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Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Published in Anton C. de Groot, 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).
Global Regulation of Preservatives and Cosmetic Preservatives
Published in Philip A. Geis, Cosmetic Microbiology, 2020
The salts are sodium, potassium, calcium, magnesium, ammonium, and ethanolamine. The anions are chlorides, bromides, sulfates, and acetates. The esters are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and phenyl.
Production of Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Hydrolysis of esters to alcohols and acids can occur during steam distillation. This can have serious implications in the case of ester-rich oils, and special precautions have to be taken to prevent or at least to limit the extent of ester degradation. The most important examples of this are lavender or lavandin oils rich in linalyl acetate and cardamom oil rich in α-terpinyl acetate. Chamazulene, a blue bicyclic sesquiterpene, present in the steam-distilled oil of German chamomile, Chamomilla recutita (L.) Rauschert, flower heads, is an artifact resulting from matricin by a complex series of chemical reactions: dehydrogenation, dehydration, and ester hydrolysis. As chamazulene is not a particularly stable compound, the deep-blue color of the oil can change to green and even yellow on aging.
Comparative chemical and biological hydrolytic stability of homologous esters and isosteres
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Hygor M. R. de Souza, Jéssica S. Guedes, Rosana H. C. N. Freitas, Luis G. V. Gelves, Harold H. Fokoue, Carlos Mauricio R. Sant’Anna, Eliezer J. Barreiro, Lidia M. Lima
Esters are one of the most explored functional groups in the preparation of prodrugs. Several bioactive compounds and drugs containing carboxylic acids and free hydroxyl groups exhibit limited oral bioavailability due to absorption and/or first-pass metabolism problems1,2. Ester pro-drugs usually display better tissue mobility and they are non-specifically hydrolysed by human esterases, such as carboxylesterases 1 and 2 (CES 1 and CES 2) to yield high circulating concentrations of the active component post absorption3,4. Therefore, the presence of an ester group in the structure of bioactive compounds is often associated with metabolic instability. In fact, ester groups could be introduced during the design of soft drugs, defined as therapeutically active compounds that undergo a predicted fast metabolism into inactive metabolites after exerting their desired therapeutic effects5.
Phenolic benzotriazoles: a class comparison of toxicokinetics of ultraviolet-light absorbers in male rats
Published in Xenobiotica, 2021
Suramya Waidyanatha, Esra Mutlu, Seth Gibbs, Jessica Pierfelice, Jeremy P. Smith, Brian Burback, Chad T. Blystone
We used a method, utilizing protein precipitaion followed by LC-MS/MS, to quantitate phenolic benzotriazoles. The use of protein precipitation for sample cleanup and incorporation of 96-well format increased the efficiency of the method and sample throughput. For all compounds, except the ester, the parent concentrations were quantified. For the ester, the corresponding acid, tBuPrA-BZT, was used. Analytical method qualification data for the quantitation of analytes are summarized in Table 3. Standard curves were linear over the concentration ranges evaluated with coefficients of determination >0.98 for all analytes. Estimated LOD values ranged from 0.166 to 1.16 ng/mL depending on the analyte (Table 3). The %RE values estimated based on calibration standards were ≤ ±18.9 and QC samples were ≤ ±22.7. The %RSD values were ≤13.7 for all except for octrizole which was ≤24.5 Taken collectively, the data show that the method is suitable for the quantitation of analytes in plasma from the investigation on TK behaviour of the class.
Liposome–ligand conjugates: a review on the current state of art
Published in Journal of Drug Targeting, 2020
This is the most frequently used linkage in terms of engineering liposome conjugates. Ester bond is formed when hydroxyl group of a molecule reacts (sometimes with the help of succinic acid as linkers) with carboxylic acid group of the liposomes or vice versa [100]. Because of the unreactive nature of carboxyl groups (due to low nucleophilic property), reactants such as carbonyl diimidazole are used to modify these carboxyl groups to make room for ester linkages. Carbonyl diimidazole is an active carbonylating agent consisting of two acylimidazole-leaving groups that react with carboxylic acids to generate N-acylimidazoles of high reactivity. The active carboxylate resulting from this reaction is then positioned to bond with hydroxyl groups through ester linkages [64]. This bond is usually meant to be broken by esterase enzymes through the process of hydrolysis; but then several factors including adjacent groups (e.g. bromide) and spacers may influence the cleavage process [101,102]. Guo and Szoka [103] utilised diortho ester to successfully synthesise low pH-sensitive PEG-diortho ester-distearoyl glycerol conjugate (POD). Distearoyl glycerol containing two saturated hydrocarbon side chains is coupled to the diortho ester (3,9-diethyl-2,4,8,10-tetraoxaspiro[5]undecane) in order to facilitate the anchoring of PEG2000 into lipid bilayers. The formed liposome conjugate was found to be stable up to 12 h at neutral pH, but degraded at pH 5 to release the payload, and thus found to be suitable for application in tumour targeting.