Experimental study on phototoxicity and the photosensitization potential of ketoprofen, suprofen, tiaprofenic acid and benzophenone and the photocross-reactivity in guinea pigs

Discovery of a Series of Pyrimidine Carboxamides as Inhibitors of Vanin-1

A diaryl ketone series was identified as vanin-1 inhibitors from a high-throughput screening campaign. While this novel scaffold provided valuable probe 2 that was used to build target confidence, concerns over the ketone moiety led to the replacement of this group. The successful replacement of this moiety was achieved with pyrimidine carboxamides derived from cyclic secondary amines that were extensively characterized using biophysical and crystallographic methods as competitive inhibitors of vanin-1. Through optimization of potency and physicochemical and ADME properties, and guided by co-crystal structures with vanin-1, 3 was identified with a suitable profile for advancement into preclinical development.

Ketoprofen-induced photoallergic dermatitis

Drug-induced photosensitivity reactions are significant adverse effects. Ketoprofen is one of the most common drugs that can cause skin rash in sun-exposed areas. Non-steroidal anti-inflammatory drugs (NSAIDs), such as ketoprofen, are often used for a variety of symptoms, including pain and fever. An understanding of the presentation and clinical course of ketoprofen-induced photosensitivity is necessary to correctly diagnose and manage this condition. Ketoprofen-induced photosensitivity reactions usually present as photoallergic dermatitis, which is a cell-mediated immune process. The benzophenone moiety in ketoprofen plays a major role in ketoprofen's ability to act as a photosensitizer. Several agents, such as fenofibrate and octocrylene have been found to be associated with aggravation of ketoprofen-induced photoallergic dermatitis or cross-photosensitization, and these reactions result from structural similarities with ketoprofen. Treatment of ketoprofen-induced photoallergic dermatitis includes discontinuation of ketoprofen, topical or systemic corticosteroids and avoidance of sun exposure and agents known to exacerbate dermatitis. In conclusion, photoallergic dermatitis is a significant adverse effect of ketoprofen. Some agents known to worsen dermatitis may be found in sun protection products (notably, octocrylene in sunscreen). Educating the patient to avoid these products is critical to treatment. Since NSAIDs, such as ketoprofen, are used commonly for a variety of illnesses, drug-induced photoallergic dermatitis should be high on the differential in individuals using these medications who present with acute onset of a rash in sun-exposed areas.

The effect of solvent relaxation in the ultrafast time-resolved spectroscopy of solvated benzophenone

Modeling time-resolved spectra to unravel ultra fast solvent reorganization.

In vitro assessment of skin sensitization, photosensitization and phototoxicity potential of commercial glyphosate-containing formulations

This study evaluated the applicability of a modified Direct Peptide Reactivity Assay (DPRA) (OECD N° 442C, 2015) through the 10-fold reduction of reaction volume (micro-DPRA, mDPRA) for skin sensitization evaluation of six commercial glyphosate-containing formulations. In addition, another modification of DPRA was proposed by adding a UVA (5J/cm2) irradiation step, namely photo-mDPRA, to better characterize (photo)sensitizer materials. The phototoxicity profile of pesticides was also evaluated using the 3T3 Neutral Red Uptake Phototoxicity Test (3T3-NRU-PT) (OECD N° 432, 2004). The mDPRA could represent an environmentally acceptable test approach, since it reduces costs and organic waste. Peptide depletion was greater in photo-mDPRA and changed the reactivity class of each test material, in comparison to mDPRA. Thus, the association of mDPRA with photo-mDPRA was better for correctly characterizing human (photo)sensitizer substances and pesticides. In general, cysteine depletion was greater than that of lysine for all materials tested in both mDPRA and photo-mDPRA. Furthermore, while 3T3-NRU-PT is unable to predict (photo)sensitizers, it was capable of correctly identifying the phototoxic potential of the tested agrochemical formulations. In conclusion, mDPRA plus photo-mDPRA and 3T3-NRU-PT seem to be preliminary non-animal test batteries for skin (photo)sensitization/phototoxicity assessment of chemicals, agrochemical formulations and their ingredients.

Ketoprofen-loaded polymer carriers in bigel formulation: an approach to enhancing drug photostability in topical application forms

The purpose of the study was to investigate the stability and biopharmaceutical characteristics of ketoprofen, loaded in polymeric carriers, which were included into a bigel in a semisolid dosage form. The polymer carriers with in situ-included ketoprofen were obtained by emulsifier-free emulsion polymerization of the monomers in aqueous medium or a solution of the polymers used. The morphological characteristics of the carriers, the in vitro release and the photochemical stability of ketoprofen were evaluated. The model with optimal characteristics was included in a bigel formulation. The bigel was characterized in terms of pH, rheological behavior, spreadability, and in vitro drug release. Acute skin toxicity, antinociceptive activity, anti-inflammatory activity, and antihyperalgesic effects of the prepared bigel with ketoprofen-loaded polymer carrier were evaluated. The carriers of ketoprofen were characterized by a high yield and drug loading. The particle size distribution varied widely according to the polymer used, and a sustained release was provided for up to 6 hours. The polymer mixture poly(vinyl acetate) and hydroxypropyl cellulose as a drug carrier, alone or included in the bigel composition, improved the photostability of the drug compared with unprotected ketoprofen. The bigel with ketoprofen-loaded particles provided sustained release of the drug and had optimal rheological parameters. In vivo experiments on the bigel showed no skin inflammation or irritation. Four hours after its application, a well-defined analgesic, anti-inflammatory, and antihyperalgesic effect was registered. The polymer mixture of poly(vinyl acetate) and hydroxypropyl cellulose as a carrier of ketoprofen and the bigel in which it was included provided an enhanced photostability and sustained drug release.

Ibuprofen and ketoprofen potentiate UVA-induced cell death by a photosensitization process

Nonsteroidal 2-arylproprionic acids are widely used, over-the-counter, anti-inflammatory drugs. Photosensitivity is a commonly overlooked adverse effect of these drugs. Based on the combined use of cell viability assays and molecular modeling, we prove and rationalize the photochemical pathways triggering photosensitization for two drugs, ibuprofen and ketoprofen. As its parent compound benzophenone, ketoprofen produces singlet oxygen, upon triplet manifold population. However, ibuprofen and ketoprofen photodissociate and hence may generate two highly reactive radicals. The formation of metastable aggregates between the two drugs and B-DNA is also directly probed by molecular dynamics. Our approach characterizes the coupled influence of the drug's intrinsic photochemistry and the interaction pattern with DNA. The photosensitization activity of nonsteroidal 2-arylproprionic acids, being added to gels and creams for topical use, should be crucially analyzed and rationalized to enact the proper preventive measures.

Ketoprofen-induced formation of amino acid photoadducts: possible explanation for photocontact allergy to ketoprofen

Photocontact allergy is a well-known side effect of topical preparations of the nonsteroidal anti-inflammatory drug ketoprofen. Photocontact allergy to ketoprofen appears to induce a large number of photocross allergies to both structurally similar and structurally unrelated compounds. Contact and photocontact allergies are explained by structural modification of skin proteins by the allergen. This complex is recognized by the immune system, which initiates an immune response. We have studied ketoprofen's interaction with amino acids to better understand ketoprofen's photoallergenic ability. Irradiation of ketoprofen and amino acid analogues resulted in four different ketoprofen photodecarboxylation products (6-9) together with a fifth photoproduct (5). Dihydroquinazoline 5 was shown to be a reaction product between the indole moiety of 3-methylindole (Trp analogue) and the primary amine benzylamine (Lys analogue). In presence of air, dihydroquinazoline 5 quickly degrades into stable quinazolinone 12. The corresponding quinazolinone (17) was formed upon irradiation of ketoprofen and the amino acids N-acetyl-l-Trp ethyl ester and l-Lys ethyl ester. The formation of these models of an immunogenic complex starts with the ketoprofen-sensitized formation of singlet oxygen, which reacts with the indole moiety of Trp. The formed intermediate subsequently reacts with the primary amino functionality of Lys, or its analogue, to form a Trp-Lys adduct or a mimic thereof. The formation of a specific immunogenic complex that does not contain the allergen but that can still induce photocontact allergy would explain the large number of photocross allergies with ketoprofen. These allergens do not have to be structurally similar as long as they can generate singlet oxygen. To the best of our knowledge, there is no other suggested explanation for ketoprofen's photoallergenic properties that can account for the observed photocross allergies. The formation of a specific immunogenic complex that does not contain the allergen is a novel hypothesis in the field of contact and photocontact allergy.

Stimulation of Langerhans cells with ketoprofen plus UVA in murine photocontact dermatitis to ketoprofen

BACKGROUND

Ketoprofen (KP) clinically evokes the allergic type of photocontact dermatitis when applied to the skin and irradiated with ultraviolet A (UVA). We have established a murine model of photocontact dermatitis to KP, which is a T cell-mediated delayed type hypersensitivity.

OBJECTIVE

To further explore the mechanism underlying this sensitivity, we investigated whether KP plus UVA activates the antigen-presenting ability of Langerhans cells (LCs).

METHODS

We analyzed the expression of surface molecules on LCs in the murine epidermis treated with KP plus UVA by immunohistochemistry and flow cytometry. Changes in the cytokine expression of epidermal cells from KP-phototreated skin were also examined by real-time PCR.

RESULTS

LCs became larger after treatment with KP plus UVA. The number of LCs was significantly decreased 2-3 days after KP phototreatment and recovered on day 5. A flow cytometric analysis revealed that KP plus UVA increased the percentage of LCs that highly expressed MHC class II, CD86, CD80, CD54 and CD40, whereas neither KP nor UVA alone enhanced the expression. KP phototreatment augmented the expression of I-A and CD86 on LCs in KP and UVA dose-dependent manners. A real-time PCR analysis of KP-phototreated skin showed that the expression of mRNA for IL-1alpha and GM-CSF was immediately increased after treatment.

CONCLUSION

A photosensitizing regimen of KP plus UVA activates LCs at least partly by stimulating keratinocytes to produce cytokines. Two strains of mice (BALB/c and AKR) differ in responsiveness to KP and the difference is not related to the activation of keratinocytes.

Ketoprofen: experimental overview of dermal toxicity

Ketoprofen (KP) is a widely used non-steroidal anti-inflammatory drug (NSAID). However, an increasing number of case reports suggest that in broad use, KP can cause allergic dermatitis. Most of these adverse effects have been attributed to the photoallergic potential of KP and photosensitivity. With the exception of a few reports in experimental animals, there is little evidence that KP actually causes dermal toxicity. In this study, in order to investigate the eventual underlying causes of KP dermal toxicity, we conducted primary irritation, skin cumulative, skin sensitization, phototoxicity and photosensitization tests in rodents and rabbits. Primary irritation and skin cumulative testing using New Zealand white rabbits revealed that application of KP (22, 15 and 10%) did not induce erythema or edema formation. Moreover, in skin sensitization and skin phototoxicity testing, using Hartley albino guinea pigs, there was no evidence of allergic or phototoxic potential. In the photosensitization test, KP induced skin reactions in six of eight guinea pigs with signs of erythema on the application site. Histologically, in photosensitized skin, epidermal hyperplasia, including incremental stratum granulosum, acanthosis, keratinocyte hypertrophy and dermal inflammatory cell infiltration, was observed. In this animal study, no primary irritation, cumulative irritation, skin sensitization or skin phototoxicity was observed with KP treatment. However, we identified photosensitization as the underlying cause of KP dermal toxicity.

Study on the mechanism of photosensitive dermatitis caused by ketoprofen in the guinea pig

To investigate the mechanism on photosensitive dermatitis caused by ketoprofen (KP) in humans, the following experiments were performed by topical application on guinea pigs. The phototoxicity study involving treatment with 10% solution of KP, its enantiomers (R-KP and S-KP), loxoprofen, and flurbiprofen revealed no phototoxic reactions. In the photoallergenicity study, KP and its enantiomers (0.5-2% solution) induced skin reaction at all dosages; however, loxoprofen and flurbiprofen (1-5% solution) did not induce such a photoallergenic reaction. These results suggest that the chemical structure of the benzophenone chromophore in KP would be one of the important factors for induction of the photoallergy since both loxoprofen and flurbiprofen do not possess this structure and hence lack photoallergenic potential. Furthermore, to assess time profiles of KP concentration in the skin and plasma, guinea pigs received a repeated topical application of R-KP and S-KP at a dosage of 40 mg/kg over a period of 3 days. Plasma KP concentrations were extremely low as compared to skin KP concentrations and were not detected at 72 h after the final dosing. At 24 h after the final dosing, KP concentrations in the skin with R-KP and S-KP treatment were 187.4 and 254.7 microg/g, respectively, and their half-lives were 80.5 and 84.4 h, respectively. KP concentrations at 336 h after final dosing were 11.3 microg/g for R-KP and 15.7 microg/g for S-KP treatment. The acylglycerol-combined KP concentrations at 336 h were 2% or less as compared to KP concentrations with R-KP and S-KP treatment. There were no differences in KP concentrations in the skin between R-KP and S-KP and in combined KP concentrations between the enantiomers. The present study indicates that photosensitive dermatitis after topical application of KP in humans, caused by photoallergenicity and not phototoxicity, can be reproduced in the animal testing, and suggests that the skin reaction may be caused by the long period of retention of KP in the skin.

Establishment of murine model of allergic photocontact dermatitis to ketoprofen and characterization of pathogenic T cells

BACKGROUND

Ketoprofen is well known to evoke the allergic type of photocontact dermatitis when it is applied to the skin and irradiated with ultraviolet A (UVA) light.

OBJECTIVE

We aimed to establish a murine model of this photosensitivity and to characterize pathogenic T cells concerned with the sensitivity.

METHODS

Various strains of mice were sensitized on two consecutive days by application of ketoprofen to the shaved abdomen and irradiation of the skin with UVA. Five days later, they were elicited with ketoprofen plus UVA on the earlobes. Immune lymph node cells and epidermal cells from the challenged sites were analyzed by RT-PCR.

RESULTS

Mice were successfully sensitized and challenged with 4% and 2% ketoprofen, respective, plus UVA at 20J/cm2. The responses in H-2k mice were higher than those in the other strains examined. Immune lymph node CD4+ or CD8+ cells from ketoprofen-photosensitized H-2k mice were transferred i.v. to naïve syngeneic recipients. Mice receiving CD4+ but not CD8+ cells exhibited ketoprofen photosensitivity, but transference of both CD4+ and CD8+ cell populations was more effective. Lymph node cells from photosensitized mice expressed high levels of mRNA for Th2 cytokine (IL-4) and Th2 chemokine receptor (CCR4) as well as Th1 cytokine (IFN-gamma) and Th1 chemokine receptor (CXCR3), as assessed by RT-PCR. In addition, epidermal cells from challenged earlobes expressed increased levels of both Th1 (TARC) and Th2 (Mig) chemokines.

CONCLUSION

It is considered that not only Th1 but also Th2 cells participate in the pathogenesis of murine photocontact dermatitis to ketoprofen.

Photosensitizing effect of some nonsteroidal antiinflammatory drugs on natural and artificial membranes: dependence on phospholipid composition

Previous studies have clarified the molecular mechanism of photosensitization on red blood cell membranes induced by some drugs belonging to the class of nonsteroidal antiinflammatory drugs: ketoprofen, naproxen, and diflunisal. This process involves the participation of photodegradation products, free radicals, and reactive oxygen species. The aim of the present paper is to investigate the photohemolytic process using red blood cells of mammalian species, with different membrane phospholipid compositions. Human and bovine red blood cell membranes were selectively enriched with phosphatidylcholine and sphingomyelin. For this purpose, a new approach for phospholipid investigation was undertaken. Moreover, the phototoxic effect was tested with liposomes at different phospholipid compositions. A structure-function relationship between the erythrocyte membrane phospholipid composition and the photohemolytic process induced by the sensitizers can be proposed. Indeed, the different contents of the photoperoxidable double bond and the variable architecture of the membrane bilayer, due to the different phosphatidylcholine and sphingomyelin contents, strongly influence the resistance of the cell to an osmotic shock induced by photogenerated transient species or by the lytic activity of drug photoproducts. The higher content of sphingomyelin, its asymmetric disposition at the outer surface of membrane bilayers, the high level of saturated acyl fatty chains, and the presence of photoperoxidable trans double bonds in the hydrophilic region greatly decrease the fluidity of bilayers and enhance the resistance of the membrane to phototoxic damage. On the other hand, an increase in the content of phosphatidylcholine, which is rich in species with unsaturated acyl fatty chains, decreases the membrane resistance, because these latter can be easily oxidized by drug-photogenerated reactive oxygen species.

PHOTOTOXICITY STUDY OF A KETOPROFEN POULTICE IN GUINEA PIGS

Ketoprofen has been reported to have such side effects as photosensitive dermatitis in humans (The Ministry of Health, Labour and Welfare, 2001). In the present study, as part of a safety evaluation of Miltax, an application drug containing ketoprofen, phototoxicity of Miltax was examined in guinea pigs. In the present skin phototoxicity study, Miltax was applied for 12 hr. Ultraviolet (UV) rays were irradiated to examine whether or not Miltax elicited skin reaction. Two kinds of UV-A plus UV-B dual irradiation and UV-A single irradiation were used for the elicitation. With UV-A plus UV-B dual irradiation on the Miltax application site, no skin reaction was observed at UV irradiation side in any animals, in contrast to the case of the positive control article, 8-methoxypsoralen (8-MOP). Similar results were obtained with UV-A single irradiation. From these results, Miltax that contained ketoprofen did not show any skin phototoxicity in the guinea pig.

Topically applied vitamin C and cysteine derivatives protect against UVA-induced photodegradation of suprofen in ex vivo pigskin

Exposure of the nonsteroidal anti-inflammatory drug suprofen (SUP) to UV-radiation results in the formation of radicals, reactive oxygen species (ROS), photodecarboxylated products and photoadducts with biomacromolecules. Using an ex vivo pigskin explant model, we investigated whether topical coapplication of the water-soluble antioxidants vitamin C (Lascorbic acid, ASC), N-acetyl-L-cysteine (NAC) or L-cysteine ethylester (CYSET) with SUP reduced ultraviolet A (UVA)-induced decomposition of SUP. UVA-induced changes in antioxidant bioavailability in the stratum corneum and epidermis were also studied. Epidermal bioavailability of SUP in sham-irradiated pigskin increased 2.2- to 4.1-fold after the lowest antioxidant doses (P < 0.05). As compared with no applied antioxidant, increasing doses of all tested antioxidants resulted in increased levels of SUP and decreased levels of photoproducts (P < 0.05). A maximal protection against SUP photodegradation of 70% was found after an ASC dose of 1 micromol/cm2; these values were 60% for a NAC dose of 10 micromol/cm2 and 50% for a CYSET dose of 5 micromol/cm2. Skin antioxidant levels increased with increasing applied dose (P < 0.05); the bioavailability of CYSET was approximately three-fold lower than that of ASC and NAC. UVA exposure resulted in 30-50% consumption of the topically applied ASC or NAC in the stratum corneum, whereas CYSET was not consumed. In conclusion, the topically applied water-soluble antioxidants ASC, NAC and CYSET protect against UVA-induced decomposition of SUP by scavenging radicals and ROS. Coapplication of these antioxidants may therefore be an effective way to reduce or prevent the phototoxic effects of SUP in vivo.