The importance of formulation in the successful lyophilization of influenza reference materials

Process and isothermal storage stabilities of a live veterinary vaccine formulated with Plectranthus esculentus tuber starch derivatives as stabilizers

Comparability stability studies of a live Newcastle Disease LaSota vaccine were conducted post freeze-drying and during storage at 5±2, 25±2 and 37±1 °C to demonstrate the equivalence/inequivalence of stability profiles of vaccines stabilized with peptone (reference), trehalose and starch derivatives (acetylated xerogel and carboxymethylated) from Plectranthus esculentus tubers. Variations in moisture content during storage at 5±2 °C; physical collapse/shrinkage, partial microcollapse, and hydrophilicity of lyophilisates were prominent in starch stabilized vaccines without additives. Using the mean embryo infective dose (EID50) test, the derivatives and peptone stabilized vaccines had < 0.5 logEID50 loss in titre during freeze-drying. At the storage temperatures of 5±2, 25±2 and 37±1 °C, using peptone, acetylated xerogel starch, carboxymethylated starch, and trehalose, the average shelf lives of the vaccines were 23-55, 21-26, and 2.6-4.9 months respectively. Acetylated xerogel and carboxymethylated derivatives of Plectranthus esculentus tuber starch with/without additives were able to keep the live ND LaSota vaccine stable during freeze-drying at 1-3 % w/v. The stability of all the vaccines declined as storage temperatures increased. The acetylated xerogel stabilized vaccines were more stable than all of the others at 25±2 and 37±1 °C temperatures.

Impact of nanocarrier aggregation on EPR-mediated tumor targeting

The aim of this study was to investigate the influence of excipients on retaining the particle size of methotrexate (MTX) loaded chitosan nanocarriers (CsNP) during lyophilization, which relates to the ability to enlarge the particle size and target specific areas. The nanocarriers were prepared using the ionic gelation technique with tripolyphosphate as a crosslinker. Three lyophilized formulations were used: nanosuspension without Lyoprotectant (NF), with mannitol (NFM), and with sucrose (NFS). The lyophilized powder intended for injection (PI) was examined to assess changes in particle size, product integrity, and comparative biodistribution studies to evaluate targeting ability. After lyophilization, NFS was excluded from in-vivo studies due to the product melt-back phenomenon. The particle size of the NF lyophile significantly increased from 176 nm to 261 nm. In contrast, NFM restricted the nanocarrier size to 194 nm and exhibited excellent cake properties. FTIR, XRD, and SEM analysis revealed the transformation of mannitol into a stable β, δ polymorphic form. Biodistribution studies showed that the nanocarriers significantly increased MTX accumulation in tumor tissue (NF = 2.04 ± 0.27; NFM = 2.73 ± 0.19) compared to the marketed PI (1.45 ± 0.25 μg), but this effect was highly dependent on the particle size. Incorporating mannitol yielded positive results in restricting particle size and favoring successful tumor targeting. This study demonstrates the potential of chitosan nanocarriers as promising candidates for targeted tumor drug delivery and cancer treatment.

Impact of Formulation Choices on the Freeze-Drying of an Interleukin-6 Reference Material

Formulation is critical to successful delivery of lyophilized biologics. We have compared the impact of buffer choice and the addition of sodium chloride (a formulant often viewed as unfavorable for freeze-drying applications) on the outcome of trial lyophilization of an interleukin-6 reference material. While phosphate buffer was a preferred choice and yielded well-formed cakes associated with fair recovery of biological activity, the resultant residual moisture content was high (2–4% w/w). By inclusion of isotonic levels of NaCl, the freeze-dried appearance and process were not impaired, but the residual moisture delivered was considerably reduced to levels <1% w/w. We postulate that this is due to the presence of a more open-cake structure and support this with evidence from thermal analysis and scanning electron microscopy. This work illustrates the importance of wide ranging empirical investigation of formulation options in order to optimize freeze-drying outcomes for biologics.

Effects of Autoclaving and Freeze-Drying on Physicochemical Properties of Plectranthus esculentus Starch Derivatives

The goal of this research was to assess the effects of autoclaving followed by freeze-drying on acetylated xerogel (AXS) and carboxymethylated (CMS) derivatives of Plectranthus esculentus starch as potential vaccine stabilizers. Starch extracted from tubers of P. esculentus were modified by single (carboxymethylation) and dual (acetylation followed by xerogel formation) methods. The derivatives were formulated into vaccine stabilizer suspensions, autoclaved, and freeze-dried without additives or antigen. The derivatives and freeze-dried products were assessed by physical appearance, titration, moisture content (MC), TGA, DSC, XRD, SEM, and FTIR analyses. The degrees of substitution (DS) of the CMS and AXS derivatives were 0.345 and 0.033, respectively. Modification significantly reduced the MC of the derivatives. Freeze-dried AXS (FAXS) had lower MC than freeze-dried CMS (FCMS). The lower degree of hydrophilicity/MC of AXS and FAXS was confirmed by TGA and FTIR band intensities and shifts. Reduction in DSC water desorption/evaporation enthalpies (ΔH) from - 1168.8 mJ (NaS) to - 407.48 mJ (AXS) confirmed the influence of modification on moisture. FTIR confirmed acetylation and carboxymethylation of the derivatives by the presence of 1702.9 cm^-1 and 1593 cm^-1 bands, respectively (FTIR). Increasing concentrations of the derivatives yielded uncollapsed/unshrunken lyophilisates. SEM and XRD showed that modification, autoclaving, and freeze-drying yielded beehive-like microstructures of FCMS and FAXS that were completely amorphous. Processing (autoclaving and freeze-drying), therefore, enhanced the amorphousness of the starch derivatives which is required in vaccine stability during processing and storage. These findings indicate that these starch derivatives have potential as novel vaccine stabilizers.

Analytical Techniques for Structural Characterization of Proteins in Solid Pharmaceutical Forms: An Overview

Therapeutic proteins as biopharmaceuticals have emerged as a very important class of drugs for the treatment of many diseases. However, they are less stable compared to conventional pharmaceuticals. Their long-term stability in solid forms, which is critical for product performance, depends heavily on the retention of the native protein structure during the lyophilization (freeze-drying) process and, thereafter, in the solid state. Indeed, the biological function of proteins is directly related to the tertiary and secondary structure. Besides physical stability and biological activity, conformational stability (three-dimensional structure) is another important aspect when dealing with protein pharmaceuticals. Moreover, denaturation as loss of higher order structure is often a precursor to aggregation or chemical instability. Careful study of the physical and chemical properties of proteins in the dried state is therefore critical during biopharmaceutical drug development to deliver a final drug product with built-in quality that is safe, high-quality, efficient, and affordable for patients. This review provides an overview of common analytical techniques suitable for characterizing pharmaceutical protein powders, providing structural, and conformational information, as well as insights into dynamics. Such information can be very useful in formulation development, where selecting the best formulation for the drug can be quite a challenge.

Application of Magnetic Resonance to Assess Lyophilized Drug Product Reconstitution

Purpose

Dynamic in-situ proton (¹H) magnetic resonance imaging (MRI) and ¹H T₂-relaxometry experiments are described in an attempt to: (i) understand the physical processes, that occur during the reconstitution of lyophilized bovine serum albumin (BSA) and monoclonal antibody (mAb) proteins; and (ii) objectify the reconstitution time.

Methods

Rapid two-dimensional ¹H MRI and diffusion weighted MRI were used to study the temporal changes in solids dissolution and characterise water mass transport characteristics. One-shot T₂ relaxation time measurements were also acquired in an attempt to quantify the reconstitution time. Both MRI data and T₂-relaxation data were compared to standard visual observations currently adopted by industry. The ¹H images were further referenced to MRI calibration data to give quantitative values of protein concentration and, percentage of remaining undissolved solids.

Results

An algorithmic analysis of the ¹H T₂-relaxation data shows it is possible to classify the reconstitution event into three regimes (undissolved, transitional and dissolved). Moreover, a combined analysis of the 2D ¹H MRI and ¹H T₂-relaxation data gives a unique time point that characterises the onset of a reconstituted protein solution within well-defined error bars. These values compared favourably with those from visual observations. Diffusion weighted MRI showed that low concentration BSA and mAb samples showed distinct liquid-liquid phase separation attributed to two liquid layers with significant density differences.

Conclusions

T₂ relaxation time distributions (whose interpretation is validated from the 2D ¹H MR images) provides a quick and effective framework to build objective, quantitative descriptors of the reconstitution process that facilitate the interpretation of subjective visual observations currently adopted as the standard practice industry.

Electronic supplementary material

The online version of this article (10.1007/s11095-019-2591-x) contains supplementary material, which is available to authorized users.