Swellable and Rigid Matrices: Controlled Release Matrices with Cellulose Ethers

The benefits offered by modified release systems include reduced dosing frequency with improved patient compliance, better and more uniform clinical effects with lower incidence of side effects and possible enhanced bioavailability. Characteristics of a modified release system as stated by USP is “The drug release characteristics of time, course and / or location are chosen to accomplish therapeutic or convenience objectives not offered by conventional dosage forms” [1]. This includes technologies that modify the site of drug delivery. Extended release dosage forms extend the life of a drug so that dosage regiment shifts from 3 times a day dosing just once or twice a day. The successful formulation of a modified release device requires a comprehensive understanding of the mechanism of drug release from the macroscopic effects of size, shape and structure through to chemistry and molecular interaction. Multiparticulate dosage forms shown to be less prone to food effects than monolithic and is often the preferred formulation for extended and / or delayed release. Extended release drug formulation is conventionally produced as compressed tablets by hydrogel tablet technology. To produce these extended release tablet dosage forms, active ingredient is conventionally compounded with cellulose ethers like methylcellulose, ethyl cellulose or hydroxyl propyl methylcellulose with or without excipients and the resulting mixture is pressed into tablets. When the tablets are orally administered, cellulose ethers in the tablet swell upon hydration from moisture in the digestive system, thereby limiting exposure of active ingredient to moisture. As the cellulose ethers are gradually leached away by moisture, water more deeply penetrates the gel matrix and the active ingredient slowly dissolves and diffuses through the gel, making it available for absorption by the body. An appropriately designed controlled release drug delivery system can be a major advance towards solving problems concerning the targeting of a drug to specific organ or tissue and controlling the rate of drug delivery to the target sites. The development of the oral controlled release system has been a challenge to formulation scientists due to their inability to restrain and localize the system at targeted areas of the gastro intestinal tract. Matrix type drug delivery systems as carriers for the active ingredients are interesting and promising option in developing an oral controlled release system. Tablets are the preferred dosage form for many drugs and are still the most widely used formulations for both new and existing modified released products.

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Controlled release antibiotics for dry powder lung delivery

Drug Development and Industrial Pharmacy ◽

10.1080/03639040903099769 ◽

2009 ◽

Vol 00 (00) ◽

pp. 090805050810080-8 ◽

Cited By ~ 1

Author(s):

Handoko Adi ◽

Paul Michael Young ◽

Hak-Kim Chan ◽

Rania Salama ◽

Daniela Traini

Keyword(s):

Controlled Release ◽

Dry Powder ◽

Lung Delivery

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Controlled Release Polymeric Formulations

10.1021/bk-1976-0033 ◽

1976 ◽

Cited By ~ 34

Keyword(s):

Controlled Release

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A New Controlled Release System for Standard 0.052â³ and 0.038â³ Gianturco Coils

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(97)84371-9 ◽

1998 ◽

Vol 31 (2) ◽

pp. 153A ◽

Cited By ~ 1

Author(s):

C Owada

Keyword(s):

Controlled Release ◽

Release System ◽

Controlled Release System ◽

Gianturco Coils

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Controlled Release of Metformin Hydrochloride I. In vitro Release from Physical Mixture Containing Xanthan Gum as Hydrophilic Rate Retarding Polymer

Dhaka University Journal of Pharmaceutical Sciences ◽

10.3329/dujps.v4i1.200 ◽

1970 ◽

Vol 4 (1) ◽

Author(s):

Mashkura Ashrafi ◽

Jakir Ahmed Chowdhury ◽

Md Selim Reza

Keyword(s):

Controlled Release ◽

Xanthan Gum ◽

In Vitro Release ◽

Correlation Coefficients ◽

High Ratio ◽

Water Soluble ◽

Metformin Hydrochloride ◽

Model Drug ◽

Very High

Capsules of different formulations were prepared by using a hydrophilic polymer, xanthan gum and a filler Ludipress. Metformin hydrochloride, which is an anti-diabetic agent, was used as a model drug here with the aim to formulate sustained release capsules. In the first 6 formulations, metformin hydrochloride and xanthan gum were used in different ratio. Later, Ludipress was added to the formulations in a percentage of 8% to 41%. The total procedure was carried out by physical mixing of the ingredients and filling in capsule shells of size 1. As metformin hydrochloride is a highly water soluble drug, the dissolution test was done in 250 ml distilled water in a thermal shaker (Memmert) with a shaking speed of 50 rpm at 370C &plusmn 0.50C for 6 hours. After the dissolution, the data were treated with different kinetic models. The results found from the graphs and data show that the formulations follow the Higuchian release pattern as they showed correlation coefficients greater than 0.99 and the sustaining effect of the formulations was very high when the xanthan gum was used in a very high ratio with the drug. It was also investigated that the Ludipress extended the sustaining effect of the formulation to some extent. But after a certain period, Ludipress did not show any significant effect as the pores made by the xanthan gum network were already blocked. It is found here that when the metformin hydrochloride and the xanthan gum ratio was 1:1, showed a high percentage of drug release, i.e. 91.80% of drug was released after 6 hours. But With a xanthan gum and metformin hydrochloride ratio of 6:1, a very slow release of the drug was obtained. Only 66.68% of the drug was released after 6 hours. The percent loading in this case was 14%. Again, when Ludipress was used in high ratio, it was found to retard the release rate more prominently. Key words: Metformin Hydrochloride, Xanthan Gum, Controlled release capsule Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

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