In vivo studies of amylose- and ethylcellulose-coated [13C]glucose microspheres as a model for drug delivery to the colon

Cummings, John H.; Milojevic, Snezana; Harding, M.; Coward, W. A.; Gibson, Glenn R.; Botham, R.L.; Ring, Stephen G.; Wraight, E. P.; Stockham, M. A.; Allwood, M. C.; Newton, John

doi:10.1016/0168-3659(95)00186-7

Cited by 62 publications

(18 citation statements)

References 34 publications

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“…These mixed coating formulations exhibited in vitro resistance to gastric and small intestinal conditions yet remained sensitive to digestion by enzymes of colonic bacterial origin [ 9,10]. Testing in human volunteers verified the results obtained in vitro [3,11], thereby confirming the colon-specificity of these amylose-based delivery systems.…”

Section: Introductionsupporting

confidence: 49%

“…To this end, systems that utilize materials that are susceptible to degradation by bacterial enzymes within the colon are believed to hold more promise than pH-and time-dependent systems [1,2]. In addition, natural materials, such as those found in the diet, are preferred over synthetic materials for colonic delivery because they are safer and more available [3].…”

Section: Introductionmentioning

confidence: 99%

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The potential of organic-based amylose-ethylcellulose film coatings as oral colon-specific drug delivery systems

2000

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Amylose-ethylcellulose film coatings obtained from organic-based solvents were investigated as potential vehicles for colonic drug delivery. Amylose, in the form of an amylose-butan-1-ol dispersion, and ethylcellulose, dissolved in either ethyl lactate, ethanol, or propanol and plasticized with dibutyl sebacate, were mixed in various proportions and applied using a fluidized bed coater to achieve a range of film thicknesses on 5-aminosalicylic acid pellets. Drug release from the coated pellets was assessed under gastric and small intestinal conditions in the presence and absence of pepsin and pancreatin using dissolution methodology, and also within a simulated colonic environment involving fermentation testing with human feces in the form of a slurry. Under upper gastrointestinal tract conditions, the rate and extent of drug release were found to be related to the thickness of the coating and the ratio of amylose to ethylcellulose within the film. Modeling of the drug release data revealed that the ratio was more important than coat thickness in controlling drug release, irrespective of the solvent used for coating. Coatings with a thick film and/or low amylose content were relatively impermeable and able to delay drug release under conditions mimicking the upper gastrointestinal tract. Furthermore, drug release was unaffected by the presence of pepsin and pancreatin and by long-term storage. Under simulated colonic conditions, drug release was more pronounced from coating formulations containing higher proportions of amylose. Colon-specificity can therefore be achieved using such systems by judicious choice of the appropriate ratio of amylose to ethylcellulose and coat thickness.

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Section: Introductionsupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%

The potential of organic-based amylose-ethylcellulose film coatings as oral colon-specific drug delivery systems

2000

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“…Milojevic et al (1996), and Wilson and Basit (2005) showed that amylose and ethylcellulose (aqueous dispersion) coated dosage forms were resistant to simulated gastric and small intestinal conditions for 12 h, but showed release of drug in an inoculum of mixed human faecal bacteria. With the same coatings, in vivo, Cummings et al (1996) and Basit et al (2004) showed radiolabelled drug release from pellets when the dosage form was known, by gamma scintigraphic methods, to have reached the colon. Similar work has been carried out using ethylcellulose in organic solution (Siew et al 2000a(Siew et al , b, 2004Tuleu et al 2002), however aqueous systems are preferable, in terms of toxicological and environmental issues.…”

Section: Introductionmentioning

confidence: 89%

Colonic drug delivery using amylose films: the role of aqueous ethylcellulose dispersions in controlling drug release

et al. 2006

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Amylose, a plant polysaccharide from starch, can be combined with ethylcellulose to produce a film coating capable of effecting colon specific drug release from a dosage form through bacterial fermentation of the amylose component. Ethylcellulose is present in the system as a structuring agent in the form of the aqueous dispersion Surelease Ò grade EA-7100. There are, however, two other grades of Surelease Ò (E-7-7050 and E-7-19010), which vary slightly in terms of their composition. The aim of the study was to establish whether these grades differ in their drug release profiles, when used as a film coat, either as onecomponent coatings, or in combination with amylose. The dissolution profiles of Surelease Ò coated pellets were investigated and it was found that there was no difference between the grades when used as coating materials on their own. However, when used in combination with amylose, it was found that grade EA-7100 showed retardation of drug release in simulated upper gastro-intestinal (GI) conditions, whereas grades E-7-7050 and E-7-19010 did not limit the release to the same extent. E-7-19010 showed very poor controlled release properties when combined with amylose. These differences could not be attributed to the minimum film forming temperature (MFT) of the coating formulation, which was found to be independent of the grade of Surelease Ò . It was also confirmed that the film coated pellets prepared from amylose and EA-7100 showed good release in human faecal slurry, i.e. simulated colonic conditions. It was concluded that the grades of Surelease Ò , when combined with amylose, are not interchangeable.

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“…Indeed, the in vitro faecal fermenter has been used for many years as a model for human colonic bacterial activity 22,[27][28][29][30][31][32] and good in vitro-in vivo correlations have been found with amylose based colonic drug delivery systems. 8,[33][34][35] Such an in vitro model was therefore used in our studies.…”

Section: Introductionmentioning

confidence: 99%

An Investigation into the Digestion of Chitosan (Noncrosslinked and Crosslinked) by Human Colonic Bacteria

McConnell

Murdan

Basit

2008

Journal of Pharmaceutical Sciences

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In vivo studies of amylose- and ethylcellulose-coated [13C]glucose microspheres as a model for drug delivery to the colon

Cited by 62 publications

References 34 publications

The potential of organic-based amylose-ethylcellulose film coatings as oral colon-specific drug delivery systems

The potential of organic-based amylose-ethylcellulose film coatings as oral colon-specific drug delivery systems

Colonic drug delivery using amylose films: the role of aqueous ethylcellulose dispersions in controlling drug release

An Investigation into the Digestion of Chitosan (Noncrosslinked and Crosslinked) by Human Colonic Bacteria

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