Source: Peoples’Friendship University of Russia –
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Imagine you need to measure a speck of dust that is a thousand times thinner than a human hair. Moreover, the speck does not stay still but moves chaotically in a liquid. This is exactly the task that pharmacists face every day when controlling the quality of modern medicines. And now – for the first time in Russia – they will have a single, legally approved recipe for such a measurement.
The Ministry of Health of Russia has approved the draft general pharmacopoeia monograph developed by the team of the Department of Pharmaceutical and Toxicological Chemistry of RUDN Institute of Medicine. The document establishes a state quality control standard for a whole class of drugs — colloidal solutions, emulsions, nanoparticles, and even vaccines.
The team: who created the quality standard
- Anton Vladimirovich Syroeshkin – Doctor of Biological Sciences, Professor, Head of the Department.
- Tatyana Vadimovna Pleteneva – Doctor of Chemical Sciences, Professor.
- Olga Valerievna Levitskaya – PhD in Chemical Sciences, Associate Professor.
- Elena Valerievna Uspenskaya – Doctor of Pharmaceutical Sciences, Professor.
What is a “colloid” and why can’t it be seen?
When we buy drops, a spray, or an injection solution at the pharmacy, we think the liquid in the ampoule is absolutely transparent and homogeneous. But that is not really true. Many modern medicines are colloidal systems. In simple words, tiny solid particles or oil droplets float in the liquid — so small that the eye cannot see them.
Examples from everyday life:
- protargol (nose drops) is a colloidal silver solution;
- polyglucin and hemodez, which save lives in blood loss are also colloids;
- even some next‑generation vaccines are based on virus‑like particles smaller than 150 nanometres.
The problem is that particles up to 400 nanometres are invisible to optical microscopes — they are smaller than the wavelength of light. Controlling their quality is like checking the evenness of a seam while wearing very thick mittens.
Laser magic: how to “catch” the invisible?
The method standardized by RUDN scientists is called Dynamic Light Scattering (DLS).
A colloidal solution is illuminated with a laser, and a special sensor detects how the intensity of the scattered light changes over time. The particles in the liquid are in constant thermal motion. Large particles “tremble” slowly, small ones quickly. By analysing this “trembling”, a computer calculates the exact size.
The particle size in a drug is a safety and efficacy factor. “Particles that are too large can clog capillaries or not be absorbed. Non‑uniform size means the dose of the active substance will ‘wander’ from ampoule to ampoule. And in vaccines based on virus‑like particles, size critically affects how the immune system ‘sees’ the enemy,” says Elena Uspenskaya.
RUDN sets the standard
The DLS principle itself has been used in science and industry since the 1990s. However, it was only included in the list of mandatory drug control methods of the European Union in 2023–2024. Russia is not copying Western regulations but is developing its own, deeper and more precise.
The European version describes the method quite generally. The RUDN version contains an extensive block of theory and mathematical models, eliminating any ambiguity. It specifies requirements for sample preparation —how to filter the solvent and at what temperature to measure. Moreover, the monograph is tailored to the national regulatory framework and uses terminology familiar to Russian pharmacists.
“The development of a general pharmacopoeia monograph turns the DLS method from a suitable analytical tool into a mandatory element of regulated control. The monograph introduces universal criteria: what polydispersity index is considered acceptable, what Z‑average value should be recorded in the drug passport. This will reduce variability of methods and related errors in particle size determination for medical solutions. It will also facilitate comparability of results both at the stage of drug registration and when publishing scientific results – through a unified terminology, test parameters, and experimental quality criteria,” says Elena Uspenskaya.
Regarding the impact on the educational process, after the monograph is approved, changes may be made to the content of the discipline “Physical and Colloidal Chemistry”. At the same time, as Elena Valerievna notes, the content of the disciplines “Methods of Pharmacopoeial Analysis” and “Drug Quality Control” at the RUDN Institute of Medicine already includes blocks on dynamic light scattering.
Currently, the draft general pharmacopoeia monograph is undergoing scientific and technical editing at the Institute of Pharmacopoeia and Standardization. It is expected that already in the first quarter of 2026, an order of the Ministry of Health will approve this monograph as part of the State Pharmacopoeia of the Russian Federation.
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