In vitro dissolution kinetics of Captopril from microspheres manufactured by solvent evaporation
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
Culture as a discursive resource opposing legal abortion
- Macleod, Catriona I, Sigcau, Nomakhosi, Luwaca, Pumeza
- Authors: Macleod, Catriona I , Sigcau, Nomakhosi , Luwaca, Pumeza
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6293 , http://hdl.handle.net/10962/d1014721 , http://dx.doi.org/10.1080/09581596.2010.492211
- Description: The notion of ‘culture’ features in the abortion literature to explicate, first, contestation of the meaning of abortion (as in the ‘culture wars’ about abortion), second, the normalisation of abortion in certain countries (as in ‘abortion culture’), third, the response of women to abortion within a particular social milieu and fourth, cross-cultural variability in attitudes towards and experiences of abortion. What is missing is an exploration of how ‘culture’ may be deployed as a discursive resource to oppose legal abortion. In this article, we report on a study conducted in a rural area of South Africa. We conducted focus group discussions utilising hypothetical vignettes to stimulate talk. Although, inconsistencies were evident in participants’ talk, in the context of cultural discussions, abortion was constructed as killing and inevitably destructive of cultural values and traditions. Abortion was equated with colonialist interventions and as something that should be opposed in the preservation of culture. Furthermore, cultural opposition to abortion was rooted in fears around the breakdown of gendered and generational power relations. Examples of how culture may be used in everyday interactions to induce shame and negative experiences are also discussed.
- Full Text:
- Date Issued: 2011
- Authors: Macleod, Catriona I , Sigcau, Nomakhosi , Luwaca, Pumeza
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6293 , http://hdl.handle.net/10962/d1014721 , http://dx.doi.org/10.1080/09581596.2010.492211
- Description: The notion of ‘culture’ features in the abortion literature to explicate, first, contestation of the meaning of abortion (as in the ‘culture wars’ about abortion), second, the normalisation of abortion in certain countries (as in ‘abortion culture’), third, the response of women to abortion within a particular social milieu and fourth, cross-cultural variability in attitudes towards and experiences of abortion. What is missing is an exploration of how ‘culture’ may be deployed as a discursive resource to oppose legal abortion. In this article, we report on a study conducted in a rural area of South Africa. We conducted focus group discussions utilising hypothetical vignettes to stimulate talk. Although, inconsistencies were evident in participants’ talk, in the context of cultural discussions, abortion was constructed as killing and inevitably destructive of cultural values and traditions. Abortion was equated with colonialist interventions and as something that should be opposed in the preservation of culture. Furthermore, cultural opposition to abortion was rooted in fears around the breakdown of gendered and generational power relations. Examples of how culture may be used in everyday interactions to induce shame and negative experiences are also discussed.
- Full Text:
- Date Issued: 2011
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