PHOTOTOXICITY STUDY OF A KETOPROFEN POULTICE IN GUINEA PIGS

Evaluation of skin phototoxicity of transdermally administered pharmaceuticals in Sprague-Dawley rats

Some drugs cause phototoxicity in humans when exposed to light, thus there is a need for an in vivo phototoxicity test to evaluate them. However, an in vivo phototoxicity test method to evaluate this has not been established. This study aimed to establish an in vivo phototoxicity test method for transdermally administered drugs. For this, we evaluated the phototoxicity using Sprague-Dawley (SD) rats for transdermal administered drugs and we studied the appropriate UVA dose using 8-methoxypsalen, which is a well-known phototoxic drug. We found that a UVA dose of 15 J/cm2 was dose and time dependent response compared to other UVA doses. We performed the Minimum Erythema Dose (MED) test because UVB can cause skin irritation by itself and selected 0.01 J/cm2 as an appropriate dose of UVB. Using the selected UVA and UVB doses, we performed a phototoxicity study of 6 pharmaceutical drugs, which included phototoxic and non-phototoxic drugs. As a result of the phototoxicity test, 100% accuracy was obtained when compared with previous studies. In addition, we performed histopathology to confirm the new findings. We found that histopathology can be used as an additional indicator of phototoxicity test for transdermally administered drugs.

Synthesis and evaluation of novel chlorophyll a derivatives as potent photosensitizers for photodynamic therapy

Chlorophyll a exhibits excellent photosensitive activity in photosynthesis. The unstability limited its application as photoensitizer drug in photodynamic therapy. Here a series of novel chlorophyll a degradation products pyropheophorbide-a derivatives were synthesized and evaluated for lung cancer in PDT. These compounds have strong absorption in 660-670 nm with high molar extinction coefficient, and fluorescence emission in 660-675 nm upon excitation with 410-415 nm light. They all have much higher ROS yields than pyropheophorbide-a, and compound 10 was even higher than [3-(1-hexyloxyethyl)]-pyrophoeophorbide a (HPPH). Distinctive phototoxicity was observed in vitro and the inhibition effect was in light dose-dependent and drug dose-dependent style. They can effectively inhibit the growth of lung tumor in vivo. Among them, compound 8 and 11 have outstanding photodynamic anti-tumor effects without obvious skin photo-toxicity, so they can act as new drug candidates for photodynamic therapy.

Evaluation of the skin phototoxicity and photosensitivity of honeybee venom

OBJECTIVE

Bee (Apis mellifera L.) venom (BV) has been used as a cosmetic ingredient owing to its anti-aging, anti-inflammatory, and antibacterial effects. The aim of this study was to assess the skin safety of BV.

METHODS

For this purpose, skin phototoxicity and sensitization tests were conducted in healthy male Hartley guinea pigs. The animals were divided into three groups (n=5) for the phototoxicity test: G1 (negative control), G2 (BV gel treatment), and G3 (positive control). After specified treatments, the animals were irradiated with ultraviolet A (15 J/cm² ). The photosensitivity test was also performed in three groups: G4 (negative control, n=5), G5 (BV gel treatment, n=10), and G6 (positive control, n=5).

RESULTS

Erythema and edema were observed after 24, 48, and 72 hours in the positive control group, but not in the negative control and BV gel groups. Application of BV to the guinea pig skin had no toxic effects on any clinical signs, body weight, or mortality. In addition, it did not evoke a skin reaction in both either the skin phototoxicity and skin photosensitization tests.

CONCLUSION

Therefore, it can be concluded that BV has the potential to be developed as a drug ingredient for topical uses.

Evaluation of skin phototoxicity study using SD rats by transdermal and oral administration

Guinea pigs are the most frequently used animals in phototoxicity studies. However, general toxicity studies most often use Sprague-Dawley (SD) rats. To reduce the number of animals needed for drug development, we examined whether skin phototoxicity studies could be performed using SD rats. A total of 19 drugs that had previously been shown to have phototoxic potential and 3 known phototoxic compounds were administered transdermally to guinea pigs and SD rats. Eleven of the potentially phototoxic drugs and 2 of the known phototoxic compounds were also administered orally to guinea pigs and SD rats. After administration, the animals were irradiated with UV-A (10 J/cm(2)) and UV-B (0.25 J/cm(2) in guinea pigs and 0.031 J/cm(2) in SD rats) with doses based on standard phototoxicity study guidelines and the results of a minimum erythema dose test, respectively. In the transdermal administration study, all of the known phototoxic compounds and 7 of the drugs induced phototoxic reactions. In the oral administration study, both known phototoxic compounds and 5 drugs induced phototoxic reactions in both species; one compound each was found to be toxic only in SD rats or guinea pigs. The concordance rate of guinea pigs and SD rats was 100% in the transdermal administration study and 85% in the oral administration study. This study demonstrated that phototoxicity studies using SD rats have the same potential to detect phototoxic compounds as studies using guinea pigs.

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.