The influence of polymer excipients on the dissolution and recrystallization behavior of ketoconazole: Application, variation and practical aspects of a pH shift method

The formulation of amorphous solid dispersions (ASDs) is an effective way to improve the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). The combination of an amorphous state of the drug and the presence of crystallization-inhibiting polymers retains a high amount of dissolved API over time. ASDs with ketoconazole and different polymers were manufactured by spray drying and their characteristics as well as performance were analyzed. Dissolution tests with a change of the dissolution medium from 0.1 M HCl to phosphate buffer at pH 6.8 to simulate pH conditions for instant release formulations, and a direct dissolution of the ASDs in phosphate buffer pH 6.8 to simulate conditions for an enteric formulation, were performed. All ASDs with API contents between 25 and 50% by weight were completely X-ray amorphous. Varying dissolution behaviors between medium change and direct dissolution occurred. It was possible to identify the superior ASD-compositions for both types of tests. The acidic polymers methacrylic acid-ethyl acrylate copolymer, hypromellose acetate succinate and the solubilizer macrogolglycerol hydroxystearate showed the best performances. The combination of the acidic polymers with macrogolglycerol hydroxystearate showed an improved dissolution behavior at higher API contents. The optimization of such formulations with different release-patterns plays an important role for the enhancement of the oral bioavailability of poorly water-soluble drugs

Needle-free vaccination: formulation and dermal delivery of diphtheria toxin CRM197 mutant

The unsafe use of needles propagates cross infections with bloodborne pathogens and reduces the positive impact of vaccinations on global health. While a plethora of needle-free injection devices exist, the reformulation of protein-based vaccines is largely empirical and costly, which presents a barrier to their widespread clinical application. This thesis contributes to the identification of approaches that facilitate rapid vaccine reformulation and enhance the immunogenicity of needle-free dry-powder vaccines with the help of novel antigen delivery platforms. We hypothesised that the thermodynamic stabilisation of diphtheria toxin mutant 197 (CRM197), a glycoconjugate vaccine carrier protein, may enhance its structural preservation during spray-freeze-drying (SFD), and that its formulation in either soluble, surface-adsorbed, or nanoparticle form impacts the elicited immune response. Differential scanning fluorimetry was used to study the effect of excipients on the thermal stability of CRM197. Dry-powder formulation of CRM197 used i) encapsulation into a thermodynamically stabilising excipient matrix by SFD, ii) surface-immobilisation via physisorption onto a novel potassium-doped hydroxyapatite (kHA) carrier microparticle formed by molten salt synthesis, and iii) chemical conjugation and surface presentation on amphiphilic block copolymer nanoparticles that were incorporated into SFD-powders (SFD-NP). The structural integrity of CRM197 was assessed by size separation in addition to various spectral and thermal analysis methods. The immunogenicity of dry-powder CRM197 formulations was subsequently tested in vivo. The results suggest that the thermodynamic stability of CRM197 in solution does not ensure its structural stability during SFD. While needle-free dermal vaccination with kHA-adsorbed CRM197 induced comparable antibody titres to conventional IM injection of alum-adjuvanted CRM197, needle-free SFD and SFD-NP powders were less immunogenic. The highest mean IgG titre and most balanced Th1/Th2 response was achieved with nanoparticle-conjugated CRM197 by IM, which outperformed the current clinical standard. Therefore, future vaccine design should combine thermodynamic and kinetic stability screening, and place special emphasis on the delivery and structural presentation of the antigen to the immune system.This thesis is not currently available in ORA

Spray freeze dry process for MenY-CRM₁₉₇ powders.

<p>The spray freeze drying set-up used a 48 kHz ultrasound nozzle to atomise the 35% wt. TMDD (3:3:3:1) excipient solution containing 0.5% wt. MenY-CRM₁₉₇, at 3.2W power and a 0.5mL/min flow rate. Particles were shock-frozen into liquid nitrogen and transferred into a pre-equilibrated LyoStar I and lyophilized. The product was filled into injector device powder cassettes, and stored at -80°C until use.</p

Semi-quantitative size analysis of MenY-CRM₁₉₇ by SDS-PAGE.

<p>Semi-quantitative size analysis of MenY-CRM₁₉₇ by SDS-PAGE.</p

Chemico-physical integrity of MenY-CRM₁₉₇ assessment by SDS-PAGE.

<p>SDS-PAGE used precast 4–20% Precise Tris-Glycine gels and the PrecisionPlus Protein Dual-colour protein standard. Samples were applied to the 15-well gel in every other lane. Control lanes were loaded with CRM₁₉₇ stock protein (2.0 ng), 35% (w/w) TMDD matrix without MenY-CRM₁₉₇ (10 μg), untreated MenY-CRM₁₉₇ stock (12 ng), and resuspended SFD MenY-CRM₁₉₇ (12 ng) SFD powder.</p

Serum bactericidal antibody responses to MenY-CRM₁₉₇ administered IM, ID or by needle free powder injector.

<p>hSBA end-point titres in Balb/c mice were measured after two 5μg doses of MenY-CRM₁₉₇ delivered either ID, IM or by needle free powder injector (NDPI). ID and IM vaccinations were performed with or without Alum indicated in the axis. The geometric means for each group are indicated by bars. The limit of detection is indicated by the dashed line. n = five or 6 per group. * = P < 0.05 by Kruskal-Wallis with Dunns post-test compared with Naïve group. SBA titres below 1:4 were designated an arbitrary value of 1.</p