pH-Sensitive Polymer Blends Used as Coating Materials to Control Drug Release from Spherical Beads: Elucidation of the Underlying Mass Transport Mechanisms

Lecomte, Florence; Siepmann, Juergen; Walther, Mathias; MacRae, Ross J.; Bodmeier, Roland

doi:10.1007/s11095-005-5421-2

Cited by 73 publications

(20 citation statements)

References 24 publications

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“…This is underlined by the change in pellet diameter and by the lack of change in roundness. The constant flow of water into the pellet would initially increase its size up to a limit when the crack appears (33). At this point, the inner liquid would flow out of the pellet and its diameter would decrease suddenly.…”

Section: Dissolution Studies Of Coated Pelletsmentioning

confidence: 99%

Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

et al. 2010

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Abstract. The objective of the present study was to investigate the effect of the pellet core materials isomalt, sugar, and microcrystalline cellulose on the in vitro drug release kinetics of coated sustainedrelease pellets as well as to evaluate the influence of different ratios of polymethacrylate copolymers exhibiting different permeability characteristics on the drug release rate. For characterization of the drug release process of pellets, the effect of osmolality was studied using glucose as an osmotically active agent in the dissolution medium. The pellet cores were layered with diclofenac sodium as model drug and coated with different ratios of Eudragit® RS30D and Eudragit® RL30D (ERS and ERL; 0:1 and 0.5:0.5 and 1:0 ratio) in a fluid bed apparatus. Physical characteristics such as mechanical strength, shape, and size proved that the inert cores were adequate for further processing. The in vitro dissolution tests were performed using a USP Apparatus I (basket method). The results demonstrated that, besides the ratio of the coating polymers (ERS/ERL), the release mechanism was also influenced by the type of starter core used. Sugar-and isomalt-type pellet cores demonstrated similar drug release profiles.

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Section: Dissolution Studies Of Coated Pelletsmentioning

confidence: 99%

Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

et al. 2010

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“…[136][137][138][139] To optimize the benefits, the design of a controlled release system requires simultaneous considerations of several factors, 140 such as the chemical-physical properties of the drug, the route of administration, 141 the nature of the delivery vehicle, the mechanism of drug release, the potential for targeting, and biocompatibility. Because of the extensive interdependency of those factors, it is not easy to establish a sequential process for designing a controlled drug delivery system, 142 which can bring both therapeutic and commercial value to health care products. 143 Many drug delivery technology companies enjoy a good return on their investments in the form of increased revenues and market share, and it is a very fast-growing segment of the economy.…”

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confidence: 99%

Evolving application of biomimetic nanostructured hydroxyapatite

Roveri¹,

Iafisco²

2010

NSA

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By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative thirdgeneration biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical-physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical-physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical-physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications.

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“…Since the ratio of carboxyl to ester groups in the polymer chains of Eudragit® S100 is 1:2 and 1:1 in Eudragit® L100, the lower ratio of carboxyl groups in S100 causes a lesser degree of ionization in an alkaline environment and therefore a decreased rate of solubilization [46]. By varying the type of Eudragit® polymer blend and ratio, the resulting drug release and dissolution kinetics in response to changing pH can be varied accordingly [47]. A ratio of 4:1 of Eudragit® L100 to Eudragit® S100 [48,49] was used in this study (Table 1) for the purpose of allowing the increased presence of Eudragit® L100 to cause pore formation, creating channels for alkaline media to penetrate the coating, causing dissolution of the polymer coat, and releasing the capsule contents.…”

Section: Discussionmentioning

confidence: 99%

Oral immunization of rhesus macaques with adenoviral HIV vaccines using enteric-coated capsules

Mercier

Nehete

Passeri

et al. 2007

Vaccine

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Targeted delivery of vaccine candidates to the gastrointestinal (GI) tract holds potential for mucosal immunization, particularly against mucosal pathogens like the human immunodeficiency virus (HIV). Among the different strategies for achieving targeted release in the GI tract, namely the small intestine, pH sensitive enteric coating polymers have been shown to protect solid oral dosage forms from the harsh digestive environment of the stomach and dissolve relatively rapidly in the small intestine by taking advantage of the luminal pH gradient. We developed an enteric polymethacrylate formulation for coating hydroxy-propyl-methyl-cellulose (HPMC) capsules containing lyophilized Adenoviral type 5 (Ad5) vectors expressing HIV-1 gag and a string of six highly-conserved HIV-1 envelope peptides representing broadly cross-reactive CD4 + and CD8 + T cell epitopes. Oral immunization of rhesus macaques with these capsules primed antigen-specific mucosal and systemic immune responses and subsequent intranasal delivery of the envelope peptide cocktail using a mutant cholera toxin adjuvant boosted cellular immune responses including, antigen-specific intracellular IFN-γ-producing CD4 + and CD8 + effector memory T cells in the intestine. These results suggest that the combination of oral adenoviral vector priming followed by intranasal protein/peptide boosting may be an effective mucosal HIV vaccination strategy for targeting viral antigens to the GI tract and priming systemic and mucosal immunity.

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pH-Sensitive Polymer Blends Used as Coating Materials to Control Drug Release from Spherical Beads: Elucidation of the Underlying Mass Transport Mechanisms

Abstract: The obtained new knowledge can be used to effectively adjust desired drug release mechanisms and, thus, release patterns.

Cited by 73 publications

References 24 publications

Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

Evolving application of biomimetic nanostructured hydroxyapatite

Oral immunization of rhesus macaques with adenoviral HIV vaccines using enteric-coated capsules

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