Tablets and capsules are the most popular final dosage forms to deliver
drugs orally as they provide advantages of patient compliance, low
cost and formulation related factors. Their popularity as a dosage platform
for solid dispersions is evident by the fact that most (if not all) of
the marketed products are either tablets or capsules [108]. Spray dried
powders as such are not ideal for conversion into tablets or capsules
and require downstream processing. The CQA of spray dried ASD
which are important with respect to their downstream processing are
residual solvent, particle size, bulk density, flowability, compressibility
and compatibility, disintegration and stability. Various aspects of the
downstream processing are depicted in Fig. 8. For large-scale
manufacturing, powder flowability is a relevant CQA irrespective of
the intended final dosage form. Spray dried powders generally have a
relatively small particle size and low bulk density resulting in poor
flowability. Depending on the droplet drying rate and temperature,
the particles may have hollowspheremorphologywith a lowbulk density
(b0.2 g/cm3) or shriveled raisin morphology having high bulk density
(0.2–0.4 g/cm3) [95]. Other morphologies are also possible,
however, large sized spherical particles generally give better flow properties
and compressibility which can be achieved via spray drying by
process optimization [89]. Pressure nozzle is useful to achieve such particles
which might even be suitable for direct compression. A precompaction
step can be employed for lowbulk-density solid dispersions
to improve their flowability [231]. Furthermore, dry granulation and
wet-granulation are viable strategies to improve solid dispersion
handling.