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Microbial Growth Inhibition and Decomposition of Milk Mineral and Sodium Tripolyphosphate Added to Media or Fresh Ground BeefTansawat, Rossarin 01 May 2009 (has links)
Milk mineral (MM) is a type II antioxidant (metal chelator) that can bind iron and prevent iron catalysis of lipid oxidation. Thus, MM might have microbial growth inhibition effects on iron-dependent bacteria. Objective 1 was to evaluate effects of MM on growth of non-pathogenic iron-dependent bacterial strains (Listeria innocua, Eschericia coli, Pseudomonas fluorescens). MM (1.5 % w/v) did not significantly inhibit growth of Listeria and E. coli. However, growth of Pseudomonas fluorescens was consistently and significantly reduced by ~1 log colony forming units per ml (CFU/ml) with all levels of MM (0.5, 0.75, 1.5 % w/v). All levels of MM also had no growth inhibition effects against the mixed microflora of fresh ground beef during storage for up to 10 days at 2°C. In conclusion, MM had little or no effect to inhibit microbial growth. The strong affinity of MM to ionic iron inhibits lipid oxidation, but does not inhibit bacterial growth supported by other forms of iron (heme or amino acid + iron complexes).
Several studies report that MM has greater antioxidant effect than sodium tripolyphosphate (STP) in ground meats, especially at longer storage time. Objective 2 was to compare stability of MM and STP in ground beef patties by monitoring the decomposition to soluble orthophosphates (Pi). Patties (control) and patties with 0.75 % MM or 0.5 % STP were stored at 2 or 22°C for 0, 1, or 2 days. CFU/g and Pi were measured. As expected, CFU/g at 22°C was much higher than treatment at 2°C. Pi levels at 2°C were lower (P < 0.05) than at 22°C. At day 0, for both temperatures, patties formulated with MM had the highest Pi levels. However, after 2 days storage, samples with added STP had the highest level of Pi, followed by MM and control. Thus, decomposition as measured by release of Pi was significantly higher for STP than for MM added to beef patties. There was a significant positive correlation (0.77) between CFU/g and Pi during storage of beef patties for 2 days at 22°C. In conclusion, increased Pi during storage of beef patties was at least partially due to bacterial phosphatases. A third experiment was conducted to examine the stability of 0.75 % MM or 0.5 % STP added to growing cultures of Pseudomonas fluorescens at 2°C or 22°C for 0, 1, and 2 days. Neither MM nor STP was stable in autoclaved media (Pi increased significantly). The factors responsible for decomposition of MM or STP in autoclaved media remain to be determined.
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Synthesis of peptide-loaded chitosan nanoparticles for the treatment of sexually transmitted infections (STI’s)Phathekile, Bonke January 2019 (has links)
>Magister Scientiae - MSc / Peptides are among the main drugs which attract much attention because of their great potential
in treating sexually transmitted diseases and other chronic diseases. There has been a major
challenge of delivering these drugs in mucosal sites with low pH environment. The aim of this
study is to synthesize acidic pH stable peptide loaded chitosan nanoparticles gels that could
penetrate mucus layers covering the epithelial cells and kill HIV virus. Chitosan nanoparticles
were synthesized by crosslinking method called Ionic gelation with Sodium
tripolyphosphateTPP. / 2023
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Formulation, characterisation and in vivo efficacy of dapsone and proguanil in trimethylated chitosan microparticles / Jacobus van HeerdenVan Heerden, Jacobus January 2014 (has links)
Malaria is an infectious disease caused by various forms of the Plasmodium parasite. It is
responsible for thousands of deaths yearly with 90 % of those deaths being in sub-Saharan
Africa, thus making it a disease of global importance. The global burden of malaria is
worsened by resistance to current treatment, a lack in funding and limited research outputs.
More alternative ways of treatment must be explored and may include the co-formulation of
antimalarial drug substances as well as alternative ways of drug delivery.
Antifolates are drugs which interfere with an organism’s folate metabolism by inhibiting
dihydropteroate synthase (DHPS) or dihydrofolate reductase (DHFR). Dapsone is a synthetic
sulfone which has a mechanism of action that is very similar to that of sulphonamides. The
mechanism of action is characterised by the inhibition of folic acid synthesis through the
inhibition of dihydropteroate synthase (DHPS). Another antifolate drug, proguanil, is the
prodrug of cycloguanil. Its mechanism involves the inhibition of dihydrofolate reductase
(DHFR), thus inhibiting the malaria parasite to metabolise folates and therefore stunting its
growth. Unfortunately, dapsone has a serious side-effect in people with a deficiency of the
enzyme glucose-6-phosphate dehydrogenase (G6PD) causing oxidative stress on the red
blood cells leading to the rupturing of these cells.
The main objective of this study was to formulate and characterise TMC-TPP microparticles
loaded with the effective but toxic drug combination of dapsone and proguanil and to
determine if these drug-containing microparticles had in vivo efficacy against malaria.
N-trimethyl chitosan chloride (TMC), a partially quaternised chitosan derivative, shows good
water solubility across a wide pH range thus having mucoadhesive properties and excellent
absorption enhancing effects even at neutral pH. A faster, more efficient microwave
irradiation method was developed as an alternative to the conventional synthesising method
of TMC. TMC with the same degree of quaternisation (DQ), ± 60 %, was obtained in a quarter
of the reaction time (30 min) by using the newly developed method. The TMC synthesised
with the microwave irradiation method also exhibited less degradation of the polymer
structure, thus limiting the chance for the formation of any unwanted by-products (Omethylation,
N,N-dimethylation and N-monomethylation).
The formation of complexes by ionotropic gelation between TMC and oppositely charged
macromolecules, such as tripolyphosphate (TPP), has been utilised to prepare microparticles
which are a suitable drug delivery system for the dapsone-proguanil combination. Both these
drugs were successfully entrapped. These particles were characterised and the in vivo
efficacy against the malaria parasites was determined. The microparticles with both the
drugs, separately and in combination, displayed similar or better in vivo efficacy when
compared to the drugs without the TMC microparticles.
An in vitro dissolution study was also performed by subjecting the dapsone and proguanil
TMC formulations to 0.1N HCl dissolution medium. Samples were withdrawn after
predetermined time points and the drug concentration was determined with HPLC. It was
found that the TMC microparticles resulted in a sustained release profile since only 73.00 ±
1.70 % (dapsone) and 55.00 ± 1.90 % (proguanil) was released after 150 minutes. The in vivo
bioavailability of the dapsone and proguanil TMC formulations was evaluated in mice by
collecting blood samples at predetermined time points and analysing the samples with a
sensitive and accurate LC-MS/MS method. The in vivo bioavailability of the dapsone TMC
formulation relative to the normal dapsone formulation was found to be 244 % and 123 % for
the proguanil TMC formulation relative to the normal proguanil formulation.
These TMC-TPP microparticles formulations showed better in vivo efficacy and bioavailability
when compared to the normal formulation. Together with the sustained release, these
formulations may be a promising cheaper and more effective treatment against malaria. / PhD (Pharmaceutics), North-West University, Potchefstroom Campus, 2015
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Formulation, characterisation and in vivo efficacy of dapsone and proguanil in trimethylated chitosan microparticles / Jacobus van HeerdenVan Heerden, Jacobus January 2014 (has links)
Malaria is an infectious disease caused by various forms of the Plasmodium parasite. It is
responsible for thousands of deaths yearly with 90 % of those deaths being in sub-Saharan
Africa, thus making it a disease of global importance. The global burden of malaria is
worsened by resistance to current treatment, a lack in funding and limited research outputs.
More alternative ways of treatment must be explored and may include the co-formulation of
antimalarial drug substances as well as alternative ways of drug delivery.
Antifolates are drugs which interfere with an organism’s folate metabolism by inhibiting
dihydropteroate synthase (DHPS) or dihydrofolate reductase (DHFR). Dapsone is a synthetic
sulfone which has a mechanism of action that is very similar to that of sulphonamides. The
mechanism of action is characterised by the inhibition of folic acid synthesis through the
inhibition of dihydropteroate synthase (DHPS). Another antifolate drug, proguanil, is the
prodrug of cycloguanil. Its mechanism involves the inhibition of dihydrofolate reductase
(DHFR), thus inhibiting the malaria parasite to metabolise folates and therefore stunting its
growth. Unfortunately, dapsone has a serious side-effect in people with a deficiency of the
enzyme glucose-6-phosphate dehydrogenase (G6PD) causing oxidative stress on the red
blood cells leading to the rupturing of these cells.
The main objective of this study was to formulate and characterise TMC-TPP microparticles
loaded with the effective but toxic drug combination of dapsone and proguanil and to
determine if these drug-containing microparticles had in vivo efficacy against malaria.
N-trimethyl chitosan chloride (TMC), a partially quaternised chitosan derivative, shows good
water solubility across a wide pH range thus having mucoadhesive properties and excellent
absorption enhancing effects even at neutral pH. A faster, more efficient microwave
irradiation method was developed as an alternative to the conventional synthesising method
of TMC. TMC with the same degree of quaternisation (DQ), ± 60 %, was obtained in a quarter
of the reaction time (30 min) by using the newly developed method. The TMC synthesised
with the microwave irradiation method also exhibited less degradation of the polymer
structure, thus limiting the chance for the formation of any unwanted by-products (Omethylation,
N,N-dimethylation and N-monomethylation).
The formation of complexes by ionotropic gelation between TMC and oppositely charged
macromolecules, such as tripolyphosphate (TPP), has been utilised to prepare microparticles
which are a suitable drug delivery system for the dapsone-proguanil combination. Both these
drugs were successfully entrapped. These particles were characterised and the in vivo
efficacy against the malaria parasites was determined. The microparticles with both the
drugs, separately and in combination, displayed similar or better in vivo efficacy when
compared to the drugs without the TMC microparticles.
An in vitro dissolution study was also performed by subjecting the dapsone and proguanil
TMC formulations to 0.1N HCl dissolution medium. Samples were withdrawn after
predetermined time points and the drug concentration was determined with HPLC. It was
found that the TMC microparticles resulted in a sustained release profile since only 73.00 ±
1.70 % (dapsone) and 55.00 ± 1.90 % (proguanil) was released after 150 minutes. The in vivo
bioavailability of the dapsone and proguanil TMC formulations was evaluated in mice by
collecting blood samples at predetermined time points and analysing the samples with a
sensitive and accurate LC-MS/MS method. The in vivo bioavailability of the dapsone TMC
formulation relative to the normal dapsone formulation was found to be 244 % and 123 % for
the proguanil TMC formulation relative to the normal proguanil formulation.
These TMC-TPP microparticles formulations showed better in vivo efficacy and bioavailability
when compared to the normal formulation. Together with the sustained release, these
formulations may be a promising cheaper and more effective treatment against malaria. / PhD (Pharmaceutics), North-West University, Potchefstroom Campus, 2015
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The effect of pharmaceutical excipients on isoniazid release from chitosan beads / Deon van RensburgVan Rensburg, Andries Gideon January 2007 (has links)
In controlled release applications a drug is molecularly dispersed in a polymer phase. In
the presence of a thermodynamically compatible solvent, swelling occurs and the
polymer releases its content to the surrounding medium. The rate of the drug release can
be controlled by interfering with the swelling rate of the beads or by influencing diffusion
through the viscosity of the polymer.
Beads that contain chitosan were prepared through the ionotropic gelation method where
tripolyphosphate (TPP) was used as the crosslinking agent. Beads that consisted of 3%
w/v isoniazid (lNH) and 5% w/v chitosan were prepared in a 5% w/v TPP solution (pH
8.7) as the primary beads. To improve the drug loading of chitosan isoniazid beads (ClB)
the TPP concentration, pH of the TPP solution and the INH concentrations were altered
for maximum drug loading. To increase the porosity of the beads of chitosan beads
Explotab® (EXPL), Ac-Di-Sol® (ADS) and Vitamin C (VC) were added individually to
chitosan solutions at concentrations of 0.1, 0.25 and 0.5% w/v before adding the mixture
to the TPP solution. Morphology, swelling and drug loading studies were used to
evaluate the different formulations. After these excipients were added individually they
were also added in combinations of two excipients respectively and characterised. From
the results of the drug loading studies the beads that contained only chitosan and
isoniazid showed a percentage drug loading of (43.92%) which is the best of all the beads
that were analyzed. The multi excipient combination of Ac-Di-Sol® and Explotab®
showed the best swelling capability at both pH levels.
Dissolution studies were conducted on all the formu lations over a period of 6 hours (360
minutes) at pH 5.6 and pH 7.4. From the dissolution results it were clear that no chitosan
dissolved at both pH values. The dissolution of single pharmaceutical excipient (SPE)
and multi pharmaceutical excipient (MPE) formulations can be arranged in the following
order: VC/ADS < VC < ADS/EXPL < ADS < VC/EXPL < CIB < EXPL. Explotab® is a
potential excipient for enhanced drug release over a wide pH range. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
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The effect of pharmaceutical excipients on the release of indomethacin from chitosan beads / Riana HavingaHavinga, Riana January 2006 (has links)
Contents: Chitosan -- Controlled drug delivery -- Indomethacin -- Inotropic gelation -- Tripolyphosphate (TPP) -- Explotab® -- Ac-Di-Sol® -- Vitamin C / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
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The effect of pharmaceutical excipients on the release of indomethacin from chitosan beads / Riana HavingaHavinga, Riana January 2006 (has links)
Chitosan has proven through the years as a versatile biomaterial to be used in pharmaceutical applications. Its mucoadhesive properties as well as its ability to manipulate the tight junctions in epithelium membranes have qualified it as an effective drug carrier in controlled drug delivery systems. Microparticles or beads as they are forward called in this study have advantages over conventional drug dosage forms because of a large surface to volume ratio and have the ability to target a specific site for drug release. Indomethacin is an anti-inflammatory drug that causes gastrointestinal side effects in conventional immediate-release dosage forms.
The goal is to manipulate the drug delivery vehicle to target the intestines/colon as the site for drug delivery and to minimize this side effect. Thus chitosan beads have been chosen as a drug delivery system for indomethacin in this study.
Chitosan beads have been prepared through the ionotropic gelation method using tripolyphophate (TPP) as a cross-linking agent. To prepare the most effective bead to encapsulate indomethacin different formulation and system variables (pH of the TPP solution, the concentration of the TPP solution as well as the indomethacin concentration) have been evaluated according to the following parameters: morphology, drug loading capacity and swelling capability. The ideal pH of the TPP solution was determined at 8.7 and the most effective TPP and indomethacin concentration were 5% w/v and 4% w/v respectively. The chitosan concentration was kept at 3% w/v throughout the study. These concentrations were used to examine the effect of pharmaceutical excipients on the indomethacin release from chitosan beads.
The effect of the different excipients namely, ExplotabⒽ(0.25% w/v), Ac-Di-SolⓀ (0.5% w/v) and Vitamin C (0.25% w/v), on the morphology, drug loading capacity, swelling capability as well as the drug release of indomethacin chitosan beads (ICB's) were also studied. The excipients were used in the individually above mentioned concentrations and in combination with each other in the same concentrations. These formulations were used in dissolution studies over a period of 6 hours in PBS pH 7.4 solutions. The indomethacin release rate increased when an excipient was added to the formulation and it dramatically increased when the excipients were added in their various combinations, compared to the formulation that did not contain excipients. / Contents: Chitosan -- Controlled drug delivery -- Indomethacin -- Inotropic gelation -- Tripolyphosphate (TPP) -- Explotab® -- Ac-Di-Sol® -- Vitamin C / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
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The effect of pharmaceutical excipients on rifampicin release from chitosan beads / Mangaabane Gorden MohlalaMohlala, Mangaabane Gorden January 2004 (has links)
Controlled release systems aim at achieving a predictable and reproducible drug
release over a desired time period. These systems allow reduced dosing frequency,
constant drug levels in the blood, increased patient compliance and decreased adverse
effects. In a recent study, Chitosan beads, containing N-trimethyl Chitosan chloride,
have shown a potential in the delivery of rifampicin. However, because of inadequate
amounts of rifampicin released over 24 hours, incorporation of other pharmaceutical
excipients to increase the swelling behaviour of the beads to improve drug release,
was considered in this study.
Chitosan beads were prepared through ionotropic gelation with tripolyphosphate
(TPP) as a crosslinking agent. To increase the porosity if the Chitosan beads
Explotab®, Ac-Di-Sol® and vitamin C were added individually to Chitosan solutions
at concentrations of 0.1, 0.25 and 0.5 % w/v before adding the mixture to the TPP
solution. Swelling and morphology studies were used in the evaluation of the different
formulations. The swelling and morphology results were then used to select a set of
combination and concentrations of two excipients sand then prepare and characterise
beads containing two combinations. The combination formulations and formulations
containing single excipients were then loaded with rifampicin. Pure chitosan beads
exhibited a higher drug loading capacity (67.49 %) compared to the lowest loading
capacity of 41.61 % exhibited by chitosan beads containing a combination of
Explotab®, Ac-Di-Sol®.For all the other formulations the drug loading capacity
ranged within 48 and 63 %.
These formulations were used for dissolution studies over a period of 6 hours at pH
5.60 and 7.40. The dissolution results showed that no chitosan has dissolved at both
pH values. A significant amount of rifampicin was, however, released from the beads,
especially at pH 7.40. chitosan beads containing vitamin C also exhibited high
rifampicin release (48.34 ± 1.00) %) at pH 5.60 compared to the other formulations
and this makes vitamin C a potential excipient for enhanced drug release over a wide
pH range (both acidic and alkalinic). However, further studies are necessary to
optimise the preparation method to minimise drug loss during loading and to improve
the drug loading capacity of the beads. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2005.
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The effect of pharmaceutical excipients on the release of indomethacin from chitosan beads / Riana HavingaHavinga, Riana January 2006 (has links)
Chitosan has proven through the years as a versatile biomaterial to be used in pharmaceutical applications. Its mucoadhesive properties as well as its ability to manipulate the tight junctions in epithelium membranes have qualified it as an effective drug carrier in controlled drug delivery systems. Microparticles or beads as they are forward called in this study have advantages over conventional drug dosage forms because of a large surface to volume ratio and have the ability to target a specific site for drug release. Indomethacin is an anti-inflammatory drug that causes gastrointestinal side effects in conventional immediate-release dosage forms.
The goal is to manipulate the drug delivery vehicle to target the intestines/colon as the site for drug delivery and to minimize this side effect. Thus chitosan beads have been chosen as a drug delivery system for indomethacin in this study.
Chitosan beads have been prepared through the ionotropic gelation method using tripolyphophate (TPP) as a cross-linking agent. To prepare the most effective bead to encapsulate indomethacin different formulation and system variables (pH of the TPP solution, the concentration of the TPP solution as well as the indomethacin concentration) have been evaluated according to the following parameters: morphology, drug loading capacity and swelling capability. The ideal pH of the TPP solution was determined at 8.7 and the most effective TPP and indomethacin concentration were 5% w/v and 4% w/v respectively. The chitosan concentration was kept at 3% w/v throughout the study. These concentrations were used to examine the effect of pharmaceutical excipients on the indomethacin release from chitosan beads.
The effect of the different excipients namely, ExplotabⒽ(0.25% w/v), Ac-Di-SolⓀ (0.5% w/v) and Vitamin C (0.25% w/v), on the morphology, drug loading capacity, swelling capability as well as the drug release of indomethacin chitosan beads (ICB's) were also studied. The excipients were used in the individually above mentioned concentrations and in combination with each other in the same concentrations. These formulations were used in dissolution studies over a period of 6 hours in PBS pH 7.4 solutions. The indomethacin release rate increased when an excipient was added to the formulation and it dramatically increased when the excipients were added in their various combinations, compared to the formulation that did not contain excipients. / Contents: Chitosan -- Controlled drug delivery -- Indomethacin -- Inotropic gelation -- Tripolyphosphate (TPP) -- Explotab® -- Ac-Di-Sol® -- Vitamin C / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
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The effect of pharmaceutical excipients on rifampicin release from chitosan beads / Mangaabane Gorden MohlalaMohlala, Mangaabane Gorden January 2004 (has links)
Controlled release systems aim at achieving a predictable and reproducible drug
release over a desired time period. These systems allow reduced dosing frequency,
constant drug levels in the blood, increased patient compliance and decreased adverse
effects. In a recent study, Chitosan beads, containing N-trimethyl Chitosan chloride,
have shown a potential in the delivery of rifampicin. However, because of inadequate
amounts of rifampicin released over 24 hours, incorporation of other pharmaceutical
excipients to increase the swelling behaviour of the beads to improve drug release,
was considered in this study.
Chitosan beads were prepared through ionotropic gelation with tripolyphosphate
(TPP) as a crosslinking agent. To increase the porosity if the Chitosan beads
Explotab®, Ac-Di-Sol® and vitamin C were added individually to Chitosan solutions
at concentrations of 0.1, 0.25 and 0.5 % w/v before adding the mixture to the TPP
solution. Swelling and morphology studies were used in the evaluation of the different
formulations. The swelling and morphology results were then used to select a set of
combination and concentrations of two excipients sand then prepare and characterise
beads containing two combinations. The combination formulations and formulations
containing single excipients were then loaded with rifampicin. Pure chitosan beads
exhibited a higher drug loading capacity (67.49 %) compared to the lowest loading
capacity of 41.61 % exhibited by chitosan beads containing a combination of
Explotab®, Ac-Di-Sol®.For all the other formulations the drug loading capacity
ranged within 48 and 63 %.
These formulations were used for dissolution studies over a period of 6 hours at pH
5.60 and 7.40. The dissolution results showed that no chitosan has dissolved at both
pH values. A significant amount of rifampicin was, however, released from the beads,
especially at pH 7.40. chitosan beads containing vitamin C also exhibited high
rifampicin release (48.34 ± 1.00) %) at pH 5.60 compared to the other formulations
and this makes vitamin C a potential excipient for enhanced drug release over a wide
pH range (both acidic and alkalinic). However, further studies are necessary to
optimise the preparation method to minimise drug loss during loading and to improve
the drug loading capacity of the beads. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2005.
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