Therapeutic peptides are a special class of medicinal agents that combine certain advantages of small molecules and therapeutic proteins. Their main therapeutic areas of application include metabolic diseases, oncology, and cardiovascular diseases. To ensure the safety, quality, and efficacy of peptide drugs, regulatory agencies require the evaluation of oligomeric and aggregation states. For this purpose, size-exclusion chromatography is most commonly used.
The aim of this master's thesis was to develop a stability-indicating analytical method based on size-exclusion chromatography for determination of aggregates in a medicinal product with a peptide drug substance. The key desired properties of the method were sufficient sensitivity and resolution between the aggregates and the drug substance. We tested different chromatographic columns and studied the influence of basic chromatographic conditions: column temperature, flow rate, and mobile phase composition. We found that the key to quality separation was to choose a column with the smallest possible particle diameter of the stationary phase and appropriate pore size. Additionally, the content of trifluoroacetic acid and acetonitrile in the mobile phase had a significant impact. We decided to finalize the method development on a column intended for UHPLC analyses. Optimization involved increasing the column temperature, the flow rate and the content of the organic modifier propan-1-ol in the mobile phase.
The final analytical method was validated according to the internal plan and criteria of Lek d. d. We determined repeatability, rigidity, limit of detection, limit of quantification, linearity, accuracy, robustness and selectivity.
The validated analytical method was then used to determine the content of aggregates in stability samples of the studied drug product. The content of aggregates was found to increase with temperature and time, thus confirming the usefulness and suitability of the method for monitoring the stability of the peptide drug substance in the studied drug product.
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