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multidimensional statistics on AlphaS<strong>of</strong>t V12.3 s<strong>of</strong>tware. Each sample (granules) w<strong>as</strong> testedon <strong>the</strong> Astree e-tongue at le<strong>as</strong>t 4 times with three replicates <strong>for</strong> each sample <strong>for</strong> <strong>the</strong> statisticalanalysis. The average values between 100 and 120 s were used to build <strong>the</strong> maps. Astreesensors were cleaned up in deionised water between each sample me<strong>as</strong>urement. Each samplew<strong>as</strong> diluted <strong>for</strong> 60 seconds under magnetic stirring in 25 ml <strong>of</strong> deionised water to reach APIconcentration corresponding to a final PMOL dose <strong>of</strong> 200 mg. The mixtures were filteredwith Buchner funnel fitted with filter paper <strong>of</strong> 2.5 µm pore size.3.0 Results and Discussion3.1. Solubility parameters and <strong>extrusion</strong> processThe PMOL miscibility with EPO and VA64 w<strong>as</strong> investigated prior to <strong>extrusion</strong> byestimating <strong>the</strong> Hansen solubility parameter using <strong>the</strong> method <strong>of</strong> H<strong>of</strong>tyzer and van Krevelen<strong>for</strong> pure PMOL and both polymers. The prediction <strong>of</strong> drug/polymers miscibility in soliddispersions h<strong>as</strong> successfully been achieved by <strong>the</strong> solubility parameters () [24-27] . Thismiscibility is caused by balancing <strong>the</strong> energy <strong>of</strong> mixing rele<strong>as</strong>ed by inter-molecularinteractions between <strong>the</strong> components by <strong>the</strong> energy rele<strong>as</strong>ed by intra molecular interactionswithin <strong>the</strong> components [21] . Three dimensional partial solubility parameters by Hansen (1969)calculated by group contributions <strong>of</strong> dispersion <strong>for</strong>ces, polar <strong>for</strong>ces and hydrogen bonding<strong>for</strong>ces w<strong>as</strong> provided byVan Krevelen/H<strong>of</strong>tyzer (1976) and Fedors (1974). The <strong>the</strong>oreticalapproach <strong>of</strong> <strong>the</strong> solubility parameter suggests that compounds with similar values are likelyto be miscible. The re<strong>as</strong>on is that <strong>the</strong> energy <strong>of</strong> mixing from intramolecular interactions isbalanced with <strong>the</strong> energy <strong>of</strong> mixing from intermolecular interactions. It w<strong>as</strong> demonstratedthat compounds with < 7 MPa 1/2 were likely to be miscible and compounds with > 10MPa 1/2 were likely to be immiscible [28] . Thus, solubility parameters provide a simple andgeneric capability <strong>for</strong> rational selection <strong>of</strong> carriers in <strong>the</strong> preparation <strong>of</strong> solid dispersions [29] .As can be seen in Table 4.1, <strong>the</strong> difference between <strong>the</strong> calculated solubility parameters <strong>of</strong><strong>the</strong> polymers and <strong>the</strong> drug indicate that PMOL is likely miscible with both polymers. Byusing <strong>the</strong> Van Krevelen/H<strong>of</strong>tyzer <strong>the</strong> values <strong>for</strong> PMOL and EPO/VA64 are 6.86 and 6.17respectively.However, a two dimensional approach proposed by Bagley et al. [30] w<strong>as</strong> used also topredict drug – polymer miscibility <strong>as</strong> shown in Table 4.1. By using <strong>the</strong> two – dimensionalapproach Bagley et al. observed that p and d have similar <strong>the</strong>rmodynamic effects in contr<strong>as</strong>tto h and introduced <strong>the</strong> volume – dependent solubility parameter, v, where68 | P a g e

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