Detection of photogenotoxicity in skin and eye in rat with the photo comet assay (original) (raw)
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Journal of Photochemistry and Photobiology B: Biology, 2005
Phototoxic side effects of pharmaceutical and cosmetic products are of increasing concern for patients, dermatologists and the chemical industry. Moreover, the need of new chemicals and drugs puts pressure on pre-clinical test methods for side effects, especially interactive adverse-effects with UV-light. So, the predictive potential of different established test methods, which are used regularly in our departments in order to detect the phototoxic potential of chemicals, were analyzed. Namely the fibroblast 3T3 test, the photo henÕs egg test, a guinea pig test for measuring acute photoreactions, and a modified Local Lymph Node Assay, the Integrated Model for the Differentiation of Skin Reactions. Various agents with different photoreactive potential were tested: quinolones like Bay y 3118, ciprofloxacin, enoxacin, lomefloxacin, moxifloxacin, ofloxacin, sparfloxacin, as well as promethazine, chlorpromazine, 8-methoxypsoralen and olaquindox serving as control. Special emphasis was taken to evaluate the capability of the employed test procedures to predict phototoxic side effects in patients. Following our results, both in vitro assays were useful tools to detect photoirritancy while the photoallergic potentials of tested compounds were exclusively detected by an in vivo assay. As long as no in vitro model for photoallergy is available, the UV-IMDS should be considered to evaluate photoallergic properties of a supposed photoreactive agent.
Drug-induced Photosensitivity: Photoallergic, Phototoxic and Adverse Drug Reactions
International Journal of Medical Sciences and Nursing Research 2, 2024
Background: Drug-induced photosensitivity refers to skin reactions caused by exposure to ultraviolet light following the use of certain medications, which can be administered topically or orally. When ultraviolet radiation interacts with a chemical present in adequate concentrations within the skin, it may trigger various reactions, particularly in susceptible individuals. The most common responses are photoallergic and phototoxic reactions. Methods: In this paper, we discussed about drug-induced photosensitivity: Photoallergic, phototoxic and adverse drug reactions, and some of those medication that leads to these conditions. Results: Photosensitive drug eruptions are cutaneous adverse events due to exposure to a medication and either ultraviolet or visible radiation. Conclusion: Photosensitive drugs (PSDs) represent an important research area and more investigations would be helpful to better predict drug photosensitizing potential, prevent and manage cutaneous adverse events and find the most appropriate alternative therapeutic strategy. As well as, various medications, particularly antibiotics and analgesics, can induce both photoallergic and phototoxic reactions, there are significant differences between the two, including their onset timing, requirement for prior exposure, underlying mechanisms, clinical presentation, and histopathological features. Keywords: drug-induced photosensitivity, photoallergic, phototoxic, adverse drug reactions, medications.
Frontiers in Allergy
Drug-induced photosensitivity (DIP) is a common cutaneous adverse drug reaction, resulting from the interaction of ultraviolet radiations, mostly ultraviolet A, with drugs. DIP includes phototoxicity and photoallergy. A phototoxic reaction is obtained when topical and systemic drugs or their metabolites absorb light inducing a direct cellular damage, while a photoallergic reaction takes place when the interaction between drugs and ultraviolet radiations causes an immune cutaneous response. Clinically, phototoxicity is immediate and appears as an exaggerated sunburn, whereas photoallergy is a delayed eczematous reaction. DIP may show several clinical subtypes. In this mini-review we report the pathogenetic mechanisms and causative drugs of DIP. We offer a detailed description of DIP clinical features in its classical and unusual subtypes, such as hyperpigmentation/dyschromia, pseudoporphyria, photo-onycolysis, eruptive teleangiectasia, pellagra-like reaction, lichenoid reaction, phot...
A new in vitro protocol for assessing phototoxic effects of xenobiotics on human keratinocytes
2012
Routine protocols of phototoxicity tests are based on cultured mouse fibroblasts, mainly because these cells are robust and easy to culture in vitro. However, in a real-life situation, phototoxic reactions take place primarily in the epidermis, comprised of keratinocytes -cells which differ substantially from fibroblasts with regard to structure and function. Therefore, keratinocyte cultures seem more appropriate for the phototoxicity testing of xenobiotics, such as cosmetic ingredients or drugs. Aim: To design and implement a test protocol for in vitro assessment of phototoxic properties of xenobiotics in normal human keratinocytes. Material and methods: As a starting point, we applied the EU-approved protocol for testing phototoxicity in mouse fibroblast cultures (3T3 Neutral Red Uptake Phototoxicity Assay, DB-ALM No. 78). The protocol was modified and adjusted in a series of experiments to the specific demands of cultured normal human keratinocytes. After obtaining a stable growth of keratinocytes in microcultures, the cells were exposed for 1 hour to model agents with phototoxic properties known from clinical observations: chlorpromazine, 8-methoxypsoralen, chloroquine, promethazine, etofenamate, ketoprofen, doxycycline, lymecycline, and isotretinoin in a series of concentrations of 0, 1, 3, 11, 33, and 100 μg/ml. Subsequently, the cultures were exposed to the cumulative dose of 5 J/cm 2 of artificial sunlight using the EU-recommended solar simulator. The survival of keratinocytes was assessed by their uptake of neutral red (NR) dye. Results: Using the proposed test protocol, we were able to achieve stable growth of normal adult human keratinocytes in vitro. In the absence of phototoxic agents, no effects of light on cell viability were noticeable up to the dose of 10 J/cm 2 . The proposed system was capable of demonstrating phototoxicity of model phototoxic xenobiotics selected for the tests, which was in line with the clinical experience regarding phototoxic effects of these agents in humans. Conclusions: We have developed an in vitro protocol for assessment of the phototoxic potential of xenobiotics in normal human keratinocytes. Its functionality and reliability has been confirmed by tests results with known phototoxic agents. Although more difficult to culture than mouse fibroblasts, and therefore neglected in routine phototoxicity testing, human keratinocytes seem more appropriate for predicting in vitro phototoxic effects of xenobiotics in human skin, as phototoxic processes predominantly involve the epidermis which consists of keratinocytes.
Chemical Research in Toxicology, 2006
This paper reports the results of an in vitro evaluation of the phototoxic potential of stable photoproducts formed by UVA photolysis of three phenothiazines, perphenazine, fluphenazine, and thioridazine, in a water environment. Perphenazine gave a single product due to dechlorination. From thioridazine, the two major products formed; the endocyclic sulfoxide and the endocyclic N-oxide in which the 2-SCH 3 substituent was replaced by a hydroxy group were tested. From fluphenazine, two products have been examined as follows: an exocyclic N-piperazine oxide and a carboxylic acid arising from hydrolysis of the 2-CF 3 group. The phototoxicity of the isolated photoproducts has been studied in order to determine their possibile involvement in the photosensitizing effects exhibited by the parent drugs, using hemolysis and 3T3 fibroblasts viability as in vitro assays. As fluphenazine, perphenazine, and thioridazine did, some photoproducts proved phototoxic. In particular, the perphenazine dechlorinated photoproduct and the thioridazine N-oxide were found to exert phototoxic properties similar to the parent compounds. Therefore, our data suggest that some phenothiazine photoproducts may play a role in the mechanism of photosensitivity of these drugs. Because some of these photoproducts correspond to metabolic products of phenothiazines found in humans, it cannot be ruled out that metabolites of phenothiazines can be phototoxic in vivo.
Journal of Photochemistry and Photobiology B: Biology, 1992
Anecdotal reports suggest that the dihydropyridine calcium antagonist, nifedipine (NIF), may be phototoxic in human skin. We have studied NIF phototoxicity in vitro using UVA fluorescent tubes (Sylvania PUVA). NIF was phototoxic to Cundidu albicans and induced photohaemolysis both with NIF present during irradiation and with pre-irradiated drug. In V79 hamster fibroblasts, NIF (10 pg ml-') was phototoxic MIT assay) 24 h after irradiation (O-112 kJ m-'); at 7.5 kJ m-', about 70% of cells were damaged whilst at 37.5 kJ m-', only about 45% of cells were damaged. A similar pattern was seen with preirradiated NIF. Absorption spectroscopy showed that the NIF absorption maximum (A,,= 340 nm) blue-shifted to 314 nm at low UVA doses (7.5 kJ m-' or less) and redshifted to 345 nm at higher doses (isosbestic point, 325 nm). Thin layer chromatography of irradiated NIF showed a single photoproduct (PPl; A,,=314 nm) formed at 7.5 kJ m-' or less which disappeared at higher UVA doses to give further photoproducts. PPl was highly dark toxic to V79 cells (50% damage at about 5 pg ml-') but PPl pre-irradiated with UVA was non-toxic. Preliminary gas chromatography-mass spectroscopy studies suggest that PPl is the nitroso derivative of NIF. These results indicate that NIF phototoxicity in vitro is partially mediated by initial formation of a toxic photoproduct (PPl) but, paradoxically, subsequent UVA irradiation may reduce phototoxicity. The NIF concentrations required to induce in vitro phototoxicity are much greater than therapeutic plasma levels. Unless there is skin accumulation of NIF or PPl, our in vitro results suggest that NIF may not be an important skin-photosensitizing agent in vivo.
Photochemistry and Photobiology, 1994
Tiaprofenic acid is a photosensitizing nonsteroidal anti-inflammatory drug, whose major photoproduct (decarboxytiaprofenic acid) is also a potent photosensitizer. Because of the lack of the carboxylate moiety, this photoproduct is more lipophilic and might bind more efficiently to cell membranes, thereby causing phototoxic damage. To verify the feasibility of this hypothesis, we have prepared the 3H-labeled analogs of tiaprofenic acid and its photoproduct and examined the binding, persistence and phototoxicity of the photoproduct using poorly metabolizing (fibroblasts) and actively metabolizing cells (hepatocytes). The photoproduct of tiaprofenic acid accumulates in both cell types as it is formed. Upon removal of the photoproduct from the culture medium, it rapidly disappears from hepatocytes but not from fibroblasts. Consequently, irradiation of fibroblasts previously incubated with the photoproduct and kept in culture in the dark for 20 h results in generalized cell damage while this effect is not observed in hepatocytes. Because of its long persistence in poorly metabolizing skin cells and its reluctance to photobleaching, the formation of this photoproduct in skin may be of relevance to explain the in vivo phototoxicity of tiaprofenic acid.
Toxicology in Vitro, 2000
ÐMany therapeutic drugs induce phototoxic skin responses following exposure to solar or arti®cial ultraviolet radiation sources. Several in vitro model systems have been developed to predict drug phototoxicity but none have been conducted in parallel with controlled clinical phototoxicity studies on systemically administered pharmaceuticals. The in vitro phototoxicity of eight¯uoroquinolone (FQ) antibiotics (cipro¯oxacin, grepa¯oxacin, lome¯oxacin, nor¯oxacin, o¯oxacin, trova¯oxacin, BAYy3118, moxioxacin) was determined by exposing Chinese hamster ®broblasts to UVA radiation. Cell damage was quanti®ed with standard MTT or neutral red assays and an in vitro phototoxic index calculated (PI vit = % cell viability with UVA alone 6% cell viability with UVA + FQ) for each endpoint. Clinical photosensitising ability of the eight systemically administered FQ was investigated using double-blind, placebo and positive controlled, clinical skin phototesting of normal subjects. Minimal erythema doses at 365 230 nm were determined before and after 6±7 days of FQ ingestion and PI clin (minimal erythema dose without FQ6minimal erythema dose with FQ) calculated. Linear regression analysis of PI vit vs PI clin gave correlations of up to 0.893. Principal components analysis of PI vit , daily dose, plasma levels and photophysical (absorption) properties of the eight FQ showed that phototoxic (arbitrarily de®ned as PI clin e2) and non-phototoxic (PI clin < 2) FQ could be completely discriminated using these parameters, and that the in vitro models were able to rank the relative phototoxic potential of the eight FQ.