Pharmaceutical Technology: Controlled Drug Release, Volume 2

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CH. 5] AN OPTIMIZED PROLONGED RELEASE FORMULATION 61 Table 2—Optimized process results (2) Is porosity associated with the dissolution profile, and with one of the studied parameters? (3) As the AUC value is almost the same, may the β parameter of the Weibull function be used for evaluating the variability between tablets and between processes? The flowability test The flowability test was carried out in a Jenike cell [3,13]. The flow function illustrated in Fig. 1 reveals a singular behaviour of the powders which may be associated with the process or with the high percentage of PVC. In fact, even if the curves were obtained by linear regression, a marked dispersion may be seen, particularly for the compaction of the mixture and, curiously, for the wet granulation powder. Regarding the flow function values, powders may be classed in two groups: (1) the direct compression powder, representing poor flow; (2) the granulated powders, giving easy flow. Because of this singular behaviour of the powders, it was supposed that the powder blends were not homogeneous even though the variability of the tablet weight was at a minimum. This means that the test is very sensitive to the technological modifications of the same formula.
62 MATRIX FORMULATIONS [CH. 5 Fig. 1—Flow function and flowability (ic) of the optimized formulations. The porosimetry measurements In order to characterize the microstructure of the matrices, the total porosimetry factor, the pore volume, the pore surface and the mean pore diameter were measured using a mercury porosimeter (Micrometrics) [3]. The mean of three replicates and their coefficient of variation are indicated in Table 3. From the results, it is possible to draw the following conclusions. (1) In accordance with the Dubinin classification [14], all the matrix tablets exhibited macropores (mean pore diameter >200Å). (2) The tablets obtained by direct compression in a single punch machine (Frogerais) and those obtained by wet granulation had very similar values; only the coefficient of variation differentiate these two processes. (3) As expected, as the applied UPF increased, the porosimetry parameters decreased (UPF values: direct compression and wet granulation, 7 kN; double compression, 12 kN; separate compaction, 19 kN; compaction of the mixture, 31 kN). (4) The variability of the porosity parameters may be used to differentiate the processes. It also explains the variability of the dissolution parameters because of the same order of variation (CV): wet granulation (3.0)
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PHARMACEUTICAL TECHNOLOGY Controlle
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3 TABLET MACHINE INSTRUMENTATION IN
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First published in 1991 by ELLIS HO
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7 10 Controlled delivery of theophy
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Slow and steady wins the race Poems
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112 MULTIPARTICULATES [CH. 9 Fig. 7
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114 MULTIPARTICULATES [CH. 9 Fig. 8
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118 CH. 10] CONTROLLED DELIVERY OF
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126 CH. 11] THE EFFECT OF FOOD ON G
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128 CH. 11] THE EFFECT OF FOOD ON G
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132 CH. 12] BIODEGRADABLE POLYMERS
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142 CH. 13] A COMPARISON OF DISSOLU
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156 OPHTHALMIC FORMULATION [CH. 14
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162 CH. 15] A SUSTAINED RELEASE OPH
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172 IMPLANTS [CH. 16 The purpose of
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174 IMPLANTS [CH. 16 times with 5 m
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176 IMPLANTS [CH. 16 noted that the
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178 IMPLANTS [CH. 16 Fig. 1—The e
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180 IMPLANTS [CH. 16 Table 3—Tobr
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184 CH. 17] SILICON MATRIX SYSTEMS
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194 INDEX dry granulation, 43 elect
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Pharmaceutical Technology: Controlled Drug Release, Volume 2

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