In addition, SAS results in particles that have highly desirable properties for inhalation medicines. The particles generally
are smaller than 10 µm and have a narrow size distribution. The process is tunable and can make 1–3-µm particles (e.g., for
targeting the deep lung) or 3–5-µm particles (e.g., for targeting the upper respiratory airways). Particles made through SAS
also are highly crystalline, free from amorphous domains, and, thus, highly stable. The particles' surfaces tend to be smooth
and regular with low surface energy, and these characteristics reduce agglomeration and help improve downstream handling.
In the past 15 years, technology has advanced to the point where SAS can produce materials at manufacturing scale that comply
with cGMP. New developments at CrystecPharma enable composite particles containing defined ratios of two or more drug substances
(e.g., for combined drug therapy) to be manufactured. Clinical evidence indicates that SAS improves the performance of drug
materials, compared with other manufacturing techniques. Products containing SAS-processed particles have improved drug bioavailability,
led to simplified formulations, and reduced required doses, says York.
SAS also is superior to micronization in several ways. During micronization, particles are bombarded against the walls of
a mill, and this intensive process can create high-energy sites on the surfaces of the materials being milled. These high-energy
sites can cause potential chemical or physical changes in the material. One of the most problematic changes is the introduction
of noncrystalline or amorphous domains in the product, which can reduce its stability. Micronized material also has highly
charged surfaces and tends to be cohesive and difficult to disperse into an aerosol, says York.
Yet many drugmakers might be reluctant to abandon micronization because they have years of experience with the process—and
have invested considerable sums into the technology and training required. The industry's overall conservatism and antipathy
to change also could slow companies' adoption of SAS, in spite of the method's advantages.
If FDA approves Levadex, however, it would be the first product on the market manufactured through SAS. "That will take the
risk out of these processes for a lot of potential clients," says York.