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Reactor-Produced Radionuclides
Published in Frank Helus, Lelio G. Colombetti, Radionuclides Production, 2019
High chemical purity is an important requirement for radionuclides employed as tracers or as intermediates for the preparation of labeled compounds. Chemical purity may be defined as the percentage of the specified chemical form in the preparation regardless of any isotopic substitution, vehicles, carriers, preservatives, and essential additives being excluded. However, the chemical concentration levels of most radiotracer preparations are very small and are in the range of micro or millimolar and are often below the concentration levels of many other ingredients which may be present. For example, in a solution of sodium iodide 131I of concentration 10 mCi/mℓ, the concentration of Nal will be in the range of 2 to 10 μM whereas that of carbonate, chloride, sulfate, etc., may be in the range of 10 to 100 μM. The chemical purity of such preparations is hence specified in terms of the absence of undesirable impurities such as heavy metal contaminants (these should be below 2 parts per million of the solution), and reducing agents such as oxalate, thiosulfate, sulfite, etc. The latter are undesirable in solutions of 125I and 131I used for labeling of proteins and hormones, but do not interfere in the use of these nuclides for thyroid function studies. Table 7 outlines the currently accepted criteria of chemical purity for some reactor-produced radionuclides.
Radiochemical Processing of Activated Targets
Published in Frank Helus, Lelio G. Colombetti, Radionuclides Production, 2019
The chemical purity of radioactive products is a reflection of the chemical composition of the sample, with specific emphasis on the amounts of nonradioactive components. The requirements for chemical purity associated with radionuclide production are sometimes less clear than are those for radionuclidic or radiochemical purity. Certainly in some applications, such as the sealed sources used as counting standards, the chemical composition of the product is of little concern. At the other extreme, in radiopharmaceutical preparations which are intended for human use, the most stringent limitations on chemical purity come into effect.
Solid Lipid Nanoparticles for Anti-Tumor Drug Delivery
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Ho Lun Wong, Yongqiang Li, Reina Bendayan, Mike Andrew Rauth, Xiao Yu Wu
The drug-derivatization strategy was adopted for SLN encapsulation of 5-FU. The water solubility of 5-FU is 12.2 mg/ml that makes it very difficult to be loaded in SLN. Wang et al. reduced the water solubility by conjugating two octanoyl groups to the 5-FU molecule,90 resulting in 3′,5′-dioctanoyl-5-fluoro-2′-deoxyuridine (FuDR). This lipophilic drug derivative could be loaded into SLN with an encapsulation efficiency at over 90%. This strategy, however, requires tedious procedures of chemical synthesis. The chemical purity and identity of the final product have to be confirmed, and the toxicity and efficacy of the derivative also needs to be evaluated. All these steps demand substantial amounts of work. Drugs like 5-FU can be easily diluted and administered without the concern for drug precipitation such as in the cases of the lipophilic compounds, this probably provides very little motivation for the researchers to go through all these tedious procedures. However, one must keep in mind that SLN provide more than just drug solubilization and stabilization. They also allow controlled release, and they possibly improve the anti-tumor (activities, side effect profiles, and biodistribution patterns of the loaded drugs. Successful development of SLN formulations for this class of anti-tumor drugs can still be rewarding.
Changes in corneal and anterior chamber indices due to methamphetamine abuse
Published in Clinical and Experimental Optometry, 2022
Monireh Mahjoob, Samira Heydarian
Pharmaceutical companies produce only a small percentage of these drugs, while most of them are manufactured illegally for non-medical purposes. The relatively simple production of meth and the low cost of illegal laboratories in addition to its high risk for dependency have resulted in the widespread usage of this substance and have made it a serious health challenge around the world. Meth exists in different forms and at various degrees of chemical purity.1,3 It is taken orally, intravenously, or intra-nasally. Each root of (crystal) meth administration is associated with differences in ischaemic and haemorrhagic lesions. Specifically, intranasal administration is associated with a higher risk of ischaemic lesions. The euphoric effects of Amphetamine-type stimulants are temporary, which encourages repeated consumption after a short period of time.4,5 This, in turn, may cause permanent changes to the function and structure of the eye.
Pharmacokinetics, tissue distribution and excretion of five rhubarb anthraquinones in rats after oral administration of effective fraction of anthraquinones from rheum officinale
Published in Xenobiotica, 2021
Di Zhao, Su-Xiang Feng, Hao-Jie Zhang, Na Zhang, Xue-Fang Liu, Yan Wan, Yu-Xiao Zhou, Jian-Sheng Li
The reference substances of aloe-emodin, rhein, emodin, chrysophanol, physcion and 1, 8-dihydroxyanthraquinone (internal standard (IS)) were obtained from the National Institute for Food and Drug Control (Beijing, China). Chemical purity of these reference substances was more than 98% on high-performance liquid chromatography (HPLC). Solid phase extraction (SPE) cartridges (C18, 3 mL, packed with 200 mg of 50 μm particle sizes) were purchased from Bonna-Agela Technologies (Tianjin, China). HPLC grade methanol was purchased from Dikma Technology Inc. (Beijing, China). The ultrapure water was produced by the Millipore Milli-Q system (Bedford, MA, USA). All other reagents and solvents were commercially available and analytical grade. Rheum palmatum L., Sichuan, was purchased from Zhengzhou Ruilong pharmaceutical Co., Ltd. (Zhengzhou, China) and authenticated by Dr. Sui-qing Chen (College of Pharmacy, Henan University of Traditional Chinese Medicine). Rhubarb extract was prepared in our laboratory. The contents of five anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) in rhubarb extract were 87, 115, 231, 263 and 176 mg/g, respectively (Feng et al. 2013, 2014).
Absorption, distribution, metabolism and excretion of an isocitrate dehydrogenase-2 inhibitor enasidenib in rats and humans
Published in Xenobiotica, 2019
Zeen Tong, Christian Atsriku, Usha Yerramilli, Xiaomin Wang, Yan Li, Josephine Reyes, Bin Fan, Hua Yang, Matthew Hoffmann, Sekhar Surapaneni
Enasidenib (chemical purity > 99%), [14 C]enasidenib (2.5 µCi/mg, radiochemical purity and chemical purity > 99%) and the reference standards for metabolites, AGI-16903 (M1) and AGI-17011 (M2) were supplied by Celgene (Summit, NJ). Carbo-Sorb® E Scintillation Liquid, PERMAFLUOR E+ Scintillation Liquid and Ultima Gold Scintillation Liquid were purchased from PerkinElmer (Downers Grove, IL). Ammonium acetate, formic acid and other chemicals were ordered from Sigma-Aldrich (St. Louis, MO). Acetonitrile, methanol and other organic solvents were purchased from Fisher (Fair Lawn, NJ). Water was prepared in-house using a Millipore Water Purification System (Bedford, MA).