https://doi.org/10.15255/KUI.2024.047
Published: Kem. Ind. 74 (11-12) (2025) 457–466
Paper reference number: KUI-47/2024
Paper type: Original scientific paper
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The Influence of Excipients’ Chemical Nature on the Degradation of Metformin and Vildagliptin

A. Demirović, A. Uzunović and A. Veledar-Hamalukić

Abstract

The influence of the chemical nature of excipients (magnesium stearate, povidone, microcrystalline cellulose, lactose, crospovidone, and talc) on the degradation of metformin and vildagliptin was tested by forced degradation, using acid hydrolysis, base hydrolysis, oxidation, and thermal degradation. The quantification of the content of metformin and vildagliptin before and after degradation was performed using the reversed-phase HPLC method. This method demonstrated good selectivity and specificity, with no interference from the peaks of degraded excipients on the peaks of metformin and vildagliptin, or excipient-excipient interaction. An alternative degradation pathway was discovered for vildagliptin with povidone and with magnesium stearate, as well as for metformin with povidone. Based on the results, recommendations were made regarding desirable and undesirable excipients. For vildagliptin, it is desirable to add lactose, while povidone and magnesium stearate should be avoided. Microcrystalline cellulose is recommended for metformin, whereas povidone should be avoided due to the impurities it introduces, which can lead to oxidative degradation of metformin. In the case of the combination of metformin and vildagliptin, lactose should not be included in the formulation, as it accelerates the degradation of the active substances. An exception is in the case of base hydrolysis, where lactose has a stabilising effect, absorbing moisture, thus reducing the degradation of both metformin and vildagliptin.

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Keywords

excipients, degradation, metformin, vildagliptin, HPLC