Purpose: This thesis aimed to gain a better understanding of the effects of salts in modifying in vitro phase behaviour of lecithin and cholesterol solid implants and to obtain further information on in vitro protein release and stability. Methods: Raman spectroscopy and partial least squares regression (PLSR) were used to investigate lecithin-cholesterol molecular interactions as a function of method of preparation. Lipid-salt interactions were studied by attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopy using principal component analysis (PCA). In vitro release of bovine serum albumin (BSA), a model protein, from lecithin and lecithin:cholesterol implants comprising 10 and 30% NaCl and CaCl₂ were performed. Size exclusion (SE) HPLC was used for quantitative and qualitative analysis of the released BSA. On hydration, changes in phase behaviour and implant morphology were studied by ATR spectroscopy and light microscopy. SE-HPLC, ATR and fluorescence spectroscopy were used to evaluate the structure of unreleased BSA. Protein adsorption on lipid films was studied by flow through ATR spectroscopy. Increased amide II peak area upon recirculation of BSA in salt solutions over hydrated lecithin and lecithin:cholesterol films cast on ZnSe prisms was used to quantify the deposition of BSA onto the lipid surfaces. Results: Shifts in the Raman spectra suggested the lecithin headgroup may be involved in lecithin-cholesterol interactions. Greater R� and root mean square error of cross validation in the calibration curves of physical mixing and heating (120�C) methods reflected poor mixing in these preparations. The mean absolute residue and mean Mahalanobis distance values from the physical mixing and granulation methods indicated their spectral similarity and comparable level of lecithin-cholesterol interactions. Calcium exhibited stronger affinity for phospholipids than sodium and it induced headgroup hydration and reorganisation upon binding. PCA of ATR spectra was sensitive to cholesterol addition, calcium binding and method of preparation whilst PCA of Raman spectra only differentiated the presence of cholesterol. In vitro release of BSA from implants produced from wet granulation mixtures of lecithin and lecithin:cholesterol in the absence of salt showed retention of a high monomer content and the release profiles were similar to the literature. Cholesterol increased the swelling, induced phase transformation of lecithin and, subsequently, reduced the BSA release. Salts only slightly modified the BSA release from the lecithin implants. In contrast, for lecithin:cholesterol matrices salts greatly enhanced implant swelling, induced the formation of hydrated lecithin of heterogeneous size and inhibited the in vitro BSA release. Analyses of the protein showed increased aggregation of BSA with a high retention of native structure while retained within the swollen matrices. ATR spectra suggested that salts promoted protein adsorption onto hydrated lecithin surfaces and the effects depend on salt types (NaCl > CaCl₂) and concentration (0.1 M > 1.0 M) but not on lecithin:cholesterol surfaces. Conclusion: PLSR and PCA can be used to investigate molecular interactions in the solid lipid matrices. In lecithin:cholesterol implants, salts modified the phase behaviour of lecithin which resulted in enhanced swelling, formation of hydrated lecithin of altered morphology and inhibition of in vitro BSA release.

Purpose: The aim of this thesis was to investigate a suitable formulation for the topical delivery of growth factors to chronic wounds, and then to determine the concentrations reached within an animal wound model. A secondary aim was to determine if the chosen growth factor was present at levels able to stimulate the production of other cytokines, specifically IL-1β and MCP-1. Methods: An in vitro testing apparatus was designed and made and the release of model actives [bromophenol blue (BPB) and horseradish peroxidase (HRP)] from gels and films of hydroxylpropylmethylcellulose (HPMC) (E4M CR, K4M CR and E10M CR) was determined. In this study, Fibroblast Growth Factor -2 (FGF-2) (0.3 [mu]g) was incorporated into three formulations (solution, gel and dried gel film on Melolin[TM] backing) and together with a control formulation were administered to punch biopsy wounds in rats. The in vivo release was followed over three time periods (two, five and eight hours) and the amount of FGF-2 at various wound depths was quantified by ELISA. Two biological markers IL-1β and MCP-1 were quantified using ELISA. The FGF-2 was additionally tagged with a fluorescent dye so that visualisation of the penetration could be obtained via confocal microsopy. Results: For the HPMC gels, the more viscous gel (E10M) provided a greater diffusional barrier and slowed the release of BPB (12 � 3.5 [mu]g/min compared with 16 � 1.7 [mu]g/min and 18 � 1.4 [mu]g/min for K4M and E4M respectively). However, when HPMC was formulated as a dried film a burst release was seen and release of BPB was slowest from the more rapidly hydrating K4M. With the larger model active HRP, there was a slower diffusion through the gel barrier formed upon film hydration, such that time of 100% release was up to 300 minutes compared to approximately 60 minutes for BPB. When the film was dried onto a supportive backing, the initial burst release was minimised as the film did not break apart on contact with the wound, and hence film integrity was maintained and release prolonged. The in vivo studies showed that, two hours after application, the highest concentration of FGF-2 was seen in the surface granulation tissue of rats that received the solution formulation (2280 � 790 pg/g). The concentration decreased with increasing tissue depth but was significantly greater than the saline control in the surface granulation and subcutaneous fat layers (p<0.05). Tissue concentrations following application of the gel and film formulations were only marginally greater than control in the surface granulation layer. After eight hours, rats that received the solution retained elevated surface tissue concentrations (surface granulation and subcutaneous fat) of FGF-2. Repeated measures ANOVA using a general linear model showed statistically significant differences in the mean FGF-2 level with respect to formulation and length of time of application of the formulation (p<0.05). In terms of other cytokines, there was a release of both IL-1β and MCP-1 in all groups, immediately post-wounding, probably in response to cellular damage. After eight hours, the film formulation appeared to elevate IL-1β levels which may be useful to drive wound healing. Confocal microscopy images showed diffuse distribution of FGF-2 eight hours after application of the solution formulation after eight hours and that with the gel formulation FGF-2 initially aggregated at the wound surface. Conclusion: In vitro experiments investigating the effect of hydration rate and viscosity of HPLC polymers allowed a formulation to be chosen for further in vivo study. Elevated FGF-2 could be measured in superficial wound tissues up to eight hours after application of a solution. However, application of a comparable amount of FGF-2 in HPMC gels or films did not produce appreciable elevations in FGF-2 in wound tissues, although confocal microscopy indicated the penetration of FGF-2 into the wound for up to eight hours.

Sixteen millions of people are diabetics in the United States. Finding an oral way to deliver the insulin they need would improve the quality of their life. For this purpose biodegradable and biocompatible nanovesicles encapsulating some insulin have been synthesized. Those nanovesicles are made by self-assembly of a triblock copolymer poly(ethylene glycol)-bpoly( lactic acid)-b-poly(glutamic acid) (PEG-b-PLA-b-PGlu). The triblock copolymer has been prepared in several steps by multi-step anionic ringopening polymerization. The first step consisted in the preparation of the diblock copolymer PEG-b-PLA. This diblock copolymer was synthesized by ring opening of racemic lactide, using a zinc alkoxide as an initiator. The second step was the synthesis of the poly(glutamic acid). The polybenzyl(glutamic acid) was obtained by ring opening polymerization of the N-Carboxyanhydride of the corresponding amino acid. Finally, the benzyl group was deprotected via protonolysis, to generate the homopolymer. This triblock was successfully obtained by coupling a diblock copolymer PEG-bxv PLA and a homopolymer poly(glutamic acid). In the presence of an aqueous solution of insulin where the pH is between 7 and 9, the triblock copolymer self-assembles in nanovesicles containing a part of the free insulin. In the intestine, the vesicles are highly solvated due to the deprotonnated poly(glutamic acid) hair which are expected to be located on the outside. Moreover, to resist from the gastric acidity, the nanovesicles are protected with gastro resistant polymer, Eudragit, which stay solid at acidic pH but get dissolved in the intestine (where the pH is slightly basic), releasing the vesicles. All the polymers have been characterized using 1H NMR and GPC. The percentage of encapsulation of insulin has been measured by HPLC some in-vivo experiments have been done on Sprague-Dawley rats.

This thesis describes evaluation of a gastric retention device (GRD) developed at Oregon State University. The device was originally fabricated from Xanthan gum and Locust bean gum. A modified gastric retention device containing other additives was developed and investigated in this work. The modified device was evaluated in vitro for swelling and dissolution properties using riboflavin as a model drug. Different shapes and sizes of GRDs were tested in dogs to study the gastric retention potential of these devices. The effect of the device on food emptying from the stomach in dogs was also investigated. Endoscopic studies in dogs also showed that the device swells rapidly and considerably in gastric fluid. The bioavailability of riboflavin from three different size GRDs was determined in six fasted human volunteers and compared to an immediate release formulation. The biostudy indicated that the bioavailability of riboflavin from a large size GRD was more than triple that measured after administration of the immediate release formulation. Deconvolution was used to determine gastric residence time of the different size GRDs. A new colonic delivery system made of acetaminophen loaded beads produced by extrusion and spheronization and coated with different ratios of pectin and ethylcellulose coating solutions in a spray coating apparatus was also developed in this work. Such beads release their drug content in the colon due to susceptibility of pectin in the outer coat to enzymatic action of colonic bacteria. The new delivery system was evaluated in vitro by conducting release studies in different dissolution media to mimic transit times, pH and enzyme conditions in the gastrointestinal tract. The gastrointestinal transit behavior of drug beads was also assessed by conducting gamma-scintigraphic studies in dogs. The bioavailability and pharmacokinetic parameters of acetaminophen from several colonic delivery system formulations were determined in human volunteers and compared to the immediate release commercial product Tylenol®. A selected pectin-ethylcellulose coat formulation in the ratio 1:3 was further evaluated in six volunteers under both fed and fasting conditions and was found to be effective and to provide sustained drug release in the colon over a period of 12 hours. / Graduation date: 2003

This thesis describes 1) development of a gastric retention device (GRD) to increase gastric retention time of certain drugs, 2) product formulations of an immediate release itraconazole and controlled-release ketoprofen. GRD was fabricated from crosslinked carbohydrate polymers. Rate and extent of hydration of the film in water and in simulated gastric fluid, compressibility of film, shape of the film, and in vivo gastric transit time in the stomach of dog were used as tools to evaluate gastric retention properties. Hydration studies were carried out at 37��C. Evaluation of the device containing radio-opaque agents, in dogs for gastric retention was carried out with the help of X-rays. The device was found to stay in the stomach of dogs for at least 10 hours. GRD containing amoxicillin trihydrate caplets were evaluated in a human. The area under the excretion rate curve was found to increase by 30% when compared to without the device. A successful development of a formulation of water insoluble itraconazole, without the use of organic solvents, was achieved with modifications from eutectic mixture techniques. Solubilization of the drug was achieved in polyethylene glycol of higher molecular weight. A series of formulations made by varying the amounts ingredients therein, were evaluated for dissolution profile in comparison with the reference, Sporanox��. Effect of molecular weights of PEG and types of PEG were evaluated for desired drug dissolution. Preliminary study from 6 subjects under the conditions of fasting and fed indicated that bioavailability from the new formulation was increased slightly when compared to the reference. This may be correlated to difference in the rate of in vitro dissolution, where the new formulation has initial faster dissolution. A controlled-release formulation of ketoprofen was also developed using a diffusion-controlled polymer, which was coated onto the drug beads. Release of drugs from such beads is controlled by the thickness of the coat. Thickness of the coat was evaluated by SEM and was correlated to the desired in vitro drug release in comparison to the reference Oruvail��. A three-way cross over study involving the new formulation and two marketed products in 12 subjects under fasting conditions indicated that there was a significant difference between the new product and marketed products, so as to be considered non-bioequivalent. Use of In Vitro-In Vivo Correlations and Convolution- Deconvolution relations predicted desired in vitro drug dissolution in a subsequent modification of the formulation. / Graduation date: 1999

Near IR (NIR) sensitive Au-Au₂S nanoparticles were prepared by mixing HAuCl₄ and Na₂S in aqueous solutions. An anti-tumor drug, cis-platin, was adsorbed onto Au-Au₂S nanoparticle surface via the 11-mercaptoundecanoic acid layers. The results showed that the degree of adsorption of cis-platin onto Au-Au₂S nanoparticles was controlled by the pH value of solution, and the drug release was sensitive to NIR irradiation. The cis-platin loaded Au-Au₂S nanoparticles can be potentially applied as NIR activated drug delivery carrier. / Singapore-MIT Alliance (SMA)

Studies of submillimeter gels composed of covalently cross-linked poly(acrylic acid)-g-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic-PAA) networks are reviewed in light of potential applications of the microgels as drug carriers in oral delivery. The microgels are capable of volumetric transitions in response to environmental stimulae such as pH and temperature. It is shown that the type of Pluronic used in the microgel synthesis changes the structure of the resulting microgels, with the more hydrophobic Pluronic imparting porosity. Microgels based on Pluronic L92 (L92-PAA-EGDMA) possess higher ion-exchange capacity than microgels based on Pluronic F127 (F127-PAA-EGDMA), albeit the former are more hydrophobic. Analogously, more hydrophobic but heterogeneous L92-PAA-EGDMA exhibit superior capacity for equilibrium loading of hydrophobic drugs such as taxol, camptothecin and steroid hormones, as well as higher capacity for weakly basic drugs such as doxorubicin, mitomycin C, and mitoxantrone. / Singapore-MIT Alliance (SMA)

A magnetic target drug delivery system consisting of biodegradable polymeric microspheres (poly D, L-lactic acid) loaded with magnetite nanoparticles (10-100 nm) and anticancer drug (paclitaxel) was studied. The magnetite nanoparticles were synthesized by chemical precipitation. The as-synthesized magnetite nanoparticles were subsequently introduced into a mixture of polymer magnetic polymeric composite particles were investigated and further correlated with the reaction parameters. It was found that the size and characteristics of the polymeric composite particles depended on the viscosity of the polymer solution. Preliminary drug release experiments showed that the loaded drug was released with the degradation of the polymer. The release rates could be enhanced by an oscillating external magnetic field. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D.)--University of Rhode Island, 2006. / Typescript. Includes bibliographical references (leaves 210-235).

An in vivo study with 19 rabbits was completed. Half of the exposed rabbits had a magnetic field placed externally over their right lung. Magnetic resonance images of the lungs were acquired to determine the iron concentrations in the right and left lung of each animal. The right/left ratio increased in the middle and basal regions of the lung. With further optimization, this technique could be an effective method for targeted drug delivery. Additionally, the feasibility of increasing the length of high aspect ratio particles for improved targeted drug delivery was explored. An ultrasonic nozzle was pulsed into a large evaporation chamber. Individual particles were found to be double the original length. However, due to locally increased humidity the droplets were not dried, except with the use of an orifice to rapidly accelerate and break apart the larger droplets. The complications associated with this method make it an undesirable and unfeasible method of creating longer particles.