Pharmaceutical Manufacturing Handbook: Production and

1012 TABLET DESIGN
Regression coefficients
Regression coefficients
0.6
0.4
0.2
0.0
-0.2
-0.4
2
0
-2
-4
-6
-8
cEx
cEx
DT
DT
Variables and interactions, t 30%
ce
ce
FIGURE 23
cEx*cEx
cEx*cEx
Regression coeffi cients.
Cetyl alcohol (ce in Figure 23 ) has a signifi cant positive effect on both responses
in the range studied. This may be because the hydrophobic polymer prevents the
fast release of PPL for the fi rst few hours with an increase in the diffusional pathlength
of the drug because the swelling of hydrophilic polymers (DT and HPMC)
retards the rate of release. Interaction of cetyl alcohol and hydrophilic polymers –
PPL was observed for t 30% . If a prolonged release rate is desired during this period,
the ratio of hydrophilic polymers to cetyl alcohol can be increased, resulting in a
decreased interspace volume after erosion of cetyl alcohol. In contrast to other
products, such as lactose [15] , cetyl alcohol as hydrophobic polymer can be increased.
The viscosity and texture of the gel layer and some modifi cations in polymer –
polymer and polymer – solvent interaction are present.
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DT*DT
DT*DT
ce*ce
ce*ce
cEx*DT
cEx*DT
cEx*ce
Variables and interactions, t 100%
cEx*ce
DT*ce
DT*ce