The aim of this study is the identification, structural characterization, and qualification of a degradation impurity of bisoprolol labeled as Impurity RRT 0.95. This degradation product is considered as a principal thermal degradation impurity identified in bisoprolol film-coated tablets. The impurity has been observed in the stress thermal degradation study of the drug product. Using HPLC/DAD/ESI-MS method, a tentative structure was assigned and afterwards confirmed by detailed structural characterization using NMR spectroscopy. The structure of the target Impurity RRT 0.95 was elucidated as phosphomonoester of bisoprolol, having relative molecular mass of 406 (positive ionization mode). The structural characterization was followed by qualification of Impurity RRT 0.95 using several different in silico methodologies. From the results obtained, it can be concluded that no new structural alerts have been generated for Impurity RRT 0.95 relative to the parent compound bisoprolol. The current study presents an in-depth analysis of the full characterization and qualification of an unidentified impurity in a drug product with the purpose of properly defining the quality specification of the product.

The purpose of this study was to develop and validate a discriminative dissolution method for the metformin film-coated tablet with immediate release of the active substance that belongs to class III of the Biopharmaceutical Classification System (BCS). Different conditions such as type of dissolution medium, volume of dissolution medium, rotation speed, apparatus, and filter suitability were evaluated. The most discriminative release profile for the metformin film-coated tablet was accomplished by using Apparatus II (paddle) and 1000 mL of phosphate buffer pH 6.8 as the dissolution medium and maintained on 37 ± 0.5°C with a rotation speed of 75 rpm. The quantification of the released active substance was performed by UV/Vis spectrophotometry, at 232 nm. Acceptance criteria for not less than 75% (Q) of the labeled content for 45 minutes were set. The dissolution method was validated according to the current international guidelines using the following parameters: specificity, accuracy, precision, linearity, robustness, and stability of the solutions, found to be meeting the predetermined acceptance criteria. A developed dissolution method has discriminatory power to reflect the characteristics of the medicinal product and is able to distinguish any changes related to quantitative formulation and can be also applied for routine batch testing.

Daratumumab is a fully human anti-CD38 monoclonal antibody with strong potential as a targeting vector for therapeutic radionuclides. This study aimed to develop a freeze-dried daratumumab immunoconjugate kit by selecting a suitable chelator (DOTA-NHS, p -SCN-Bn-DOTA, or p -SCN-Bn-1B4M-DTPA) for the ¹⁷⁷ Lu-labelling, optimising the freeze-drying formulation, and evaluating the physicochemical properties and purity profiles. Conjugation performed in carbonate buffer at elevated temperature enhanced chelator incorporation and supported the selection of daratumumab- p -SCN-Bn-DOTA as the most suitable candidate, achieving radiolabelling yield up to 99.8 % without additional purification. Among the evaluated freeze-dried formulations, a saline-based, buffer-free sucrose-mannitol formulation containing polysorbate 20 (S.F5) provided the most favourable characteristics, including minimal residual moisture and the highest monomer purity with non-detectable HMWS species under the applied SE-HPLC conditions. ATR-FTIR and Raman spectroscopy confirmed preservation of the antibody structural integrity after conjugation and freeze-drying. In an in vitro study using human serum, [ ¹⁷⁷ Lu]Lu-daratumumab- p -SCNBn-DOTA maintained higher radiochemical purity for 168 h than [ ¹⁷⁷ Lu]Lu-daratumumab- p -SCN-Bn-1B4MDTPA, indicating greater stability. These results support the feasibility of a ready-to-use freeze-dried daratumumab- p -SCN-Bn-DOTA kit for the ¹⁷⁷ Lu-labelling.