Conversion of liquid and semisolid lipids into
free flowing powders is an advantageous technique, as
the carriers display high surface area, strong adsorption
capacity, ease of processing, and ability to generate lipid
loaded free flowing powders which can be converted to
solid dosage forms like tablets and capsules. A combination
of density, adsorption capacity and desorption is
found to be of importance in the selection of the right
adsorbent. Adsorbents like magnesium aluminium silicates
(MAS), granulated fumed silica (GFS) and mesoporous
silica gel (MSG) were characterized by flow property
measurements, particle size, scanning electron microscopy
(SEM) and pore structure by mercury (Hg) intrusion
study. SEM results reveal adsorbent morphology,
whereas an intrusion-extrusion study reveal pore size distributions.
Tablets and capsules of oil loaded adsorbents
were prepared by conventional methods. Oil loaded adsorbents
were evaluated for the ability to convert oil into
powder, easy of processing into tablets and capsules, and
release of the loaded oil (Vitamin E) or active (Glyburide).
All adsorbents possess good flow property while MSG has
higher density than GFS and MAS. This helps to deliver
maximum active per unit volume. A wider pore size distribution
of MAS was observed in comparison to MSG and
GFS. MAS exhibited poor oil release from powder and its
formulations, whereas GFS demonstrated closely similar
release to MSG. Maximum 70% oil loaded MSG can be delivered
in tablet dosage form andMSG can deliver the highest
amount in limited volume capsules due to its high density.
Hence, lower density and poor oil release from MAS
limit its applications in solid oral drug delivery,while both
MSG and GFS proved to be suitable.