Development of a protective lyophilisation medium and conditions to stabilise the erythrocyte diagnostic preparation of tularaemia immunoglobulin

Abstract

Liquid erythrocyte diagnostic preparations have a practical disadvantage; i.e., long-distance transportation involving possible non-compliance with cold-chain requirements may result in a complete loss of biological activity. A lyophilisation technology is necessary to ensure that the preparations retain their original properties for a long time. The aim of the work was to develop a protective medium and conditions for lyophilisation to stabilise the erythrocyte diagnostic preparation of tularaemia immunoglobulin. Materials and methods: Gelatin, thiourea, trehalose, sucrose, dextran, and Tween 80 were used as excipients for protective media. The authors used nine strains of homologous and heterologous microorganisms of different genera and species to control the lyophilised diagnostic preparation sensitivity and specificity. Evaluation of the main stability-related quality attributes (appearance of the dried preparation, loss on drying, solubility, appearance after reconstitution, appearance after settling, sensitivity, specificity) considered the temperatures specific to the climatic zones where the in vitro diagnostics is intended to be marketed and used. Results: The authors developed protective stabilising media with different compositions, used them in freeze-drying of the preparation and carried out control testing. The most promising was the lyophilisation medium containing a smaller amount of ingredients —6% of dextran, 0.06% of Tween 80 and up to 0.01% of sodium azide—as it was the simplest one to prepare and ensured complete preservation of the quality attributes. The authors carried out practical evaluation of lyophilisation procedures, and the 12–14-hour procedure proved to be the most cost-effective. Conclusions: The results of long-term, or real time, and accelerated stability testing of the lyophilised diagnostic preparation demonstrated the possibility of two-year storage at a labelled temperature of 2–8 °C, as well as at elevated and low temperatures of 30±2 °С and –18 °С, respectively. The tests showed no negative effects of the temperatures on the controlled quality attributes.