Principles of Radioiodination and Iodine-Labeled Tracers in Biomedical Investigation †
Garimella V. S. Rayudu, Lelio G. Colombetti in Radiotracers for Medical Applications, 2019
The synthesis of NP-59 and 19-iodocholesterol is shown in Figure 27. The authors synthesized cholest-5-ene-3,19-diol-3-acetate (I) by multistep synthesis described by Kalvoda et al.218 Treatment of this compound with p-toluene sulfonyl chloride in pyridine yielded the desired tosylate (II). The acetate ester (II) was subjected to selective hydrolysis with an aqueous methanolic alkali solution under mild conditions to obtain compound III. Cholest-5-ene-3,19-diol tosylate (III) was refluxed with Nal and absolute alcohol under a stream of nitrogen for 4 hr. The alcohol was evaporated under vacuum, extracted with ether, and dried over anhydrous Na2SO4. The resulting products were ⋍90% NP-59 (6β-iodomethyl-19-nor-cholest-5[10]-en-3β-ol) and ⋍10% 19-iodocholesterol. When the mixture containing 19-iodocholesterol and ⋍30% NP-59 was refluxed under nitrogen in isopropanol or absolute ethanol with Nal, the resulting products contained 90% NP-59 and 10% 19-iodocholesterol.
Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Anton C. de Groot in Monographs in Contact Allergy, 2021
General aspects of corticosteroids used on the skin and mucous membranes are discussed in Chapter 2.4. A practical guideline for diagnosing allergic reactions to corticosteroids is presented in ref. 2. Methylprednisolone base is used in oral forms only. Esters used in other applications include methylprednisolone acetate (Chapter 3.119), methylpredni- solone hemisuccinate (Chapter 3.220), and methylprednisolone aceponate (Chapter 3.218). As methylprednisolone base is used as tablet only, this implies that by far most allergic reactions to ‘methylprednisolone’ have in fact been the result of sensitization to an ester of methylprednisolone or of cross-reactivity to another corticosteroid. It is also likely that there has been confusion in some publications on the correct forms of the drugs used, e.g. that methylprednisolone was mentioned where in fact an ester form should have been mentioned (1,3).
Alcohol, drugs, toxins and post-mortem toxicology
Helen Whitwell, Christopher Milroy, Daniel du Plessis in Forensic Neuropathology, 2021
Ethanol is an alcohol consumed in alcoholic beverages. It produces neurological dysfunction both directly and secondary to vitamin deficiencies and metabolic dysfunction (Sutherland et al. 2014a). Alcohol is typically consumed orally and rapidly absorbed by the gastrointestinal tract, mostly in the small bowel. It is not bound by plasma proteins, so is rapidly diffused in the blood stream. Because it is essentially not absorbed by fat or bone, its volume of distribution is related to the total body water. As such men have a lower blood ethanol compared with women when the same amount of ethanol is consumed. Alcohol is metabolised to acetaldehyde via three main enzyme pathways: alcohol dehydrogenase (ADH), microsomal ethanol oxidising system (MEOS), which requires the CYP2E1 enzyme system, and peroxisomal catalase, though the latter pathway is not significant in vivo. Non-oxidative pathways also occur. ADH is the main pathway at low concentrations but with chronic use MEOS becomes more important. The rate of metabolism of ethanol is typically 15–18 mg/100 mL per hour but may vary between 10 and 25 mg/100 mL per hour. Alcohol elimination is a zero order process at high concentrations, but this is not the case with very low concentrations. Most ethanol is metabolised in the liver. This results in the production of acetoacetate which is converted to acetate.
The role of short-chain fatty acids in the interplay between gut microbiota and diet in cardio-metabolic health
Published in Gut Microbes, 2021
Ana Nogal, Ana M. Valdes, Cristina Menni
Acetate can be synthesized through two different pathways. Firstly, acetyl-CoA can be produced by decarboxylation of pyruvate, then, acetyl-CoA is hydrolyzed to acetate by an acetyl-CoA hydrolase.80 Most of the acetate is produced by enteric bacteria, including Prevotella spp., Ruminococcus spp., Bifidobacterium spp., Bacteroides spp., Clostridium spp., Streptococcus spp., A. muciniphila, and B. hydrogenotrophica, using this pathway.81 Secondly, the Wood-Ljungdahl pathway can be also used by acetogenic bacteria to form acetate from acetyl-CoA. Here, the reduction of carbon dioxide generates carbon monoxide, which reacts with a coenzyme A molecule and a methyl group to produce acetyl-CoA. At the same time, acetyl-CoA is the substrate to obtain acetate.82
Use of cellulose acetate butyrate as a carrier for preparation of alcohol-resistant matrix tablet
Published in Pharmaceutical Development and Technology, 2020
Rebaz Ali, Langa Toufik, Andriy Dashevskiy
Polymers such as polyvinyl acetate (Kollidon® SR), ammonium methacrylate copolymer (Eudragit® RS/RL) and ethylcellulose (Ethocel®) are used as water-insoluble carriers (Katikaneni et al. 1995; Song et al. 2016; Ali 2017). Cellulose acetate butyrate esters are a group of water-insoluble polymers that dissolve in highly flammable organic solvents such as acetone. However, CAB with high hydroxyl level dissolves in a less dangerous organic solvent such as alcohol (Eastman 2006). Alcohol soluble CAB, as a water-insoluble polymer, was investigated as a new coating material for osmotic pump tablets (Ali et al. 2018). Despite the advantages of extended-release dosage forms, the potential drug release acceleration associated with alcohol consumption is a general concern. In mid-1970 through 1980, few studies were conducted to determine the effect of ethanol on the in vitro and in vivo dissolution of a drug from microencapsulated and extended-release tablets (Frömming and Topaloglu 1975; Frömming and Schwabe 1980). Hydromorphone, formulated into extended-release pellets (Palladone XL®) using ethylcellulose and Eudragit® RS, was withdrawn from the US market due to the potentially fatal dose dumping caused by alcohol (Meyer and Hussain 2005). Hence, there is a strong need to investigate the potential of alcohol to alter the drug release profile from extended-release products.
Fractionation and bioassay-guided isolation of antihypertensive components of Senecio serratuloides
Published in Cogent Medicine, 2020
Charlotte Mungho Tata, Derek Ndinteh, Benedicta Ngwenchi Nkeh-Chungag, Opeopluwa Oyehan Oyedeji, Constance Rufaro Sewani-Rusike
The polarity of solvents used in extraction determines the difference in type, composition, and bioactivity of phytochemicals extracted (Dehkharghanian, Adenier, & Vijayalakshmi, 2010). Ethyl acetate is a semipolar solvent that can dissolve sterols, alkaloids, glycosides, terpenoids, and flavonoids. Methanol is polar and can dissolve polar compounds such as sugar, amino acid, glycosides, phenolic compounds, flavonoids, terpenoid, saponin, tannin, flavone, phenone, and polyphenol (Sri Widyawati, Budianta, Kusuma, & Wijaya, 2014). Although the two solvents had great disparity in yield, they extracted similar phytochemicals some of which were not found in SSDCM and SSHex. Hexane is non-polar and can dissolve nonpolar compounds, such as lignin, wax, lipid, aglycon, sterol, and terpenoid (Sri Widyawati et al., 2014). This suggests that S. serratuloides had fewer phytochemicals with non-polar properties.
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