles, comparable to traditional methods but at milder temperatures.
Area of Science:
- Chemical Engineering
- Materials Science
- Pharmaceutical Technology
Background:
- Traditional spray-freeze drying often requires cryogenic temperatures.
- Encapsulation processes aim to protect sensitive compounds and control release.
Purpose of the Study:
- To develop and evaluate a novel spray-freeze drying encapsulation process using atomization into chilled extraction solvent (ACES).
- To determine the optimal conditions for ACES to achieve efficient encapsulation with minimal phase separation and high-quality particle formation.
Main Methods:
- Development of a spray-freeze drying process using direct atomization into a chilled extraction solvent (ACES).
- Utilized heat transfer models to estimate droplet freezing times (t(f)).
- Investigated the effect of ACES conditions on particle morphology, phase separation, and residual solvent levels.
Main Results:
- ACES process, without liquefied gas, successfully produced encapsulated particles.
- Rapid freezing (t(f) < 12 ms, Stefan number > 1.3) in ACES yielded smooth, spherical-cap particles with solid cores.
- Particle quality, including residual solvent levels, was comparable or superior to atomization into liquid nitrogen (ALN2).
- Milder operating temperatures were achieved compared to ALN2.
Conclusions:
- Encapsulation by ACES is feasible and effective when rapid freezing is achieved.
- The ACES method offers a viable alternative for producing high-quality microparticles under milder conditions.
- Optimizing freezing kinetics is crucial for successful ACES encapsulation.
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