Original research The effect of membrane filtration on the accuracy of quantitative determination of aprepitant in an aqueous medium
Ubushaev SV, Sepp VV, Bakulin KS, Sen OYu
Validation of analytical methods for poorly soluble BCS Class II/IV drugs like Aprepitant in aqueous media is complicated due to instability of samples at the stage of preparation. The goal of the research is to detect the mechanism of loss of Aprepitant analytical signal during filtration and determine the conditions for an exact diagnosis. In this paper, the effect of membrane materials (PES, PVDF, Nylon, PP) on analyte concentration measurements via UV spectrophotometry was examined. Filtration of aqueous solutions is established to cause significant analyte losses ranging from 15.1% (PP) to 83.9% (PES), depending on the initial concentration. It is proved that the main loss factor is not passive adsorption, but mechanically induced heterogeneous nucleation on the membrane surface, which is confirmed by an increase in optical scattering within the 300–500 nm range. Fraction filtration revealed abnormal desorption effects on PES filters. It has been shown that the use of an acidic medium (0.1 M HCl) prevents nucleation due to protonation of the molecule: filtration losses are reduced to statistically insignificant values (<1.6%). To ensure the accuracy of aprepitant analysis, it is recommended to exclude filtration of neutral aqueous solutions, replacing it with centrifugation, or to use acidic dissolution media.
Received: 2026-01-21
Published online: 2026-02-25
DOI: 10.24075/dc.2026.002
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Review Mnemotropic effects of thymus peptides in normal and pathological conditions
Kiseleva NM, Korolev AG, Inozemtsev AN, Romanov BK
The abstract presents the results of research that reported how immune and nervous systems collaborate to regulate learning and memory processes. The research was conducted by the Department of Higher Nervous Activity of Lomonosov Moscow State University from 2009 to 2020. Wistar rats served as experimental subjects. A study was made of the effect of thymic preparations such as tactivin, 5th fraction of thymosin and thymalin on production of conditioned reflexes (conditioned active avoidance reflex (СAAR), conditioned passive avoidance reflex (СPAR), conditioned food-procuring reflex (CFPR) both in normal and pathological conditions (thymectomy, aging, neurotoxic effect of heavy metals and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)). Research indicates that thymus peptides showed a positive effect on cognitive functions. In normal conditions, they enhanced production of CAAR and CFPR with a prolonged retention of the memory trace in the CPAR task. Thymectomy resulted in restoration of conditioned reflexes lost after surgery. Cognitive functions were also improved in 18–24-month-old rats and following neurotoxic exposure. Thus, thymus peptides exert broad regulatory effects beyond immunity. The thymus also communicates with the central nervous system (CNS), potentially influencing cognitive processes like learning and memory.
Received: 2026-01-19
Published online: 2026-02-16
DOI: 10.24075/dc.2026.001
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