Resumo

GUIZAR-RUIZ, J. I.; ANAYA-MARTIN, E.  e  GONZALEZ-SOLIS, J. L.. Drug expiration study using Raman spectroscopy and super paramagnetic clustering. Rev. mex. fis. [online]. 2024, vol.70, n.6.  Epub 12-Jan-2026. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.70.061302.

Currently, there is a belief that drugs used after their expiration date no longer work or can even cause some damage. In the present work, several types of drugs on the market with different expiration dates are analyzed to find out if those with expired expiration dates present spectroscopic differences from those whose expiration dates are still valid. This study used the Raman spectroscopy technique to determine the chemical composition of the drugs. To measure the drug Raman spectra, Horiba equipment, LabRam HR800, was used with an Olympus confocal microscope focusing a laser of 830 nm and 17 mW on the drugs through a 50× Leica long-range objective. The Super Paramagnetic Clustering (SPC) method was applied to classify the Raman spectra. In the SPC method, the clustering process is based on a phenomenon observed in nature at the atomic level and perfectly described by a statistical physics model known as the Potts model, which describes the interacting spins on a crystalline lattice. This clustering method allows for identifying hierarchical structures in the spectral data banks. Fourteen drugs were analyzed, including 2 capsules, 5 tablets, 2 liquid samples, 4 ointments, and one spray, with 1 to 3 expired expiration dates. Comparing drugs with expiration dates that are still valid and expired, the SPC results applied to the Raman spectra showed that although some drugs indicated chemical differences, others indicated no chemical differences, even among those with up to two expired expiration dates. The results showed that Raman spectroscopy and SPC are excellent tools for discriminating between expired and non-expired drugs. Principal Components Analysis (PCA) was also applied as a cross-checking method of the SPC results, obtaining consistent results. To our knowledge, this is the first preliminary result evaluating the usefulness of Raman spectroscopy and SPC in identifying expired drugs distributed on the market.

Palavras-chave : Drugs expiration; Raman spectroscopy; super paramagnetic clustering; PCA.

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