tableting the microcapsules or fill

tableting the microcapsules or filling these
microcapsules into hard gelatin capsules.
Therefore, the Carr’s (consolidation) index and
Hausner ratio of microcapsules were calculated in
order to determine the flow ability of the
microcapsules.
MATERIALS
In this experiment we utilized the following:
Gelatin bloom 275 (granular) type A (Fisher
Scientific Company, Chemical Manufacturing
Division USA), grewia gum (processed in our
laboratory) distilled water, 10% acetic acid,
sodium hydroxide, 95% ethanol (BDH Chemicals,
England ), formaldehyde 37% (Sigma Aldreich
Ltd., England), acacia gum (processed in our
laboratory), and ibuprofen (Mallinckrodt
Chemicals Inc. USA).
METHODS
Preparation of Ibuprofen Microcapsules
The method of Palmieri et al. (1996) was adapted.
A certain amount of the ibuprofen powder was
incorporated into a 2%w/v Grewia gum solution at
40o
C. Then an equal volume of 8% w/v gelatin
solution at 40o
C was added to the suspension and
the system was continually stirred. The final ratio
between the drug and the two polymers was 1:1.
This new suspension was then diluted with pre-
warmed (40o
C) distilled water. Afterward, the pH
of the system was adjusted with 2% sodium
hydroxide to give a pH of 4.5 with continuous
stirring for 30 mins. at 40o
C. 4 ml formaldehyde
(37% w/v) was added with continuous stirring for
30 mins. The system was then cooled rapidly to 4-
5ᵒC by submerging the beaker containing the
microcapsules in an ice bath. The supernatant
was decanted and the microcapsules were filtered
and freeze- dried.
Freeze-drying
An SB4 freeze-drying machine (Crawley,
England) was used for this process. The
coacervate was filtered and shared into Petri
dishes. These Petri dishes were placed in the
specimen chamber of the SBA machine. To
freeze the products, the specimen chamber
refrigeration button was pressed on the control
panel. When the products were frozen to the
desired temperature (-47 to 22◦
C), the specimen
chamber refrigeration was switched off, leaving
only the condenser refrigeration running. Once
the condenser chamber temperature was below -
30◦
C, the vacuum pump was switched on. As
vapor went off from the products, it formed as
frost on the sides of the condenser chamber.
Heat going into the product caused the ice to
sublimate or vaporize. All the ice in the products
eventually boiled off. The dried product was then
collected and analyzed.
Micromeritic Studies
The bulk density as well as the tapped density of
each of the batches of microcapsules were
determined using a measuring cylinder; while the
true density was determined using a liquid
pycnometer with kerosene as the displacement
fluid. The flowability of the microcapsules was
indicated by the angles of repose, Carr’s
(consolidation) index and Hausner ratio. The flow
rate of the microcapsules was determined using
an Erweka flow meter, while the angle of repose
was evaluated using the fixed height method.
Furthermore, Carr’s index was calculated using