Methods for Detecting Subvisible Particles in Medicines (Review)

INTRODUCTION. Modern methods for determining particle sizes with the necessary reliability make it possible to study the granulometric composition of medicines and to assess the potential risks in the medical use of medicines in the presence of subvisible particles. This is especially necessary in relation to injectable, inhalation, ophthalmic forms of medicines. Each of the known methods has its own characteristics and the scope of its application.
AIM. Systematization of methods for determining the size of subvisible particles in medicines.
DISCUSSION. The paper considers the most commonly used methods for determining the size of subvisible particles and particle size distribution. The paper considers the most commonly used methods for determining the size of subvisible particles and particle size distribution. The laser diffraction method is used to determine the total number of particles in a sample and the particle size distribution of both the total volume of all particles and the total number of all particles. Dynamic light scattering is mainly used to estimate the size of subvisible dispersed particles suspended in solution. Both methods are based on the use of laser light scattered by particles of the test sample, while the principles of operation of the equipment are different. To identify subvisible particles, the presence of which is undesirable in medicines, the counting light blocking method and the microscopy method are provided. The microscopy) method, based on counting subvisible particles on the surface of a dried membrane filter after passing drug solutions through the membrane, is used to identify subvisible particles if the counting light blocking method cannot be used. The microscopic method with flow visualization and the scanning electron microscopy method are not used for routine control of medicines, but are important additional tools for determining the features of the granulometric composition and detecting undesirable contamination by foreign particles in medicines.
CONCLUSION. The choice of method depends on the task and the object of the study. When applying each of the considered methods, the type and size of particles, the technology of the drug, the physico-chemical properties of the test sample, the speed of analysis, the requirements for the accuracy of the method, the availability of equipment and software, and the competence of personnel should be taken into account. In some cases, it is necessary to combine different methods to obtain the most reliable results or to use the most universal methods, in particular, the microscopic method with flow visualization, which will determine the size, shape, and nature of subvisible particles and the content of particles of a specific size in total.

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