Cyclic voltammetry and spectroelectrochemistry of a novel manganese phthalocyanine substituted with hexynyl groups
- Quinton, Damien, Antunes, Edith M, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
- Authors: Quinton, Damien , Antunes, Edith M , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248450 , vital:51687 , xlink:href="https://doi.org/10.1016/j.inoche.2010.11.029"
- Description: We report here on the synthesis of a new manganese phthalocyanine complex, namely Mn tetrakis(5-hexyn-oxy) phthalocyanine (3), specifically designed to possess an alkyne moiety for its potential use in controlled immobilization on electrodes via the so called “click” chemistry reaction. The electrochemical activity of complex 3 was investigated by cyclic voltammetry and the nature of the observed redox couples was elucidated by spectroelectrochemistry. This work has also shown that the reduction of Mn(III)Pc complex to Mn(II)Pc is accompanied by the formation of MnPc μ-oxo species. Further reduction results in the formation of Mn(II)Pc(− 3) rather than Mn(I)Pc(− 2).
- Full Text:
- Date Issued: 2011
Drug transport mechanisms from carbopol/eudragit verapamil sustained-release tablets
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184801 , vital:44273 , xlink:href="https://doi.org/10.14227/dt180311p30"
- Description: The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured inhouse and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate–methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets. The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol. The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics. The mechanism of drug release was established using the Korsmeyer–Peppas model. In general, all tablets showed high mechanical resistance with less than 1% friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product. The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form. The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
- Full Text:
- Date Issued: 2011
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184801 , vital:44273 , xlink:href="https://doi.org/10.14227/dt180311p30"
- Description: The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured inhouse and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate–methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets. The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol. The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics. The mechanism of drug release was established using the Korsmeyer–Peppas model. In general, all tablets showed high mechanical resistance with less than 1% friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product. The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form. The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
- Full Text:
- Date Issued: 2011
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