Assessment of prekallikrein content is essential for safety control of human immunoglobulin and albumin products. The inherent variability of human prekallikrein reagents and chromogenic substrates indicates the need for standardisation of the chromogenic assay, using the components of a reference standard (RS) not only for construction of calibration curves, but also for confirmation of validity, consistency, and reproducibility of results within different established ranges.The aim of the study was to improve the quality control of human plasma products in terms of prekallikrein activator content.Materials and methods: prekallikrein activator content was determined by the chromogenic assay according to the procedure described in General Monograph 1.8.2.0013.18 of the Russian Pharmacopoeia, using various prekallikrein reagents. An RS was developed in a spiking test, using human albumin solution and Hageman factor beta-fragment reagent. Shewhart control charts were prepared based on the results of determination of prekallikrein activator content in the RS control component.Results: a two-component RS for prekallikrein activator content with an assigned Hageman factor beta fragment content was developed using the spiking test. The authors substantiated the necessity of using a Russian-produced prekallikrein reagent as the RS component. The in-house reference standard IRS 42-28-445 was certified using all available human prekallikrein reagents, and the IRS 42-28-446 was certified using the prekallikrein reagent included in the kit. The certified prekallikrein activator content is: 51 IU in the batches 1 of IRS components intended for prekallikrein determination; 8.3–11.9 IU/mL in the IRS 42-28-445 control component, after reconstitution in 1.0 mL of purified water, and 5.4–6.6 IU/mL after reconstitution in 2.0 mL of purified water; and 9.1–11.1 IU/mL and 5.6–6.4 IU/mL in the IRS 42-28-446 control component after reconstitution in 1.0 mL and 2.0 mL of purified water, respectively. The IRS component intended for prekallikrein determination is designed for calibration curve construction, while the IRS control component is designed for assessing the validity of test results and preparation of control charts. The analysis of the control charts for the control component made it possible to evaluate the consistency of the analytical process.Conclusions: the components of the developed RSs in combination with Shewhart control charts allow for both determination of prekallikrein activator content, and control of the analytical process, as well as assessment of changes related to the replacement of the reagent batch. The RS control component allows for assessment of analytical process consistency and ensures the standardisation of the test procedure.

The light obscuration method described in the State Pharmacopoeia of the Russian Federation for subvisible particle testing, provides for preparation of a pooled sample with a minimum volume of 25 mL to be used in four measurements, each with 5.0 mL of the test sample. In the case of, for example, ready-to-use 0.2–0.3 mL pre-filled syringes, the method requires pooling the contents of a large number of products, which is economically costly. The use of small volumes of test samples in measurements by the light obscuration method is especially relevant for expensive medicines. Current particle counters allow for testing of 0.1 mL samples, but this requires assessment of the procedure’s accuracy.The aim of the study was to assess the accuracy of subvisible particle testing by the light obscuration method for small volumes of test samples.Materials and methods: we used an HIAC 9703+ liquid particle counter; particle count reference standards containing 0.998×106 particles/mL and 3.800 particles/mL; suspensions of standard latex particles with a known size (20 μm).Results: the study assessed the accuracy of subvisible particle determination by the light obscuration method for small test samples of 0.1‒0.5 mL: trueness was 96–100%; repeatability was 0.8–1.8%; linear correlation coefficients for the calculated versus theoretical number of particles were more than 0.999. The use of 0.1 mL test samples is impractical because of insufficient accuracy of the test results. The relative standard deviation of subvisible particle measurements obtained with 0.2–5.0 mL test samples did not exceed the measurement error of the instrument. The use of small test samples (0.2–1.0 mL) requires the use of a 1 mL sampling syringe. The study demonstrated the need for determination of the pre-run volume (not less than 0.1 mL). Comparative testing of standard (5.0 mL) and small (0.5 mL) samples of protein-based biological products showed comparable results.Conclusions: the study demonstrated that the light obscuration method could be used for small volumes of test samples.

One of the factors influencing the uncertainty of residual moisture measurements in biological medicinal products is the accumulation of electrostatic charge on the surfaces of weighing bottles and laboratory balances, which results in poor weighing reproducibility. The authors believe that the simplest and most economical solution to this problem is to use weighing bottles made of a conductive material, e.g. metal. The aim of the work was to evaluate the influence of the material of weighing bottles on the reproducibility of loss-on-drying (LOD) methods. Materials and methods: Model samples for the study were prepared from a sucrose-gelatin medium by lyophilisation and subsequent moisture sorption to achieve a certain residual moisture content. The authors assessed the samples’ mass uniformity using Shewhart’s X-charts, and analysed their residual moisture content using a loss-on-drying procedure with glass and metal weighing bottles. Statistical processing of the results was carried out by calculating the main statistical indicators: Student’s t-test and Fisher’s F-test. Results: Four batches of model samples were prepared and standardised in terms of average mass using Shewhart’s charts. The effect of weighing bottle materials was most pronounced at low residual moisture contents (less than 0.5%), with the relative standard deviation (RSD) values for the results obtained with glass and metal weighing bottles reaching 76% and 35%, respectively. For the samples with a higher residual moisture content (2–5%), the minimum RSDs with glass and metal weighing bottles were 15% and 6%, respectively. Conclusions: The study allowed for evaluating the influence of the material of weighing bottles on the results of LOD measurements and demonstrated a higher reproducibility with metal weighing bottles. This confirms the possibility of using metal weighing bottles in quality assessment of biological medicinal products for human use with LOD methods.