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Title: The influence of shape on the properties of pharmaceutical pellets
Author: Chopra, Ranjana
ISNI:       0000 0001 3548 0137
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1997
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A common aim of all pharmaceutical pelletization techniques is to produce good quality spheres of uniform size with smooth surfaces to facilitate adequate performance in further processing such as capsule filling, film coating, and drug release. Although the need to work with uniform smooth spheres has been recognized in the literature, the full extent of the influence of shape on the properties of pellets has not been investigated directly. Batches of pellets were produced using different techniques such as extrusion- spheronisation and granulation, with the same basic formulation but differing slightly to manipulate shape and surface properties of the end product. The pellets were then film coated with different thicknesses of insoluble polymer coating. The shapes of the different pellet batches were determined using the relatively new shape factors ec3 (three-dimensional) and eR (two-dimensional), as well as more conventional shape descriptors such as Heywood's and aspect ratios. The pellets were characterized in terms of internal structure, external features and evaluated by studying drug release and capsule filling performance. Commonly used techniques such as mercury penetration for determining porosity and air permeametry for studying surface area were employed, and also novel methods such as laser profilimetry for characterizing surface roughness of pellets. The results were looked at in terms of the effect of coating pellets with increasing thickness of filmcoat, and also identifying differences between the various batches. Relationships between different properties were examined, in particular the influence of shape on pellet properties and performance. The dissolution tests found that drug release was mainly controlled by the thickness of the filmcoat resulting in different mean dissolution times, but all batches demonstrated similar release mechanisms. Capsule filling studies indicated that rounded pellets perform better than elongated pellets, and it was possible to assign an approximate minimum value of shape required for successful filling.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Pharmacology & pharmacy & pharmaceutical chemistry