Enteric polymers as binders and coating materials in multiple-unit site-specific drug delivery systems

Marvola, Martti; Nykänen, Pirjo; Rautio, Saija; Isonen, N.; Autere, Anna-Maija

doi:10.1016/s0928-0987(98)00032-3

Cited by 86 publications

(30 citation statements)

References 20 publications

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“…The drug release gradually increased with greater pH levels as can be seen in the graph. Contrary to previous studies (Marvola et al, 1999) however, the drug release, although increased, was not abrupt but instead showed a slow and steady rise in release. This indicated that the PA and SA resist the gastric environment and will not release drug suddenly but gradually in the intestinal environment.…”

Section: Determination Of Disintegration Phcontrasting

confidence: 99%

“…This suggests it is possible to retard drug release or extend lag time in relation to commencement of drug absorption by making the coat thicker at 15% rather than 5%. This is contrary to the findings with conventional enteric polymers (Aqoat AS-HF) as this polymer shows no significant effect of coatings above a 20% level (Marvola et al, 1999). This might be due to the inherent property of materials evaluated and their solubility mechanism.…”

Section: In Vitro Dissolutioncontrasting

confidence: 89%

“…Intestinal transit times for different dosage forms, independently of diameter, are 2-4 h with a mean of 3 h (Clarke et al, 1993;Coupe et al, 1991). It can therefore be calculated that most of a pellet formulation should be at the end of the small intestine 4 h after drug administration (Marvola et al, 1999).…”

Section: In Vitro Dissolutionmentioning

confidence: 99%

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Development and evaluation of a hot-melt coating technique for enteric coating

Patil

Khobragade

Chafle

et al. 2012

Braz. J. Pharm. Sci.

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Conventional enteric coating requires the use of organic based polymers which are equally hazardous to the environment and operating personnel. Hot-melt coating avoids the use of solvents and is a safer and time-saving process. The present study was designed to assess the efficacy of hot-melt coating (HMC) as an enteric coating technique. Pellets prepared by extrusion spheronization were selected as the core formulation for a model of the gastric irritant drug diclofenac sodium (DFS) because of their innate advantages over single-unit formulations. Stearic acid (SA) and palmitic acid (PA) were evaluated as enteric hot-melt coating materials. HMC was carried out in a specially modified coating pan by applying SA and PA in molten state onto preheated pellets to achieve a coating level of 5-15 %w/w. Hot-melt coated pellets were evaluated for disintegration pH and in vitro dissolution in the pH range 1.2 to 6.8, along with basic micromeritics. SEM of coated pellets showed a uniform and smooth coating. These results indicated that HMC of both SA and PA exhibited very good enteric coating ability. The coated pellets showed negligible drug release in acidic pH. As the pellets were subsequently transferred to a higher pH level, a gradual increase in release of the drug from the pellets was observed with increasing pH of the dissolution media. The release was dependent upon coating extent, providing sustained enteric release as opposed to abrupt release with mixed release kinetics.Uniterms: Pellets/coating/evaluation. Enteric coating/evaluation. Hot-melt coating/evaluation. Disintegration pH. Diclofenac sodium/pellets/coating. Palmitic acid/pellets/coating. Stearic acid/pellets/ coating. O revestimento entérico convencional requer o uso de polímeros orgânicos os quais são igualmente danosos ao meio ambiente e ao pessoal que o executa. O revestimento por fusão a quente evita o uso de solventes e é processo mais seguro e que consome menos tempo. O presente estudo foi planejado para avaliar a eficácia do revestimento por fusão a quente (RFQ) como técnica de revestimento entérico. Os péletes preparados por esferonização por extrusão foram selecionados como formulação central para modelo de fármaco irritante gástrico, o diclofenaco sódico (DFS) em razão das vantagens inerentes sobre as formulações de única dose. O ácido esteárico (AE) e o ácido palmítico (AP) foram avaliados como materiais para o revestimento de fusão a quente. O RFQ foi realizado em recipiente especialmente modificado, aplicando AS e PA no estado fundido em péletes pré-aquecidos para atingir nível de revestimento de 5 a 15% p/P. Os péletes revestidos por fusão a quente for avaliados quanto ao pH de desintegração e à dissolução in vitro na faixa de pH de 1,2 a 6,8, juntamente com base micromerítica. O SEM dos péletes revestido mostrou revestimento uniforme e plano. Esses resultados indicaram que o RFQ tanto do AE quanto do AP apresentou capacidade de revestimento muito boa. Os péletes revestidos mostraram pouca liberação do fármaco em pH baixo. Como os pélete...

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Section: Determination Of Disintegration Phcontrasting

confidence: 99%

Section: In Vitro Dissolutioncontrasting

confidence: 89%

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Development and evaluation of a hot-melt coating technique for enteric coating

Patil

Khobragade

Chafle

et al. 2012

Braz. J. Pharm. Sci.

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“…A particular challenge in the pharmaceutical field is the development of a site-specific delivery system that could control delivery time for the release of active ingredient in the lower part of the small intestine, or in the colon. The approaches used in achieving colonic delivery of drugs include the use of prodrugs, 1,2 pH-sensitive polymer coating, 3,4 and time-dependent formulations. 5,6 In addition, the use of biodegradable polymers such as azopolymer and polysaccharide (eg, pectin and dextrin) for colon targeting are also reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Eudragit-coated pectin microspheres of 5-fluorouracil for colon targeting

et al. 2007

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An objective of the present investigation was to prepare and evaluate Eudragit-coated pectin microspheres for colon targeting of 5-fluorouracil (FU). Pectin microspheres were prepared by emulsion dehydration method using different ratios of FU and pectin (1:3 to 1:6), stirring speeds (500-2000 rpm) and emulsifier concentrations (0.75%-1.5% wt/vol). The yield of preparation and the encapsulation efficiencies were high for all pectin microspheres. Microspheres prepared by using drug:polymer ratio 1:4, stirring speed 1000 rpm, and 1.25% wt/vol concentration of emulsifying agent were selected as an optimized formulation. Eudragit-coating of pectin microspheres was performed by oil-in-oil solvent evaporation method using coat:core ratio (5:1). Pectin microspheres and Eudragit-coated pectin microspheres were evaluated for surface morphology, particle size and size distribution, swellability, percentage drug entrapment, and in vitro drug release in simulated gastrointestinal fluids (SGF). The in vitro drug release study of optimized formulation was also performed in simulated colonic fluid in the presence of 2% rat cecal content. Organ distribution study in albino rats was performed to establish the targeting potential of optimized formulation in the colon. The release profile of FU from Eudragit-coated pectin microspheres was pH dependent. In acidic medium, the release rate was much slower; however, the drug was released quickly at pH 7.4. It is concluded from the present investigation that Eudragit-coated pectin microspheres are promising controlled release carriers for colon-targeted delivery of FU.

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“…Drug release studies were then continued in phosphate buffer (pH 7.4) medium for the remaining period of study. This medium was considered suitable as the drug was freely soluble at this pH and it also mimics the alkaline environment of distal small intestine and colon (37).…”

Section: Resultsmentioning

confidence: 99%