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Chemical Permeation through Disposable Gloves
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
There are several similar standard tests for measuring the permeation of chemicals through protective gloves or other protective materials. The most commonly used methods are the American standard ASTM F 739 and the European standards EN 374-1 and EN 16523-1.10–12 They both use a similar test cell with two chambers: a flow-through chamber for the collection medium and a chamber with an inlet for a test chemical (Figure 24.1). A sample of the protective material being studied is clamped between the chambers. The permeation of a test chemical is measured periodically from the flow of the collection medium. Methods of analytical chemistry such as chromatography and spectrometry are used; the collecting medium is usually nitrogen, purified air, or water. The test is carried out for the time specified in the standard or until a specified permeation rate is exceeded. BT is used as the criterion of the resistance to permeation. The BT is the time between the application of the test chemical onto the outer surface of the sample material and the detection of the test chemical permeating the material at a specified rate (in µg/cm2/min). The major differences in the standards are discussed elsewhere in this book, as well as in a review by Banaee and Que Hee.13
Approaches for Identification and Validation of Antimicrobial Compounds of Plant Origin: A Long Way from the Field to the Market
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Lívia Maria Batista Vilela, Carlos André dos Santos-Silva, Ricardo Salas Roldan-Filho, Pollyanna Michelle da Silva, Marx de Oliveira Lima, José Rafael da Silva Araújo, Wilson Dias de Oliveira, Suyane de Deus e Melo, Madson Allan de Luna Aragão, Thiago Henrique Napoleão, Patrícia Maria Guedes Paiva, Ana Christina Brasileiro-Vidal, Ana Maria Benko-Iseppon
Taken together, laboratory approaches of analytical chemistry, biochemistry, molecular biology and biotechnology can and shall successfully be complemented by omics data and bioinformatics, favoring the development of more precise, personalized and optimized medicine.
Drug Design, Synthesis, and Development
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Understanding organic reaction mechanisms and the step-by-step processes by which molecules can be combined and altered enables chemists to design novel compounds. This is of fundamental importance to drug discovery because new drug molecules can be rationally designed to interact with a biological target associated with a disease and therefore have a biological effect that improves the condition of the patient. Subtle modification of molecular structures and lead compound optimisation can be done by implementing techniques in organic synthesis to yield the best possible drug properties of a lead compound. A key example of where this is important is asymmetric synthesis, where a stereospecific drug-target interaction is required, which could otherwise lead to side effects; note the case of thalidomide. While it is imperative to synthesise drugs with the least possible side effects, it is also essential to ensure the purity of drugs. This is the role of the analytical chemist, who has the important occupation of screening for and eliminating contaminants. Analytical techniques have improved greatly in modern times; contaminants can be traced below nano-gram levels, and methods such as spectroscopic techniques can be used to characterise the contaminants. As technologies advance in the future, medicinal chemists will be well equipped to manage the challenges that are presented to the field of medicine in the coming decades.
Implementation of a dermal sensitization threshold (DST) concept for risk assessment: structure-based DST and in vitro data-based DST
Published in Critical Reviews in Toxicology, 2022
Taku Nishijo, Anne Marie Api, G. Frank Gerberick, Masaaki Miyazawa, Mihwa Na, Hitoshi Sakaguchi
Non-animal test methods have been developed largely focusing on individual chemical substances, which is defined as the main constituent present at a concentration of at least 80% (w/w) (OECD 2018a, 2018b) because chemicals in the dataset used for the analysis of predictive performance are mostly substances with a characterized hazard of skin sensitization. However, in practice, for risk assessment of ingredients in consumer products, it is inherently essential to address not only the main components but also minor constituents contained in the ingredients/products (Giménez-Arnau 2019). Furthermore, complex mixtures from natural sources, such as essential oils and botanical extracts, are also commonly used in consumer products. Some constituents in the ingredients may be structurally identified (or predicted) based on knowledge of material and analytical chemistry. In contrast, others may be only partially characterized or, for many others, unidentified.
Development of UV–visible spectrophotometric methods for the quantitative and in silico studies for cilazapril optimized by response surface methodology
Published in Drug Development and Industrial Pharmacy, 2021
Moreover, the assessment of donor–acceptor interaction by the chemists and biologist is to single out their practicality that could cater the breadth of applications not simply in biological and chemical fields but the industrial domain and material sciences as well [7–9]. Use of this phenomenon-based approach is a critical step in proposing cost-effective, rapid, and well-grounded methods for the determination, detection, and quantitative assay of drugs in bulk and pharmaceutical formulations and to study the potential mechanism of their action [10]. Donor species containing N, O, and S atoms have drawn marked importance in this phenomenon [11]. Donor–acceptor phenomenon typically starts when the discrete donor (electron-rich species) and acceptor species (electron-deficient species) combines and non-covalent interaction of lower intensity comes into play [12]. Of late, the enactment of a new strategy called quality by design (Qbd) approach has taken the analyst by storm in the development of analytical methods. This approach in the way of analytical chemistry is used to determine impurities in drug substance and drug products and is called Analytical Quality by Design approach [13].
Global optimization of the Michaelis–Menten parameters using physiologically-based pharmacokinetic (PBPK) modeling and chloroform vapor uptake data in F344 rats
Published in Inhalation Toxicology, 2020
Marina V. Evans, Christopher R. Eklund, David N. Williams, Yusupha M. Sey, Jane Ellen Simmons
Physiologically based pharmacokinetic (PBPK) models are well-established frameworks used to describe time-course data after exposure to xenobiotics (Caldwell et al. 2012). One of the advantages of PBPK models is that they can include multiple exposure routes, such as dermal, inhalation or oral, alone or in combination with each other. For volatile chemicals, two major routes of exposure include inhalation (as a vapor) and oral ingestion from contaminated water. When studying inhalation, two different types of inhalation chambers are used. One chamber type, the flow-through chamber, maintains a constant concentration by adding additional chemicals as needed. The second chamber type uses a bolus injection of the chemical and the rodents are exposed in a closed system. The bolus type inhalation or vapor uptake experiments is a well-established method for estimating metabolic constants for volatile organic compounds (VOC) (Andersen et al. 1980; Gargas et al. 1990; Filser 1992; Evans et al. 1994). In this case, the rodent is placed in a chamber that is sealed to room air, while providing oxygen and removing CO2 and humidity. After the initial bolus injection, the concentration of the chemical in the chamber air will decrease following inhalation by the animal; this decrease typically occurs in two phases, with the first phase dominated by distribution within the animal, and the second phase dominated by metabolism within the animal. The chemical concentration is measured over time using automated analytical chemistry techniques. The vapor uptake chamber is an experimental method that lends itself to estimate metabolism by using the decline in chemical concentration inside the closed chamber (Gargas et al. 1990; Filser et al. 2004).