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    Suitability of cellulose ester derivatives in hot melt extrusion.Thermal, rheological and thermodynamic approaches used in the characterization of cellulose ester derivatives for their suitability in pharmaceutical hot melt extrusion

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    PhD Thesis (9.374Mb)
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    Publication date
    2015
    Author
    Karandikar, Hrushikesh M.
    Supervisor
    Paradkar, Anant R.
    Gough, Timothy D.
    Kelly, Adrian L.
    Keyword
    Hot Melt Extrusion (HME); Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS); Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP); Plasticisers; Thermal degradation-kinetics and mechanism; Polymer-plasticiser interactions; Thermodynamics of miscibility; Low-high shear rate rheology; Impurity quantitation; chlorpropamide
    Rights
    Creative Commons License
    The University of Bradford theses are licenced under a Creative Commons Licence.
    Institution
    University of Bradford
    Department
    School of Life Sciences
    Awarded
    2015
    
    Metadata
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    Abstract
    Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.
    URI
    http://hdl.handle.net/10454/14862
    Type
    Thesis
    Qualification name
    PhD
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