• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 190
  • 72
  • 42
  • 8
  • 6
  • 4
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 352
  • 148
  • 118
  • 59
  • 57
  • 54
  • 49
  • 45
  • 35
  • 35
  • 33
  • 30
  • 29
  • 27
  • 24
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Mapping the Distribution of the EPS Matrix Within Mixed Microbial Flocs

Khezry, Mojtaba 22 May 2012 (has links)
The efficacy Biological wastewater treatment process is largely dependent on the formation of microbial flocs and settleability before the water is released into the environment. Settleability and flocculation are reliant upon stable physicochemical parameters. Extracellular polymeric substance constituents dictate physicochemical parameters of flocs. The fluctuation of these constituents within mixed microbial flocs is poorly studied. A novel aspect of this research was the use of CLSM data to get a semi- quantitative assessment of the constituents within mixed microbial flocs. Wastewater treatment flocs were characterized for eubacterial ecology, physicochemical properties, and they were visualized through correlative microscopy. It was observed that the microbial communities from the three sampling sites exhibited significant variability in numerous physicochemical properties. Overall, these results provide a first step to examine micro-localization of physicochemical properties, architecture and processes within flocs that may help better understand the causes of floc- related inefficiencies in biological wastewater treatment. / Canadian Hemophilia Society
142

Structural and functional characterization of red kidney bean (Phaseolus vulgaris) proteins and enzymatic protein hydrolysates

Mundi, Sule 09 August 2012 (has links)
Kidney bean proteins and peptides can be developed to serve as an important ingredient for the formulation of high quality foods or therapeutic products that may positively impact on body function and human health. The main goal of this thesis was to determine the in vitro structural and functional characteristics of major proteins and enzymatic protein hydrolysate of red kidney bean (Phaseolus vulgaris). Selective aammonium sulfate precipitation of the kidney bean proteins yielded 88% globulin and 7% albumin.The globulin and albumin are glycoproteins that contained ~4% and 45% carbohydrate contents, respectively. Physicochemical and functional characteristics of the globulin fraction, such as, gelation concentration, foam stability, emulsion capacity, and emulsion stability were superior to those of albumin. Reducing SDS-PAGE revealed vicilin with molecular weight of ~45 kDa as the major globulin in kidney beans. Circular dichroism spectroscopy of the purified vicilin showed reductions in α-helix, and β-pleated sheet conformations upon addition of NaCl or changes in pH. Likewise, the tertiary structures as observed from the near-UV CD spectra were also changed by shifts in pH conditions and NaCl addition. Far UV-CD showed increased β-sheet content up till 60oC from room temperature, but a steady loss in the tertiary structure as temperature was further increased; however, β-sheet structure was still detectable at 80oC. Differential scanning calorimetry thermograms showed a prominent endothermic peak with denaturation temperature at around 90oC, attributed to thermal denaturation of vicilin. Alcalase hydrolysis of kidney bean globulin produced multifunctional peptides that showed potential antihypertensive properties because of the in vitro inhibition of activities of renin and angiotensin I converting enzyme as well as the antioxidant properties. The <1 and 5-10 kDa peptide fractions exhibited highest (p<0.05) renin inhibition and the ability to scavenge 2, 2-Diphenyl-1-picrylhydrazyl free radical, inhibit peroxidation of linoleic acid and reduce Fe3+ to Fe2+. Based on this study, incorporation of kidney bean globulin as an ingredient may be useful for the manufacture of high quality food products. Likewise, the kidney bean protein hydrolysates, especially the <1 kDa fraction represent a potential source of bioactive peptides for the formulation of functional foods and nutraceuticals.
143

Influence of selected formulation factors on the transdermal delivery of ibuprofen / Aysha Bibi Moosa.

Moosa, Aysha Bibi January 2012 (has links)
A pharmaceutical dosage form is an entity that is administered to patients so that they receive an effective dose of an active pharmaceutical ingredient (API). The proper design and formulation of a transdermal dosage form require a thorough understanding of the physiological factors affecting percutaneous penetration and physicochemical characteristics of the API, as well as that of the pharmaceutical exipients that are used during formulation. The API and pharmaceutical excipients must be compatible with one another to produce a formulation that is stable, efficacious, attractive, easy to administer, and safe (Mahato, 2007:11). Amongst others, the physicochemical properties indicate the suitability of the type of dosage form, as well as any potential problems associated with instability, poor permeation and the target site to be reached (Wells & Aulton, 2002:337). Therefore, when developing new or improved dosage forms, it is of utmost importance to evaluate the factors influencing design and formulation to provide the best possible dosage form and formulation for the API in question. Delivery of an API through the skin has long been a promising concept due to its large surface area, ease of access, vast exposure to the circulatory and lymphatic networks, and non-invasive nature of the therapy. This is true whether a local or systemic pharmacological effect is desired (Aukunuru et al., 2007:856). However, most APIs are administered orally as this route is considered to be the simplest, most convenient and safest route of API administration. Since ibuprofen is highly metabolised in the liver and gastrointestinal tract, oral administration thereof results in decreased bioavailability. Furthermore, it also causes gastric mucosal damage, bleeding and ulceration. Another obstacle associated with oral API delivery is that some APIs require continuous delivery which is difficult to achieve (Bouwstra et al., 2003:3). Therefore, there is significant interest to develop topical dosage forms for ibuprofen to avoid side effects associated with oral delivery and to provide relatively consistent API levels at the application site for prolonged periods (Rhee et al., 2003:14). The aim of this study was to determine the influence of selected formulation factors on the transdermal delivery of ibuprofen. In order to achieve this aim, the physicochemical properties of ibuprofen had to be evaluated. The aqueous solubility, pH-solubility profile, octanol-water partition coefficient (log P-value) and octanol-buffer distribution coefficient (log D-values, pH 5 and 7.4) of ibuprofen were determined. According to Naik et al., (2000:319) the ideal aqueous solubility of APIs for transdermal delivery should be more than 1 mg.ml-1. However, results showed that ibuprofen depicted an aqueous solubility of 0.096 mg.ml-1 ± 25.483, which indicated poor water solubility and would therefore be rendered less favourable for transdermal delivery if only considering the aqueous solubility. The pH-solubility profile depicted that ibuprofen was less soluble at low pH-values and more soluble at higher pH-values. Previous research indicated that the ideal log Pvalues for transdermal API permeation of non steroid anti-inflammatory drugs (NSAIDs) are between 2 and 3 (Swart et al., 2005:72). Results obtained during this study indicated a log P-value of 4.238 for ibuprofen. This value was not included in the ideal range, which is an indication that the lipophilic/hydrophilic properties are not ideal, and this might therefore; contribute to poor ibuprofen penetration through the skin. Furthermore, the obtained log D-values at pH 5 and 7.4 were 3.105 and 0.386, respectively. Therefore, it would be expected that ibuprofen incorporated into a formulation prepared at a pH of 5 would more readily permeate the skin compared to ibuprofen incorporated into a formulation prepared at a pH of 7.4. A gel, an emulgel and a Pheroid™ emulgel were formulated at pH 5 and 7.4, in order to examine which dosage form formulated at which pH would deliver enhanced transdermal delivery. Obtained diffusion results of the different semi-solid formulations were furthermore compared to a South African marketed commercial product (Nurofen® gel) in order to establish if a comparable formulation could be obtained. An artificial membrane was used to conduct the membrane permeation studies over a period of 6 h, in order to determine whether ibuprofen was in fact released from the formulations through the membrane. Skin permeation studies were conducted using Franz diffusion cells over a period of 12 h where samples were withdrawn at specified time intervals. All the formulations exhibited an increase in the average cumulative amount of ibuprofen released from the formulations and that permeated the membrane when compared to Nurofen® gel. This increase was statistically significant (p<0.05) for the gel, emulgel and Pheroid™ emulgel at pH 7.4. The gel at pH 7.4 exhibited the highest cumulative amount of ibuprofen that permeated the membrane. Preparations formulated at a pH of 5, did not differ significantly from Nurofen® when the average cumulative amount of ibuprofen that permeated the membrane were compared. The following rank order for the average cumulative amount released from the formulations could be established: Gel (pH 7.4) >>>> Pheroid™ emulgel (pH 7.4) > Emulgel (pH 7.4) >>> Gel (pH 5)> Pheroid™ emulgel (pH 5) ≈ Emulgel (pH 5) > Nurofen® gel. On the other hand, all the formulations exhibited an increase in the average cumulative amount of ibuprofen that permeated the skin when compared to Nurofen® gel. This increase was statistically significant (p < 0.05) for the gel, emulgel and Pheroid™ emulgel at pH 5, as well as the emulgel and Pheroid™ emulgel at pH 7.4. The emulgel at pH 5 exhibited the highest cumulative amount of ibuprofen that permeated the skin. The following rank order for the average cumulative amount released from the formulations and that permeated the skin could be established: Emulgel (pH 5) >> Pheroid™ emulgel (pH 5) > Gel (pH 5) > Emulgel (pH 7.4)> Pheroid™ emulgel (pH 7.4) ≈ Emulgel (pH 7.4) >> Nurofen® gel > Gel (pH 7.4). From this rank order it was clear that a trend was followed where the pH of formulation also played a role in ibuprofen permeation. All the formulations exhibited a higher release rate and flux when compared to Nurofen® gel. This was statistically significant for the emulgel, gel and Pheroid™ emulgel at pH 7.4. The gel at pH 7.4 exhibited the highest release rate and flux. This was observed for the membrane and skin permeation studies. All the formulations (including Nurofen® gel) presented a correlation coefficient (r2) of 0.972 – 0.995 for membrane permeation studies, and 0.950 – 0.978 for skin permeation studies; indicating that the release of ibuprofen from each of the formulations could be described by the Higuchi model. Furthermore, all the formulations exhibited a prolonged lag time compared to Nurofen® gel which indicated that the ibuprofen was retained for a longer time by the base. This was statistically significant (p < 0.05) for the emulgel at pH 7.4, the gel and Pheroid™ emulgel at pH 5. The gel at pH 7.4 exhibited a lag time closest to that of Nurofen® gel and this difference could not be classified as statistically significant (p > 0.286). This was observed for the membrane and skin permeation studies. Nurofen® gel exhibited the highest ibuprofen concentration in the stratum corneum as well as in the epidermis followed by the gel at pH 7.4. However, results obtained for all the formulations indicated that topical as well as transdermal delivery of ibuprofen was achieved. The pH of a formulation plays an important role with respect to API permeation. Ibuprofen is reported to have a pKa value 4.4 (Dollery, 1999:I1); and by application of the Henderson-Hasselbach equation, at pH 5, 20.08% of ibuprofen will be present in its unionised form and at pH 7.4, 0.1% ibuprofen will exist in its unionised form. Since the unionised form of APIs is more lipid soluble than the ionised form, unionised forms of APIs permeate more readily across the lipid membranes (Surber & Smith, 2000:27). Therefore, it would be expected that ibuprofen formulated at pH 5 would be more permeable than formulations at pH 7.4. However, this did not correspond to the results (membrane studies) obtained in this study. It may be attributed to the solubility of ibuprofen in the different formulations. According to the pH-solubility profile of ibuprofen obtained in this study, it was more soluble at pH 7.4 than at pH 5. This was due to the fact that ibuprofen is a weak acidic compound, and for every 3 units away from the pKa-value, the solubility changes 10-fold (Mahato, 2007:14). However, with regard to the skin permeation studies, enhanced permeation was obtained with the formulations prepared at pH 5. This was in accordance with Corrigan et al., (2003:148) who stated that NSAIDs are less soluble and more permeable at low pH values, and more soluble and less permeable at high pH values. This was most probably due to the fact that unionised species, although possessing a lower aqueous solubility than the ionised species, resulted in enhanced skin permeation due to being more lipid-soluble. Finally, stability tests on the different semi-solid formulations for a period of three months at different temperature and humidity conditions were conducted to determine product stability. The formulations were stored at 25 °C/60% RH (relative humidity), 30 °C/60% RH and 40 °C/75% RH. Stability tests included: mass variation, pH, zeta potential, droplet size, visual appearance, assay, and viscosity. No significant change was observed for mass variation, pH, zeta potential and droplet size over the three months for any of the different formulations stored at the different storage conditions. In addition, no significant change in colour was observed for the gel and emulgel formulations at pH 5 and 7.4 over the three months at all the storage conditions. However, it was observed that the formulations containing Pheroid™ showed a drastic change in colour at all the storage conditions. This might have been due to oxidation of certain components present in the Pheroid™ system. Consequently, further investigation is necessary to find the cause of the discolouration and a method to prevent it. The gel formulated at pH 5 depicted the formation of crystals. This might have been due to the fact that the solubility of ibuprofen was exceeded, leading to it precipitating from the formulation. A possible contributing factor to the varying assay values obtained during the study might have been due to non-homogenous sample withdrawal. On the other hand, no significant change was observed for the emulgel and Pheroid™ emulgel formulated at pH 5 and 7.4. The emulgel and Pheroid™ emulgel formulated at pH 5 depicted relative instability (according to the International Conference on Harmonisation of Technical Requirements For Registration of Pharmaceuticals for Human Use, ICH) only at 40 °C/75% RH with a change in ibuprofen content of more than 5% (6.78 and 6.46%, respectively). The gel, emulgel and Pheroid™ emulgel at pH 7.4 exhibited the least variation in ibuprofen concentration at all of the storage conditions. This might indicate that the pH at which a semi-solid formulation is produced will have a direct influence on the stability of the product. No significant changes in viscosity (%RSD < 5) was observed for the gel and emulgel formulated at pH 7.4 and stored at 25 °C/60% RH. The remaining formulations at all of the specified storage conditions exhibited a significant change in viscosity (%RSD > 5) with a decrease in viscosity being more pronounced at the higher temperature and humidity storage conditions. A possible contributing factor to the change in viscosity over three months at the specified storage conditions might have been due to the use of Pluronic® F-127 (viscosity enhancer). This viscosity enhancer possesses a melting point of approximately 56 °C (BAST Corporation. s.a). The problem with this might have been the temperature (70 °C) at which the formulations were prepared. The higher preparation temperature might have caused the Pluronic® F-127 to degrade, thereby losing its ability to function appropriately. A balance must be maintained between optimum solubility and maximum stability (Pefile & Smith, 1997:148). Despite the lower skin permeation of the gel formulated at pH 7.4, this formulation performed the best, as it was considered stable (least variation during the 3 month stability test) and the obtained tape stripping results showed that this formulation depicted the highest ibuprofen concentrations in the stratum corneum and epidermis. Thus, topical as well as transdermal delivery were obtained. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.
144

Influence of selected formulation factors on the transdermal delivery of ibuprofen / Aysha Bibi Moosa.

Moosa, Aysha Bibi January 2012 (has links)
A pharmaceutical dosage form is an entity that is administered to patients so that they receive an effective dose of an active pharmaceutical ingredient (API). The proper design and formulation of a transdermal dosage form require a thorough understanding of the physiological factors affecting percutaneous penetration and physicochemical characteristics of the API, as well as that of the pharmaceutical exipients that are used during formulation. The API and pharmaceutical excipients must be compatible with one another to produce a formulation that is stable, efficacious, attractive, easy to administer, and safe (Mahato, 2007:11). Amongst others, the physicochemical properties indicate the suitability of the type of dosage form, as well as any potential problems associated with instability, poor permeation and the target site to be reached (Wells & Aulton, 2002:337). Therefore, when developing new or improved dosage forms, it is of utmost importance to evaluate the factors influencing design and formulation to provide the best possible dosage form and formulation for the API in question. Delivery of an API through the skin has long been a promising concept due to its large surface area, ease of access, vast exposure to the circulatory and lymphatic networks, and non-invasive nature of the therapy. This is true whether a local or systemic pharmacological effect is desired (Aukunuru et al., 2007:856). However, most APIs are administered orally as this route is considered to be the simplest, most convenient and safest route of API administration. Since ibuprofen is highly metabolised in the liver and gastrointestinal tract, oral administration thereof results in decreased bioavailability. Furthermore, it also causes gastric mucosal damage, bleeding and ulceration. Another obstacle associated with oral API delivery is that some APIs require continuous delivery which is difficult to achieve (Bouwstra et al., 2003:3). Therefore, there is significant interest to develop topical dosage forms for ibuprofen to avoid side effects associated with oral delivery and to provide relatively consistent API levels at the application site for prolonged periods (Rhee et al., 2003:14). The aim of this study was to determine the influence of selected formulation factors on the transdermal delivery of ibuprofen. In order to achieve this aim, the physicochemical properties of ibuprofen had to be evaluated. The aqueous solubility, pH-solubility profile, octanol-water partition coefficient (log P-value) and octanol-buffer distribution coefficient (log D-values, pH 5 and 7.4) of ibuprofen were determined. According to Naik et al., (2000:319) the ideal aqueous solubility of APIs for transdermal delivery should be more than 1 mg.ml-1. However, results showed that ibuprofen depicted an aqueous solubility of 0.096 mg.ml-1 ± 25.483, which indicated poor water solubility and would therefore be rendered less favourable for transdermal delivery if only considering the aqueous solubility. The pH-solubility profile depicted that ibuprofen was less soluble at low pH-values and more soluble at higher pH-values. Previous research indicated that the ideal log Pvalues for transdermal API permeation of non steroid anti-inflammatory drugs (NSAIDs) are between 2 and 3 (Swart et al., 2005:72). Results obtained during this study indicated a log P-value of 4.238 for ibuprofen. This value was not included in the ideal range, which is an indication that the lipophilic/hydrophilic properties are not ideal, and this might therefore; contribute to poor ibuprofen penetration through the skin. Furthermore, the obtained log D-values at pH 5 and 7.4 were 3.105 and 0.386, respectively. Therefore, it would be expected that ibuprofen incorporated into a formulation prepared at a pH of 5 would more readily permeate the skin compared to ibuprofen incorporated into a formulation prepared at a pH of 7.4. A gel, an emulgel and a Pheroid™ emulgel were formulated at pH 5 and 7.4, in order to examine which dosage form formulated at which pH would deliver enhanced transdermal delivery. Obtained diffusion results of the different semi-solid formulations were furthermore compared to a South African marketed commercial product (Nurofen® gel) in order to establish if a comparable formulation could be obtained. An artificial membrane was used to conduct the membrane permeation studies over a period of 6 h, in order to determine whether ibuprofen was in fact released from the formulations through the membrane. Skin permeation studies were conducted using Franz diffusion cells over a period of 12 h where samples were withdrawn at specified time intervals. All the formulations exhibited an increase in the average cumulative amount of ibuprofen released from the formulations and that permeated the membrane when compared to Nurofen® gel. This increase was statistically significant (p<0.05) for the gel, emulgel and Pheroid™ emulgel at pH 7.4. The gel at pH 7.4 exhibited the highest cumulative amount of ibuprofen that permeated the membrane. Preparations formulated at a pH of 5, did not differ significantly from Nurofen® when the average cumulative amount of ibuprofen that permeated the membrane were compared. The following rank order for the average cumulative amount released from the formulations could be established: Gel (pH 7.4) >>>> Pheroid™ emulgel (pH 7.4) > Emulgel (pH 7.4) >>> Gel (pH 5)> Pheroid™ emulgel (pH 5) ≈ Emulgel (pH 5) > Nurofen® gel. On the other hand, all the formulations exhibited an increase in the average cumulative amount of ibuprofen that permeated the skin when compared to Nurofen® gel. This increase was statistically significant (p < 0.05) for the gel, emulgel and Pheroid™ emulgel at pH 5, as well as the emulgel and Pheroid™ emulgel at pH 7.4. The emulgel at pH 5 exhibited the highest cumulative amount of ibuprofen that permeated the skin. The following rank order for the average cumulative amount released from the formulations and that permeated the skin could be established: Emulgel (pH 5) >> Pheroid™ emulgel (pH 5) > Gel (pH 5) > Emulgel (pH 7.4)> Pheroid™ emulgel (pH 7.4) ≈ Emulgel (pH 7.4) >> Nurofen® gel > Gel (pH 7.4). From this rank order it was clear that a trend was followed where the pH of formulation also played a role in ibuprofen permeation. All the formulations exhibited a higher release rate and flux when compared to Nurofen® gel. This was statistically significant for the emulgel, gel and Pheroid™ emulgel at pH 7.4. The gel at pH 7.4 exhibited the highest release rate and flux. This was observed for the membrane and skin permeation studies. All the formulations (including Nurofen® gel) presented a correlation coefficient (r2) of 0.972 – 0.995 for membrane permeation studies, and 0.950 – 0.978 for skin permeation studies; indicating that the release of ibuprofen from each of the formulations could be described by the Higuchi model. Furthermore, all the formulations exhibited a prolonged lag time compared to Nurofen® gel which indicated that the ibuprofen was retained for a longer time by the base. This was statistically significant (p < 0.05) for the emulgel at pH 7.4, the gel and Pheroid™ emulgel at pH 5. The gel at pH 7.4 exhibited a lag time closest to that of Nurofen® gel and this difference could not be classified as statistically significant (p > 0.286). This was observed for the membrane and skin permeation studies. Nurofen® gel exhibited the highest ibuprofen concentration in the stratum corneum as well as in the epidermis followed by the gel at pH 7.4. However, results obtained for all the formulations indicated that topical as well as transdermal delivery of ibuprofen was achieved. The pH of a formulation plays an important role with respect to API permeation. Ibuprofen is reported to have a pKa value 4.4 (Dollery, 1999:I1); and by application of the Henderson-Hasselbach equation, at pH 5, 20.08% of ibuprofen will be present in its unionised form and at pH 7.4, 0.1% ibuprofen will exist in its unionised form. Since the unionised form of APIs is more lipid soluble than the ionised form, unionised forms of APIs permeate more readily across the lipid membranes (Surber & Smith, 2000:27). Therefore, it would be expected that ibuprofen formulated at pH 5 would be more permeable than formulations at pH 7.4. However, this did not correspond to the results (membrane studies) obtained in this study. It may be attributed to the solubility of ibuprofen in the different formulations. According to the pH-solubility profile of ibuprofen obtained in this study, it was more soluble at pH 7.4 than at pH 5. This was due to the fact that ibuprofen is a weak acidic compound, and for every 3 units away from the pKa-value, the solubility changes 10-fold (Mahato, 2007:14). However, with regard to the skin permeation studies, enhanced permeation was obtained with the formulations prepared at pH 5. This was in accordance with Corrigan et al., (2003:148) who stated that NSAIDs are less soluble and more permeable at low pH values, and more soluble and less permeable at high pH values. This was most probably due to the fact that unionised species, although possessing a lower aqueous solubility than the ionised species, resulted in enhanced skin permeation due to being more lipid-soluble. Finally, stability tests on the different semi-solid formulations for a period of three months at different temperature and humidity conditions were conducted to determine product stability. The formulations were stored at 25 °C/60% RH (relative humidity), 30 °C/60% RH and 40 °C/75% RH. Stability tests included: mass variation, pH, zeta potential, droplet size, visual appearance, assay, and viscosity. No significant change was observed for mass variation, pH, zeta potential and droplet size over the three months for any of the different formulations stored at the different storage conditions. In addition, no significant change in colour was observed for the gel and emulgel formulations at pH 5 and 7.4 over the three months at all the storage conditions. However, it was observed that the formulations containing Pheroid™ showed a drastic change in colour at all the storage conditions. This might have been due to oxidation of certain components present in the Pheroid™ system. Consequently, further investigation is necessary to find the cause of the discolouration and a method to prevent it. The gel formulated at pH 5 depicted the formation of crystals. This might have been due to the fact that the solubility of ibuprofen was exceeded, leading to it precipitating from the formulation. A possible contributing factor to the varying assay values obtained during the study might have been due to non-homogenous sample withdrawal. On the other hand, no significant change was observed for the emulgel and Pheroid™ emulgel formulated at pH 5 and 7.4. The emulgel and Pheroid™ emulgel formulated at pH 5 depicted relative instability (according to the International Conference on Harmonisation of Technical Requirements For Registration of Pharmaceuticals for Human Use, ICH) only at 40 °C/75% RH with a change in ibuprofen content of more than 5% (6.78 and 6.46%, respectively). The gel, emulgel and Pheroid™ emulgel at pH 7.4 exhibited the least variation in ibuprofen concentration at all of the storage conditions. This might indicate that the pH at which a semi-solid formulation is produced will have a direct influence on the stability of the product. No significant changes in viscosity (%RSD < 5) was observed for the gel and emulgel formulated at pH 7.4 and stored at 25 °C/60% RH. The remaining formulations at all of the specified storage conditions exhibited a significant change in viscosity (%RSD > 5) with a decrease in viscosity being more pronounced at the higher temperature and humidity storage conditions. A possible contributing factor to the change in viscosity over three months at the specified storage conditions might have been due to the use of Pluronic® F-127 (viscosity enhancer). This viscosity enhancer possesses a melting point of approximately 56 °C (BAST Corporation. s.a). The problem with this might have been the temperature (70 °C) at which the formulations were prepared. The higher preparation temperature might have caused the Pluronic® F-127 to degrade, thereby losing its ability to function appropriately. A balance must be maintained between optimum solubility and maximum stability (Pefile & Smith, 1997:148). Despite the lower skin permeation of the gel formulated at pH 7.4, this formulation performed the best, as it was considered stable (least variation during the 3 month stability test) and the obtained tape stripping results showed that this formulation depicted the highest ibuprofen concentrations in the stratum corneum and epidermis. Thus, topical as well as transdermal delivery were obtained. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.
145

Percutaneous delivery of thalidomide and its N-alkyl analogues for treatment of rheumatoid arthritis / Colleen Goosen

Goosen, Colleen January 1998 (has links)
Rheumatoid arthritis (RA) is a chronic inflammatory joint disease associated with high levels of tumour necrosis factor-alpha (TNF-a) in synovial fluid and synovial tissue (Saxne et al., 1989). Thalidomide is a proven inhibitor of the biological synthesis of TNF-a (Sampaio et al., 1991) and is believed to rely on this action for its suppression of the wasting of tissue which accompanies RA. Oral administration of thalidomide has proven to be effective in RA, but unacceptable side effects are easily provoked (Gutierrez-Rodriguez, 1984). Administration of thalidomide via the dermal route can down-regulate TNF-a production in and around the affected joint, and this without raising the systemic blood level to a problematical level. Based on thalidomide's physicochemical properties, it is unlikely that it can be delivered percutaneously at a dose required for RA. Therefore, we have embraced the idea of using N-alkyl analogues of thalidomide. The most important feature that an analogue of this compound might contribute is decreased crystallinity and increased lipophilicity. Ordinarily both these parameters should favour percutaneous delivery. The current study was primarily aimed at exploring the feasibility of percutaneous delivery of thalidomide and subsequently, three of its odd chain IV-alkyl analogues (methyl, propyl and pentyl) via physicochemical characterization and assessment of their innate abilities to diffuse through skin as an initial step towards developing a topical dosage form for the best compound. The biological activities, more specifically their potential to inhibit the production of TNF-a was determined for thalidomide and its N-alkyl analogues. In order to achieve the objectives, the study was undertaken by synthesizing and determining the physicochemical parameters of thalidomide and its N-alkyl analogues. A high level of crystallinity is expressed in the form of a high melting point and heat of fusion. This limits solubility itself, and thus also sets a limit on mass transfer across the skin. Generally, the greater a drug's innate tendency to dissolve, the more likely it is that the drug can be delivered at an appropriate rate across the skin (Ostrenga et al., 1971). Therefore, the melting points and heats of fusion were determined by differential scanning calorimetry. Aqueous solubility and the partition coefficient (relative solubility) are major determinants of a drug's dissolution, distribution and availability. N-octanollwater partition coefficients were determined at pH 6.4. Solubilities in water, a series of n-alcohols and mixed solvents were obtained, as well as the solubility parameters of the compounds in study. Secondly, in vitro permeation studies were performed from these solvents and vehicles using vertical Franz diffusion cells with human epidermal membranes. Thirdly, tumour necrosis factor-alpha (TNF-a) inhibition activities were assessed for thalidomide and its N-alkyl analogues. By adding a methyl group to the thalidomide structure, the melting point drops by over 100°C and, in this particular instance upon increasing the alkyl chain length to five -CH2- units the melting points decrease linearly. Heats of fusion decreased dramatically upon thalidomide's alkylation as well. Methylation of the thalidomide molecule enhanced the aqueous solubility 6-fold, but as the alkyl chain length is further extended from methyl to pentyl, the aqueous solubility decreased exponentially. The destabilization of the crystalline structure with increasing alkyl chain length led to an increase in lipophilicity and consequently an increase in solubility in nonpolar media. Log partition coefficients increased linearly with increasing alkyl chain length. Solubilities in a series of n-alcohols, methanol through dodecanol, were found to be in the order of pentyl > propyl > methyl > thalidomide. The N-alkyl analogues have more favourable physicochemical properties than thalidomide to be delivered percutaneously. The in vitro skin permeation data proved that the analogues can be delivered far easier than thalidomide itself. N-methyl thalidomide showed the highest steady-state flux through human skin from water, n-alcohols and combination vehicles. Thalidomide and its N-alkyl analogues were all active as TNF-a inhibitors. Finally, active as a TNF-a inhibitor, N-methyl thalidomide is the most promising candidate to be delivered percutaneously for treatment of rheumatoid arthritis, of those studied. / Thesis (PhD (Pharmaceutics))--PU for CHE, 1999.
146

Structural and functional characterization of red kidney bean (Phaseolus vulgaris) proteins and enzymatic protein hydrolysates

Mundi, Sule 09 August 2012 (has links)
Kidney bean proteins and peptides can be developed to serve as an important ingredient for the formulation of high quality foods or therapeutic products that may positively impact on body function and human health. The main goal of this thesis was to determine the in vitro structural and functional characteristics of major proteins and enzymatic protein hydrolysate of red kidney bean (Phaseolus vulgaris). Selective aammonium sulfate precipitation of the kidney bean proteins yielded 88% globulin and 7% albumin.The globulin and albumin are glycoproteins that contained ~4% and 45% carbohydrate contents, respectively. Physicochemical and functional characteristics of the globulin fraction, such as, gelation concentration, foam stability, emulsion capacity, and emulsion stability were superior to those of albumin. Reducing SDS-PAGE revealed vicilin with molecular weight of ~45 kDa as the major globulin in kidney beans. Circular dichroism spectroscopy of the purified vicilin showed reductions in α-helix, and β-pleated sheet conformations upon addition of NaCl or changes in pH. Likewise, the tertiary structures as observed from the near-UV CD spectra were also changed by shifts in pH conditions and NaCl addition. Far UV-CD showed increased β-sheet content up till 60oC from room temperature, but a steady loss in the tertiary structure as temperature was further increased; however, β-sheet structure was still detectable at 80oC. Differential scanning calorimetry thermograms showed a prominent endothermic peak with denaturation temperature at around 90oC, attributed to thermal denaturation of vicilin. Alcalase hydrolysis of kidney bean globulin produced multifunctional peptides that showed potential antihypertensive properties because of the in vitro inhibition of activities of renin and angiotensin I converting enzyme as well as the antioxidant properties. The <1 and 5-10 kDa peptide fractions exhibited highest (p<0.05) renin inhibition and the ability to scavenge 2, 2-Diphenyl-1-picrylhydrazyl free radical, inhibit peroxidation of linoleic acid and reduce Fe3+ to Fe2+. Based on this study, incorporation of kidney bean globulin as an ingredient may be useful for the manufacture of high quality food products. Likewise, the kidney bean protein hydrolysates, especially the <1 kDa fraction represent a potential source of bioactive peptides for the formulation of functional foods and nutraceuticals.
147

Investigation of environmental staining and storage on discolouration and cooking quality in Faba bean (Vicia faba L.)

Nasar-Abbas, Syed Muhammad January 2007 (has links)
[Truncated abstract] Faba bean (Vicia Faba L.) ranks third worldwide in overall production among coolseason legume crops and is used as a main source of protein both for food and feed purposes in many parts of the world. Australia is a major exporter of faba beans and the price received depends on the quality of the seed especially colour of the seed coat. Consumers don?t like faba beans that are dark coloured or that have blemishes on the seed coat. Environmental staining and storage discolouration deteriorate seed colour causing substantial economic losses to growers and grain handlers. To investigate the influence of environmental conditions, especially during pod/seed development and maturity, on the degree of environmental staining, field trials were conducted using four faba bean varieties (Fiord, Fiesta, Ascot and Cairo) in a range of environmental conditions under the Mediterranean-type climate of south western Australian grain belt. Although a majority of seeds had good colour but 3-25% were stained up to an unacceptable level across the trials and this varied with location and variety. Seeds formed later in plant development (located on the upper nodes of the plant) were more stained than seeds formed earlier (located on the lower nodes). This may be due to end of season environmental factors, such as high temperature and light intensity, and water and nutrient stress. Similarly seeds formed on small and weak plants, which may have developed under stressful conditions, had more staining than seeds formed on normal sized and healthy plants. Genotypic variation was also evident with Fiord showing greater staining than Ascot, Fiesta and Cairo. The cause of environmental staining appears to be complex but was associated with phenolic contents. Storage discolouration was influenced by a number of factors including temperature, seed moisture content, light and storage period and these were critical in determining storage life. ... Faba bean hardness, examined by the hard-to-cook test, also increased with increased storage temperature. There was a high negative correlation (r2 = 0.98) between storage temperature and cooking ability of faba bean. There was a three-fold increase in lignin content of faba bean stored at 50°C compared to those stored at 5°C and it was correlated with bean hardness (r2 = 0.98). Reduction in free phenolics was negatively correlated (r2 = 0.75) with bean hardness. The environmental staining in faba bean can be minimized with correct choice of varieties, robust agronomic practices to establish and maintain healthy plants and the use of mechanical graders and colour sorters. For minimizing storage discolouration faba beans must be dehydrated to ≤12% seed moisture content and stored in insulated bins (silos) or at least bins painted white and constructed under trees shades. In addition occasional flushing with N2 will further help reduce the colour darkening. The above approaches will improve quality, market opportunities, price and hence profitability of faba bean in the farming systems.
148

Avaliação da estabilidade de derivação farmacêutica hospitalar de tizanidina

Gobetti, Caren January 2017 (has links)
O cloridrato de tizanidina é um relaxante muscular esquelético de ação central, utilizado no tratamento de espasticidade. Esse fármaco é comercializado apenas sob a forma de comprimidos, o que evidencia a necessidade do desenvolvimento de formulações líquidas orais. No ambiente hospitalar, este aspecto é contornado com a preparação de suspensões derivadas, de modo a permitir a administração em crianças e em adultos com deglutição prejudicada, mas não há dados sobre sua estabilidade. O objetivo deste trabalho foi avaliar a estabilidade físico-química e microbiológica de formas farmacêuticas líquidas preparadas em ambiente hospitalar a partir da derivação de comprimidos de cloridrato de tizanidina, empregando como metodologia a cromatografia líquida de alta eficiência (CLAE) e análise microbiológica. Um método simples e indicativo de estabilidade foi desenvolvido e validado por CLAE quanto a especificidade, linearidade, limite de detecção e quantificação, precisão, exatidão e robustez. As formulações líquidas foram preparadas em triplicata e acondicionadas em frasco de polietileno tereftalato (PET) âmbar e de vidro âmbar, que foram armazenados sob três diferentes condições: em temperatura ambiente, sob refrigeração e à 40 °C. Foram coletadas amostras a cada 7 dias por um período de 56 dias para a estabilidade físico-química. As formulações líquidas foram analisadas e demonstraram ser quimicamente estáveis durante 56 dias, permitindo um período de utilização prolongado. Entretanto, a determinação da estabilidade microbiológica mostrou que estas formulações estão propensas à contaminação microbiana, o que reduziu drasticamente a sua estabilidade para 7 dias, em ambos os frascos e em todas as temperaturas avaliadas. A qualidade microbiológica foi uma questão crítica, uma vez que as formulações foram produzidas apenas em água para injetáveis e não havia conservantes presentes na formulação. Os resultados deste estudo podem servir de referência para preparar derivações de cloridrato de tizanidina em uso hospitalar, uma vez que se demonstrou a confiabilidade do intervalo de tempo de armazenamento e as condições adequadas para o uso. De acordo com os resultados deste estudo de estabilidade, este fármaco pode ser incorporado na rotina de preparo das derivações dos hospitais, atendendo a uma demanda já há tempos sinalizada. / Tizanidine hydrochloride is a centrally acting skeletal muscle relaxant, used in the manegement of spasticity. This drug is sold only as tablets, which highlights the need to develop oral liquid formulations. In the hospital environment, this aspect is circumvented by the preparation of derived suspensions, to allow administration to children and adults with impaired swallowing, but there is no data regarding their stability. The objective of this work was to evaluate the physicochemical and microbiological stability of liquid dosage forms prepared in hospital environment from tizanidine hydrochloride tablets, applying high performance liquid chromatography (HPLC) and microbiological analysis. A simple and stability-indicating HPLC method was developed and validated for specificity, linearity, limits of detection and quantification, precision, accuracy and robustness. The liquid formulations were prepared in triplicate and placed in amber PET and glass bottles, which were stored under three different conditions: at room temperature, under refrigeration and at 40 °C. Samples were collected every 7 days along 56 days for physicochemical stability. The liquid formulations were analyzed and demonstrated chemical stability for 56 days, allowing the use for long period. However, the determination of microbiological stability showed that these formulations are prone to microbial contamination, which has dramatically reduced its stability to 7 days, in both bottles and all evaluated temperatures. Microbiological quality was a critical issue, since formulations were produced only in water for injectables and there was no preservatives present in the formulation. Results of this study could be applied as a reference for tizanidine hydrochloride derived preparation in hospital, once it was demonstrated the reliability of storage time interval and proper conditions for use. According to the results of this stability study, this drug could be incorporated into the routine of hospital derivations preparation, meeting a demand already indicated.
149

Uso de conservadores naturais na elaboração de carne de sol com teores reduzidos de cloreto de sódio / Use of natural conservative agents production of carne de sol with lower levels of sodium chloride

Campêlo, Maria Carla da Silva 26 February 2016 (has links)
Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-03-06T15:39:05Z No. of bitstreams: 1 MariaCSC_DISSERT.pdf: 1659077 bytes, checksum: 3f0b26007c83f86ae5035f55e49dc67a (MD5) / Made available in DSpace on 2017-03-06T15:39:06Z (GMT). No. of bitstreams: 1 MariaCSC_DISSERT.pdf: 1659077 bytes, checksum: 3f0b26007c83f86ae5035f55e49dc67a (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Meat and meat products undergo deterioration processes very easily, for this reason, we often use conservational methods to increase shelf life and add value to these products. Among these, salting is a very common technique, used for a very long time, to expand shelf life. However, ingesting great amounts of sodium chloride may lead to the development of arterial hypertension and secondary cardiovascular diseases. Hence, we aimed to evaluate the quality of carne de sol produced with lower levels of sodium chloride and the addition of natural conservative agents. For such purpose, we obtained beef in natura, which was then cut and divided into the following four sample groups: CLS – carne de sol with sodium lactate; CAL – carne de sol with lactic acid; CAL+LS – carne de sol with lactic acid and sodium lactate; and Control – carne de sol with no treatment. Afterwards, the meat underwent the salting process with the sodium chloride level at 2% and was stored at refrigeration temperature 4°C ±1°C. Microbiological and physicochemical analyses were performed on the in natura beef, to evaluate the quality of the raw material that was used, and on the carne de sol produced with each treatment, which were analyzed on day 0, immediately after the addition of the conservative agents, and on days 3, 6, 9 and 12 of refrigerated storage. The carne de sol containing natural conservative agents presented lower microbiological counts when compared to the Control group, and group CAL should be highlighted, because it demonstrated increase in shelf life of up to six days of storage. Regarding the physicochemical parameters, the conservative agents did not significantly change the quality of the samples. Therefore, lactic acid and sodium lactate can be considered as feasible alternatives to prolong the shelf life of carne de sol, and reduce the levels of sodium chloride that are used / Carnes e produtos cárneos sofrem processo de deterioração muito facilmente, por isso, muitas vezes são utilizados métodos de conservação para aumentar a vida útil além de agregar valor a estes produtos. Dentre eles, a salga é bastante utilizada, desde os primórdios, para estender a vida de prateleira. No entanto, o elevado consumo de cloreto de sódio pode levar ao desenvolvimento de hipertensão arterial e doenças cardiovasculares secundárias. Diante disso, objetivou-se avaliar qualidade de carne de sol elaborada com teores reduzidos de cloreto de sódio e adição de conservadores naturais. Para tanto, foi adquirida carne bovina in natura, em seguida esta carne foi cortada e dividida em quatro grupos amostrais, sendo eles: CLS: carne com lactato de sódio, CAL: carne com ácido lático, CAL+LS: carne com ácido lático e lactato de sódio e Controle: carne sem nenhum tratamento. Posteriormente, a carne foi então salgada com teor de cloreto de sódio à 2% e armazenada a temperatura de refrigeração 4ºC±1º. Foram realizadas análises microbiológicas e físico-químicas na carne in natura, para avaliar a qualidade da matéria – prima utilizada e nas carnes de sol com os tratamentos, as quais foram analisadas nos tempos 0, imediatamente após a inserção dos conservadores, e com 3, 6, 9 e 12 dias de armazenamento refrigerado. As carnes de sol contendo os conservadores naturais demostraram menores contagens microbianas quando comparadas com a carne controle, havendo destaque para o grupo amostral CAL, que demostrou um incremento na vida de prateleira de até seis dias de armazenamento. Em relação aos parâmetros físico-químicos, os conservadores não alteraram significativamente a qualidade das amostras. Portanto, o ácido lático e lactado de sódio podem ser considerados alternativas viáveis para prolongar a vida útil da carne de sol, reduzindo ainda o teor de cloreto de sódio utilizado / 2017-03-06
150

[en] INFLUENCE OF SYNTHESIS CONDITIONS ON PHYSICOCHEMICAL PROPERTIES OF SNO2 / [pt] INFLUÊNCIA DOS PARÂMETROS DE SÍNTESE SOBRE PROPRIEDADES FÍSICO-QUÍMICAS DE SNO2

RENATO MOUTINHO DA ROCHA 27 October 2005 (has links)
[pt] Resultados de testes preliminares para a reação de obtenção de formaldeído a partir de metóxi metano (DME) utilizando um catalisador Mo/SnO2 indicaram a necessidade de sistemas altamente ativos. Considerando-se que espécies dispersas de Mo parecem ser as mais efetivas para essa reação, e que a obtenção dessas espécies deve ser favorecida com o uso de um suporte de elevada área específica, estudou-se, neste trabalho, a influência dos parâmetros de síntese nas propriedades fisico-químicas do SnO2 preparado a partir de três diferentes métodos: a partir do ataque de Sn0 com HNO3, a partir da reação entre Sn+4 e NH4OH, e a partir da reação entre Sn+4 e dodecilamina. Foram realizadas alterações na forma de mistura das soluções, no tempo e na temperatura de reação, e na razão de aquecimento durante a calcinação. As amostras obtidas foram caracterizadas por adsorção de N2 para medições de área específica e distribuição de tamanho de poros, difração de raios-X e espectroscopia de reflectância difusa na região do UV-visível. Os resultados mostraram que todas as amostras obtidas são mesoporosas, embora apresentem diferentes valores de área específica, de tamanho de cristal, e de diferença de energia entre os orbitais HOMO-LUMO. Dentre os métodos estudados, o que partiu da reação entre Sn+4 e NH4OH apresentou maior sensibilidade às alterações realizadas, e as amostras assim obtidas apresentaram maiores valores de área específica; por outro lado, as amostras obtidas a partir do ataque de Sn0 com HNO3 não apresentaram variações texturais e estruturais significativas. Os resultados indicam ainda que, dentre os parâmetros alterados, a temperatura e o tempo da reação parecem ser os mais importantes. / [en] Preliminary tests on the reaction for formaldehyde production from metoxi methane (DME) using a Mo/SnO2 catalyst have indicated the necessity of highly active systems. Dispersed species of Mo seem to be the most effective for this reaction which may be favored by the use of a support of high specific area. Therefore the influence of the synthesis parameters on the physicochemical properties of the SnO2 has been studied in this work. This oxide has been prepared by three different methods: by the oxidation of Sn0 using HNO3, by the reaction of Sn+4 with NH4OH, and by the reaction of Sn+4 with dodecylamine. Variations on the way of mixing the solutions, on the time and the temperature of the reaction, and on the heating rate of the calcinations step have been carried out. These samples have been characterized by N2 adsorption for measurements of specific area and pore size distributions, X-ray diffraction and UV-visible diffuse reflectance spectroscopy. The results have shown that all samples are mesoporous even though they have exhibited distinct values of specific area, crystal size and HOMO-LUMO gap energy. The reaction of Sn+4 with NH4OH has presented the greatest sensitivity to the synthesis parameters, and it has provided samples with the highest specific area values. However the samples prepared by the oxidation of Sn0 using HNO3 have not been influenced. The results have also indicated that the temperature and the reaction time seem to be the most important parameters.

Page generated in 0.0695 seconds