10
Particle Technology
Process
Spray-drying a drug solution to achieve finely
dispersed drug particles.
Performance Small and homogeneous particle size.
Spray Drying
Challenges
Good for water-soluble drugs. For poor water solubility
drug, organic solvent will increased operating cost and
caused environmental problems.
Process
RESS (rapid expansion of supercritical solutions
technique) : For drug soluble in supercritical CO
2
, drug
particles can be precipitated by rapid expansion of the
SCF.
ASES (aerosol solvent extraction system process): For
limited solubility in supercritical CO
2
. The drug is
dissolved in a solvent and precipitate in the SCF.
Performance Uniform particle size and shape.
SCF (Super Critical Fluid
Technology)
Challenges High
operating
cost.
Process
Precipitating the drug by a liquid solvent change
process (salting out). Stabilizing agent required (e.g.
poloxamer and gelatin). Spray-drying or freeze-drying
to obtain stable product.
Performance Mean particle size 270 nm.
Controlled Crystallization-
solvent change process
Challenges
High content of stabilizing agent caused low
dissolution rate.
Process
Precipitation from drug solution by solvent change
process in the presence of protective hydrophilic
polymer followed by spray-drying.
Performance
Applicable for both water-soluble and water-insoluble
drugs. Homogeneous particle size distribution.
In-situ Micronization
Challenges N/A
Process
Drug solution dissolved in dichloromethane or ether is
heated above boiling point under pressure. The solution
is sprayed into a heated aqueous phase. The resulting
aqueous suspension is then spray-dried or freeze-dried.
Performance
Increased wettability, small particle size and reduced
crystallinity.
EPAS (evaporative
precipitation into aqueous
solution)
Challenges N/A
Process
A drug solution is sprayed into liquid nitrogen, after
freeze-drying the solidified droplets, the drug is
abtained in micron-size form.
Performance Suitable for production of peptide particles.
Spray freezing into liquid
Challenges N/A
CURRENT AND FUTURE DEVEPLOPMENT
Manufacturing of drug products is a challenge besides Research and development in this field. The
economic and efficiency of each processing steps need to be balanced up with the stringent specification
of the drug products. Controlling the drug particle size is at utmost important because it will affect the
drug solubility and thus the effectiveness to human body.
The methods listed in Table 1 are used in the current manufacturing processes and further improvement is
on-going, especially in the particle engineering field. One of the recent studies reported by Berggren, et.
al (2004) shown that the compression behaviour and tablet-forming ability of spray-dried amorphous
lactose can be modulated by the addition of stabilizing polymers or surfactants to the spray feed solution.
Another studies in 2004 (Bandi, et.al.) proposed a solvent-free single-step SCF approach that provides
