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Future Medicinal Chemistry Oct 2017Photostability tests applied on commercial specialties for topical use have demonstrated a greater vulnerability of several drugs, due to greater exposure to light than... (Review)
Review
Photostability tests applied on commercial specialties for topical use have demonstrated a greater vulnerability of several drugs, due to greater exposure to light than other pharmaceutical forms. Photodegradation of a drug can considerably modify its pharmacokinetic behavior by varying the therapeutic index. The evaluation of the degradation profile of a drug, according to the ICH rules, is of primary importance in developing an appropriate topical formulation. Advanced strategies have been proposed to increase the protection from the light of the photolabile drugs. Supramolecular systems have been investigated to improve both pharmacokinetic profile and photostability. In this review, the more recent stability-monitoring methods for the analysis of drugs in topical formulations are collected and the main approaches for the drug photostabilization are discussed.
Topics: Administration, Topical; Drug Carriers; Drug Compounding; Drug Stability; Humans; Light; Nanoparticles; Pharmaceutical Preparations; Photolysis
PubMed: 28925725
DOI: 10.4155/fmc-2017-0105 -
Water Research Jan 2019This study investigated the contribution of direct, indirect, and self-sensitized photolysis to the photochemical fate of three model fluoroquinolones (FQs), i.e.,...
This study investigated the contribution of direct, indirect, and self-sensitized photolysis to the photochemical fate of three model fluoroquinolones (FQs), i.e., lomefloxacin (LOM), norfloxacin (NOR), and ofloxacin (OFL), and demonstrated the influence of chemical speciation on their photodegradation behavior, a topic that has received relatively little attention. Results suggest that these FQs in water transformed mainly via direct photolysis, while hydroxyl radical played a key role in their indirect and self-sensitized photolysis. Chemical speciation of such zwitterionic compounds significantly affected the kinetics of their phototransformation, with the quantum yields of photodegradation decreased in the order of zwitterionic (FQsH) > anionic (FQs) > cationic (FQsH). The photodegradation pathways of FQs depended on both their structures and chemical speciation. Defluorination for LOM in C-8 and NOR in C-6 was more significant when they were present in zwitterionic form than in the other forms. Cationic FQs underwent direct piperazinyl ring cleavage, and zwitterionic ones underwent piperazinyl ring oxidation, while the degradation pathway of piperazinyl ring for FQs in anionic form was structure dependent. Decarboxylation for zwitterionic FQs occurred more slowly compared to both cationic and anionic ones, and the FQs bearing electron-donating groups in C-8 position degraded more easily in cationic form than the anionic ones, while the opposite was true for the FQs without such a group in C-8 position. Results of Vibrio fischeri bioluminescence inhibition tests showed the toxicity of zwitterionic NOR and OFL significantly decreased after photodegradation, while the degradation products of LOM exhibited greater toxicity. These findings indicate that chemical speciation of zwitterionic compounds could affect the kinetics and pathways of their photochemical transformation, and thus have important implications on their fate and risk in aquatic environment.
Topics: Anti-Bacterial Agents; Fluoroquinolones; Kinetics; Photolysis; Water; Water Pollutants, Chemical
PubMed: 30343195
DOI: 10.1016/j.watres.2018.10.027 -
Annual Review of Biophysics and... 1989
Review
Topics: Indicators and Reagents; Light; Photochemistry; Photolysis
PubMed: 2660825
DOI: 10.1146/annurev.bb.18.060189.001323 -
Photochemistry and Photobiology Jan 1986
Topics: Lasers; Photolysis; Spectrophotometry, Ultraviolet; Tryptophan
PubMed: 3952159
DOI: 10.1111/j.1751-1097.1986.tb05585.x -
Journal of Photochemistry and... Aug 2017A recently developed antimicrobial technique utilizing hydroxyl radicals generated by hydrogen peroxide (HO) photolysis represents a promising new therapy for preventing...
A recently developed antimicrobial technique utilizing hydroxyl radicals generated by hydrogen peroxide (HO) photolysis represents a promising new therapy for preventing and treating dental caries. The present study compared the antimicrobial time-kill kinetics of HO photolysis, conventional antiseptics, and antimicrobial photodynamic therapy (aPDT) against biofilm-forming Streptococcus mutans (cariogenic bacteria) grown on hydroxyapatite disks. HO photolysis was performed by irradiating the biofilm immersed in 3% HO with 365-nm light-emitting diode (LED) light at an irradiance of 1000mW/cm for up to 1.5min. Antiseptic treatments consisted of 0.2% chlorhexidine gluconate, 0.5% povidone-iodine, and 3% HO. The biofilm was immersed in each antiseptic for up to 4min. aPDT was performed by irradiating the biofilm immersed in 100μM methylene blue or toluidine blue O with 655-nm laser light at 1000mW/cm for up to 4min. Based on the time-kill assay, the decimal reduction value (D-value) of each treatment was determined. With a D-value of 0.06min, HO photolysis exhibited the highest bactericidal effect against biofilm-forming S. mutans. In contrast, antiseptics and aPDT exerted a slower bactericidal effect, with D-values of 0.9-2.7min. In conclusion, the antimicrobial technique based on HO photolysis using 365-nm LED represents a strong adjunctive chemotherapy for dental caries treatment.
Topics: Anti-Infective Agents; Biofilms; Chlorhexidine; Durapatite; Hydrogen Peroxide; Kinetics; Light; Microscopy, Confocal; Photolysis; Povidone-Iodine; Streptococcus mutans; Time Factors
PubMed: 28666212
DOI: 10.1016/j.jphotobiol.2017.06.023 -
Journal of Agricultural and Food... Feb 2019Neonicotinoids (NN), first introduced in 1991, are found on environmental surfaces where they undergo photolytic degradation. Photolysis studies of thin films of NN were...
Neonicotinoids (NN), first introduced in 1991, are found on environmental surfaces where they undergo photolytic degradation. Photolysis studies of thin films of NN were performed using two approaches: (1) transmission FTIR, in which solid films of NN and the gas-phase products were analyzed simultaneously, and (2) attenuated-total-reflectance FTIR combined with transmission FTIR, in which solid films of NN and the gas-phase products were probed in the same experiment but not at the same time. Photolysis quantum yields using broadband irradiation centered at 313 nm were (2.2 ± 0.9) × 10 for clothianidin (CLD), (3.9 ± 0.3) × 10 for thiamethoxam (TMX), and (3.3 ± 0.5) × 10 for dinotefuran (DNF), with all errors being ±1 s. At 254 nm, which was used to gain insight into the wavelength dependence, quantum yields were in the range of (0.8-20) × 10 for all NNs, including acetamiprid (ACM) and thiacloprid (TCD). Nitrous oxide (NO), a potent greenhouse gas, was the only gas-phase product detected for the photolysis of nitroguanidines, with yields of ΔNO/ΔNN > 0.5 in air at both 313 and 254 nm. The atmospheric lifetimes with respect to photolysis for CLD, TMX, and DNF, which absorb light in the actinic region, are estimated to be 15, 10, and 11 h, respectively, at a solar zenith angle of 35° and 12, 8, and 10 h at a solar zenith angle of 15°.
Topics: Insecticides; Neonicotinoids; Nitrous Oxide; Photolysis; Spectroscopy, Fourier Transform Infrared; Sunlight
PubMed: 30698961
DOI: 10.1021/acs.jafc.8b05417 -
Analytical Chemistry Feb 1988
Topics: Chromatography, High Pressure Liquid; Pesticides; Photolysis; Spectrometry, Fluorescence
PubMed: 3354833
DOI: 10.1021/ac00154a007 -
Chemosphere Jan 2007This paper studies the pH effect on the photonitration of catechol, 1-naphthol, naphthalene, and benzene. The pH trend is influenced by the generation of HNO(2) and...
This paper studies the pH effect on the photonitration of catechol, 1-naphthol, naphthalene, and benzene. The pH trend is influenced by the generation of HNO(2) and peroxynitrous acid (HOONO) upon nitrate photolysis. HNO(2) can be involved in a direct and an indirect nitration process. Direct nitration follows the pH distribution of HNO(2) (flexus around 3). Indirect nitration, possibly involving nitrosation+oxidation, would be highest around pH3. HOONO can be involved in electrophilic nitration, where the initial formation rate of the nitroderivatives is proportional to [H(+)], or take part in nitration directly, in which case a less important pH effect in photonitration is observed. The relative importance of the various nitration pathways for each substrate determines the resulting pH effect in photonitration upon nitrate photolysis.
Topics: Benzene; Catechols; Hydrogen-Ion Concentration; Infrared Rays; Naphthalenes; Naphthols; Nitrates; Photolysis
PubMed: 16996108
DOI: 10.1016/j.chemosphere.2006.07.082 -
Environmental Science & Technology Dec 2016Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY)...
Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY) for DMS photolysis varied according to the quantity and quality of its photosensitizers, chiefly chromophoric dissolved organic matter (CDOM) and nitrate. AQY compiled from the literature and unpublished studies ranged across 3 orders of magnitude at the 330 nm reference wavelength. The smallest AQY(330) were observed in coastal waters receiving major riverine inputs of terrestrial CDOM (0.06-0.5 m (mol quanta)). In open-ocean waters, AQY(330) generally ranged between 1 and 10 m (mol quanta). The largest AQY(330), up to 34 m (mol quanta)), were seen in the Southern Ocean potentially associated with upwelling. Despite the large AQY variability, daily photolysis rate constants at the sea surface spanned a smaller range (0.04-3.7 d), mainly because of the inverse relationship between CDOM absorption and AQY. Comparison of AQY(330) with CDOM spectral signatures suggests there is an interplay between CDOM origin (terrestrial versus marine) and photobleaching that controls variations in AQYs, with a secondary role for nitrate. Our results can be used for regional or large-scale assessment of DMS photolysis rates in future studies.
Topics: Nitrates; Oceans and Seas; Photobleaching; Photolysis
PubMed: 27993080
DOI: 10.1021/acs.est.6b04278 -
Photochemistry and Photobiology Mar 2022The photolysis of vanillin produces a short-lived triplet state where its lifetime is controlled by efficient self-quenching (k ~ 2 × 10 m s ) which also...
The photolysis of vanillin produces a short-lived triplet state where its lifetime is controlled by efficient self-quenching (k ~ 2 × 10 m s ) which also generates radicals. Free radical reactions, including vanillin dimer formation, are responsible for the degradation of vanillin and is accompanied by yellowing of the acetonitrile solutions. Laser flash photolysis studies reveal a triplet absorbing at 390 nm, readily quenched by naphthalenes, conjugated dienes and oxygen. Vanillin is also a good singlet oxygen sensitizer as revealed by its characteristic NIR emission at 1270 nm.
Topics: Benzaldehydes; Photochemistry; Photolysis; Singlet Oxygen
PubMed: 34570372
DOI: 10.1111/php.13520