Abstract

Hydrophilic matrix tablets present a convenient method for oral modified
drug delivery. The performance of such dosage forms is affected by
multiple factors, amongst which the influence of tablet shape and
structural properties have been partially investigated in previous
literature. This work focused on investigating the influence of changing
tablet properties on the in-vitro behaviour of hydrophilic matrix tablets, in
particular, the influence of tablet face curvature on the hydration and drug
release behaviour of round and elongated Xanthan Gum tablets
containing the two model drugs Orphenadrine Citrate and Orphenadrine
Hydrochloride. The influences of tablet overall porosity and of the
formulation used on tablet behaviour were also investigated, in addition to
the investigation of any interactions between the influences of tablet and
formulation variables.
Initially the properties of the powders incorporated into the various
formulations used were characterised. The physical properties of the dry
tablets were then investigated in terms of tablet tensile strength and
Abstract
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structural properties. The hydration behaviour of the various tablets was
investigated quantitatively using live in-situ swelling studies and
qualitatively using rheological and calorimetric methods. Finally the
process of drug and polymer dissolution from the tablets was
investigated.
The results of the work indicated that tablet face curvature had a
significant influence on the physical properties of the dry tablets as well
as on the hydration and dissolution patterns associated with the hydrated
tablets. The influence of tablet overall porosity was profound on the
properties of the dry tablets but became rather minor upon tablet
hydration. The type of formulation had a major influence on the properties
of dry tablets. Moreover, ionic interactions between the two drugs and
Xanthan Gum had a significant influence on the properties of hydrated
tablets. Thus, tablet face curvature, porosity of the tablets and physicochemical
properties of the drugs need to be considered when formulating
a hydrophilic matrix tablet.