A Co-Processed API Approach for a Shear Sensitive Compound Affording Improved Chemical Stability and Streamlined Drug Product Processing.

The physical properties of active pharmaceutical ingredients (API) are critical to both drug substance (DS) isolation and drying operations, as well as streamlined drug product (DP) processing and the quality of final dosage units. High aspect ratio, low bulk density, API 'needles' in particular are a hindrance to efficient processing, with a low probability that conventional crystallization routes can modify the challenging morphology. The compound evaluated in this manuscript demonstrated this non-ideal morphology, with the added complexity of shear sensitivity. Modest shear exposure resulted in conversion of the thermodynamically stable crystalline phase to the amorphous phase, with the amorphous phase then undergoing accelerated chemical degradation. Slow filtration during DS isolation resulted in uncontrolled and elevated amorphous levels, while subsequent DP operations including blending, densification and compression increased amorphous content still further. A chemically stable final dosage unit would ideally involve a high bulk density, free flowing API that did not require densification in order to be commercialized as an oral dosage form with direct encapsulation of a single dosage unit. Despite every effort to modify the crystallization process, the physical properties of the API could not be improved. Here, an innovative isolation strategy using a thin film evaporation (TFE) process in the presence of a water soluble polymer alleviated filtration and drying risks and consistently achieved a high bulk density, free flowing co-processed API amenable to direct encapsulation. Characterization of the engineered materials suggested the lower amorphous levels and reduced shear sensitivity were achieved by coating surfaces of the API at relatively low polymer loads. This particle engineering route blurred conventional DS/DP boundaries that not only achieved improved chemical stability but also resulted in a optimized material, with simplified and more robust processing operations for both drug substance and drug product.

Effect of composition of simulated intestinal media on the solubility of poorly soluble compounds investigated by design of experiments.

The composition of the human intestinal fluids varies both intra- and inter-individually. This will influence the solubility of orally administered drug compounds, and hence, the absorption and efficacy of compounds displaying solubility limited absorption. The purpose of this study was to assess the influence of simulated intestinal fluid (SIF) composition on the solubility of poorly soluble compounds. Using a Design of Experiments (DoE) approach, a set of 24 SIF was defined within the known compositions of human fasted state intestinal fluid. The SIF were composed of phospholipid, bile salt, and different pH, buffer capacities and osmolarities. On a small scale semi-robotic system, the solubility of 6 compounds (aprepitant, carvedilol, felodipine, fenofibrate, probucol, and zafirlukast) was determined in the 24 SIF. Compound specific models, describing key factors influencing the solubility of each compound, were identified. Although all models were different, the level of phospholipid and bile salt, the pH, and the interactions between these, had the biggest influences on solubility overall. Thus, a reduction of the DoE from five to three factors was possible (11-13 media), making DoE solubility studies feasible compared to single SIF solubility studies. Applying this DoE approach will lead to a better understanding of the impact of intestinal fluid composition on the solubility of a given drug compound.

Use of MALDI-MS Combined with Differential Hydrogen-Deuterium Exchange for Semiautomated Protein Global Conformational Screening.

Matrix-assisted laser desorption/ionization (MALDI) coupled with a time-of-flight (TOF) mass-spectrometry (MS) detector is acknowledged to be very useful for analysis of biological molecules. At the same time, hydrogen-deuterium exchange (HDX) is a well-known technique for studying protein higher-order structure. However, coupling MALDI with HDX has been challenging because of undesired back-exchange reactions during analysis. In this report, we survey an approach that utilizes MALDI coupled with an automated sample preparation to compare global conformational changes of proteins under different solution conditions using differential HDX. A nonaqueous matrix was proposed for MALDI sample preparation to minimize undesirable back-exchange. An automated experimental setup based on the use of a liquid-handling robot and automated data acquisition allowed for tracking protein conformational changes as a difference in the number of protons exchanged to deuterons at specified solution conditions. Experimental time points to study the deuteration-labeling kinetics were obtained in a fully automated manner. The use of a nonaqueous matrix solution allowed experimental error to be minimized to within 1% RSD. We applied this newly developed MALDI-HDX workflow to study the effect of several common excipients on insulin folding stability. The observed results were corroborated by literature data and were obtained in a high-throughput and automated manner. The proposed MALDI-HDX approach can also be applied in a high-throughput manner for batch-to-batch higher-order structure comparison, as well as for the optimization of protein chemical modification reactions.

Visualizing small differences using subtractive chromatographic analysis.

Subtraction of chromatograms coming from two different samples collected under identical conditions can highlight small variations, serving as a useful tool for visualizing differences between experimental and control groups. While the basis for this general approach has been known for decades, the technique is seldom used in modern chromatographic analysis. We report an investigation into the application of subtractive chromatographic analysis in several areas of pharmaceutical research where detection of small differences between samples is important. Our investigation found that elimination of artifacts caused by peak misalignment was often necessary, especially for extremely sharp chromatographic peaks obtained in rapid injection MISER chromatography. Alignment of individual peaks prior to subtraction, combined with fast detector sampling rates, or data interpolation in cases where this is not possible, was found to afford convenient visualization of small differences (∼1%) among samples, suggesting potential utility in high throughput screening of process adsorbents or other applications in pharmaceutical research and development.

Development of a directly correlated Raman and uHPLC-MS content uniformity method for dry powder inhalers through statistical design, chemometrics and mathematical modeling.

CONTEXT: Content uniformity (CU) is a critical quality attribute measured and monitored throughout the development and commercial supply of pharmaceutical products. Traditional high-performance liquid chromatography (HPLC) methods are time-consuming in both sample preparation and analysis. Thus, a rapid, nondestructive and preparation free spectroscopy based method such as Raman is preferred. OBJECTIVE: Multiple mathematical algorithms were used to establish robust and directly correlated Raman and ultra-HPLC-mass spectrometry (uHPLC-MS) CU methods for the rapid analysis of blends and agglomerates formulated for dry powder inhalers (DPIs). MATERIALS AND METHODS: Model samples included blends of caffeine and lactose; albuterol and lactose; and albuterol and lactose agglomerates. Design of experiments (DoE) was employed to optimize Raman spectra. Multivariate curve resolution (MCR) was leveraged to assess Raman method robustness. Mathematical modeling provided direct method to method correlation by allowing samples to be scanned first for Raman spectra and then dissolved for uHPLC-MS analysis. Several chemometric models were developed and evaluated for the quantitative analysis of CU. RESULTS: The DoE revealed Raman power and exposure time were negatively correlated when optimizing albuterol and caffeine spectra but positively correlated for lactose. MCR revealed regions in which small changes to power and time resulted in an 8-10% change in concentration predictions. A PCR model worked well for the analysis of caffeine blend samples and a PLS model worked best for both albuterol blends and agglomerates. DISCUSSION AND CONCLUSION: Utilization of DoE, chemometrics and mathematical modeling provided a robust and directly correlated CU method for DPIs.

Multicomponent chemical imaging of pharmaceutical solid dosage forms with broadband CARS microscopy.

We compare a coherent Raman imaging modality, broadband coherent anti-Stokes Raman scattering (BCARS) microscopy, with spontaneous Raman microscopy for quantitative and qualitative assessment of multicomponent pharmaceuticals. Indomethacin was used as a model active pharmaceutical ingredient (API) and was analyzed in a tabulated solid dosage form, embedded within commonly used excipients. In comparison with wide-field spontaneous Raman chemical imaging, BCARS acquired images 10× faster, at higher spatiochemical resolution and with spectra of much higher SNR, eliminating the need for multivariate methods to identify chemical components. The significant increase in spatiochemical resolution allowed identification of an unanticipated API phase that was missed by the spontaneous wide-field method and bulk Raman spectroscopy. We confirmed the presence of the unanticipated API phase using confocal spontaneous Raman, which provided spatiochemical resolution similar to BCARS but at 100× slower acquisition times.