ASPECTS OF MEDICINES QUALITY EVALUATION BY ELECTRICAL SENSING ZONE METHOD

The article describes standard methodological approaches to the determination of subvisible particles by electrical sensing zone method (the Coulter principle). The standard procedure of lyophilisate and powder preparation includes their dilution with Isoton® II Diluent (Beckman Coulter, USA) — 0.9 % sodium chloride solution containing a preservative agent (hereinafter — Isoton) under conditions free from particulate matter. The article provides a brief description of the Coulter principle which was included into the General monograph «Subvisible particulate matter in parenteral preparations» of the State Pharmacopoeia of the Russian Federation, 13th edition. It was demonstrated that most solutions for injection and infusion do not need special preparation before testing, whereas 13 % of such preparations need the addition of the diluent Isoton to increase their electrical conductivity for determination of subvisible particulate matter. The article presents the results of experimental studies that were aimed at modification of the standard sample preparation procedure for different medicinal products for the purpose of their evaluation in terms of subvisible particulate matter. A number of lyophilisates, powders, suspensions, and oily solutions can not be diluted with Isoton because of precipitate formation, so recommendations are offered for these types of products regarding the choice of alternative diluents (water, 4 % sodium chloride solution, ammonium thiocyanate solution in isopropanol, acetone, etc.) for obtaining electrically conductive solutions. Alternatively, it may be recommended to change the dilution mode (increase the time of dilution and/or diluent volume). Thus, the article provides rationale for using the Coulter principle for determination of subvisible particulate matter in various pharmaceutical forms.

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