The time course of topical PUVA erythema following 15- and 5-minute methoxsalen immersion

BACKGROUND: Limited data exist in the literature concerning the characteristics of erythema following psoralen UV-A (PUVA) treatment using topical methoxsalen. To optimize the phototherapeutic regimen and reduce short- and long-term risks, knowledge of such basic information is essential. OBSERVATIONS: The characteristics of PUVA erythema following 15- and 5-minute immersion in methoxsalen was determined. The PUVA erythema after 15-minute methoxsalen immersion exhibited a broad peak, with the lowest median minimal phototoxic dose (MPD) at 96, 120, and 144 hours after UV-A irradiation. Seventy-three percent of subjects experienced peak erythema at 120 hours compared with only 45% at 72 hours. From the dose-response data, an increase in the erythema index of 0.025 (equivalent to the MPD) was significantly lower when determined at 120 hours after UV-A irradiation than at 72 hours (P =.03). The median maximum slope of the dose-response curve occurred at 144 hours. After 5-minute immersion, PUVA erythema displayed a broad peak from 72 hours. Erythema summation scores followed a trend similar to that of 15-minute immersion, but the intensity was significantly reduced. CONCLUSIONS: Methoxsalen-UV-A erythema exhibited a broad plateau between 96 and 144 hours, with most subjects at peak erythema at 120 hours. Reduction of methoxsalen immersion time significantly lowered the erythemal intensity. Minimum phototoxic dose reading at 72 hours underestimates the phototoxic effect of topical methoxsalen PUVA, and a change in the MPD assessment time should be considered.     

An intraindividual comparative study of psoralen-UVA erythema induced by bath 8-methoxypsoralen and 4, 5', 8-trimethylpsoralen

BACKGROUND: Limited work has been conducted on the characteristics of topical trimethylpsoralen (TMP) psoralen-UVA (PUVA) erythema. OBJECTIVE: We sought to determine the time-course and dose-response characteristics of erythema induced by topical TMP, and to compare these parameters with those for topical 8-methoxypsoralen (MOP) within patients. METHODS: After photosensitization of one forearm with topical TMP, test sites were exposed to a UVA dose series. The procedure was repeated on the other forearm using 8-MOP solution. Erythema was assessed visually and with a reflectance instrument every 24 hours for 7 days. RESULTS: TMP PUVA erythema followed a similar time course to 8-MOP PUVA erythema. The majority of patients were at maximal erythema at or beyond 96 hours. TMP PUVA had a significantly steeper dose-response curve at 48, 72, and 96 hours compared with 8-MOP PUVA. CONCLUSION: On the basis of these data, the optimal time to read the TMP minimal phototoxic dose is 96 hours. In view of the steeper dose-response curve for TMP PUVA, a lower UVA incremental regimen should be considered compared with that for 8-MOP PUVA.     

The relationship between plasma psoralen concentration and psoralen-UVA erythema

The plasma 8-methoxypsoralen (8-MOP) concentration was measured in 60 patients commencing psoralen photochemotherapy (PUVA). At the time of blood sampling each patient was phototested using a series of 10 exposures to UVA. The resulting erythema was measured objectively 72 h after irradiation and dose-response curves for psoralen-UVA erythema were constructed. Although the dose of 8-MOP was calculated according to body weight, patients receiving 30 mg of 8-MOP had a significantly lower mean plasma concentration than those receiving higher doses. There was no significant correlation between plasma 8-MOP concentration and minimal phototoxic dose, either estimated visually or calculated from the dose-response curves. However the slope of the dose-response curve showed significant correlation with plasma 8-MOP concentration. The variation between patients in the rate of increase of the erythemal response, but not the variation in threshold sensitivity, can be explained by difference in plasma psoralen concentration.     

The effect of methoxsalen dose on ultraviolet-A-induced erythema

There is considerable interindividual variation in bioavailability of Methoxsalen (8-methoxypsoralen) after ingestion of the standard dose used in photochemotherapy (psoralen plus ultraviolet A). A dose change may be used to alter the degree of photosensitivity, although there is limited information on the effect of 8-methoxypsoralen dose alterations on phototoxicity within individuals. We studied the effect of changes of 8-methoxypsoralen dose over a narrow range in 15 subjects with psoriasis. Two hours after ingestion, serum 8-methoxypsoralen concentration was determined and phototesting was performed at 350 +/- 30 nm (0.45-14 J per cm2). The minimal phototoxic dose at 72 h was recorded, erythema was measured using a reflectance instrument, and dose-response curves were constructed. Each subject was tested on three occasions using doses of 25 mg per m2 (conventional dose) or conventional dose +/- 10 mg. Median serum 8-methoxypsoralen concentration increased from 96 to 143 to 229 ng per ml with dose increases from conventional dose - 10 mg to conventional dose and conventional dose + 10 mg, respectively (p < 0.001). The median minimal phototoxic dose and D0.025 (the objective equivalent of the minimal phototoxic dose derived from the dose-response curve) were significantly reduced with increasing 8-methoxypsoralen dose from conventional dose minus 10 mg (minimal phototoxic dose 1.7 J per cm2; D(0.025) 2.8 J per cm2) to conventional dose (1.2; 1.4 J per cm2) and conventional dose plus 10 mg (0.9; 1.0 J per cm2) (p < 0.001). Change in 8-methoxypsoralen dose had no detectable effect on the maximum slope of the psoralen plus ultraviolet A erythema dose-response curve. Thus, 8-methoxypsoralen dose changes within individuals, over a narrow but clinically relevant range, significantly altered the threshold response to psoralen plus ultraviolet A erythema but not the rate of increase in erythema with increasing ultraviolet A dose.     

The time-course of psoralen ultraviolet A (PUVA) erythema.

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.     

Failure of coconut oil to accelerate psoriasis clearance in narrow-band UVB phototherapy or photochemotherapy

Despite a widely held belief that the use of emollients prior to broad-band UVB irradiation accelerates clearance of psoriasis, only one single-blind controlled study exists in support of this. No similar study has been carried out with photochemotherapy (PUVA) or narrow-band UVB (311–313 nm) phototherapy. As some emollients absorb UV radiation, and thereby inhibit psoriasis clearance, there is a need to identify emollients suitable for pre-irradiation use. Coconut oil may be useful in this respect. In two randomized groups of patients with chronic plaque psoriasis undergoing either routine PUVA(n=14) or narrow-band UVB phototherapy (n=15), a single-blind controlled (half-body) study was undertaken to assess the died of pre-irradiation application of coconut oil. Patients were given PUVA twice weekly, or TL-01 therapy thrice weekly. The initial UV dose was 70% of previously determined minimal phototoxic (MPD) or minimal erythema doses (MED), with 40% incremental steps at each visit (reduced if adverse effects occurred). Psoriasis severity was scored on each side after every three treatments. No significant acceleration of psoriasis clearance was seen in either group. We do not, therefore, recommend the routine use of emollients prior to PUVA or TL-01 therapy when using near erythemogenic irradiation regimens.     

The relation between constitutional skin color and photosensitivity estimated from UV-induced erythema and pigmentation dose-response curves

In 54 healthy volunteers we assessed predictors of sensitivity to ultraviolet (UV) light, including Fitzpatrick's sun reactive skin types and constitutional skin color, and compared these with one another and with responses of the skin to UV irradiation, as determined experimentally by a minimal erythema dose (MED), a minimal melanogenic dose (MMD), and dose-response curves for UV-induced erythema and pigmentation. For these studies, a xenon arc solar simulator was used as the source of UV irradiation, and a chromameter interfaced with a computer for objective measurement of UV-induced erythema and pigmentation was employed. The skin type did not correspond well to the constitutional skin color, as measured by a chromameter prior to UV irradiation. Within each skin type, there were large ranges of MED and MMD values and great variability in the shapes of the dose-response curves. Constitutional skin color was also not a good predictor of the measured MED and MMD values but did appear to correlate with the steepness of the dose-response curves for erythema and for pigmentation. From these studies, we propose that objectively measured constitutional skin color is a better predictor of UV responses of the skin than skin type and that steepness of dose-response curves for erythema is a better measure of the response of the skin to UV irradiation than is a MED measurement.     

Age dependence of ultraviolet light-induced erythema following narrow-band UVB exposure

BACKGROUND/PURPOSE: A report in the literature suggests longer duration and greater intensity of late phase UVB erythema in older people. The aim of this study was to identify differences in minimum erythema dose (MED) and intensity of UV-induced erythema after narrow band UVB exposure between older and younger individuals in the late phase of UVB erythema. METHODS: Using the UVA/TL 01 UV skin tester (Waldmann Medizintechnik, Villingen-Schwenningen, Germany), MED was determined for narrow-band UVB exposure in 20 young subjects aging from 20-40, and 20 elderly subjects over 70 years of age. The intensity of UV-induced erythema was measured by chromametry (a*-value and L-value) and laser Doppler 48 h after irradiation. Minimum erythema dose (MED) was additionally assessed visually. RESULTS: Elderly subjects showed no statistical different MED compared to younger subjects. However, the erythema intensity 48 h after narrow-band UVB exposure was significantly greater in the elderly. CONCLUSIONS: Narrow-band UVB therapy may, in case of over dosage, produce more intense erythema in the late phase of UVB erythema in old people than in younger individuals.     

Dose-response and time-course characteristics of UV-A1 erythema

OBJECTIVE: To determine the time course and dose-response characteristics of UV-A1 erythema in the Tayside region of Scotland. DESIGN: Adult volunteers (skin types I and II [n = 13] and III and IV [n = 11]) were exposed to geometric dose series of UV-A1 irradiation from a high-output source on photoprotected lower back and inner forearm skin. SETTING: Photobiology unit in a university hospital. MAIN OUTCOME MEASURES: The minimal erythema dose (MED) was recorded visually and erythema was assessed objectively by erythema meter at 4, 8, 24, and 48 hours after exposure. RESULTS: Peak erythema (lowest visual MED) was seen at 8 hours on the back and arm in 11 subjects with skin types I and II and on the back at 8 hours in 9 subjects and on the arm at 4 hours in 10 subjects with skin types III and IV. The lowest median (range) MED was 20 J/cm(2) (14-56 J/cm(2)) on the back and 42 J/cm(2) (20 to >80 J/cm(2)) on the arm at 8 hours for subjects with skin types I and II and 28 J/cm(2) (20-112 J/cm(2)) at 8 hours on the back and 56 J/cm(2) (28-80 J/cm(2)) at 4 hours on the arm for subjects with skin types III and IV. The D(0.025), an objective measure that corresponds approximately to the visual MED, demonstrated a broad peak from 8 to 24 hours. CONCLUSIONS: Our local population is more erythemally sensitive to UV-A1 radiation than reports suggest. Daily dose regimens may risk cumulative erythema. Lower starting doses should be used in this population. The wide range of MEDs highlights the need for MED testing.     

Time course of skin photosensitivity following trimethylpsoralen bath PUVA

One aspect of bath photochemotherapy (PUVA) that requires clarification is the duration of psoralen-induced cutaneous photosensitisation under conditions simulating clinical use. Using a half back comparison study technique, we investigated the persistence of trimethylpsoralen (TMP)-induced photosensitivity in skin irradiated to simulate a first PUVA exposure compared with un-irradiated skin. Baseline UVA minimal erythema dose and minimal phototoxic dose (MPD) were determined in 13 healthy volunteers. After readings at 72 h, subjects were bathed in TMP bath water for 15 min and one half of the back was immediately exposed to 40% of the MPD. Test sites (1.5 cm2) on both halves of the back were then irradiated with a UVA dose series at 15 min, 5, 10, 24, 34, 48 and 72 h after the bath. MPD readings were recorded visually at 72 h after each UVA exposure. The UVA MED was >25 J/cm2 in all the subjects. At each time point, a phototoxic index (PI) was calculated as UVA MED/MPD. In un-irradiated skin, photosensitivity returned to normal (PI=1) within 24 h after the TMP bath. In contrast, skin pre-irradiated to simulate the first PUVA treatment was still significantly photosensitive (PI=2.3; P=0.002) at 48 h. Contrary to previous recommendations, these data suggest that patients should be advised to avoid ambient or artificial sources of UVA throughout their course of TMP bath PUVA to reduce the risk of phototoxic erythema.     

Erythemal and therapeutic response of psoriasis to PUVA using high-dose UVA

In PUVA treatment of psoriasis, clinical observation suggests that uninvolved skin is more susceptible to PUVA erythema than lesions of psoriasis. If this is the case, then the efficacy of PUVA treatment might be increased by using localized high-dose UVA restricted to lesional skin. We have therefore studied the erythemal and therapeutic response of psoriasis to PUVA using high-dose UVA and, for comparison, the erythemal response to UVB. In 14 patients, an area of psoriasis and adjacent uninvolved skin were exposed to a series of UVA doses (350 ± 30 nm, 1–16 J/cm²), using an irradiation monochromator. Six other patients were similarly phototested with a series of UVB doses (300 ± 5 nm, 20–112 mJ/cm²) to both uninvolved and lesional skin. Erythema was judged visually at 72 h for psoralen–UVA, and at 24 h for UVB, and measured using a scanning laser–Doppler velocimeter. In 10 patients, PUVA therapy using high-dose UVA was subsequently given to lesional skin (8–16 J/cm² twice weekly) in addition to conventional whole-body PUVA. For psoralen–UVA, the minimal phototoxic dose within psoriasis was increased by a factor of 4 compared with non-lesional skin (P < 0.01, Wilcoxon signed-rank test). For UVB, the minimal erythema dose within psoriasis was higher than that for non-lesional skin (medians > 112 and 28 respectively, P < 0.05). Laser–Doppler measurements confirmed that the reduced erythemal sensitivity was not due to masking of response by pre-existing increased blood flux within psoriasis. In six patients, the sites subsequently treated twice weekly with PUVA, using high-dose UVA, cleared faster (median number of treatments 3), but with a similar cumulative UVA dose, compared with adjacent lesional skin treated with conventional PUVA (median number of treatments 12). This study demonstrates that psoriasis may clear rapidly, without burning, using high-dose UVA. Availability of a suitable irradiation apparatus would allow rapid and effective PUVA treatment to be used for localized, resistant disease.     

Prophylactic PUVA and UVB therapy in polymorphic light eruption—a controlled trial

A double-blind controlled trial of low-dose prophylactic oral psoralen photochemotherapy (PUVA) and ultraviolet-B (UVB) irradiation therapy was undertaken from April to September 1983 in 42 patients with polymorphic light eruption (PLE). Patients were randomly allocated to three groups, PUVA with oral 8-methoxypsoralen (8-MOP), UVB with oral placebo, and control low-dose UVA with oral placebo. The initial dose given to each active treatment group was a third of the predetermined minimal phototoxic or erythema dose, followed three times weekly for 6 weeks by doses incremented by an eighth on each occasion in the PUVA group and by a seventh in the UVB group. Ultraviolet radiation exposure was monitored throughout with polysulphone film lapel badges. Patients recorded their symptoms on a visual analogue scale. Symptoms of rash and itch in patients treated with PUVA and UVB were significantly less affected by increasing exposure to ultraviolet radiation than were these symptoms in control patients.     

A quantitative study of the effect of topical indomethacin on cutaneous erythema induced by UVB and UVC radiation

The effect of indomethacin gel on UVB and UVC erythema was assessed objectively using a reflectance instrument. When indomethacin was applied immediately after irradiation, UVR (ultraviolet radiation) dose-dependent suppression of erythema was demonstrated for both wavelengths until 36 h after irradiation when both indomethacin and control gel base-treated sites were equally erythematous. Suppression of erythema also occurred when application of indomethacin was delayed until 24 h after irradiation, showing that for both wavelengths prostaglandin synthesis remains increased throughout this period. The degree of suppression at any time, however, was no greater than that achieved by a single application immediately after irradiation, indicating that the eventual equal erythema of indomethacin and gel base-treated sites was not due to tachyphylaxis or inadequate dosage. Construction of dose-response curves for the indomethacin-responsive and indomethacin-unresponsive components of erythema shows that in human skin the difference in erythemal response to UVB and UVC radiation is not due to the formation of different mediators at these wavelengths.     

Occurrence of neutrophils and activated Th1 cells in UVB-induced erythema.

We investigated the sequential changes in infiltrating inflammatory cells and several cytokine levels over a period of 48 h in human back skin exposed to 3 minimal erythematous doses of UVB. The measurement of blood flow, using a laser Doppler method, indicated that UVB-induced erythema reached a peak 12-24 h after irradiation. Immunohistochemically, an increase in the number of CD4+ T cells was observed in perivascular areas 6 h after the UVB treatment and continued for up to 48 h. CD8+ T cells were scarce until 24 h, but their numbers gradually increased thereafter. HLA-DR+ cells were detected perivascularly and interstitially in parallel with the pattern of CD4+ T-cell infiltration. In contrast, neutrophils were found 3 h after UVB exposure and reached a peak at 24 h. Using a RT-PCR method, we demonstrated that mRNAs for the Th1 cytokines (interferon-gamma and interleukin-2), together with a proinflammatory cytokine (interleukin-8), became detectable at 6 h, whereas mRNA for the Th2 cytokine (interleukin-4) was not found at all during the first 48 h. In contrast, we found an increase in mRNA levels for C3 and tumor necrosis factor-alpha even at 3 h, suggesting a relationship between complement activation and accumulating neutrophils. Our results suggest that neutrophils and CD4+ T cells in UVB-induced inflammation play different roles: neutrophils are more closely related to UVB-induced erythema, while T cells appear to be involved in subsequent dermal and epidermal inflammation accompanied by epidermal hyperproliferation.     

The onset of ultraviolet erythema

The onset of erythema induced by UVB and by UVC radiation was monitored in two subjects using a reflectance instrument. It was shown that vasodilation occurred some time before erythema became visible, even with small exposure doses of UVB or UVC, after which visible erythema was not apparent for several hours. In one subject, vasodilation was detected very shortly after irradiation and may have even begun during irradiation. In the other subject vasodilation was detected later at most exposure doses, but still some time before erythema became visible. We conclude that the so-called 'latent period' between irradiation and appearance of erythema is an artificial concept arising from the insensitivity of the eye.     

Influence of UVA pre-exposure on UVB-induced erythema: A chromometric study

We examined the influence of ultraviolet A (UVA) pre-exposure on UVB minimal erythemal dose in 9 Caucasian subjects. Three zones were tested. One zone received only UVB, the second zone received a low UVA dose+UVB, and the third zone received a high UVA dose+UVB. Each zone was divided into 9 circles receiving increasing doses of UVB in order to obtain 3 different UVA-exposed series of 9 circles. Visual and chromometric readings were performed 24 h later. Pre-exposure to UVA caused variations in the slope of the dose-response curve (colorimetric index as a function of the UVB dose). In relation to UVB erythema, these variations indicated a protective effect for 6/9 subjects and an aggressive effect for 3/9 subjects. No predictive criteria were found for inclusion within a group.     

Correlation between bathing time and photosensitivity in 8-methoxypsoralen (8-MOP) bath PUVA

Bath PUVA (psoralen plus ultraviolet A) using 8-methoxypsoralen has become increasingly popular in recent years as an effective treatment option for a continuously expanding range of skin disorders. Among the various variables of bath PUVA treatment, the impact of bathing time on photosensitivity has never been investigated in detail. We therefore determined the threshold UVA dose for erythema induction after different bathing periods. A marked influence of bathing time on photosensitivity was found. Increasing the soaking period from 5 min to 30 min resulted in a greater than 60% reduction of the minimal phototoxic and minimal perceptible phototoxic dose. Our results demonstrate that the duration of the psoralen bath is a critical parameter in bath PUVA treatment and has a major influence on UVA dose requirements.     

Kinetics and dose-response of photosensitivity in cream psoralen plus ultraviolet A photochemotherapy: comparative in vivo studies after topical application of three standard preparations

BACKGROUND: Topical photochemotherapy with bath psoralen plus ultraviolet (UV) A irradiation (PUVA) has been developed to reduce possible side-effects of oral PUVA therapy. Although the efficacy of bath PUVA therapy appears to be similar to oral PUVA therapy, provision of bathing facilities has obvious economic, logistic and sanitary implications. Cream PUVA therapy has recently been developed as a variation of topical PUVA. OBJECTIVES: To understand the photobiological effects and to increase the safety and effectiveness of this novel topical PUVA therapy, we assessed the kinetics and dose-response of phototoxicity of 8-methoxypsoralen (8-MOP) cream in order to develop a treatment schedule for this treatment option. METHODS: Ninety-eight patients (63 men and 35 women) undergoing cream PUVA therapy were studied. The phototoxic properties of topically applied 8-MOP in three different water-in-oil creams as vehicles were assessed. In a dose-response study, four concentrations of 8-MOP cream (0.0006-0.005%) were used for determination of the minimal phototoxic dose (MPD). The kinetics of photosensitization were tested by determination of MPDs after different application times of 8-MOP cream (10, 20, 30 and 60 min). The persistence of phototoxicity was assessed by UVA exposure at defined time intervals after application of 8-MOP cream (0, 30, 60 and 120 min). RESULTS: The concentration required to produce sufficient but not undue photosensitization of the skin was 0.001% 8-MOP. The duration of application leading to the lowest MPD was 30 min. Greatest photosensitization was achieved when UVA irradiation was performed between 0 and 30 min after 8-MOP removal. These findings showed no significant difference between the three vehicles used. CONCLUSIONS: Based on our data we recommend application of 0.001% 8-MOP in a water-in-oil cream for 30 min. Irradiation with UVA should be performed within 30 min after removal of 8-MOP cream, as there is a rapid decrease in photosensitivity thereafter.     

Assessment of minimal phototoxic dose following 8-methoxypsoralen bath: maximal reaction on average after 5 days

An essential procedure before starting bath psoralen ultraviolet (UV) A (PUVA) photochemotherapy is the evaluation of the minimal phototoxic dose (MPD), which is traditionally assessed 3 days after irradiation. However, there are no controlled studies supporting the 72 h peak of bath-PUVA erythema. The aim of this study was therefore to determine the exact time course of the erythematous reaction in human skin following bath-PUVA. For this purpose, the skin of 10 volunteers was exposed to 0.5-3.0 J/cm2 UVA directly after a 20-min 8-methoxypsoralen bath (0.5 mg/L, 37 degrees C). At 24, 48, 72, 96, 120 and 144 h (1-6 days) after irradiation, the MPD and the erythema sum score (ESS) were determined in each subject. The results showed a maximal erythematous reaction on average 5 days after irradiation. The mean MPD gradually decreased from day 2 (> 3.0 J/cm2) to day 5 (mean +/- SD 1.15 +/- 0.63 J/cm2) and started to increase at day 6 (mean +/- SD 1.6 +/- 0.52 J/cm2). The mean +/- SD ESS correspondingly increased from day 2 (0 +/- 0) to day 5 (10.5 +/- 3. 7) with a decrease at day 6 (7.5 +/- 3.1) (difference between day 3 and beyond statistically significant at P < 0.05). As our study indicates a maximal erythematous reaction to the bath-PUVA up to 5 days after irradiation, the traditional MPD assessment at 3 days generates a risk of phototoxic side-effects within the phototherapy course by underestimating the phototoxic effect in some patients. These findings contribute towards a more defined understanding of the kinetics of the phototoxic reaction in bath-PUVA therapy.     

Influence of corticosteroids on ultraviolet light erythema and pigmentation in man

Summary Topical hydrocortisone and betamethasone-17-valerate were tested in alcoholic solution in human skin for their influence on a developing ultraviolet light erythema. Although the normal response was augmented by the ethanol vehicle, both drugs, applied before exposure, inhibited the erythema induced by irradiation of the sunburn range (UVB). They did not inhibit a phototoxic erythema induced by 8-methoxy-psoralen and long-wave irradiation (UVA). The pigmentation caused by the UVA exposure also appeared after UV stimulation which was too weak to evoke erythema.

---

Zusammenfassung Auf die Haut aufgelegte alkoholische Lösungen von Hydrokortisonacetat und Betamethason-17-valerat wurden wegen einer eventuellen Einwirkung auf das ultraviolette Erythem in homo untersucht. Beide Substanzen, vor der Lichtexposition aufgetragen, zeigten eine Hemmung des Sonnenbranderythems (UVB). Ein phototoxisches Erythem, ausgelöst durch 8-Methoxypsoralen und langwellige UV-Strahlung (UVA) wurde dagegen nicht beeinflußt. Die Pigmentierung im UVA-Versuch war auch bei kurzen UV-Belichtungen, die kein Erythem hervorriefen, deutlich.