WO1993003720A2

WO1993003720A2 - Methods and compositions for treating sunburns

Info

Publication number: WO1993003720A2
Application number: PCT/CA1992/000353
Authority: WO
Inventors: John R. Trevithick
Original assignee: Trevithick John R
Priority date: 1991-08-16
Filing date: 1992-08-14
Publication date: 1993-03-04
Also published as: AU2434992A; WO1993003720A3

Abstract

A method of treating sunburn in human or animal skin comprises applying to the sunburned area a topical composition containing as active ingredient a tocopherol ester such as tocophero acetate or tocopherol polyethylene glycol succinate.

Description

METHODS AND COMPOSITIONS FOR TREATING SUNBURNS

This invention relates to compositions of vitamin E esters (tocopherol esters) and uses thereof. More particularly, it relates to skin treating compositions of tocopherol esters and uses thereof.

Vitamin E acetate, also known as tocopherol acetate, has the full chemical name 3,4-dihydro-2,5,7,8- tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-l-benzopyran-6- ol acetate, and the chemical formula:

It is widely used as a vitamin E (tocopherol) supplement.

Tocopherol itself is used as an antioxidant, e.g. in vegetable oils and shortenings. Its antioxidant activity is derived from the presence of the free phenolic hydroxyl group on the chromanol ring. The free hydroxyl group can act as a scavenger of free radicals or singlet oxygen, usually being itself oxidised to the tocopheroxy radical, semiquinone or quinone. Accordingly, tocopherol is subject to air oxidation on storage. When the phenolic hydroxyl group is esterified, as in tocopherol acetate, the storage stability of the compound is much improved, but the antioxidative properties are lost. Thus it is commonly preferred to make and use tocopherol acetate, rather than tocopherol itself, in areas where the antioxidative properties are not of importance.

Some of the undesirable effects of ultraviolet radiation on the human skin have been linked in the scientific literature with oxidative mechanisms. For example, Fuchs et.al.. "Photochemistry and Photobiology" Vol.50, No.6, pp.739-744, 1989, report that antioxidants may play a significant role in ameliorating or preventing photobiologic damage in skin, because of the damaging^' effects of reactive oxygen species. This paper teaches that skin is naturally endowed with a variety of enzymic and non-enzymic antioxidants, including tocopherol, which can prevent oxidative damage, but may be overcome by strong pro-oxidative stimuli such as ultraviolet radiation. Accordingly, they studied the effect of exposure of the skin of hairless mice to near ultraviolet (UVA)/visible radiation, and reported a partial impairment of the cutaneous antioxidant defense system, and a decrease (not statistically significant) in the natural tocopherol level. The level of tocopherol in skin is low by comparison to that in most tissues of the body.

Potapenko et. al.. "Archives of Dermatological Research", (1984) 276:12-16, in an article entitled "PUVA- Induced Erythema and Changes in Mechanoelectrical Properties of Skin. Inhibition by Tocopherols," described experiments conducted on human and rabbit skin to determine the influence of antioxidants on two phototoxic effects of 8-methoxypsoralen, namely changes in mechanoelectrical properties of skin and erythema, with long wavelength ultraviolet radiation. They reported that tocopherol and its analogs inhibited both phototoxic effects if the antioxidants were present during the irradiation, but produced no inhibitory effect when applied after irradiation. No inhibitory effect for tocopherol acetate, which as noted above is not an antioxidant, is reported, even when applied before irradiation. Having studied the effects of various tocopherol analogs, the authors conclude that it is the presence of a chromane structure containing a hydroxyl group that matters.

Roshchupkin et.al.. "Archives of Dermatological Research," (1979), 266:91-94, essentially the same research group, showed protection by tocopherol and butylated hydroxytoluene, but not tocopherol acetate, when applied to the skin before exposure to UV radiation of the wavelength considered responsible for sunburn. They stated, "a- tocopherol acetate, which has, in contrast to a-tocopherol, almost no antioxidative activity, was inefficient".

It is an object of the present invention to provide a novel treatment for the alleviation of sunburn.

It is a further object of the present invention to provide a novel pharmaceutical preparation for topical application to human or animal skin for treating sunburn.

The present invention is based upon the discovery that the 6-(Cl-C4)lower alkylcarbonyloxy derivatives, and the carboxylated and polyethyleneoxycarbonyl substituents thereof, of tocopherol, as exemplified by tocopherol acetate, tocopherol succinate and tocopherol polyethylene- glycol succinate, are surprisingly effective in alleviating the effects of sunburn, when applied topically to a sunburnt area of human or animal skin. This is despite all the prior art indications that the effects of sunburn are associated with oxidative effects on skin, so that treatment would be expected to be effective with materials having antioxidative properties, which are properties which these tocopherol esters do not possess to any significant extent. Whilst it is not intended that this invention should be interpreted as limited by any potential theory of mechanism, it is postulated that the effectiveness of these ester materials could be a consequence of their possible hydrolysis to free acid in the mammalian cells after topical application.

Thus according to a first aspect of the present invention, there is provided a method for treating or alleviating the effects of sunburn on human or animal skin, which comprises applying topically to the area of sunburnt skin an effective amount of a 6-(Cl-C4)lower alkylcar- bonyloxy derivative, or a carboxylated or polyethyleneoxy- carbonyl substituent thereof, of tocopherol, in association with a skin compatible and acceptable carrier.

According to another aspect of the present invention, there is provided a pharmaceutical preparation for topical application to human or animal skin to alleviate the effects of sunburn thereon, said preparation comprising an effective amount of a 6-(Cl-C4)lower alkylcarbonyloxy derivative, or a carboxylated or poly- ethyleneoxycarbonyl substituent thereof, of tocopherol, in association with a skin compatible and acceptable carrier.

There is additionally provided a method for treating or alleviating the effects of sunburn on human or animal skin, which comprises applying topically to the area of sunburnt skin an effective amount of β-carotene, optionally in association with a skin compatible and acceptable carrier. β-carotene is a provitamin A, and is naturally occurring in both plants and animals, as well as being manufactured synthetically. It is commonly used as a yellow coloring agent for foods, as a vitamin A precursor, and as an ultraviolet screen. Thus, there is also provided a pharmaceutical preparation of topical application to human or animal skin to alleviate the effects of sunburn thereon, said preparation comprising an effective amount of β-carotene optionally in association with a skin compatible and acceptable carrier.

The preferred active ingredient for use in the present invention is tocopherol acetate, tocopherol succinate or tocopherol polyethylene glycol succinate.

Tocopherol acetate is a liquid oil. Because it is a lipid or fat, it can diffuse across skin cell membranes, enter cells and be associated with other hydrophobic membranous structures present in the cells, for instance mitochondria, and membranes of the endoplasmic reticulum and nuclear membranes. Tocopherol polyethylene glycol succinate and tocopherol succinate have the added property of limited water solubility.

The application of tocopherol acetate to sunburnt skin, promptly after the exposure to sunburning UV irradiation, has been found to reduce both erythema(skin reddening)skin sensitivity and skin thickness or swelling observed after sunburn, and to promote more rapid healing, as evidenced by the earlier appearance of epidermal desquamation or "peeling" of the skin after sunburn. This has been demonstrated in experiments using hairless mouse models, a model frequently used for testing human sunscreens. Free tocopherol, on the other hand is irritating to the skin of hairless mice when applied topically, resulting in mild increase in erythema.

The topically applicable compositions of the present invention are suitably prepared as ointments, creams, lotions, emulsions, aerosols, liposomes or gels, optionally with appropriate inert but skin compatible carrier or base materials. The compositions suitably contain from about 1 to 100% by weight of active ingredient, preferably from about 1-10% by weight of active ingredient. Suitable inert base carriers are well known to those skilled in the art of topical formulation compounding, and include petroleum jelly, lanolin, wax, cold creams, plant seed oils such as sesame, canola, corn oil, etc, mineral oil, yristyl acetate, myritol 318* etc. Other active ingredients such as sunscreens, insect repellents, anti-microbials and topical anaesthetics can also be included in the formulations.

Appropriate dosage rates of the active ingredient, to be applied on a per square centimetre area of sunburnt skin, are in the approximate range 25 - 10,000 micrograms, depending of course upon the severity of the sunburn. For mild cases, dilute preparations are best applied, to give a topical application towards the lower end of the above range. Preferred dosages are in the range 50 - 5,000 micrograms per square centimetre, and most preferably and most commonly for sunburns of average severity, in the range from about 100 - 1,000 micrograms per square centimetre.

The dose of composition according to the invention should preferably be applied to the affected area as soon as possible after the sunburn has been experienced, but beneficial effects are still obtained with topical application up to at least eight hours after the burn. If the recommended, preferred dosage is applied to the affected area very shortly after the burn has been experienced, a second topical application is not normally necessary, but some benefits .may accrue, particularly in cases of severe burn, by second or even third applications, at about 24 hour intervals.

* trademark β-carotene is suitably used in the same amounts as in the case of tocopherol acetate and the like, and by the same administration method sand regimens. Preferably, it is compounded in neutral base, e.g. corn oil or similar carriers, as used with tocopherol acetate.

The invention is further described, for illustrative purposes, in the following non-limiting examples.

Skh-l hairless mice used in these experiments were from two groups: young (6 - 8 week old) females, and retired breeding males approximately 1 year old at the time of the experiment. Prior to each UV exposure daily measurements of erythema index were taken using an erythema meter ^~ (Dia-stron, Sandhurst, Surrey, England), at a site on the upper back approximately 1 cm above the top of the V-shaped wedge between the haunches, at a place which approximated the highest position or hump of the back of the resting mouse. A minimum of 18 readings of the erythema index were usually obtained each day at approximately the same time of day. These were obtained in an initial experiment for 2 days prior to UVB (peak 310 nm) exposure and in all later experiments for 6 days prior to irradiation with UVB. This trained the mice to the procedure and also permitted a stable baseline erythema index to be obtained over a number of days. The pre- exposure erythema index was obtained by averaging these values.

The erythema index is effectively a measure of skin colour. Red and green light is shone on the affected area, whereupon the hemoglobin in the skin absorbs the green light but reflects back the red light. Thus a ratio of red to green reflected light is obtained, and the redder the colour of the skin, the more red light is reflected and the higher the erythema index recorded. The index is recorded in numbers from 10 - 300, the higher the number the redder the colouration or discolouration of the skin area.

For UV exposure, mice were placed in one litre glass beakers (Corning, 10 cm diameter x 15 cm high) containing 100 ml dry measure of cedar chips (2-3mm square) and usually 2 food pellets (Agway Prolab diet: RMH 3000) and a small piece of apple and/or raisin, so that they would stay in a prone position during the irradiation while feeding, and not stand up for prolonged periods: standing would alter the UV dose received at the central back position chosen for monitoring. Mice were exposed for defined periods of time, and the dose of the erythema- producing UVB was calculated from the dose measure at the same location using a UVB meter (UVX Digital Radiometer, UVP, San Gabriel, CA. ) with the UVB (310 nm) sensor placed in the same position and at the same distance (25.5 cm) from the source, four Phillips TL40W/12 tubes placed in a standard four-tube fluorescent unit and operated at a voltage of 110 volts (after initially starting at 140 v followed by a 10 minute warm-up period to stabilize prior to irradiation of the mice). In most experiments this resulted in a UVB level of approximately 450 μW/cm². Testing with the UVA sensor (360-nm peak) revealed that these tubes emit approximately 4 times as much UVB (310-nm peak irradiation) as UVA.

The application of the composition containing the tocopherol acetate composition to the incident area of the mice was done by applying 100% pure material to the area by means of a swab so that the entire incident area was covered by a thin film or coating of the material. It was applied at a concentration of approximately 5 mg/cm², gently rolling the oil-soaked cotton applicator longitudinally along the back of the mouse.

EXAMPLE 1

Histopathological changes observed in skin biopsies taken from the UVB-exposed skin at a location 2.5 cm above the base of the tail revealed apoptosis (sunburn cells) and inflammation typically seen after sunburn.

To monitor these changes non-invasively on a continuing basis until healing of the sunburn was complete the erythema index was monitored following UVB exposure. A minimum of 18 readings of the erythema index were recorded each day at the area of skin located at the peak of the back, approximately 5 cm anterior to the base of the tail. The difference in erythema reading was obtained by averaging the values for each post-exposure day and subtracting the pre-exposure value from the average daily value.

This change in erythema index was subjected to multiple regression analysis using the SPSS statistical program ² with time in days, UVB exposure, and treatment with topical VEA as independent variables. The results (Table 1) indicated that the erythema increased with time after exposure and that the rate of increase was significant during a three day period after UVB exposure. For the young female skh-1 mice exposed at 450 μw/cm² for 8.5 minutes as described, to a dose of 0.23 J/cm², this rate of increase was reduced by 46% (p, the probability of error, < 0.001) over the three-day period if topical tocopherol acetate was applied one time only, immediately after the UVB exposure. One year old male mice, exposed for 4.25 min to half the above dose (0.115 J/cm²) showed a rate of erythema increase of 9.10 ± 1.69 / day (p<0.00001) which was significantly reduced after one tocopherol acetate application by 54.9% (p<0.004) in the first experiment. In a second experiment, a reduction of 40.2% (p<0.05) in rate of erythema increase was found following one tocopherol acetate treatment of UVB-exposed mice.

TABLE 1: RATE OF ERYTHEMA INDEX INCREASE AFTER UV TREATMENT

Experiment Age Sex

1 6-8 Wk F .230 10.0 ± 1.9 (p<0.00001) 46% (p<0.019)

2 1 yr M .115 9.1 ± 1.69 (p<0.00001) 54.9% (p<0.004

3 1 yr M .115 9.42 ± 1.97 (p<0.00001) 40.2% (p<0.05)

* Values are average over days 0 - 3 of erythema index increases.

** Probability values are for overall regression analysis for rate of daily increase usin SPSS/PC statistical program.

For experiment 1, four groups each 6 mice were used to compare (a) irradiated ( unirradiated (c) irradiated and treated and (d) unirradiated and treated mice.

For experiments 2 and 3, three groups were used: (a) irradiated (8 mice) (b) Irradiat and treated (8 mice) and (c) unirradiated control (6 mice).

EXAMPLE 2

The skin sensitivity of the same region of the back was measured using a nylon fibre esthesiometer (Cachet and Bonner model, Luneau, Chartres, France) as previously described to measure corneal sensitivity to touch ³. The experiment was conducted as a part of Example l, with same group of young male mice and the same exposed skin areas, just a few minutes after the tests on the exposed skin areas reported in Example 1 had been conducted.

In this test, rapid aversive behaviour to a pressure of 0.96 g/mm² (fibre length 60 mm) was tested, with rapid movement by the mouse following immediately on application of the tip of the fibre to the back as an end point. Rapid aversive behaviour was scored as a 1, while a delay in response or failure to respond rapidly as normally found in unexposed animals was scored as a zero. Each animal was given a one or a zero rating. Differences between groups were analyzed by the nonparametric Wilcoxon test ^~ . At one day after UVB, UV-exposed mice were more sensitive than unexposed mice (p<0.04), and the UV-exposed tocopherol acetate-treated mice (p<0.07), but the UVB- exposed tocopherol acetate-treated mice were not significantly different from the unexposed mice (p<0.32). After two days the difference between the UV-irradiated and control unirradiated groups was still marginally significant (p<0.07) and the tocopherol acetate-treated irradiated group was marginally significantly different from the untreated irradiated group (p<0.1), but not from the untreated control group (p<0.36). In a separate experiment, when the sensitivity was followed over a six- day period after UVB irradiation, the back skin sensitivity of the irradiated mouse was significantly different from that of the UV-irradiated tocopherol acetate-treated mouse and from the control mouse.

EXAMPLE 3

Magnetic resonance imaging (MRI) of three anaesthetized mice weree used to measure skin thickness at the central back, by axial sectional images of 2 mm thickness of the thorax-upper abdomen using a Bruker MSL 80 Imaging Spectroscopy System. A 5.6 cm field of view and 256 matrix yielded an inplane pixel dimension of 217 microns. The normal mouse skin was measured in an axial section positioned in the middle of the hump of the mouse back. The section showing minimum skin thickness (in the sagittal view the one in which the skin of the back was most parallel to the horizontal plane), was chosen for measurement. The downward curvature of the back on both sides of the hump (as one proceeded in either posterior or anterior directions), increased the apparent thickness of the skin due to volume averaging, in images in sections adjacent to the one used to measure thickness of the skin. Thus, apparently thicker skin images were located on both sides of the section of minimum thickness. This selection could easily be made by comparing serial axial images and choosing the one with minimum skin thickness. For this section the thickness was measured using a minimum of 8 different locations on the back or belly skin as seen in the section. The results are shown in Table II.

In this experiment, treatment with topical tocopherol acetate significantly decreased by 61% (p<0.01) the apparent 62% (p<0.01) thickening observed 2 days after UVB exposure, when compared to unirradiated controls. After 8 days, the skin of the treated mouse had returned to a thickness (.93mm) not significantly different (p<0.1) from the control (.86mm), while the skin of the UVB-exposed untreated mouse still was significantly thicker by 24% (1.07 mm, p<0.01) than the control. In all experiments treatment did not result in any significant increase in belly skin thickness even with irradiated mice since no UVB irradiation reached the underside of the mouse. In this experiment, observation of the skin of these mice showed small flakes of skin (desquaraation) on the irradiated area at 3 through 6 days post-UVB on the irradiated treated mouse, while this was not observed until 6 - 10 days in the irradiated untreated mouse. TABLE II SKIN THICKNESS AFTER UVB EXPOSURE AND VEA TREATMENT THICKNESS IN MM X 100

DESCRIPTION UV EXPOSURE VEA THICKNESS ± SE AT OF MOUSE (J/CMJ TREATMENT DAYS AFTER UV EXPOSURE DAY 1 DAY 2 DAY 3

Control 82 ± 3 87 ± 3 86 ± 6

Exposed, Treated 0.115 104 ± 4 108 ± 3 93 ± 2 Exposed 0.115 122 ± 2 141 ± 2 107 ± 4

B, PERCENTAGE DIFFERENCES FROM SKIN THICKNESS AT ZERO TIME PRIOR TO IRRADIATIO AND TREATMENT

DESCRIPTION UV EXPOSURE VEA PERCENTAGE CHANGE IN THICKNESS OF MOUSE fJ/CMg) TREATMENT (PROBABILITY P) AT DAYS AFTER EXPOSURE

DAY 1 (P) DAY 2 (P) DAY 8 (P)

Control -7% (p<0.16) -1% (p<0.70) -2% (p<0.58

Expose , Treated 0.115 + +18%(p<0.008) +23%(p<0.001) +8% (p<0.10

Exposed 0.115 +39%(p<0.0001) +60%(p<0.0001) +24%p<0.001

C. PERCENTAGE DECREASE OF UVB EXPOSED SKIN THICKNESS AFTER TREATMENT WIT TOCOPHEROL ACETATE

TIME AFTER UVB EXPOSURE FOLLOWED BY APPLICATION OF TOPICAL TOCOPHEROL ACETAT

54% 61% 67%

Similar results for skin thickness increase were found when exposure to UVB irradiation and tocopherol acetate treatment were compared for four mice in a square protocol (Table II). On day 1 after UV exposure, the UVB- exposed skin increased 52% in thickness. This increase in thickness was diminished by 24% in the VEA-treated mouse (p<0.04), and the VEA treatment resulted in earlier appearance of epidermal desquamation or "peeling of the skin after sunburn in this experiment, in agreement with the earlier observation, indicating that healing is taking place more rapidly. Belly skin thickness did not change significantly.

TABLE II SKIN THICKNESS AFTER UVB EXPOSURE AND VITAMIN E ACETATE TREATMENT

DESCRIPTION UV TOCOPHEROL OF MOUSE (J/cm²) ACETATE TIME O DAY 1 (P DAYS 0-1) DAY 2 (P DAY 0-2)

1. Control 76.25± 2.7 93.9 + 3.3 86 ± 4

2. Control, Tr + 71.1 ± 1.2 78.1 ± 2.9 not done

3. Exposed 0.115 75.25 ± 3.3 129 ± 6 134 ± 6

4. Exposed, Tr 0.115 70.8 ± 3.8 107 ± 5 112 ± 6

Decrease After UV Treatment 29% 26%

For upper back, probability of statistical difference compared to control at day 2:1 v 2 (p<0.005) 1 vs 4 (p<0.09), 3 vs 4 (p<0.02)

B. PERCENTAGE DIFFERENCES FROM SKIN THICKNESS AT ZERO TIME PRIOR TO IRRADIATION FOLLOWE IMMEDIATELY BY VEA TREATMENT OF MOUSE

PERCENTAGE CHANGE IN THICKNESS (PROBABILITY P) AT DAYS

DESCRIPTION TOCOPHEROL AFTER UVB EXPOSURE FOLLOWED IMMEDIATELY BY VEA OF MOUSE (J/CM2) ACTATE TREATMENT OF MOUSE

DAY 1 (P DAYS 001) DAY 2 (P DAYS 0-2)

Control o +23% (P 0.009) +13% (p<0.18)

Control, Tr 0 + +9.8% (P 0.08) Not done Exposed 0.115 +71.5% (P 0.001) +78% (p<0.0001)

Exposed, Tr 0.115 + +51.5% (P 0.0001) +58% (p<0.0001)

PERCENTAGE DECREASE OF UVB-EXPOSED SKIN AFTER TREATMENT WITH VEA

TIME AFTER UVB EXPOSURE FOLLOWED IMMEDIATELY BY APPLICATION OF TOPICAL TOCOPHEROL ACETAT

DAY 1 DAY 2 29% 26%

EXAMPLE 4

The time dependence of the percent increase in skin thickness was observed, and it was determined that a thickness increase of approximately 0.2 mm/day (p<0.0001) occurred as a function of time during two days following UVB irradiation. Statistical t-testing using the SPSSPC analysis indicated an increase in thickness of 73% on day 1 (p<0.0001) and 96% by day 2 (p<0.0001) after UVB exposure. These results are shown in the following Table IV.

TABLE IV: SKIN THICKNESS AS A FUNCTION OF DAYS AFTER UVB RADIATION

REGRESSION ANALYSIS: INCREASE OF 19.82 ± 3.29 X 10^-2 MM P<0.0001) PER DAY

EXAMPLE 5

The effect of delaying application of topical tocopherol acetate after UVB irradiation was determined. After one day, the percent increase in thickness of untreated mouse skin was 73% (p<0.0001). Application of topical tocopherol acetate 0 - 8 hours after UVB exposure resulted in large reduction in the increase in skin thickness. The increase was reduced to 11 - 35%, or by more than half (P<0.029 - P<0.0001). These results are shown in the accompanying Tables 4 and 4B.

TABLE 2: TIME OF TREATMENT AFTER UVB IRRADIATION FOR 4.25 MINUTES

REGRESSION ANALYSIS OF SKIN THICKNESS IN MM X 10²

INCREASE PER DAY OF SKIN THICKNESS 17.83 ± 1.81 (P<0.00001)

INCREASE PER DAY DUE TO DELAY OF TREATMENT APPLICATION 0.12 ± 0.03 (P<0.0002)

TIME OF AFTER UVB TREATMENT TIME APPLIED DAY 0 DAY 1 DAY 2 (hr)

103.56 ± 3.6 (131%)

P< 0.253 (0-1 hr) 0.001 (0 hr-NA)

79.14 ± 2.6 107.1 ± 1.3 118.2 ± 2.5 (135%) (149%)

P< 0.0001 0.0001 (0-1 day) (0-2day)

0.0001 0.011 (1 hr-NA) (1 hr-NA)

85.2 ± 3.6 95.8 ± 5.2 111.7 ± 3.4 (112%) (131%)

P< 0.089 0.002 (0-1 day) (1-2 day)

0.275 0.016 (0-2 hr) (2hr-NA)

0.0001 (2hr-NA)

85.5 ± 2.8 115.5 ± 5.2 (135%) TABLE 4B

TIME OF TREATMENT AFTER UVB TIME APPLIED (hr) DAY 0 DAY 1 DAY 2

P< o.ooi (o-lday) 0.135 (0-4hr) 0.029 (4hr-NA)

84.1 ± 2.4 93.6 ± 7.3 (111%)

P< 0.274 (0-1 day) 0.234 (0-8 hr) 0.0001 (8hr-NA)

NOT APPLIED (NA) 75.3 ± 3.8 130.9 ± 3.2 145.0 ± 9.9 (173%) (196%)

P< o.oooi (0-1 day) 0.0001(0-2 day)

(0.001 (0 hr-NA)

EXAMPLE 6

The effect of varying the percent of tocopherol acetate in the topically applied fluid was determined. By regression analysis, the increase in skin thickness was decreased by 0.18 x 10^"2 mm/day per percent tocopherol acetate in the medium (P<0.02). In other words, for 100% tocopherol, the skin would be predicted to be 0.18 mm thinner after one day and 0.36mm thinner after two days, as compared with untreated skin. This assumes an effect which changes linearly with time after exposure or treatment, which may not be a correct assumption.

Both 5% tocopherol acetate in myritol 318 and 100% tocopherol acetate were effective, decreasing the skin thickening by 58% for 5% tocopherol acetate and by 49% for purer tocopherol acetate. The similarity of the reduction by both these concentrations raises the possibility that the effect may plateau after a minimum concentration. The results are shown in the following Table 5.

TABLE 5: PERCENT OF TOCOPHEROL ACETATE IN TOPICAL MEDIUM APPLIED TO SKIN AFTER UVB IRRADIATION

REGRESSION ANALYSIS OF PERCENT TOCOPHEROL IN MEDIUM SKIN THICKNESS PER DAY = 0.18334 ± 0.076 MM X 10^"2 PER PERCENT TOCOPHEROL IN MEDIUM (P<0.0179)

P< 0.0001 (0-5%) 0.004 (DAY 0, 0%- DAY 1, 5%)

100 103.6 ± 3.6 49% TO 51% (137.6%)

P< 0.37 (5% - 100%) 0.001 (0-100%)

EXAMPLE 7

A young human being was exposed to sub-tropical sunshine for two hours, in May in the northern hemisphere, as a result of which moderately severe skin sunburn was experienced. A cream containing tocopherol acetate, along with SOLARCAINE (trade-mark) lot SL03-BB 20413, a proprietary anti-sunburn soother, was applied to the effected areas shortly after exposure. Within two hours, the hypersensitive discomfort was prevented, and early (3 day) desquamation and healing of the skin resulted.

EXAMPLE 8

β-carotene as a 30% w/w composition in corn oil was used to alleviate UV radiation effects on skh-mice as described in the previous examples. The histology of UV exposed skin was observed after 48 hours, following immediate β-carotene application after UVB. The skin thickness increase normally caused thereby was decreased by 25% (p<0.04) at 24 hours, and decreased by 44% (p<0.034) at 48 hours, as a result of β-carotene application, when compared to untreated, UV-exposed skh mouse.

REFERENCES

1. Diffey, B.L., Oliver, R.J., and Farr, P.M. (1984) Brit. J. Dermatol. Ill 663 - 672.

2. Norusis et.al., (1988) Spss/Pc V. 2.0 Base Manual pp. 180-181. Spss Inc., Chicago, 111.

3. Trevithick et. al., (1989) Lens and Eye Toxicity Research, 6 387-393.

Claims

I CLAIM:

1. A method for treating or alleviating the effects of sunburn on human or animal skin, which comprises applying topically to the area of sunburned skin an effective amount of a 6-(Cl-C4) lower alkylcarbonyloxy derivative, or a carboxylated polyethylene oxycarbonyl substituent thereof, of tocopherol, in association with a skin compatible and acceptable carrier.

2. The method according to claim 1, wherein the active ingredient is tocopherol acetate, tocopherol succinate or tocopherol polyethylene glycol succinate.

3. The method according to claim 2, wherein the active ingredient is tocopherol acetate.

4. The method according to claim 3, wherein the applied composition comprises from 1 to 100% by weight of tocopherol acetate.

5. The method according to claim 4, wherein the composition comprises from about 1 - 10% by weight of tocopherol acetate.

6. The method according to claim 3, wherein the active ingredient is applied at a rate of from about 25 - 10,000 micrograms per square cm. per area of sunburned skin.

7. The method according to claim 6, wherein the active ingredient is applied at a rate of from about 50 - 5,000 micrograms per square cm of skin.

8. A pharmaceutical preparation for topical application to human or animal skin to alleviate the effects of sunburn thereon, said preparation comprising an effective amount of a 6-(Cl-C4) lower alkylcarbonyloxy derivative, or a carboxylated polyethylene oxycarbonyl substituent thereof, of tocopherol, in association with a skin compatible and acceptable carrier.

9. The composition according to claim 8, wherein the active ingredient is tocopherol acetate, tocopherol succinate or tocopherol polyethylene glycol succinate.

10. The composition according to claim 9, wherein the active ingredient is tocopherol acetate.

11. The composition according to claim 10, wherein the concentration of active ingredient is from about 1 - 10% by weight.

12. A method for treating sunburn on human or animal skin, which comprises topical application thereto of an effective amount of β-carotene.

13. A pharmaceutical preparation for topical sunburn treatment, comprising an effective amount of β-carotene in association with a skin compatible and acceptable carrier.