In Vitro Stability of Radiotracers
Lelio G. Colombetti in Principles of Radiopharmacology, 1979
They are differentiated as follows: Decomposition by the primary (internal) mechanism is the inevitable result of radionuclidic disintegration of a thermodynamically unstable atom within a molecule as its drops to a more stable energy level, and pertains to the change at that specific site within the molecule.Changes produced at other locations of the same molecule or upon other molecules of the radiotracer by the direct interaction of the energy emitted by the radionuclide are classified as primary (external) effects.Secondary radiation effects are the result of interaction of the primary emission with molecules other than those of the radiotracer, with those of the solvent, for example, to produce a reactive species that is damaging to the remaining radiotracer.Chemical decomposition refers to the changes which would occur within the system during storage, independent of radiation effects.
Preclinical assessment of bioresorbable scaffolds and regulatory implication
Yoshinobu Onuma, Patrick W.J.C. Serruys in Bioresorbable Scaffolds, 2017
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.
Dictionary
Mario P. Iturralde in Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990
Radiolysis. The chemical decomposition of materials by ionizing particles or radiation. The normal chemical and pharmaceutical stability is usually altered by radiation, hence the radiopharmaceutical stability is always lower than the chemical and pharmaceutical stability; the substances with high specific activity show autodecomposition due to direct radiation damage, which becomes significant with time.
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.
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).
Antibacterial, antioxidant, and haemolytic potential of silver nanoparticles biosynthesized using roots extract of Cannabis sativa plant
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2022
Suman Suman, Lacy Loveleen, Meena Bhandari, Asad Syed, Ali H. Bahkali, Romila Manchanda, Surendra Nimesh
The synthesis of nanoparticle employs two general mechanisms: the top-down and the bottom-up approach. The top-down approach of nanoparticles formation includes the mechanical (laser/thermal ablations, ball milling, etc.) and some of the chemical methods such as chemical leaching. On the other hand, the bottom-up approach accompanies the biological method using plant parts, algae, bacteria and fungi as source of nanoparticles formation along with some of the chemical methods (spray pyrolysis, chemical decomposition, aerosol process, etc) [5]. Thus, the phytochemicals-mediated green synthesis of AgNPs using a bottom-up approach is employed due to their low toxicity, robustness, eco-friendliness, and affordability [6]. The plant extracts contain several metabolites, amongst them some act as reducing agents while some as capping agents for AgNPs [7]. Several studies have been conducted so far on the biosynthesis of AgNPs using plant extract that includes Terminalia arjuna [8] and Prosopis juliflora bark [9], Canarium ovatum [10], Cordia dichotoma [11] and Punica granatum leaf [12], orange peels [13], Putranjiva roxburghii Wall. seed [14], leaves of Eucalyptus globulus [15], Azadirachta indica [16] and Brassica oleracea [17] and many other such plants.
Related Knowledge Centers
- Acid
- Chemical Reaction
- Chemical Synthesis
- Electrolysis
- Mass Spectrometry
- Sodium Azide
- Thermogravimetric Analysis
- Molecular Entity
- Reaction Intermediate
- Gravimetric Analysis