Studies on Bacterial Pyrogenicity: III. Specificity of the United States Pharmacopeia Rabbit Pyrogen Test

The specificity of the first or “presumptive” portion of the USP rabbit pyrogen test was investigated by use of a new absolute standard of reference. The reference standard was a 0.9% sodium chloride solution prepared to be pyrogen-free. Details of the preparation were described. The hypothesis was explored that the temperature response of rabbits after intravenous injection of the standard solution was independent of exogenous pyrogen. Reactions observed among the rabbits in our colony allowed a classification of these animals ranging from “consistently reliable” to “consistently unreliable.” Details of the experimental results and implications for pyrogen testing are discussed. The recommendation was made that all rabbit test animals be “screened” in sham and actual tests before being used for pyrogen testing.     

Using USP I and USP IV for Discriminating Dissolution Rates of Nano- and Microparticle-Loaded Pharmaceutical Strip-Films

Recent interest in the development of drug particle-laden strip-films suggests the need for establishing standard regulatory tests for their dissolution. In this work, we consider the dissolution testing of griseofulvin (GF) particles, a poorly water-soluble compound, incorporated into a strip-film dosage form. The basket apparatus (USP I) and the flow-through cell dissolution apparatus (USP IV) were employed using 0.54% sodium dodecyl sulfate as the dissolution medium as per USP standard. Different rotational speeds and dissolution volumes were tested for the basket method while different cell patterns/strip-film position and dissolution media flow rate were tested using the flow-through cell dissolution method. The USP I was not able to discriminate dissolution of GF particles with respect to particle size. On the other hand, in the USP IV, GF nanoparticles incorporated in strip-films exhibited enhancement in dissolution rates and dissolution extent compared with GF microparticles incorporated in strip-films. Within the range of patterns and flow rates used, the optimal discrimination behavior was obtained when the strip-film was layered between glass beads and a flow rate of 16 ml/min was used. These results demonstrate the superior discriminatory power of the USP IV and suggest that it could be employed as a testing device in the development of strip-films containing drug nanoparticles.Key Words: BCS class II, dissolution, drug nanoparticles, flow-through cell, pharmaceutical strip-films     

Impact of Vibration and Agitation Speed on Dissolution of USP Prednisone Tablets RS and Various IR Tablet Formulations

Dissolution testing is an in vitro procedure which is widely used in quality control (QC) of solid oral dosage forms and, given that real biorelevant test conditions are applied, can also be used as a predictive tool for the in vivo performance of such formulations. However, if a dissolution method is intended to be used for such purposes, it has to deliver results that are only determined by the quality of the test product, but not by other variables. In the recent past, more and more questions were arising on how to address the effects of vibration on dissolution test results. The present study was performed to screen for the correlation of prednisone dissolution of USP Prednisone Tablets RS with vibration caused by a commercially available vibration source as well as to investigate how drug release from a range of immediate release formulations containing class 1–4 drugs of the biopharmaceutical classification scheme is affected by vibration when performing dissolution experiments at different agitation rates. Results of the present study show that the dissolution process of oral drug formulations can be affected by vibration. However, it also becomes clear that the degree of which a certain level of vibration impacts dissolution is strongly dependent on several factors such as drug properties, formulation parameters, and the design of the dissolution method. To ensure the establishment of robust and predictive dissolution test methods, the impact of variation should thus be considered in method design and validation.KEY WORDS: dissolution, USP prednisone calibrator tablets, variability, vibration meter, vibration source     

New Approach for the Application of USP Apparatus 3 in Dissolution Tests: Case Studies of Three Antihypertensive Immediate-Release Tablets

The USP Apparatus 3 is a compendial dissolution Apparatus that has been mainly used to assess the performance of modified-release drug products. However, this Apparatus can be applied to dissolution testing of immediate-release tablets as well, with several advantages such as lower consumption of dissolution media, reduced setup time in quality control routine, and minimized hydrodynamic issues. In this work, three immediate-release (IR) tablets containing antihypertensive drugs of different Biopharmaceutic Classification System (BCS) classes were evaluated in order to assess the possible interchangeability between the official dissolution method using typical USP Apparatus 1 or 2 and the proposed methods using USP Apparatus 3. Depending on the selection of the appropriate operational conditions, such as dip rate and sieve mesh size, it was observed that USP Apparatus 3 could provide similar dissolution profiles compared to USP Apparatus 1 or 2 to the drug products tested. In addition, USP Apparatus 3 avoided conning issues related to USP Apparatus 2. The successful application of USP Apparatus 3 in dissolution tests for IR drug products depends on the definition of specific test conditions for each product, considering all the equipment variables, as well as drug and formulation characteristics.     

Challenges with Developing In Vitro Dissolution Tests for Orally Inhaled Products (OIPs)

The purpose of this article is to review the suitability of the analytical and statistical techniques that have thus far been developed to assess the dissolution behavior of particles in the respirable aerodynamic size range, as generated by orally inhaled products (OIPs) such as metered-dose inhalers and dry powder inhalers. The review encompasses all analytical techniques publicized to date, namely, those using paddle-over-disk USP 2 dissolution apparatus, flow-through cell dissolution apparatus, and diffusion cell apparatus. The available techniques may have research value for both industry and academia, especially when developing modified-release formulations. The choice of a method should be guided by the question(s) that the research strives to answer, as well as by the strengths and weaknesses of the available techniques. There is still insufficient knowledge, however, for translating the dissolution data into statements about quality, performance, safety, or efficacy of OIPs in general. Any attempts to standardize a dissolution method for compendial inclusion or compendial use would therefore be premature. This review reinforces and expands on the 2008 stimulus article of the USP Inhalation Ad Hoc Advisory Panel, which "could not find compelling evidence suggesting that such dissolution testing is kinetically and/or clinically crucial for currently approved inhalation drug products."     

From Reductionism to Reintegration: Solving society’s most pressing problems requires building bridges between data types across the life sciences

Decades of reductionist approaches in biology have achieved spectacular progress, but the proliferation of subdisciplines, each with its own technical and social practices regarding data, impedes the growth of the multidisciplinary and interdisciplinary approaches now needed to address pressing societal challenges. Data integration is key to a reintegrated biology able to address global issues such as climate change, biodiversity loss, and sustainable ecosystem management. We identify major challenges to data integration and present a vision for a “Data as a Service”-oriented architecture to promote reuse of data for discovery. The proposed architecture includes standards development, new tools and services, and strategies for career-development and sustainability.

Data integration is key to the reintegration of biology and the pursuit of global issues such as climate change, biodiversity loss, and sustainable ecosystem management. This Essay defines the primary challenges in data integration and presents a vision for a "Data as a Service" (DaaS) oriented architecture that enables frictionless data reuse, hypothesis testing, and discovery.     

Affective Video Retrieval: Violence Detection in Hollywood Movies by Large-Scale Segmental Feature Extraction

Without doubt general video and sound, as found in large multimedia archives, carry emotional information. Thus, audio and video retrieval by certain emotional categories or dimensions could play a central role for tomorrow''s intelligent systems, enabling search for movies with a particular mood, computer aided scene and sound design in order to elicit certain emotions in the audience, etc. Yet, the lion''s share of research in affective computing is exclusively focusing on signals conveyed by humans, such as affective speech. Uniting the fields of multimedia retrieval and affective computing is believed to lend to a multiplicity of interesting retrieval applications, and at the same time to benefit affective computing research, by moving its methodology “out of the lab” to real-world, diverse data. In this contribution, we address the problem of finding “disturbing” scenes in movies, a scenario that is highly relevant for computer-aided parental guidance. We apply large-scale segmental feature extraction combined with audio-visual classification to the particular task of detecting violence. Our system performs fully data-driven analysis including automatic segmentation. We evaluate the system in terms of mean average precision (MAP) on the official data set of the MediaEval 2012 evaluation campaign''s Affect Task, which consists of 18 original Hollywood movies, achieving up to .398 MAP on unseen test data in full realism. An in-depth analysis of the worth of individual features with respect to the target class and the system errors is carried out and reveals the importance of peak-related audio feature extraction and low-level histogram-based video analysis.     

Comparative In Vitro Study of Six Carbamazepine Products

The purpose of present study was to evaluate commercial preparations of carbamazepine tablets with respect to drug release through a defined sequence of experiments using Minitab software. The compliance of products with respect to United States Pharmacopeia (USP) dissolution test and comparison of the products with respect to drug release in different dissolution conditions is reported in the present paper. The different dissolution conditions studied include dissolution medium (1% SLS in purified water, 0.1 N HCl), volume (900 and 1,000 ml), rpm (50 rpm, 75 rpm). Studies indicated that all six products complied with USP dissolution criteria. However, the extent of influence of dissolution conditions on drug release was varied among the products. Distinct dissolution profiles were observed and there was no correlation with disintegration time in certain products. The in vitro dissolution experimentation helped in identifying the discriminatory dissolution conditions and also the formulations that were unaffected with change of dissolution variables. In summary, commercial preparations of carbamazepine vary widely in their dissolution behavior in multi dissolution run experimentation. Identifying this behavior of the products was essential as an in vitro tool for screening a good and a bad formulation.     

Spatial indicators for nature conservation from European to local scale

The paper presents an overview of the objectives and exemplary results of the FP 5 project “Spatial Indicators for European Nature Conservation” (SPIN). The SPIN project is focused on the development and testing of advanced classification methods and spatial indicators based on multisensor satellite data and GIS to accomplish monitoring and management tasks in the context of Natura 2000 and nature conservation. A representative selection of eight regional test areas covers a pan-European network and allows comparative investigations to provide accepted recommendations for regional and European nature conservation. The selected results of four case studies are presented and discussed. The range of work covers the production of regional and local habitat maps by object-oriented classification, a case-based reasoning method for change detection as a management support tool for planning and regulating local land use, the selection and application of structural indicators for the monitoring of Natura 2000 habitats and the downscaling and disaggregation of soil information. Results and the further implementation of presented methods are discussed in the conclusions.     

Monitoring ibuprofen release from multiparticulates: In situ fiber-optic technique versus the HPLC method: A technical note

Summary and conclusions  The results from the linearity test showed that the automated FOPS method was linear and reproducible in predicting ibuprofen concentrations, as was shown by a high R² and low %RSD over a range of concentrations. Second-derivative treatment of the UV spectrum makes it possible to remove the effects of the sloping baseline often encountered in spectra of highly turbid samples. The dissolution profiles obtained by FOPS were more accurate with lower and consistent %RSD as compared with the HPLC method, particularly in the case of immediate-release multiparticulates. The FOPS method was also faster and less labor intensive. Because of its various advantages, fiber-optic dissolution is fast becoming an important tool for research and development. Its ease of use, high “data density,” high data-collection speed, and hands-free monitoring make the FOPS method extremely useful as compared with the traditional methods of dissolution testing. Published: July 6, 2007     

Partitioning variability in animal behavioral videos using semi-supervised variational autoencoders

Recent neuroscience studies demonstrate that a deeper understanding of brain function requires a deeper understanding of behavior. Detailed behavioral measurements are now often collected using video cameras, resulting in an increased need for computer vision algorithms that extract useful information from video data. Here we introduce a new video analysis tool that combines the output of supervised pose estimation algorithms (e.g. DeepLabCut) with unsupervised dimensionality reduction methods to produce interpretable, low-dimensional representations of behavioral videos that extract more information than pose estimates alone. We demonstrate this tool by extracting interpretable behavioral features from videos of three different head-fixed mouse preparations, as well as a freely moving mouse in an open field arena, and show how these interpretable features can facilitate downstream behavioral and neural analyses. We also show how the behavioral features produced by our model improve the precision and interpretation of these downstream analyses compared to using the outputs of either fully supervised or fully unsupervised methods alone.     

In Vitro Dissolution of Generic Immediate-Release Solid Oral Dosage Forms Containing BCS Class I Drugs: Comparative Assessment of Metronidazole,Zidovudine, and Amoxicillin Versus Relevant Comparator Pharmaceutical Products in South Africa and India

Biowaivers are recommended for immediate-release solid oral dosage forms using dissolution testing as a surrogate for in vivo bioequivalence studies. Several guidance are currently available (the World Health Organization (WHO), the US FDA, and the EMEA) where the conditions are described. In this study, definitions, criteria, and methodologies according to the WHO have been applied. The dissolution performances of immediate-release metronidazole, zidovudine, and amoxicillin products purchased in South African and Indian markets were compared to the relevant comparator pharmaceutical product (CPP)/reference product. The dissolution performances were studied using US Pharmacopeia (USP) apparatus 2 (paddle) set at 75 rpm in each of three dissolution media (pH1.2, 4.5, and 6.8). Concentrations of metronidazole, zidovudine, and amoxicillin in each dissolution media were determined by HPLC. Of the 11 metronidazole products tested, only 8 could be considered as very rapidly dissolving products as defined by the WHO, whereas 2 of those products could be considered as rapidly dissolving products but did not comply with the f₂ acceptance criteria in pH 6.8. All 11 zidovudine products were very rapidly dissolving, whereas in the case of the 14 amoxicillin products tested, none of those products met any of the WHO criteria. This study indicates that not all generic products containing the same biopharmaceutics classification system (BCS) I drug and in similar strength and dosage form are necessarily in vitro equivalent. Hence, there is a need for ongoing market surveillance to determine whether marketed generic products containing BCS I drugs meet the release requirements to confirm their in vitro bioequivalence to the respective reference product.KEY WORDS: BCS, dissolution testing, generic drug, immediate-release solid oral dosage forms, WHO criteria     

Development of a Material Sparing Bulk Density Test Comparable to a Standard USP Method for Use in Early Development of API’s

Bulk density can be a key indicator of performance, and may influence choice of formulation route of materials in pharmaceutical development. During early development, the cost of API’s can be expensive and the availability of material for powder property analysis is limited. The aim of this work was to investigate a suitable small-scale, low material requirement, bulk density test which would provide comparable data to the recommended large volume USP test. Materials with a range of morphological characteristics typically seen in the pharmaceutical industry were assessed to ensure that methods were suitably robust. It was found that the USP II “low volume” test does not give equivalent results to other tests in the USP, across the range of materials. An alternative test based on the FT4 powder rheometer at a scale of 25 mL gave results equivalent to the large volume USP I standard test. The use of smaller 10-mL methods was also found to give acceptable results for materials that were considered well-behaved but were more variable with difficult to handle materials with low bulk density.KEY WORDS: active pharmaceutical ingredient (API), bulk density, compressibility index, excipients, pharmaceuticals     

Integrating Interactive Computational Modeling in Biology Curricula

While the use of computer tools to simulate complex processes such as computer circuits is normal practice in fields like engineering, the majority of life sciences/biological sciences courses continue to rely on the traditional textbook and memorization approach. To address this issue, we explored the use of the Cell Collective platform as a novel, interactive, and evolving pedagogical tool to foster student engagement, creativity, and higher-level thinking. Cell Collective is a Web-based platform used to create and simulate dynamical models of various biological processes. Students can create models of cells, diseases, or pathways themselves or explore existing models. This technology was implemented in both undergraduate and graduate courses as a pilot study to determine the feasibility of such software at the university level. First, a new (In Silico Biology) class was developed to enable students to learn biology by “building and breaking it” via computer models and their simulations. This class and technology also provide a non-intimidating way to incorporate mathematical and computational concepts into a class with students who have a limited mathematical background. Second, we used the technology to mediate the use of simulations and modeling modules as a learning tool for traditional biological concepts, such as T cell differentiation or cell cycle regulation, in existing biology courses. Results of this pilot application suggest that there is promise in the use of computational modeling and software tools such as Cell Collective to provide new teaching methods in biology and contribute to the implementation of the “Vision and Change” call to action in undergraduate biology education by providing a hands-on approach to biology.     

Schizophrenia Detection and Classification by Advanced Analysis of EEG Recordings Using a Single Electrode Approach

Electroencephalographic (EEG) analysis has emerged as a powerful tool for brain state interpretation and diagnosis, but not for the diagnosis of mental disorders; this may be explained by its low spatial resolution or depth sensitivity. This paper concerns the diagnosis of schizophrenia using EEG, which currently suffers from several cardinal problems: it heavily depends on assumptions, conditions and prior knowledge regarding the patient. Additionally, the diagnostic experiments take hours, and the accuracy of the analysis is low or unreliable. This article presents the “TFFO” (Time-Frequency transformation followed by Feature-Optimization), a novel approach for schizophrenia detection showing great success in classification accuracy with no false positives. The methodology is designed for single electrode recording, and it attempts to make the data acquisition process feasible and quick for most patients.     

Measuring the Effect of Inter-Study Variability on Estimating Prediction Error

Background

The biomarker discovery field is replete with molecular signatures that have not translated into the clinic despite ostensibly promising performance in predicting disease phenotypes. One widely cited reason is lack of classification consistency, largely due to failure to maintain performance from study to study. This failure is widely attributed to variability in data collected for the same phenotype among disparate studies, due to technical factors unrelated to phenotypes (e.g., laboratory settings resulting in “batch-effects”) and non-phenotype-associated biological variation in the underlying populations. These sources of variability persist in new data collection technologies.

Methods

Here we quantify the impact of these combined “study-effects” on a disease signature’s predictive performance by comparing two types of validation methods: ordinary randomized cross-validation (RCV), which extracts random subsets of samples for testing, and inter-study validation (ISV), which excludes an entire study for testing. Whereas RCV hardwires an assumption of training and testing on identically distributed data, this key property is lost in ISV, yielding systematic decreases in performance estimates relative to RCV. Measuring the RCV-ISV difference as a function of number of studies quantifies influence of study-effects on performance.

Results

As a case study, we gathered publicly available gene expression data from 1,470 microarray samples of 6 lung phenotypes from 26 independent experimental studies and 769 RNA-seq samples of 2 lung phenotypes from 4 independent studies. We find that the RCV-ISV performance discrepancy is greater in phenotypes with few studies, and that the ISV performance converges toward RCV performance as data from additional studies are incorporated into classification.

Conclusions

We show that by examining how fast ISV performance approaches RCV as the number of studies is increased, one can estimate when “sufficient” diversity has been achieved for learning a molecular signature likely to translate without significant loss of accuracy to new clinical settings.     

High-performance thin-layer chromatographic separation of ranitidine hydrochloride and two related compounds

Ranitidine hydrochloride and its two related compounds, used in the USP TLC purity testing of the drug, were separated on a high-performance thin-layer chromatography (HPTLC) RP-18 WF_254S precoated plate using methanol–3% NH₄OH (4:1, v/v) as the mobile phase. The main advantage of the proposed HPTLC system over the USP TLC system for testing the purity of ranitidine is a better and more efficient separation of these three compounds in a shorter time and with less consumption of solvents. The system is promising from the point of view of the development of a new method for the TLC purity testing of ranitidine hydrochloride. A video system was used for imaging thin-layer chromatograms. Direct UV densitometric quantitation of the three compounds and a model for the calculation of analytical performance parameters is presented in the second part of the paper.     

100% Classification Accuracy Considered Harmful: The Normalized Information Transfer Factor Explains the Accuracy Paradox

The most widely spread measure of performance, accuracy, suffers from a paradox: predictive models with a given level of accuracy may have greater predictive power than models with higher accuracy. Despite optimizing classification error rate, high accuracy models may fail to capture crucial information transfer in the classification task. We present evidence of this behavior by means of a combinatorial analysis where every possible contingency matrix of 2, 3 and 4 classes classifiers are depicted on the entropy triangle, a more reliable information-theoretic tool for classification assessment.Motivated by this, we develop from first principles a measure of classification performance that takes into consideration the information learned by classifiers. We are then able to obtain the entropy-modulated accuracy (EMA), a pessimistic estimate of the expected accuracy with the influence of the input distribution factored out, and the normalized information transfer factor (NIT), a measure of how efficient is the transmission of information from the input to the output set of classes.The EMA is a more natural measure of classification performance than accuracy when the heuristic to maximize is the transfer of information through the classifier instead of classification error count. The NIT factor measures the effectiveness of the learning process in classifiers and also makes it harder for them to “cheat” using techniques like specialization, while also promoting the interpretability of results. Their use is demonstrated in a mind reading task competition that aims at decoding the identity of a video stimulus based on magnetoencephalography recordings. We show how the EMA and the NIT factor reject rankings based in accuracy, choosing more meaningful and interpretable classifiers.