Not available / text

Bioavailability enhancement of poorly water soluble active pharmaceutical ingredients (API) is key for improving existing therapies and allowing for formulation of certain new chemical entities. The rate limiting step for absorption of these APIs is dependent on the dissolution rate and the APIs apparent solubility. Particle engineering processes such as evaporative precipitation into aqueous solution (EPAS) and spray freezing into liquid (SFL) were developed to enhance API dissolution and bioavailbality through the production of amorphous and nanoparticulate API. The morphology, primary API domain size and miscibility of particles produced by EPAS and SFL were investigated by several complementary and novel techniques. It was found that the SFL composition displayed amorphous character, a primary danazol particle size of 30 nm and was consistent with a solid solution. The EPAS composition was mostly amorphous with slight crystallinity, a primary danazol particle size of 500 nm and was consistent with a solid dispersion. The ability of the nanoparticulate and amorphous particles to supersaturate dispersions and how this impacts oral bioavailability was tested through in vitro and in vivo models. Through the use of a testing method for supersaturation, it was found that EPAS and SFL compositions achieve higher apparent solubilities when compared to the physical mixture and commercial Danocrine® capsules. This improvement in solubility allowed for more danazol to be available for absorption in vivo. Pulmonary delivery of SFL nanoparticulate itraconazole was evaluated for pharmacokinetic parameters and steady state trough levels compared to oral delivery of an SFL oral composition and the commercial product. Inhalation of ITZ compositions is an effective method of antifungal therapy for the treatment and prophylaxis of invasive fungal infections. High and sustained lung tissue concentrations are achieved via inhalation of an amorphous ITZ pulmonary composition while maintaining serum levels which are above the minimum lethal concentration for A. fumigatus. Histology, macrophage uptake and IL-12 induction was evaluated for aerosolized amorphous ITZ nanoparticles. Pulmonary administration of amorphous ITZ nanoparticles or excipient placebo does not cause inflammation or changes in alveolar and airway histology. Uptake of ITZ by alveolar and airway macrophages occurs following inhalation of an amorphous ITZ composition. / text

No description available.

No description available.

The goal of this study was to develop a simple means of estimating the cosolvent/water solubility profile using just the available properties (logKow, dielectric constant etc.) of the solute, cosolvent and water. Ethanol was used as the model cosolvent.One of the most commonly used polarity indicators is the octanol/water partition coefficient (logKow). Numerous programs are used to predict the logKow. The calculated values of logKow from three of the most commonly used programs ClogP®, ACD/logPdb® and KowWin® were compared to experimental values. It was found that all three programs have a user friendly interface but ClogP appears to be more accurate.While the ethanol/water solubility profiles of very polar and very non-polar drugs are monotonic, many semi-polar drugs show a maximum solubility at an ethanol volume fraction (fmax) between zero and one. A new empirical function that describes this deviation from linearity was applied to the experimental data forfifty-one compounds. The proposed model was a more accurate predictor of the co-solvent solubility profile than a general third order polynomial with the samenumber of parameters. The fmax value was also accurately predicted from the first derivative of the model.A sigmoidal relationship was observed between the value of fmax and logKow of the solute. Combining this sigmoidal relationship with the previously reportedlinear relationship between logKow and the initial slope of the plot of log solubility vs. ethanol composition enables the estimation of the totalethanol/water solubility profiles of semi-polar compounds from just logKow.A new bilinear function was also introduced to address the deviation from linearity. This model accounts for both the initial and terminal slopes in theethanol/water solubility profiles of semi-polar solutes. The proposed model is dependent only on logKow and an empirical constant that is cosolvent specific. It is also more accurate than the log-linear model and a general parabolic model.A solubility case study using Antalarmin, a novel stress inhibitor was performed.This study illustrates the use of cosolvents as solubility enhancers as well as pH,surfactants, complexants and lipid based systems.

A major hurdle facing in vitro protein characterization is obtaining soluble protein from targets that tend to aggregate and form insoluble inclusion bodies. Soluble protein is essential for any biophysical data collection and new methods are needed to approach this significant problem. Directed evolution can be used to discover mutations which lead to improved solubility using an appropriate screening method. Green fluorescent protein (GFP) has been shown to be an effective solubility reporter which can be used to screen for soluble protein variants. We have chosen three diverse enzymes as targets for improving protein solubility using this technique: arachidonate 5-lipoxygenase—an enzyme which converts fatty acids into leukotrienes, PhnG—an enzyme belonging to the bacterial carbon-phosphorus lyase pathway, and RebG—a glycosyltransferase. Error-prone PCR and DNA shuffling were used to generate libraries of mutants which were subsequently cloned into a GFP-fusion screening vector. From the evolution of 5LO and RebG, much was learned about the optimization of the protocols involved in this methodology, including valuable information about how to avoid common “false-positive” results in which fluorescent colonies arise while screening but do not represent an improvement of the target. Evolution of these two targets did not result in an improvement of solubility, however truncation strategies may still prove to be effective, and more work needs to be done in this area. Evolution of PhnG successfully produced one variant, named clone B6, which showed both an improvement in expression and folding over wild type PhnG. It was also discovered that GFPuv can act as an effective solubility enhancing fusion tag for PhnG. Prior to the current studies PhnG had not been effectively expressed and purified in E. coli , however purification and refolding of resolubilized inclusion bodies of the clone B6 PhnG-GFP fusion construct was shown to yield enough soluble protein for future crystallographic studies. / Thesis (Master, Chemistry) -- Queen's University, 2009-10-09 12:26:03.353

Growing interests in dietary manipulation to reduce P excretion in animal manure and P loss from agricultural soils to the environment have led to strategies such as the use of phytase in monogastric animal diets. The efficacy of phytase has been confirmed by several studies that reported its ability to hydrolyze phytate P present in grain feeds and thus, reduce manure total P. However, the solubility of manure P from phytase supplemented diets in soils is not well known, and as thus, the environmental implications of dietary P manipulation require further investigation. Two related studies were carried out in the laboratory to investigate the fate of manure phosphorus (P) from pigs fed phytase supplemented diets in Manitoba soils. The first study characterized the forms of manure P from phytase supplemented swine diets to evaluate their potential environmental impact. The seven dietary treatments fed randomly to a total of 28 growing pigs were: a positive control that contained P at the NRC (1998) recommendations (NRC), a negative control (RED) containing 0.1 percentage units reduction (about 33%) in available P from 1998 NRC recommendations, RED with 500 U of phytase kg-1 of diet (RED + P1), RED with 1000 U of phytase kg-1of diet (RED + P2), a double negative control with no added inorganic P (DNC), DNC plus 2000 U of phytase kg-1 of diet (DNC + P3) and DNC plus 4000 U of phytase kg-1 of diet (DNC + P4). The second study examined the solubility of manure P from the manure collected from the first study. Manure collected from the first study were applied at a rate of 75 kg of total P ha-1 of soil to surface samples from four Manitoba soils (0-15 cm); Osborne clay (Rego Humic Gleysol/Gleysolic Humic Vertisol), Red River clay (Gleyed Rego Black Chernozem/Gleyed Humic Vertisol), Ladywood very fine sandy loam (Gleyed Dark Gray Chernozem), and Glenhope loamy fine sand (Gleyed Rego Black Chernozem). In the first experiment, total P in feces and manure were significantly reduced (p < 0.05) with phytase addition to the diets. The labile P concentration (sum of H2O–P and NaHCO3-P) was about 71 to 89% and 77 to 89% of total P in both feces and manure, respectively. Phytase addition to the diets reduced the labile P in feces. The solubility of P was greatest in the calcareous soils amended with the manure from the DNC diets and solubility of P varied with time and extracting solutions. Although, a combination of physico-chemical properties (e.g. CEC, Exchangeable Ca2+), texture seems to play a significant role, as P solubility increased in coarse textured soils after longer period of incubation (16wks). However, our results showed that phytase supplementation in the diets of pigs did not affect the solubility of manure P in amended soils.

Precipitation reactions of phosphorus (P) with Ca decrease the P fertilizer efficiency in calcareous soils. The hypothesis was that anion competition of sulphate with phosphate to precipitate with Ca will increase P solubility in calcareous soils. Initial experiments were conducted to investigate the effect of co-application of K2SO4, (NH4)2SO4, MgSO4 and (NH4)2CO3 on the solubility of monopotassium phosphate (MPP) and monoammonium phosphate (MAP) in different Manitoba soils. Co-application of sulphate salts enhanced P solubility by a factor that ranged from 6% to 44% in soils with greater exchangeable Ca and smaller acid-extractable Ca content (i.e. Osborne, Red River, Balmoral and St. Claude soil series). Solubility and solid-state speciation of P were investigated when MPP was banded with sulphate salts in both model and natural (Dezwood Loam soil series, DL) calcareous soils. The results of S K-edge X-ray absorption near edge structure spectroscopy (XANES) showed that CaSO4•2H2O was formed in DL soil when either K2SO4, (NH4)2SO4 or MgSO4 was applied with MPP. Phosphorus-31 magic-angle spinning nuclear magnetic resonance (MAS NMR) analysis showed that dicalcium phosphate dihydrate (DCPD) was formed in both soils, but the relative proportion of DCPD decreased in the presence of sulphate salts due to the formation of a new P compound. The results also showed that decreasing Ca saturation on the cation exchange complex increased the solubility and mobility of MAP in model calcareous soils and Ca played a more dominant role in forming P precipitates than Mg. According to 31P MAS NMR results, DCPD was the dominant P species in soils with 100% to 50% Ca saturation on the cation exchange complex while poorly ordered magnesium phosphate trihydrate was the prominent P phase with 70% to 100% Mg saturation. This study has demonstrated that the combination of solid state NMR and XANES provided complimentary information concerning anion competition and changes in P speciation due to the co-application of sulphate salts in fertilizer bands. Application of sulphate salts is a promising agronomic practice to enhance P solubility in soils with greater exchangeable Ca content due to the anion competition by sulphates with phosphate to precipitate with Ca.

Growing interests in dietary manipulation to reduce P excretion in animal manure and P loss from agricultural soils to the environment have led to strategies such as the use of phytase in monogastric animal diets. The efficacy of phytase has been confirmed by several studies that reported its ability to hydrolyze phytate P present in grain feeds and thus, reduce manure total P. However, the solubility of manure P from phytase supplemented diets in soils is not well known, and as thus, the environmental implications of dietary P manipulation require further investigation. Two related studies were carried out in the laboratory to investigate the fate of manure phosphorus (P) from pigs fed phytase supplemented diets in Manitoba soils. The first study characterized the forms of manure P from phytase supplemented swine diets to evaluate their potential environmental impact. The seven dietary treatments fed randomly to a total of 28 growing pigs were: a positive control that contained P at the NRC (1998) recommendations (NRC), a negative control (RED) containing 0.1 percentage units reduction (about 33%) in available P from 1998 NRC recommendations, RED with 500 U of phytase kg-1 of diet (RED + P1), RED with 1000 U of phytase kg-1of diet (RED + P2), a double negative control with no added inorganic P (DNC), DNC plus 2000 U of phytase kg-1 of diet (DNC + P3) and DNC plus 4000 U of phytase kg-1 of diet (DNC + P4). The second study examined the solubility of manure P from the manure collected from the first study. Manure collected from the first study were applied at a rate of 75 kg of total P ha-1 of soil to surface samples from four Manitoba soils (0-15 cm); Osborne clay (Rego Humic Gleysol/Gleysolic Humic Vertisol), Red River clay (Gleyed Rego Black Chernozem/Gleyed Humic Vertisol), Ladywood very fine sandy loam (Gleyed Dark Gray Chernozem), and Glenhope loamy fine sand (Gleyed Rego Black Chernozem). In the first experiment, total P in feces and manure were significantly reduced (p < 0.05) with phytase addition to the diets. The labile P concentration (sum of H2O–P and NaHCO3-P) was about 71 to 89% and 77 to 89% of total P in both feces and manure, respectively. Phytase addition to the diets reduced the labile P in feces. The solubility of P was greatest in the calcareous soils amended with the manure from the DNC diets and solubility of P varied with time and extracting solutions. Although, a combination of physico-chemical properties (e.g. CEC, Exchangeable Ca2+), texture seems to play a significant role, as P solubility increased in coarse textured soils after longer period of incubation (16wks). However, our results showed that phytase supplementation in the diets of pigs did not affect the solubility of manure P in amended soils.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1922. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed June 10, 2009)