ABSTRACT
Lipid nanoparticles (LNPs) are increasingly finding applications in targeted drug delivery, including for subcutaneous, intravenous, inhalation, and vaccine administration. While a variety of microscopy techniques are widely used for LNP characterization, their resolution does not allow for characterization of the spatial organization of different components, such as the excipients, targeting agents, or even the active ingredient. Herein, an approach is presented to probe the spatial organization of individual constituent groups of LNPs used for siRNA-based drug delivery, currently in clinical trials, by multinuclear solid-state magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectroscopy. Dynamic nuclear polarization is exploited (DNP) for sensitivity enhancement, together with judicious 2H labeing, to detect functionally important LNP constituents, the siRNA and the targeting agent (<1-2 w/v%), respectively, and achieve a structural model of the LNP locating the siRNA in the core, the targeting agent below the surface, and the sugars above the lipid bilayer at the surface. The integrated approach presented here is applicable for structural analysis of LNPs and can be extended more generally to other multi-component biological formulations.
ABSTRACT
The sterile barrier is one of the most important aspects of the container closure integrity (CCI) for a prefilled syringe (PFS or syringe). This crucial barrier enables the protection of the syringe contents from contamination. The plunger stopper (stopper) is naturally in a stationary position that is controlled by the static friction between the plunger stopper and the syringe barrel wall. When an applied force is greater than the static friction, which is commonly known as the break-loose force, the plunger stopper will move. In such conditions, the stopper movement can further be increased if an air bubble (AB) is introduced between the liquid fill in the syringe and the stopper during the stoppering process. This additional movement can occur when the pressure differential between the gaseous headspace inside the syringe and the external atmosphere is large enough that the force exerted on the stopper exceeds the break-loose force of the syringe. This can occur during altitude or temperature changes incurred during aerial or mountainous transport. This article, therefore, discusses the relationship between stopper movement and initial headspace (air bubble size/ABS) in a 2.25 mL Type I glass syringe using theoretical and empirical approaches. The results showed the maximum initial headspace needed to enable CCI at specified altitudes and plunger stopper movements for the syringe-plunger stopper combination used in the study. Empirical data also indicated that CCI can be maintained for this syringe-plunger stopper combination with up to 9.0 mm initial headspace at altitudes up to 17,000 feet.
Subject(s)
Drug Packaging , Syringes , Drug Packaging/methods , Drug Contamination/prevention & controlABSTRACT
PURPOSE: To enable aggregation rate prediction over a broad temperature range for complex multi-domain proteins at high concentrations. METHODS: Thermal unfolding, non-isothermal kinetics and storage stability studies were conducted on a model multi-domain protein (MDP) at moderate to high concentrations (25-125 mg/mL) over a broad temperature range (4-40°C). RESULTS: Storage stability studies indicated the aggregation of MDP in solution to be a second order process. Application of Arrhenius kinetics to accelerated stability data resulted in underestimation of the aggregation rate under refrigerated conditions. Additional studies undertaken to understand the mechanism of the aggregation process highlighted the association of the monomer (or the aggregation competent species) to be the rate-limiting step for aggregation over the temperature range studied. Thermal unfolding studies in the presence of urea were used to calculate the heat capacity change upon unfolding (Δcp,un). The resulting value of Δcp,un when used in the extended Lumry-Eyring model resulted in a more accurate and a conservative estimate of the aggregation rate under refrigerated condition. Some complicating factors for the aggregation rate prediction for multi-domain proteins at high concentration are discussed. CONCLUSIONS: The work highlights (i) the significance of incorporating unfolding thermodynamics in protein aggregation rate prediction, (ii) the advantages and challenges associated with the use of the extended Lumry-Eyring (ELE) model for rate prediction and (iii) the utility of using the Arrhenius and the ELE models in tandem during product development.