Augmented Pigmentation and Other Responses of Normal Human Skin to Solar Radiation Following Oral Administration of 8-Methoxypsoralen*†

Fitzpatrick, Thomas B.; Hopkins, Carl E.; Blickenstaff, D.; Swift, Sheldon

doi:10.1038/jid.1955.118

Cited by 74 publications

(14 citation statements)

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“…Our results are at variance with previous reports (Fitzpatrick et al, 1955;Parrish, 1976;Pathak et al, 1976;Morison et al, 1977;Wolff et al, 1977;Frain-Bell, 1985;Gupta and Anderson, 1987;British Photodermatology Group, 1994) which suggest that PUVA erythema reaches a maximum at about 48-72 h after irradiation. Statements on the time-course of PUVA erythema, however, are usually unreferenced and very little experimental data have been published.…”

Section: Discussioncontrasting

confidence: 84%

“…Contrary to previous reports (Fitzpatrick et al, 1955) we have shown that PUVA erythema is well-established 24 h after exposure, with the UVA dose required to achieve a minimal erythema response reduced, on average, by 64% in the presence of psoralen. UVB erythema was maximal at the first assessment time, 24 h after irradiation, compared with subsequent measurements.…”

Section: Discussioncontrasting

confidence: 83%

“…PUVA erythema is said to appear at 24 h after exposure and peak between 48 and 72 h after irradiation (Fitzpatrick et al, 1955;Parrish, 1976;Pathak et al, 1976;Frain-Bell, 1985;Gupta and Anderson, 1987), although there are little experimental data to support this. In this study we report the first detailed examination of the time-course for the development of PUVA erythema.…”

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confidence: 92%

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The Time-Course of Psoralen Ultraviolet A (PUVA) Erythema

Ibbotson

Farr

1999

Journal of Investigative Dermatology

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The time-course for the development of ultraviolet A-induced erythema in psoralen-sensitized skin differs from that caused by ultraviolet B or ultraviolet A but objective data are not available. During psoralen ultraviolet A therapy, the minimal phototoxic dose is determined 72 h after exposure, when psoralen ultraviolet A erythema is assumed to be maximal. This measurement is of fundamental importance in optimizing the therapeutic regimen. We examined a detailed time-course for development of psoralen ultraviolet A erythema in 16 subjects. The erythemal responses to ultraviolet B, ultraviolet A and psoralen ultraviolet A were assessed visually and using a reflectance device. Ultraviolet B erythema was maximal 24 h after exposure compared with subsequent time-points. Psoralen ultraviolet A erythema was evident at 24 h, with reduction in the median ultraviolet A minimal erythema dose from 14 to 5 J per cm2 in the presence of psoralen (p < 0.01; n = 9). Peak psoralen ultraviolet A erythema, assessed by minimal phototoxic dose, did not occur until 96 h or later in 75% of subjects. Using individual dose- response curves, we determined that only 67% of mean maximum psoralen ultraviolet A erythemal intensity had developed by 72 h. Furthermore, at the time of maximal erythema, the slope of the psoralen ultraviolet A dose-response curve was approximately 2-fold shallower than that for ultraviolet B-induced erythema. If assessment of psoralen ultraviolet A erythemal sensitivity had been made at 96 h instead of the conventional 72 h time-point, peak erythemal responses would not have been missed in any of the subjects. Based on these findings, it seems appropriate to consider whether psoralen ultraviolet A minimal phototoxic dose measurements should be performed 96 h after exposure.

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Section: Discussioncontrasting

confidence: 84%

Section: Discussioncontrasting

confidence: 83%

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confidence: 92%

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The Time-Course of Psoralen Ultraviolet A (PUVA) Erythema

Ibbotson

Farr

1999

Journal of Investigative Dermatology

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“…Exposure of psoralen solutions to ultraviolet light results in the formation of new compounds.4 External application or oral ingestion of small amounts of psoralens appears to have no effect in humans unless followed by exposure to ultraviolet light. Fitzpatrick and others 6 showed that the psoralens act as photosensitizers, not only increasing the response of skin to light but altering the wavelengths to which the human skin responds. Normally, light with wavelengths longer than 3,200 A has no effect on the skin.…”

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confidence: 99%

Use and Abuse of Psoralens

Becker¹

1960

JAMA

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The psoralens 1 are furocoumarins to which most people in the United States have been exposed. Celery contains psoralen. Oil of bergamot, widely used in perfumes, contains 5-methoxypsoralen. Thus, there are few persons who have not ingested psoralen and probably no adult woman who has not applied a psoralen to her skin. Plants containing psoralen have been used to produce pigmentation for at least 3,000 years. Recently, oil of bergamot has been used for this purpose. Scientific investigation of the psoralens began when Kuske 2 and, later, Fahmy and his group 3 isolated the active chemicals from a variety of plants. Many physicians in different countries began to study these compounds. Lerner, Denton, and Fitzpatrick4 and Kelly and Pinkus5 initiated clinical evaluation in the United States.The chemical alterations in the psoralens which occur after oral ingestion or topical application to the skin are not known. Exposure of psoralen solutions to ultraviolet light results in the formation of new compounds.4 External application or oral ingestion of small amounts of psoralens appears to have no effect in humans unless followed by exposure to ultraviolet light. Fitzpatrick and others 6 showed that the psoralens act as photosensitizers, not only increasing the response of skin to light but altering the wavelengths to which the human skin responds. Normally, light with wavelengths longer than 3,200 A has no effect on the skin. After sensitization by the psoralens, burning and tanning are produced by light with wavelengths as long as 4,000 A.7 After oral ingestion of the psoralens, the skin becomes photosensitive in about one hour. The peak of this sensitivity is reached in two hours and disappears in eight hours. The application of a psoralen solution on the skin produces greater sensitivity than does oral ingestion. The skin may remain sensitive to sunlight for several days. Increasing the dose of the psoralen increases the photosensitivity but does not appear to affect the duration of the reaction. Twenty milligrams of methoxsalen (8-methoxypsoralen) or the equivalent dose of other psoralens approaches the limit of tolerance of the skin; larger amounts commonly result in blistering. In sub-blistering doses, variations in the amount of psoralen and sunlight do not alter the reaction. Small oral doses (5 mg. of methoxsalen) followed by prolonged exposure to sunlight and larger oral doses (20 mg. of methoxsalen) followed by shorter exposure to sunlight produce the same changes in the skin.Only a few of the many psoralens have been used clinically. The original commercial preparation contained methoxsalen and 8-isoamylenoxypsoralen. The product presently available in the United States is methoxsalen. Investigations have been carried out with 5-methoxypsoralen and trimethylpsoralen. Preliminary studies indicate that trimethylpsoralen is the most potent of this group.It appears to be about twice as potent as methoxsa,en-Light Source Each photoreactive chemical has certain wavelengths of light which produce the greatest ...

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“…Prolonged exposure to the sun causes skin damage and sometimes skin cancer because of these UV rays. However, scientists have found that although the different wavelengths of light can have adverse effects, they can also be used as UV phototherapy to treat skin diseases [6,13]. UV phototherapy is exposure to intense UV light sources of a specific wavelength or narrow range of wavelengths for specified amounts of time to treat a variety of skin disorders [14,17].…”

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confidence: 99%

Minimal Erythema Dose (MED) in Normal Canine Skin by Irradiation of Narrow-Band Ultraviolet B (NB-UVB)

Mochizuki

Iwasaki

2013

The Journal of Veterinary Medical Science

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ABSTRACT. Narrow-band UVB (NB-UVB) is light over a very narrow band of wavelengths (around 311 nm) that is concentrated in the therapeutic range and minimally in the sunburn range. It has therefore become the phototherapy treatment of choice for skin diseases. The minimal erythema dose (MED) on canine skin for standardizing dosage schedules in NB-UVB treatment and histopathological analyses were performed in these dogs. In all 32 dogs tested, the MED ranged from 432 to 864 mJ/cm 2 . There were no significant differences in MED among breeds, sex and age groups. Histopathology obtained from areas irradiated by MED showed only mild vascular dilatation. These findings might be valuable for the application of NB-UVB phototherapy to canine skin diseases. Ultraviolet (UV) is invisible light that is part of the energy that comes from the sun [1]. It is made up of three types of rays from the longest wavelength to the shortest: UVA, UVB and UVC. Prolonged exposure to the sun causes skin damage and sometimes skin cancer because of these UV rays. However, scientists have found that although the different wavelengths of light can have adverse effects, they can also be used as UV phototherapy to treat skin diseases [6,13]. UV phototherapy is exposure to intense UV light sources of a specific wavelength or narrow range of wavelengths for specified amounts of time to treat a variety of skin disorders [14,17]. In human medicine, UVA and UVB irradiation has been used successfully to treat a number of diseases, including psoriasis, cutaneous T-cell lymphoma and atopic dermatitis [10,15,16,18].In human medicine, phototherapy devices use either short-wavelength broad-band UVB rays or the long rays of UVA. Broad-band UVB bulbs emit light in a broad range that includes the therapeutic wavelengths specific to the treatment of skin disorders but also is responsible for causing sunburn, which increases the risk of skin cancer. This limits the usefulness of therapeutic broad-band UVB [1]. In contrast, narrow-band UVB (NB-UVB) emits light over a very short range of wavelengths concentrated primarily in the therapeutic range [9]. In addition, NB-UVB phototherapy induces apoptosis of dermal T lymphocytes [12]. Thus, NB-UVB is considered effective for controlling human T-cell-mediated skin diseases such as cutaneous T cell lymphoma or atopic dermatitis [3,7,8,11].The minimal erythema dose (MED) is the minimum dose of radiation that produces perceptible skin erythema, and it is expressed in Joules per square centimeter (J/cm 2 ). The MED must be determined before UV therapy in order to minimize the inflammation of irradiated skin and define the initial irradiation dosage. However, in veterinary medicine, few studies have been published on the effects of the specific band of UV on canine skin. Our aims in this study were to determine the MEDs on normal canine skin in order to standardize dosage schedules in NB-UVB treatment and to determine whether MEDs vary with canine breed, gender, and age. Moreover, to confirm the effect of NB-UVB on dog s...

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Augmented Pigmentation and Other Responses of Normal Human Skin to Solar Radiation Following Oral Administration of 8-Methoxypsoralen*†

Cited by 74 publications

References 2 publications

The Time-Course of Psoralen Ultraviolet A (PUVA) Erythema

The Time-Course of Psoralen Ultraviolet A (PUVA) Erythema

Use and Abuse of Psoralens

Minimal Erythema Dose (MED) in Normal Canine Skin by Irradiation of Narrow-Band Ultraviolet B (NB-UVB)

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