الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
A polymer is a large molecule made up of many small repeating units called monomers. They
are considered as an important component of pharmaceutical dosage form. The use of polymers
in pharmaceutical preparations was developed early in the 20th century, corresponding to a rising
need for the minimization of toxic side-effects and for the lifecycle management of drugs.
It is believed that the physicochemical properties of the polymers affect the formulation and
clinical performance of the pharmaceutical dosage forms. Polymers such as polymethacrylates,
carbomers, hydrocolloids and cellulose ethers are commonly used in the formulation of oral drug
delivery system
Cellulose ethers are considered to be the most important class of ethers used in pharmaceutical
formulations. This class of polymers includes: methylcellulose, ethylcellulose,
hydroxypropylcellulose, carboxymethylcellulose and hydroxypropylmethylcellulose (HPMC).
HPMC is identified as the most popular cellulosic polymer in matrix applications due to its
safety, availability, compatibility, global compliance and ease of processing.
Drug release from modified release system is influenced by number of variables which could be
divided into drug-related variables, polymer-related variables and formulation and method of
manufacturing-related variables.
The drug related variables include drug solubility, content, molecular weight, particle size and
stability; while the polymer related variables include polymer type, content, and degree of
substitution, molecular weight and source. Variables such as system geometry (shape and size),
method of preparation, physical characteristics of the dosage form (crushing strength), and the
nature of excipients/additives (fillers, binders, surfactants, and lubricants) are examples of
formulation and method of manufacturing-related variables. These variables affect the release
pattern, and therefore can be manipulated to achieve the desirable release kinetics.
The aim of the thesis is to investigate the influence of process variables, polymer properties,
polymer source as well as the influence of additives on the gliclazide release from HPMC matrix
tablets. This aim will be achieved by evaluating different grades and sources of HPMC as a
release controlling polymer and by investigating the effect of polymer modification on the drug
release pattern. The influence of additives as well as the influence of process variables on the
performance of gliclazide matrix tablets will be assessed.