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Chemosensory Disorders and Nutrition
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
Carl M. Wahlstrom, Alan R. Hirsch, Bradley W. Whitman
Firefighters are exposed to high levels of olfactotoxins, with risk of synergy, formed during pyrolysis (application of heat to cause chemical decomposition). Combustion of wood alone produces as many as 200 toxic chemicals. Hydrogen sulfide, for example, has been demonstrated to induce olfactory loss. Oxidation of such materials as diesel fuel and fabrics produces a mixture of nitrogen oxides, including nitrogen tetroxide, acute exposures of which are olfactotoxic at low levels. Thermal degradation of polyvinyl chloride produces at least 75 toxic chemicals including the olfactotoxin chlorine. Other common olfactotoxins produced during combustion include: acrolein (from wood, at levels exceeding 3 ppm), ammonia (from household furnishings), halogen acid gases (from flame-retardant materials), isocyanates (from urethane isocyanate polymers), phosgene (from solvents), sulphur dioxide (at levels as high as 42 ppm), carbon monoxide (which ranges from 11 to 1087 ppm in fires), hydrogen cyanide (from paper and clothing, at levels up to 75 ppm), and heavy metals including cadmium, chromium, lead and zinc.
Special Problems with Biological Fluids
Published in Joseph Chamberlain, The Analysis of Drugs in Biological Fluids, 2018
Degradation before analysis is often a result of straightforward chemical decomposition due to the instability of the drug itself, particularly in fluids such as urine which may have extremes of pH, or which lack the protective effect of being bound to plasma proteins. Acidification is often used as a preservative in urine, and although it may stabilize some labile conjugates such as N-glucosides of barbiturates,233 it hydrolyze others more rapidly. Thus, it is particularly important in drug metabolism studies to be able to distinguish true metabolism (or lack of it) from such false results.
Preclinical assessment of bioresorbable scaffolds and regulatory implication
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
Tobias Koppara, Eric Wittchow, Renu Virmani, Michael Joner
In contrast to permanent metallic implants, which are nearly chemically inert within the biological environment of arterial tissue [32], fully bioresorbable devices are subject to structural and chemical alterations caused by degradation processes. The dismantling of a mechanically stable structure into smaller molecules and biologic products allows the body to metabolize degradation products using natural pathways [33]. However, these reactions are all dependent on the compounds used. In order to assess the biocompatibility of BRSs, it is necessary to identify the physicochemical structure and biological behavior of all chemical products liberated during bioresorption, including substances, which occur only in small amounts or even in traces. It is likely that the chemical decomposition of bioresorbable polymers is connected to an inherent acidification of the environment [34], whereas degrading bioresorbable metals provoke a shift toward higher pH-values [35]. Monitoring the tissue concentration of degradation products may be helpful to understand the biological response of the arterial microenvironment, but is limited by the existing analytical technologies.
Potentially toxic elements (PTEs) in fillet tissue of common carp (Cyprinus carpio): a systematic review, meta-analysis and risk assessment study
Published in Toxin Reviews, 2021
Yadolah Fakhri, Babak Djahed, Ali Toolabi, Amir Raoofi, Abdolmajid Gholizadeh, Hadi Eslami, Mahmoud Taghavi, Mohammad reza Alipour, Amin Mousavi Khaneghah
As species contaminate surface and groundwater resources as a result of natural processes such as dissolving minerals, chemical decomposition, as well as human activities such as electronics and metallurgy industries (Zaw and Emett 2002, Gholami et al. 2006, Uddin et al. 2006). As is mobile in the environment and this regard could penetrate into the hydrological cycle and food chain using different pathways such as rainfall (Mandal and Suzuki 2002). It is a toxic and accumulative substance and can inhibit SH-group enzymes (Ventura-Lima et al. 2011) which may cause dysfunction in the digestive system, liver cancer, shock leading to death, pulmonary and respiratory failures and kidney damage (Rahmani et al. 2010, Lee et al. 2014); it is also known as a carcinogenic substance that can cause bladder, lung and skin cancers (Shen et al. 2013).
Drug stability testing and formulation strategies
Published in Pharmaceutical Development and Technology, 2018
Drug stabilisation is one of the main focuses in formulation development, manufacture and extemporaneous compounding. This issue also brings together a series of articles discussing various formulation strategies to improve drug stability. Drug substances can be susceptible to various forms of chemical decomposition during storage, and some drug molecules can even be destroyed in vivo, for example in gastric juice, before transport to blood stream. Thanks to the advancement in formulation science, which successfully brings forth improvement of drug stability based on the understanding of molecular structure, mechanisms of degradation and the factors affecting drug stability. Cyclodextrin-complexation, solid dispersion, lipid-based formulation, just to name a few. The advances in nanotechnology has also contributed to the successful development of stable formulations with potential for targeted drug delivery. Furthermore, the manufacturing process can be designed to maintain the drug stability based on the knowledge of drug property and its interplay with the operation. Herein quasi-emulsion solvent diffusion method has been used as an example, albeit choice of excipients is equally vital. Besides, biological drugs, proteins and antibodies, are becoming the mainstay of the biopharmaceutical industry, innovative methodology is being sought to test their stability.
The relationship between the Hammett acidity and the decomposition of cefotaxime sodium in the solid state
Published in Drug Development and Industrial Pharmacy, 2020
Bashar M. Altaani, Khouloud A. Alkhamis, Shaima’a Abu Baker, Razan Haddad
Amorphous solids usually have desirable pharmaceutical properties, such as rapid dissolution rates. However, one of the main shortcomings of using amorphous compounds is their potential to chemical decomposition. The chemical decomposition is usually affected by several factors such as moisture content, molecular mobility and polarity. The acidity has also a significant effect on chemical decomposition, therefore the solid-state acidity [1–11] and chemical instability [1–4,8,12–18] have been the subjects of many investigations.