Pharmaceutical Forced Degradation (Stress Testing) Endpoints: A Scientific Rationale and Industry Perspective

Development and validation of the RP-HPLC method for quantification of tavaborole

The stability-indicating approach for tavaborole quantification was developed and validated to establish a precise, linear, accurate, and robust HPLC method. The development section includes optimizing the detection wavelength, the mobile phase ratio, and the type of column used to achieve the best possible separation and sensitivity for analysis. The chromatographic conditions were established, considering peak symmetry, resolution, and retention time. The mobile phase composition, comprising a buffer: acetonitrile (75 : 25, %v/v), with an injection volume of 15 μL, showed suitable elution and recovery at 265 nm. A constant column oven temperature of 35 °C and a 1 mL min-1 flow rate were maintained. The pH of the buffer was changed to 3.0 by using orthophosphoric acid. Linearity was observed from 5 to 1000 ppm (r2 = 1.00000). The capacity (retention) factor (k) of 3.43 was observed, indicating significant interaction and good separation. Forced degradation (FD) or stress tests were performed for chemical and physical photolytic stress conditions, and the results observed were within the specified limits. The stability in the analytical solution was observed for up to 35 hours at 5 °C, confirming the stability of the solution. Validation of the developed HPLC method confirmed the system's suitability, precision, linearity, accuracy, FD, robustness, and results. All validation criteria for the technique were within acceptable limits.

Identification and Characterization of Rotigotine Degradation Products by HPLC Coupled DAD and CAD Detectors and HRMS Through Q-Orbitrap and Electrospray Ionization

Rotigotine (RTG) is a dopamine agonist used in the treatment of Parkinson's disease. As it is susceptible to oxidation, stability studies must be carefully designed for the identification and characterization of all possible degradation products. Here, RTG degradation was evaluated according to the International Conference on Harmonization guidelines under various stress conditions, including acidic and basic hydrolysis, oxidative, metallic, photolytic, and thermal conditions. Additionally, more severe stress conditions were applied to induce RTG degradation. Significant degradation was only observed under oxidative and photolytic conditions. The samples were analyzed by high performance liquid chromatography coupled to photodiode array detectors, charged aerosol, and high-resolution mass spectrometry. Chromatographic analyses revealed the presence of eight substances related to RTG, four of which were already described and were qualified impurities (impurities B, C, K and E) and four new degradation products (DP-1 - DP-4), whose structures were characterized by high-resolution mass spectrometry through Q-Orbitrap and electrospray ionization. In the stress testing of the active pharmaceutical ingredient in solid form, significant RTG degradation was observed in the presence of the oxidative matrix. The results corroborate the literature that confirm the high susceptibility of RTG to oxidation and the importance of using different detectors to detect degradation products in forced degradation studies.

Structural Elucidation of Novel Degradation Impurities of Ibrutinib in Ibrutinib Tablets Using Preparative Chromatography, LCMS, HRMS and 2D NMR Techniques

Ibrutinib is an orally administered compound that functions as an irreversible covalent inhibitor of the Bruton tyrosine kinase, an essential element in multiple cellular processes including B-cell differentiation, proliferation, migration, survival and apoptosis. The compound has been found to demonstrate efficacy against a range of B-cell malignancies. The drug product is available in oral tablet and capsule formulations. The drug degradation profiles of tablets dosage form were assessed in accordance with regulatory guidelines. The results indicate that the drug substance is susceptible to alkaline and oxidative stress. The oxidation degradation led to the identification of three significant unknown degradation impurities. The three compounds were isolated through the application of preparative liquid chromatography, and their structures were determined using analytical techniques such as liquid chromatography-mass spectrometry, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Utilizing structural elucidation data, predictions were made regarding the composition of impurities, revealing them to be novel degradation impurities that bear structural resemblance to ibrutinib. Additionally, potential pathways for the formation of the impurities were proposed.