Thesis (M. Pharm.)--University of the Witwatersrand, Faculty of Health Sciences, 2013. / Ocular diseases of the anterior segment are ubiquitous, especially among elderly patients. The development of novel drug delivery systems on the journey for improved treatment is therefore imperative. Aside from anatomical and physiological barriers of the eye, the actual dosage form plays a crucial role. Although liquid eye drops are the first-choice dosage form, the shortcomings do not go unnoticed. In an attempt to circumvent these drawbacks, a novel instantly soluble eye drop device was developed. The system aimed to provide an easier administration form, comfort for the patient and improve drug bioavailability to anterior chamber. This was a steer toward attaining patient-convenience and compliance which are critically challenging factors. Preformulatory studies allowed for the screening and selection of candidate components and key processing conditions. Hydrophilic polymers and excipients were selected for attainment of small, rapid disintegrating yet robust matrices via lyophilization of solutions. Design of experiments generated formulations by means of a Face centred central composite design (FCCCD) that underwent thorough physicochemical and mechanical assessment. Overall, robust rapidly disintegrating solid eye drops were produced. Fastest disintegration time was noted to be 0.200s. Drug content ranged from 79-96%. An improved permeation of formulations compared to a pure drug dispersion was seen. Mathematical modeling was conducted for better insight into the behavior of the device on the eye surface. Statistical analysis through constraint optimization yielded a single optimal formulation. Thermal and molecular transition analysis showed congruent findings with no incompatibility between components. Combinatory surface morphology and porositometric studies confirmed the presence of interconnecting pores across the matrix surface. Drug release kinetic evaluation predicted that best model fit was first-order release. Ocular irritancy studies by means of the HET-CAM test indicated that both drug-loaded and drug-free eye drops had an irritation score of 0 with the inference of good tolerability. Ex vivo permeation across excised rabbit cornea showed an improved steady state drug flux (0.00052mg.cm-2.min-1) and permeability co-efficient (1.7x10-4cm.min-1) for the optimized device compared to pure drug and a marketed eye drop preparation. In vivo analysis was conducted on the rabbit model with insertion of the device into the ocular cul-de-sac. Subsequently, ultra performance liquid chromatography (UPLC) analysis of the aspirated aqueous humour for model drug timolol maleate detection was conducted. The device demonstrated improved drug levels (Cmax = 3ug/mL) in comparison to commercial eye drops (Cmax = 1.97ug/mL) and was well tolerated. Level A point-to-point IVIVC plots indicated a R2 value of 0.84. This served to imply that the in vitro dissolution data can be compared to and may serve as a surrogate to that of in vivo pK data. Histopathological assessment on the enucleated eye ball confirmed the lack of noxious effects of the device on ocular tissue. From this study, the solid eye drop device was concluded to be safe as a drug delivery system for the anterior eye. Looking toward innovative trends and modifications, a bi-layered solid eye drop system with enhanced permeability capabilities employing low molecular weight chitosan was further fabricated for preliminary investigation.

A novel methacrylate based nanogel system has been designed and developed for drug delivery applications. Methacrylates are optimal tuneable materials in terms of polarity, with combination of hydrophobic and hydrophilic moieties. Synthesis of these nanogels (NGs) was achieved via high dilution radical polymerisation using 2-(tert-butylamino)ethyl methacrylate (tBAEMA) as functional monomer, methacrylic acid (MAA) or ethylene glycol methyl ether methacrylate (EGMMA) as co-monomer and N,N'-methylenebis(acrylamide) (MBA) as cross-linker. Fabricated nanoparticles (NPs) were shown to possess water solubility higher than 2 mg/mL and diameter ranging from 5 to 20 nm (depending on nanogels' composition) as confirmed by either dynamic light scattering (DLS) and transmission electron microscopy (TEM). Moreover, nanogels produced have shown the ability to be employed as Pickering-Ramsden emulsion stabiliser. Their reduced size together with their emulsion capabilities make these nanoparticles a promising system for drug delivery, in particular taking into account skin as administration route. The size is in fact small enough to favour their penetration through the stratum corneum. Furthermore, in the view of their ability to form emulsions, nanogels could be used both as drug carrier and emulsifier in a final pharmaceutical formulation. NGs proved to be able to incorporate both small molecule such as fenoprofen (an anti-inflammatory non-steroidal drug) and big macromolecule such as siRNA. Cytotoxicity and cell metabolism were also evaluated by transfecting normal human dermal fibroblasts (NHDF), keratinocytes (HaCaT) and HeLa cells with nanogels. Data showed that nanoparticles did not affect viability, cells' morphology and adenosine triphosphate (ATP) levels up to high concentration of 100 μg/mL. In addition, preliminary studies indicated the ability of the nanogels to internalise and release their payload inside cells. In conclusion, the results confirmed that this novel system possesses all the desired characteristics to be used as a promising platform for drug delivery.

Conotoxins are peptides expressed by the exogenome of more than 800 species of marine mollusks belonging to the genus Conus (cone snails.) Owing to their high specificity and affinity for ion channels, transporter molecules, and cell receptors of the central and peripheral nervous systems, conotoxins have been investigated for nearly four decades. These efforts on conotoxin research made possible the FDA approved use of Ziconitide/Prialt, a conotoxin derived from the venom of Conus magus, which effectively treats patients suffering from severe chronic pain without consequent narcotic effects. Additionally, six other conotoxins have reached clinical trials and many novel ones are being discovered every day. Investigations reported in this dissertation broadens the applicability of conotoxins to non-excitable systems. Here, conotoxins from the dissected venom of the vermivorous cone snail Conus nux were isolated and purified by size exclusion and reverse phase HPLC and characterized by MALDI-TOF and MS/MS spectrometry. The purified conopeptide fractions revealed: 1) antagonist activity of conotoxin NuxVID on two human voltage-gated sodium channels, displaying capabilities as a practical molecular probe and a potential therapeutic lead. 2) Ability for two novel conotoxins to traverse artificial biological membranes, suggesting their potential as drug delivery systems. 3) In vitro capacity of several novel conopeptides to interfere with the adhesion of PfEMP1 domains, expressed in P. falciparum infected erythrocytes, to vascular endothelial and placenta receptors. Lastly, this work reveals binding of the synthetic form of α-conotoxin ImI, from the vermivorous cone snail Conus imperialis, to the α7 nAChR of macrophage-like-cells derived from the pre-monocytic leukemic cell line THP-1 in support of the involvement of this receptor in the cholinergic anti-inflammatory pathway. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

archives@tulane.edu / Transpapillary drug delivery is a novel drug administration technique that integrates the non-invasive, passive aspect of transdermal drug delivery with the targeted approach of intraductal drug delivery by capitalizing on the mammary ducts to serve as an entry point, conduit and reservoir. Although these channels have been identified as a primary transport route, their contribution to overall tissue penetration has not been quantified. By combining two fluorescence techniques, we were able to quantitatively assess the various transport routes of small molecules and drug delivery vehicles following in vitro diffusion. Analysis of fluorescent images of porcine nipple cross-sections following diffusion of model hydrophilic and lipophilic fluorescent dyes indicated that both molecules penetrated the nipple via the stratum corneum and mammary ducts, however the lipophilic molecule targeted the ducts more so than the hydrophilic molecule. Encapsulating either dye within a liposome enhanced the ductal-associated fluorescence and reduced (hydrophilic dye) or did not affect (lipophilic dye) the stratum corneum-associated fluorescence. This suggests the capability of liposomes to selectively target and improve diffusion within the ductal channels. Encapsulation of the lipophilic dye within an oil-in-water nanoemulsion, however, either substantially increased penetration via both routes or only moderately improved transductal penetration, depending on the specific formulation. The in vivo distribution and efficacy of transpapillary diffusion was evaluated by first establishing an intraductal estrogen receptor positive breast cancer model. Results from in vivo imaging elucidated two growth rates, either slow or fast, which were discernable 14 days post-injection. A pilot therapeutic efficacy study using 4-hydroxytamoxifen was then performed; however due to a small sample size, the results were inconclusive. In vivo transpapillary diffusion of a small, lipophilic molecule was confirmed, as illustrated following application of a fluorescent dye. We conclude that transpapillary drug delivery is a viable in vitro administration technique for which the penetration routes can be tailored with drug carriers on a formulation-dependent basis. Furthermore, the feasibility of intraductally establishing estrogen receptor positive lesions and tracking their growth using in vivo imaging was validated. However, the use of this model to assess in vivo efficacy of transpapillary diffusion merits further evaluation. / 1 / Samantha Kurtz

The isoenzyme heme oxygenase 1 (HO-1) is a key element for maintaining cellular homeostasis. Upregulated in response to cellular stress, the HO-1 degrades heme into carbon monoxide (CO), biliverdin, and Fe2+. By means of a local cell-protective feedback loop the enzyme triggers numerous effects including anti-oxidative, anti-apoptotic, and anti-inflammatory events associated with complex signalling patterns which are largely orchestrated by CO. Various approaches to mimic this physiological HO-1 / CO system aiming for a treatment of medical conditions have been described [1]. These preclinical studies commonly applied CO systemically via (i) inhalation or (ii) using CO-Releasing Molecules (CORMs) [2]. The clinical use of these approaches, however, is challenged by a lack of practicability and substantial safety issues associated with the toxicity of high systemic doses of CO that are required for triggering therapeutic effects. Therefore, one rational of this thesis is to describe and evaluate strategies for the local delivery of CO aiming for safe and effective CO therapeutics of tomorrow. / Das Isoenzym Hämoxygenase 1 (HO-1) ist ein zentraler Bestandteil in der Aufrechterhaltung der zellulären Homöostase. Es wird durch zellulären Stress induziert und baut daraufhin Häm zu Kohlenstoffmonoxid (CO), Biliverdin und Fe2+ ab. Im Sinne eines lokalen Rückkopplungsmechanismus stößt es damit eine Vielzahl physiologischer Mechanismen mit anti-oxidativen, anti-apoptotischen und anti-inflammatorischen Effekten an, welche zumeist durch CO reguliert und durch ein komplexes Netzwerk aus Signaltransduktionsprozessen vermittelt werden. Es wurden zahlreiche Versuche unternommen, diesen als HO-1 / CO System bezeichneten Mechanismus nachzuahmen, um dadurch eine Behandlung von verschiedenen Krankheitszuständen zu ermöglichen. In diesen präklinischen Studien wurde CO regelmäßig systemisch (i) per Inhalation oder (ii) in Form von CO freisetzenden Verbindungen (CO-Releasing Molecules - CORM) verabreicht . Die klinische Anwendung dieser Strategien ist jedoch durch Sicherheitsrisiken erheblich erschwert, insbesondere durch die Toxizität der notwendigen hohen systemischen Dosen von CO. Entsprechend beschäftigt sich diese Dissertation unter anderem mit der Beschreibung und Evaluation von Strategien zur lokalen Verabreichung von CO, mit dem Ziel sichere und effektive Konzepte zu dessen Anwendung zu entwickeln.

Delivery of complex molecules such as peptides, proteins, oligonucleotides and plasmids is an intensively studied subject, which has attracted considerable medical and pharmaceutical interest. Encapsulation of these molecules with biodegradable polymers represents one way of overcoming various problems associated with the conventional delivery of macromolecules, for example instability and short biological half-life. The use of carriers made of hydrophilic polysaccharides such as chitosan, has been pursued as a promising alternative for improving the transport of biologically active macromolecules across biological surfaces. The development of nanoparticles as a delivery system also has major advantages of achieving possible drug protection, controlled release and drug targeting by either a passive or an active means. The aim of this study was to develop a simple and effective method to formulate biodegradable nanoparticles for the delivery of a model protein-bovine serum albumin (BSA) and an angiogenesis inhibitor, arginine-rich hexapeptide (ARE peptide). Major factors which determine nanoparticle formation and loading of the protein and the peptide as well as the underlying mechanisms controlling their incorporation and release characteristics were investigated. The preparation technique, based on the complex coacervation process, is extremely mild and involves the mixture of two aqueous solutions (chitosan and dextran sulfate) at room temperature. The formation of nanoparticles is dependent on the concentrations of chitosan (CS) and dextran sulfate (DS); particles with size, of 257 to 494nm can be obtained with 0.1%w/v solutions of CS and DS. Zeta potential of nanoparicles can be modulated conveniently from -34.3mV to +52.7mV by varying the composition of the two ionic polymers. / Both bovine BSA and the ARH peptide were successfully incorporated into CS-based nanoparticles, mainly via an electrostatic interaction, with entrapment efficiency up to 100% and 75.9% for the protein and peptide respectively. Incorporation of both the protein and peptide into nanoparticles resulted in an increase in size suggesting their close association with the nanoparticle matrix material. The difference in sign and magnitude of zeta potential of empty and macromolecules-loaded nanoparticles supports the hypothesis that protein and peptide association with nanoparticles can be modulated by their ionic interaction with the oppositely charged ionic polymer (DS) in the nanoparticles. The release of BSA from the nanoparticles was very slow in water compared to that in l0mM phosphate buffer pH 7.4; whereas, ARH peptide showed extremely low level of release in water at the low ratio of DS but at the high ratio of DS, its release was in biphasic fashion, with an initial burst effect followed by an almost constant but very slow release up to 7 days in both water and 1 OmM phosphate buffer (pH 7.4). It was found that, unlike ARH peptide, the percentage of BSA released was relatively slower for the nanoparticles with a high ratio of DS. It is speculated that this difference in the release behaviour of BSA and ARH peptide, could be due to the effect of molecular size of the compounds and their interaction with the polymer matrix of the nanoparticle. The results of this study suggest that these novel CS/DS nanoparticulate system, prepared by a very mild ionic crosslinking technique, have potential to be a suitable carrier for the entrapment and controlled release of peptides and proteins.

Purpose: The aim of this thesis was to investigate a novel method of preparing crosslinked alginate matrices. Current methods use large quantities of water and hence are not suitable for large scale manufacturing of drug alginate particulate systems. Moreover, the current processes offer little scope for control of the crosslinking process. The aim was to overcome these problems through studies of paracetamol alginate granular matrices prepared by the novel method and to explore if these granules could be used to improve the taste of paracetamol. Methods: The novel method involves preparation of dried drug alginate granules (moisture content: <5-6 %) using conventional granulation followed by crosslinking treatment of the dried granules with calcium chloride or a combination of calcium and magnesium ion solution in a crosslinking bath. The effect of the process (shear rate, binder quantity) to prepare untreated granules, composition of the raw materials (drug particle size and type of alginate) and subsequently the crosslinking treatment process variables (Ca�⁺ ion concentration, agitation rate, time and temperature of Ca�⁺ solution) on the physicochemical properties of granule systems were studied using factorial designs together with supporting studies. The granules were characterized using sodium and calcium content analysis, drug release studies (mainly sub-60s release) matrix swelling rate and equilibrium swelling studies, tensile strength studies, ion permeation studies, SEM and X Ray analysis and gravimetric studies. Sensory studies correlating sub-60 s drug release (determined using a specially designed apparatus) and human taste scores (measured using an analogue scale) were then undertaken. Selected formulations were evaluated for taste improvement and to determine if mucoadhesion led to an increased unpalatability of paracetamol. Results: Of the crosslinking treatment factors, the calcium concentration had the greatest effect on crosslinked granules. Although other treatment factors also affected the granule properties, alteration of the salt concentration allowed considerable control over the crosslinking process (not possible in the conventional method) in addition to providing a mechanistic understanding of the crosslinking process in the dried state. The use of low calcium concentrations (< 20 mg/ml, CaCl₂. 2H₂O) during treatment led to granule erosion (hence drug loss) due to overall incomplete crosslinking but led to a reduction in the short-term drug release compared to the granules treated with intermediate (100- 250 mg/ml) or high calcium concentrations (>400 mg/ml) due to reduction in the granule porosity after crosslinking. Although intermediate calcium concentrations led to complete crosslinking and longer release times (T 85 %: 25 min) high calcium crosslinking restricted the crosslinking to the surface of the granules leading to faster drug release (T 85 %: 8 min) with low calcium granules showing intermediate crosslinking and drug release rates (T 85 %: 18 min). High calcium treatment limited drug loss during crosslinking (95 % recovered compared to 83 % recovery at intermediate calcium concentration) without affecting the short-term drug release much. Low calcium granules showed the lowest drug recovery (< 70 %) and slowest sub-60s drug release followed closely by intermediate and high calcium treated granules. The granule preparation factors (shear rate, binder quantity) and type of alginate used, considerably affected the sub-60s drug release by affecting surface porosity especially when a low shear rate was used. However, these factors only slightly reduced the drug loss during crosslinking treatment phase (about 4 % increase in drug recovery). Smaller drug particle size had a slightly larger incremental effect on drug recovery (about 8 % increase in the drug recovery) during crosslinking treatment due to better embedding of the drug particles inside the untreated granule matrix. This was true as long as the particle size of the drug was > 98 [mu]m. Below this size drug recovery remained unaffected by changes in drug particle size. Although granule surface porosity considerably affected the sub-60s drug release, its effect on drug release (long-term) was much less. A linear correlation was observed between the sub-60s drug release and sensory scores despite high individual variability. Both granule formulations evaluated showed taste improvement and mucoadhesion did not lead to an increase in the bitter taste of the uncrosslinked paracetamol alginate granules. Conclusions: Unlike the traditional method, the new technique of preparation of crosslinked drug alginate particulate systems uses very little water and allows greater control over the the crosslinking process compared to the swollen state crosslinking. The novel process of preparation is versatile, and should be scalable. It offers the formulator a platform to prepare a matrix, reservoir or a combination of these two systems using alginates and other drugs and polymers as well. Adequate short-term control over paracetamol release, very little loss of paracetamol during treatment (< 5 % loss), reduction in mucoadhesion of the granules and lastly improvement of the taste of paracetamol is possible using alginate based systems especially if high calcium is used during the crosslinking treatment. Hence, it is likely that these taste-improved granules could be used to prepare tablets without the need for a protective film coating to improve taste. Finally, this research established the utility of short-term drug release in taste improvement research and characterization of solid controlled release dosage forms.

A novel reverse microemulsion (RM) mediated synthesis of glucose-responsive nanoparticles was developed for controlled insulin delivery. Nanoparticles were constructed using a model system comprised of dextran, poly(α-1,6 glucose), physically crosslinked with the tetrafunctional glucose-binding protein, Con A. A rapid-screening technique was used to quantify RM phase behavior in the presence of dextran, Con A and insulin. The extent of the RM existence region diminishes with increasing dextran and Con A concentrations and with increasing dextran molecular weight. Crosslinking efficiency between Con A and fluorescein isothiocyanate dextran (FITC-Dex) was found to depend on the total concentration of Con A as well as the ratio of Con A to FITC-Dex. Functionalizing dextran with higher affinity mannose ligands and increasing dextran molecular weight both improved crosslinking efficiency. The nanoparticles dissolved when dispersed in buffered saline solutions containing elevated glucose concentrations and were most responsive within the physiological range. Finally, insulin was encapsulated in select formulations and found to release preferentially at these elevated glucose concentrations. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2006. / "May, 2006." Title from electronic dissertation title page (viewed 10/11/2006). Advisor, Daniel J. Smith; Committee members, Michael J. Taschner, Wiley J. Youngs, Kim C. Calvo, Darrell H. Reneker; Department Chair, Michael J. Taschner; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.