Awie F. Kotzé

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The absorption enhancing effects of chitosan and its derivatives have been intensively studied in recent years. It has been shown that these compounds are potent absorption enhancers. Chitosan is only soluble in acidic environments and is therefore incapable of enhancing absorption in the small intestine, the main absorption area in the gastrointestinal(More)
A wide variety of peptide drugs are now produced on a commercial scale as a result of advances in the biotechnology field. Most of these therapeutic peptides are still administered by the parenteral route because of insufficient absorption from the gastrointestinal tract. Peptide drugs are usually indicated for chronic conditions, and the use of injections(More)
Previous studies have established that a partially quaternized derivative of chitosan, N-trimethyl chitosan chloride (TMC), can be used as an absorption enhancer for large hydrophilic compounds across mucosal surfaces. This study evaluates and compares the effects of the degree of quaternization of TMC, in a neutral environment, on the permeability of(More)
N-trimethyl chitosan chloride (TMC) is a polycation that enhances drug transport across epithelia by opening tight junctions. The degree of quaternization of TMC determines the number of positive charges available on the molecule for interactions with the negatively charged sites on the epithelial membrane and thereby influences its drug(More)
Five TMC polymers with different degrees of quaternisation (12-59%) were synthesised and administered together with [14C]-mannitol in the nasal route of rats at a pH of 6.20 and 7.40, respectively. All the TMC polymers increased the nasal absorption of [14C]-mannitol significantly at pH 6.20, but only TMC polymers with higher degrees of quaternisation(More)
Therapeutic peptides are highly potent and specific in their functions, but difficulties in their administration require parallel development of viable delivery systems to improve their bioavailability. In this study the potential of a novel lipid-based colloidal delivery system for improving the absorption of nasally and intestinally administered salmon(More)
N-Trimethyl chitosan chloride (TMC) is a permanently quaternized chitosan derivative with improved aqueous solubility compared to native chitosan. TMC is able to open the tight junctions of intestinal epithelia at physiological pH values, where chitosan is insoluble and therefore ineffective. TMCs with degrees of substitution of 40 and 60% were synthesized(More)
Previous studies have established that N-trimethyl chitosan chloride (TMC) is a potent absorption enhancer for peptides and large hydrophilic compounds across mucosal surfaces, especially in neutral and basic environments where chitosan is ineffective as an absorption enhancer. The degree of quaternization of TMC plays an important role on its(More)
PURPOSE It was the aim of this study to investigate the possible enhancement of the absorption of recombinant human growth hormone (rhGH) in the nasal cavity, in the presence of a polymeric absorption enhancer, N-trimethyl chitosan chloride (TMC) and a fatty acid-based delivery system, Pheroid. METHODS Two types of Pheroid formulations, Pheroid vesicles(More)
The aim of this study was to evaluate the ability of TMC, with different degrees of quaternization, to increase insulin absorption in vivo following nasal and rectal administration in rats. Two batches of TMC with different degrees of quaternization (TMC-L, 12.3% quaternized and TMC-H, 61.2% quaternized) and chitosan hydrochloride were administered(More)