Recently, the portfolio of compounds approved for inhalation therapy has expanded rapidly for lung disease therapies. The rationale for this delivery approach includes a more targeted and localized delivery to the diseased site with reduced systemic exposure, potentially leading to decreased adverse side effects. We have proposed that brittle matrix powders prepared by thin film freezing (TFF) are a suitable platform for pulmonary drug delivery which can achieve high lung concentrations while limit the corresponding systemic levels associated with toxicity, and enhanced physicochemical and aerodynamic properties can be obtained by varying TFF processing parameters. In Chapter 2, the in vitro and in vivo performance of an amorphous formulation prepared by TFF and a crystalline micronized formulation produced by milling was compared for Tacrolimus (TAC). TFF processed matrix powders was capable of achieving deep lung delivery due to its low density, highly porous and brittle characteristics. When emitted from a Miat® monodose inhaler, TFF processed TAC formulations exhibited a fine particle fraction (FPF) of 83.3% and a mass median aerodynamic diameter (MMAD) of 2.26 µm. Single dose 24-h pharmacokinetic studies in rats demonstrated that the TAC formulation prepared by TFF exhibited higher pulmonary bioavailability with a prolonged retention time in the lung, possibly due to decreased clearance (e.g., macrophage phagocytosis), compared to the micronized TAC formulation. Additionally, TFF formulation generated a lower systemic TAC concentration with smaller variability than the micronized formulation following inhalation, potentially leading to reduced side effects related to the drug in systemic circulation. Chapter 3 investigated the impact of processing parameters in the TFF process on the physicochemical and aerodynamic properties of the resulting formulations. All of these enhanced powder properties resulted from higher freezing rate contributed to a better aerodynamic performance of the obtaining formulations. Moreover, a decreasing trend of FPF was observed for these TFF powders when the initial solid concentrations increased. The variation of the freezing rate and initial solid loading in the TFF process enabled the production of formulations with enhanced physicochemical properties and improved aerodynamic performance. / text

Many vaccines require an adjuvant to induce a strong immune response. Aluminum–containing adjuvants have been approved by the United States Food and Drug Administration for human use for many years. There are two main aluminum-containing adjuvants, aluminum hydroxide and aluminum phosphate. Due to their favorable safety profile, aluminum-containing adjuvants have been widely used in human vaccines for decades. Many currently licensed and commercially available vaccines contain aluminum-containing adjuvants. However, aluminum-containing vaccine adjuvants suffer from two major limiting factors: (1) aluminum-containing adjuvants can only weakly or moderately potentiate antigen-specific antibody responses and are generally considered incapable of inducing cellular immune responses; (2) vaccines that contain aluminum-containing adjuvants require cold-chain refrigeration for storage and distribution, and may not be frozen, because freezing of the vaccine in dispersion causes irreversible coagulation that damages vaccines (e.g., loss in potency and stability). In this dissertation, the first limitation was addressed by reducing the size of the aluminum hydroxide from micrometers (3-10 micrometer) to nanometers of less than 200 nm, and the second limitation mentioned above was addressed by freeze-drying vaccines that contain aluminum salts as adjuvants into a dry powder using thin-film freeze-drying. In addition, using an improved experimental design, the vaccine adjuvant activities of nanoparticles of around 200 nm was compared to that of the nanoparticles of around 700 nm. The smaller 200 nm nanoparticles showed a more potent adjuvant activity than the larger nanoparticles. When dispersed in an aqueous medium, both aluminum hydroxide and aluminum phosphate are physically 1–20 micrometer particulates. There are data showing that particulate vaccine carriers of around 200 nm (or less) may be optimal in potentiating the immunogenicity of vaccines. Based on this finding, aluminum hydroxide nanoparticles of 112 nm were synthesized, and its adjuvant activity was compared to that of the traditional aluminum hydroxide adjuvant, which have particulates of 3-20 micrometer. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, it was found that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced stronger antigen-specific antibody responses than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3 µm. Importantly, the inflammation reactions induced by aluminum hydroxide nanoparticles in the injection sites were milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant in suspension from micrometers into nanometers represents a novel and effective approach to improve its potency. The second limitation was addressed by converting vaccines that contain an aluminum salt as an adjuvant from an aqueous dispersion into a dried powder using thin-film freeze-drying. There is evidence that aluminum-containing vaccines can be lyophilized to dry powders using high speed freezing methods. Thin-film freezing is a high speed freezing method with a freezing rate between 100 to 10,000 K/s, but the feasibility of using thin-film freeze-drying to freeze-dry vaccines that contain aluminum salts as adjuvants has not been tested before. In this dissertation, Using ovalbumin as a model protein antigen and aluminum hydroxide or aluminum phosphate as an adjuvant, it was confirmed that vaccines that are adjuvanted with aluminum hydroxide or aluminum phosphate can be freeze-dried with as low as 2% (w/v) of trehalose as a cryoprotectant by thin-film freeze-drying without causing vaccine aggregation while preserving the immunogenicity of the vaccine. Finally, the feasibility of using the thin-film freeze-drying method to freeze-drying vaccines that contain aluminum salts as adjuvants was further confirmed by drying a commercial aluminum salt-adjuvanted tetanus toxoid vaccine. Vaccines that contain aluminum salts as adjuvants may be converted to a dry powder using the thin-film freeze-drying method to avoid loss of potency due exposure to freezing conditions during transport and storage. / text

It is estimated that 90% of new chemical entities in development pipelines exhibit poor aqueous solubility. For compounds not limited by biological membrane permeability, this poor aqueous solubility is the limiting factor in bioavailability. Therefore, the formulation of such drugs has primarily been centered on improving dissolution properties. Traditional approaches for overcoming poor aqueous solubility include salt formation of the active ingredient, complexation, the use of surface active agents, formulation into oil based systems, particle size reduction, or a combination of these methods. More recently amorphous solid dispersions have been explored. Currently, the drug loading within solid dispersions is limited resulting in large quantities of the formulation being required for a therapeutically relevant dose. In the frame of the work herein, Thin Film Freezing was utilized to generate high drug loaded amorphous solid dispersions of the poorly water soluble drug phenytoin utilizing a hydrophilic polymer or an amphiphilic graft copolymer for system stabilization. Additionally a new solvent removal technique, atmospheric freeze drying, was investigated for removal of the solvents used during Thin Film Freezing. The Thin Film Freezing materials were subsequently incorporated into a polymeric carrier for solid dispersion formulation by a novel fusion production technique termed Kinetisol® dispersing. Studies of the solid dispersions produced by Thin Film Freezing revealed an amorphous system had been obtained for both stabilizing polymers. The formulation containing a hydrophilic carrier was capable of achieving supersaturation. Conversely, the amphiphilic graft copolymer demonstrated a phenytoin-polymer interaction resulting in poor dissolution. Atmospheric freeze drying of the Thin Film Freezing product demonstrated that the alternative drying technique generated powders with significantly improved handling properties as a result of reduced electrostatic interactions due to the increased pore size, reduced surface area, larger particle size, and higher, though acceptable, residual solvent levels. The use of Thin Film Freezing powders during Kinetisol Dispersing resulted in a single phase amorphous system while solid dispersions produced from physical mixtures of bulk materials were amorphous two-phase systems. This indicates that the use of amorphous drug compositions during solid dispersion production may increase drug loading in the final system while remaining single phase in nature. / text

Advancements in pulmonary drug delivery technologies have improved the use of dry powder inhalation therapy to treat respiratory and systemic diseases. Despite remarkable improvements in the development of dry powder inhaler devices (DPIs) and formulations in the last few years, an optimized DPI system has yet to be developed. In this work, we hypothesize that Thin Film Freezing (TFF) is a suitable technology to improve inhalation therapies to treat lung and systemic malignancies due to its ability to produce brittle powder with optimal aerodynamic properties. Also, we developed a performance verification test (PVT) for the Next Generation Cascade Impactor (NGI), which is one of the most important in vitro characterization methods to test inhalation. In the first study, we used TFF technology to produce amorphous and brittle particles of rapamycin, and compared the in vivo behavior by the pharmacokinetic profiles, to its crystalline counterpart when delivered to the lungs of rats via inhalation. It was found that TFF rapamycin presented higher in vivo systemic bioavailability than the crystalline formulation. Subsequently, we investigated the use of TFF technology to produce triple fixed dose therapy using formoterol fumarate, tiotropium bromide and budesonide as therapeutic drugs. We investigated applications of this technology to powder properties and in vitro aerosol performance with respect to single and combination therapy. As a result, the brittle TFF powders presented superior properties than the physical mixture of micronized crystalline powders, such as excellent particle distribution homogeneity after in vitro aerosolization. Lastly, we developed a PVT for the NGI that may be applicable to other cascade impactors, by investigating the use of a standardized pressurized metered dose inhaler (pMDI) with the NGI. Two standardized formulations were developed. Formulations were analyzed for repeatability and robustness, and found not to demonstrate significant differences in plate deposition using a single NGI apparatus. Variable conditions were introduced to the NGI to mimic operator and equipment failure. Introduction of the variable conditions to the NGI was found to significantly adjust the deposition patterns of the standardized formulations, suggesting that their use as a PVT could be useful and that further investigation is warranted. / text