JP3337832B2 - Method and apparatus for measuring ultraviolet protection effect - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the effect of protecting against ultraviolet rays, and more particularly, to a high correlation with the SPF value (sun protection factor: the degree to which cosmetics and the like prevent sunburn caused by ultraviolet rays) measured on human skin. SPF value in v
It relates to a method and a device for obtaining in vitro.

[0002]

2. Description of the Related Art The SPF value is used as a scale indicating the effect of cosmetics for preventing sunburn caused by ultraviolet rays, so-called sun care products. This SPF value is an index indicating the effect of protecting the skin from sunburn (causing the skin to become reddish, hot, and irritating in a short time) and preventing sunburn due to ultraviolet rays, and is defined as follows.

[0003]

(Equation 1)

For example, when sun care cosmetics of SPF 8 are used, it means that when exposed to B ultraviolet rays eight times that in the case of tanning with bare skin, the same sunburn (redness) as that of bare skin is caused. In measuring the SPF value, artificial light (solar simulator) that is very close to the sun's rays is used instead of sunlight whose value may vary depending on the season or place. The measurement is performed by irradiating a certain amount of ultraviolet light to the uncoated skin and the uncoated skin respectively, and then the sunburn (erythema) the next day
By checking to see if it has occurred.

In the United States, the FDA's Federal Regist
er OTC monograph (1978) defines the SPF measurement method as follows. 1. The skin types of the test subjects are men and women aged 18 years or older of I to III ^* . 2. The number of subjects is 20 or more. 3. A sunscreen having a prescribed formulation of SPF4 is used as a standard sample. 4. The sample application amount is 2 mg (μs) / cm ² .

[0006] 5. The area of the sample application amount is 20 cm ² or more. 6. The time from sample application to irradiation is 15 minutes or more. 7. As a light source, sunlight having a UV-B wavelength of 290 to 320 nm or a solar simulator approximated to sunlight is used. 8. Irradiation is 0.5 cm ² or more.

[0007] 9. Irradiation increase width is set to be equal, and the ratio is set to 25% at the maximum. 10. The judgment of MED is performed by a skilled person in a bright place 16 to 24 hours after the end of irradiation. 11. The SPF is calculated in accordance with the formula using the MED of the panel obtained in the sample-uncoated area and the sample-coated area.

* US skin type classification Type I Very easy to burn (red) and not black. Type II Easily burns (reds) and turns slightly black. Type III Always black after sunburn (red).

Type IV: It does not burn too much (red), but immediately turns black. Type V Very black without sunburn (redness). Type VI Never black (red) and very black.

By using the SPF value measured according to the above method, it is possible to objectively evaluate the ultraviolet protection effect of the product. However, the above method requires a great deal of cost and days since the cooperation of a large number of specific skin type subjects is essential. Therefore, for example, in order to evaluate the UV protection effect of products in the development stage, etc., in vitro
In a simple manner, the in vivo S obtained by the above method can be used.
It is desired to develop a measuring method capable of obtaining an in vitro SPF value having a high correlation with the PF value.

As a method of measuring the SPF value in vitro, a method as shown in Table 1 has been proposed.
Table 2 shows the evaluation results of these measurement methods.

[0012]

[Table 1]

[0013]

[Table 2]

[0014] These are mainly concerned with sunscreen agents (sunscreen lotions and creams), and if the measurement target is limited to sunscreen agents,
Some of them show a relatively high correlation with the SPF value obtained in vivo (indicated by “△” and “○” in the column of “Sunscreen” in Table 2). However, for dosage forms other than sunscreen agents, there are many that cannot be measured because the measurable sample cannot be adjusted (indicated by x in Table 2). in v
It was not at a satisfactory level in terms of correlation with the IVO SPF value (indicated by a symbol in Table 2). In addition, as described in detail later, the measured value and in vivo
vo Since the relationship with the SPF value is slightly different, it is necessary to calculate a conversion factor for each dosage form from a large number of samples having similar dosage forms, and therefore, it is not possible to measure a sample whose dosage form is unknown (see Table 1). 2). Further, it is desirable that the SPF value can be measured up to a high range.
In many cases, the upper limit of the F value is low (Table 2). Even if an SPF of 20 or more can be measured, there is no correlation with the in vivo SPF value.

Conventionally, UV-A (320 to 400
nm), UV-B (290-320)
nm) (1/1000 to 1/1).
500) and the former was considered to give an additional effect (additive effect) to the latter, so the erythema rejuvenation effect was measured for each wavelength to calculate the erythema coefficient, and the transmitted UV amount Was multiplied by the erythemal coefficient for each wavelength, and the SPF value was directly calculated from the erythemal UV intersity (EUI) corrected. As long as such a method is taken, in vivo
There is a limit to the correlation with the SPF value, and the transmitted UV-A
It is believed that different factors require the use of different coefficients for different dosage forms.

[0016]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to determine an SPF value having a high correlation with an SPF value measured in vivo, irrespective of the dosage form of the sample.
It is an object of the present invention to provide a measuring method and an apparatus which can be obtained in o. Another object of the present invention is to calculate in terms of an arbitrary dosage form by using a common coefficient regardless of the dosage form.
The SPF value that is highly correlated with the vivo SPF value
An object of the present invention is to provide a measuring method and an apparatus which can be obtained in vitro.

Yet another object of the present invention is to provide a measurable S
An object of the present invention is to provide a measuring method and an apparatus having a high upper limit of the PF value.

[0018]

According to the present invention, there is provided a method for measuring an ultraviolet protection effect, comprising: measuring the intensity of ultraviolet light transmitted through a sample in a plurality of wavelength sections; Is multiplied by the erythema coefficient for each wavelength section, and the sum is obtained to calculate the erythema-inducing UV intensity, and the transmission UV is calculated by taking the sum of the intensities in each wavelength section belonging to the UV-A wavelength range. -A intensity is calculated, a light enhancement effect coefficient is calculated from the transmitted UV-A intensity, and the light enhancement effect coefficient is multiplied by the erythema-inducing UV intensity to calculate a final erythema-inducing UV intensity.
The method further comprises the steps of calculating an SPF value from the final erythema-inducing UV intensity.

The apparatus for measuring an ultraviolet protection effect according to the present invention further comprises means for measuring the intensity of the ultraviolet light transmitted through the sample in a plurality of wavelength sections, and the measured intensity of each wavelength section to the erythema coefficient for each wavelength section. A means for calculating the erythema-inducing UV intensity by multiplying by each of them, and a means for calculating the transmitted UV-A intensity by taking the sum of the intensity in each wavelength section belonging to the wavelength range of UV-A, Means for calculating a light enhancement effect coefficient from the transmitted UV-A intensity, means for calculating the final erythema-inducing UV intensity by multiplying the light enhancement effect coefficient by the erythema-inducing UV intensity, and SPF from the final erythema-inducing UV intensity Means for calculating a value.

[0020]

As will be described in detail later, the present inventors quantitatively confirmed that the photoenhancing effect of UV-A on the erythema-inducing effect of UV-B is not additive but synergistic. Therefore, by calculating the transmitted UV-A intensity, then calculating the light enhancement effect coefficient, and calculating the SPF value by multiplying the erythema-inducing UV intensity corrected by the erythema coefficient, a common formulation independent of the dosage form is obtained. In vivo using the conversion formula of
o An SPF value having a high correlation with the SPF value is obtained.

[0021]

FIG. 1 shows an overview of a solar simulator 10 as a light source used in the present invention. Light from a lamp built in the housing 12 is emitted from a plurality of irradiation nozzles 16 via a plurality of optical fibers 14. This is the same as that used in the above-mentioned in vivo SPF measurement method defined by the US FDA.

FIG. 2 shows a spectroradiometer 1 on the detection side.
8 represents an overview. The light received by the light receiving unit 20 is guided to the detector 24 via the optical fiber 22. Detector 24 is 2
Light in the range of 50 nm to 420 nm is separated at intervals of 2 nm, each intensity is converted into a voltage, and then A / D converted and output. The personal computer 26 is connected to the detectors 24 to 2
Enter the spectral intensity for each nm and perform the processing described later to
Calculate the F value.

FIG. 3 shows the irradiation nozzle 16 and the light receiving section 2 during measurement.
0 indicates the positional relationship. The irradiation nozzle 16 and the light receiving unit 20 are fixed at a predetermined interval, and the tape member 30 on which the sample 28 is applied with a predetermined amount is fixed at a position at a certain distance from the irradiation nozzle 16. The tape member 30 may be any material that can transmit ultraviolet rays. However, in order to approach the microscopic shape of the surface of the skin, a medical 3M Transpore ^™ tape having a myriad of pores (pores) is preferably used. use.
Further, in order to prevent the lotion from dropping into the pores of the tape and to prevent the lotion from rotating further to the back surface, a tape obtained by bonding the adhesive surfaces of two tapes to each other is used.

Embodiment 1 FIG. 4 shows a spectrum 32 of the light emitted from the solar simulator 10 and a spectrum 34 of the transmitted light for a certain sample. The transmitted light spectrum 34 is represented by a bar graph of the intensity every 2 nm. The measurement conditions are as follows. (1) UV-B intensity 2.0 MED / min (2) Irradiation distance 10 mm (3) Measurement time 500-3000 msec (optimum value is set according to transmitted UV intensity) (4) Coating amount 1.0 mg / cm ² (5 ) The sample is evenly applied to the tape with a finger and measured after 15 minutes or more. In the first embodiment of the present invention, the application amount specified in the United States is 2.0 mg / cm ² , 1.0mg
/ Cm ² is for enabling measurement up to a high SPF value.

First, based on the conventional method, 290 nm to 400 nm
Table 3 shows the transmitted UV intensity I (λ) at each wavelength λ in the range of
Erythema coefficient (relative coefficient of erythema-inducing effect) E
E (λ) is multiplied and summed to obtain the erythema-inducing UV intensity (EU
I) ΣEE (λ) Calculate I (λ) and plot the relationship between the SPF value measured in vivo and log (1 / EUI).

[0026]

[Table 3]

FIG. 5 to FIG. 8 show the in v
SPF values measured in vivo and erythema-inducing UV intensity ΔEE
(Λ) shows the relationship with log (1 / EUI) calculated from I (λ). When the measurement object is plotted by dividing it by each dosage form, there is a certain degree of correlation between the two except for the case of an oily foundation. However, the straight line obtained by the least squares method for each dosage form differs significantly between dosage forms. This means that according to the conventional method, it is necessary to use a different formula for each dosage form to calculate the SPF value, and whether the dosage form is unknown or to which classification it should be classified. When unknown, it means that measurement cannot be performed by the conventional method. Also, it is shown that accurate measurement may not be possible even if the dosage form is known, as in the case of an oily foundation (FIG. 8).

Focusing on the oily foundation which has a low correlation, it can be classified into a transparent type, a translucent type, and an opaque type according to the purpose of use. The oily foundation is composed of wax, oil and powder, and is classified in terms of formulation according to the amount of titanium oxide in the powder. Therefore, UV-A (3
(20-400 nm) and those that hardly transmit. Then, when only those which hardly transmit UV-A were extracted and plotted in the same manner, a high correlation was observed between the in vivo SPF value and the EUI as shown in FIG.

From the above results, it can be seen that the influence of UV-A is not properly evaluated by the conventional method of calculating the SPF directly from the EUI. Therefore, assuming that the action of UV-A is synergistic, a “light enhancement effect coefficient” as a function of the amount of UV-A is considered, and the value of (light enhancement effect coefficient) × (EUI) (2) Irrespective of the in vivo SPF value. Assuming that the light enhancement effect coefficient of a sample that does not transmit UV-A is 1, the light enhancement effect coefficient of any sample is equal to the in vivo S of the sample.
From the PF value, the value of the EUI (referred to as theoretical EUI) when there is no influence of UV-A obtained by using the straight line in FIG. 9 and the actual EUI can be roughly calculated by the following equation.

(Light Enhancement Effect Coefficient) = (Theoretical EUI) / (EUI) (3) FIG. 10 is a plot of the relationship between the UV-A intensity and the light enhancement effect coefficient for the oily foundation.
The UV-A intensity is the total sum of transmitted light of 320 to 400 nm obtained under the condition of a coating amount of 2.0 mg / cm ² . From FIG.
The relationship between the UV-A intensity and the light enhancement effect coefficient is α (≒ 3.
It can be seen that it is approximated by an exponential function with 3) as the base.

The light enhancement effect coefficient (= 3.3 ^UV-A ) is expressed by E
When the correlation described in FIGS. 5 to 8 is multiplied by multiplying the UI, the results are as shown in Table 4, and a high correlation is shown for each dosage form and all dosage forms.

[0032]

[Table 4]

Further, if the relationship between the UV-A intensity and the light enhancement effect coefficient is an exponential function, the base α can be calculated for each sample by the following equation. logα = {log (theoretical EUI) / (EUI)} / (UV-A intensity) (4) When this value α is plotted against EUI, the relationship becomes downward-sloping as shown in FIG. This is because when the intensity of transmitted UV-B is relatively small, the light enhancing effect of UV-A acts strongly, and as the intensity of transmitted UV-B increases, UV-A
It is explained that the light-enhancing effect of this is due to fading. This relationship can be approximated by logα = −9.94 × 10 ⁻⁴ ΣEE (λ) I (λ) +0.678 (5) Accordingly, a more precise light enhancement effect coefficient is given by 10 ** {(− 9.94 × 10 ⁻⁴ × {EE (λ) I (λ) +0.678) × (UV-A intensity)}} (6). (** means exponentiation) EUI multiplied by this light enhancement effect coefficient and in vivo
The correlation with the SPF value is as shown in Table 5, where a higher correlation is obtained for each dosage form, and at the same time, the correlation formula for each dosage form is expressed by almost the same equation.

[0034]

[Table 5]

As shown in FIG. 12, a high correlation was obtained for all the dosage forms, and a slope of 0.041 and an intercept of 3.2 were obtained. Therefore, in accordance with the present invention,
The vitro SPF value is

[0036]

(Equation 2)

Is calculated by the same conversion formula. FIG. 13 is a flowchart showing the processing of the personal computer 26 (FIG. 2) used in the SPF value measuring device according to one embodiment of the present invention. First, a measurement result I (λ) at an application amount of 1.0 mg / cm ² is taken from the detector 24 (step a), and each wavelength section is multiplied by an erythema coefficient EE (λ) to obtain 2
By taking the sum in the range of 90 to 400 nm,
(Λ) I (λ), that is, EUI is calculated (step b). Next, the measurement result I at a coating amount of 2.0 mg / cm ²
(Λ) is taken in (step c), and 320 to 400 nm
The UV-A intensity ΔI (λ) is calculated by taking the sum of the ranges (step d). Then, according to equation (7), in
An in vitro SPF value is calculated (step e).

According to the measurement method specified in the United States, the coating amount is 2.0 mg / cm ² , whereas EUI = ΔE
The amount of application for calculating E (λ) I (λ) is 1.0 mg / cm
^The reason for setting to 2 is to enable measurement up to a high SPF value in vitro.
More than 50 measurements were possible. Note that ΣEE (λ) I
If the coating amount of the sample used for calculating (λ) and ΔI (λ) is the same, the SPF value can be calculated and output by one measurement. Example 2 In this example, the amount of the sample applied for measuring the EUI and the UV-A intensity was set to 2.0 in accordance with the in vivo measurement.
mg / cm ² and inv according to a formula determined by the following more theoretical approach to the erythema reaction:
An intro SPF value is calculated.

The SPF value is the time (t) required to reach the minimum erythema volume (MED) with and without the application of the sunscreen agent.
SPF = t / t ₀ (8) Here, t ₀ is the time that sunscreen reached MED when no coating.

The effective UV light that directly causes erythema on human skin is a value obtained by multiplying the UV spectrum that has passed through the sunscreen agent by the relative effect factor that causes the erythema reaction shown in Table 3. Therefore, effective U that causes erythema
V intensity (Erythemal UV Intensity: EUI) is represented by the following equation. EUI = ΣEE (λ) I (λ) (9) where I (λ) is the transmission U of each wavelength detected by a spectroradiometer when a sunscreen agent is applied.
V intensity is shown.

EE (λ) indicates the relative effect coefficient of the working wavelength that causes the erythema reaction. On the other hand, the minimum erythema amount is
Time to reach MED (t) and UV acting on skin
This is the product of the intensities (equation (9)), and the actual minimum erythema amount should be constant for the same person, so the following equation holds. t ₀ ΣEE (λ) I ₀ (λ) = tΣEE (λ) I (λ) (10) Here, I _O (λ) indicates the transmitted UV intensity when the sunscreen agent is not applied.

Therefore, the following expression is satisfied from the expressions (8) and (10): SPF = ΣEE (λ) I ₀ (λ) / ΣEE (λ) I (λ) (11) That is, ΣEE (λ) I ₀ (λ) can be regarded as a constant since it is always constant unless the irradiation intensity of the light source changes. Therefore, we obtain the SPF value and 1 / ΣEE (λ) from equation (11).
By examining and analyzing the relationship of I (λ), the biological phenomena and effects related to the erythema reaction were examined.

All dosage forms (W / O and O / W emulsion type, powder type, oil-wax type)
Was evaluated for the sunscreen agent (N = 80). FIG. 14 shows the relationship between the SPF value and log (1 / ΣEE (λ) I (λ)). The "X" mark in the figure shows the result when no coating was performed. From FIG. 14, log (1 / ΣE
E (λ) I (λ)) and the in vivo SPF value were found to have some correlation. Therefore,
Calculated using the relative effect coefficient of the erythema action wavelength,
Transmitted UV intensity that works effectively on the skin (Erythemal UV I
ntensity (EUI) makes it possible to predict the SPF value to some extent.

By the way, the transmission UV of all the scattered samples
As a result of carefully observing the spectra, it was found that the samples located at the top and bottom of the graph had significantly different transmission UV spectra. FIG. 15 shows a transmission UV spectrum of a typical sunscreen agent of a W / O emulsion having the same SPF value and the same dosage form.
The sample A (SPF 4.9) in FIG. 15 is located at the top of the graph, and the sample B (SPF 5.5) is located at the bottom of the graph. Therefore, we thought that there was some relationship between the transmitted UVA intensity of the sunscreen and its position on the graph.

Therefore, the transmitted UVA intensity is 3.5 in FIG.
The graph distinction is made between mW / cm ² or more samples and 3.5 mW / cm ² or less of the sample shown in FIG. 16. As a result, S
In the region where the PF value was 20 or less, it was confirmed that the sample having a high transmitted UVA intensity was located at the top of the graph, and the sample having a low transmitted UVA intensity was located at the bottom of the graph. That is, the transmitted UVA of the sunscreen agent is SPF
The value, in other words, it was suggested that it acts on the skin and is involved in some form in the erythema reaction centering on UVB.

Kligman et al. Have proposed a light enhancing effect by UVA irradiation (Willis, I., Kligman, AMand).
Epstein, J., Effects of long ultraviolet rays on hum
an skin: Photoprotective or photoaugmentative? J.In
vest.Dermatol., 59, 416-420 (1972); Kaidbey, KHand Kl
igman, AM, Further studies of photoaugmentationin
humans: Phototoxic reactions.J.Invest.Dermatol., 65,
472-475 (1975)). This means that the irradiation amount of UVB (minimum erythema amount: MED) which causes an erythema reaction by UVA irradiation is reduced. We focused on the light enhancing effect of this UVA. In order to accurately verify the light-enhancing effect of UVA, it is necessary to minimize the difference in UV protection ability due to the dosage form of the sunscreen agent and the influence of the difference between the skin and the application body. Therefore, an oil-wax type sunscreen agent was used as a UV filter as a dosage form that is not easily affected by the applied body. This oil-wax type sunscreen was mixed with various ultraviolet absorbers and scattering agents to give different transmission UV spectra for verification. The point that the oil wax type sunscreen agent is excellent as a UV filter is that various ultraviolet absorbers and scattering agents can be uniformly and stably compounded. (Eg, degree of regularity, hydrophilicity and lipophilicity). These SPF
FIG. 17 shows the measurement results of the values, the EUI value (ΔEE (λ) I (λ)), and the transmitted UVA intensity value. Then, FIG.
The relationship between the PF value and the EUI value was shown. As a result, the effect of transmitted UVA was observed as in FIG.

Here, U proposed by Kligman
Considering the light-enhancing effect of VA, this indicates a decrease in minimum erythema volume (MED) centered on UVB. That is, it means that UVA acts on the skin and increases the sensitivity of the skin to UVB. In other words, since the erythema reaction induced in the skin is always the same phenomenon, from the skin side, the UVA
It is believed that B is the same as enhanced. Therefore,
For the light enhancement effect, it is necessary to verify how much UVB is enhanced by UVA. When the “reciprocity rule” is satisfied, when the expression (11) is modified, the expression (12) is derived.

ΣEE (λ) I (λ) = ΣEE (λ) I ₀ (λ) / SPF (12) In this case, when the sunscreen agent was not applied, the EUI value (Σ
Since _{EE (λ) I O (λ} )) is a constant value, constant theoretical value of EUI required to cause erythema reaction (11) ΣEE (λ) I ₀ of (lambda) (≒ 1350) It can be calculated by substituting the values and each in vivo SPF value. (Note that the X mark in FIGS. 16 and 18 indicates no coating (S
EUI value (log (1 / ＰＦEE) when PF = 1)
(Λ) I ₀ (λ)), and the solid and broken lines indicate
A theoretical value of EUI (a value of log (1 / EUI _TH )) calculated from the equation (11) with respect to the n vivo SPF value is shown, and is hereinafter referred to as a reciprocity curve. Therefore, the light-enhancing effect can be verified by observing the relationship between the transmitted UVA and the ratio of the measured EUI of the sample to the theoretical value where the influence of the transmitted UVA is hardly observed. FIG. 19 shows the light enhancing effect of UVA of the oil wax type sunscreen agent.
From FIG. 19, it was found that the light enhancement effect works exponentially with an increase in the transmitted UVA intensity. From the graph, the base α of the exponential function having the relationship of equation (13) is derived.

The theoretical value of EUI / the measured value of EUI = α ^UVA (13) Hereinafter, α ^{UVA is referred} to as a light enhancement effect coefficient, and α is referred to as a bottom of the light enhancement effect coefficient. Therefore, the theoretical value (EUI _Th ) of EUI, which is considered to cause an erythema reaction, is calculated from the light enhancing effect of UVA from equation (13). Then, the relationship between the EUI _Th value and the SPF value of the oil wax type sunscreen agent incorporating the light enhancing effect of UVA was examined (FIG. 20). The broken line in FIG. 20 indicates a reciprocity curve. Comparing the correlation coefficients, a higher value (R ² =
0.98), suggesting the existence of a photoenhancing effect of UVA. It can be seen that the "reciprocity law" holds for SPF 20 or less, but does not hold for SPF 20 or more. This suggests that there is another biological effect on the erythema reaction in the region above SPF 20. Therefore, we also verified all sunscreens by incorporating the light enhancement effect in the same manner (Fig. 2).
1). Looking at the relationship with the reciprocity curve, the correlation is higher in FIG. 21 than in the case where the light enhancement effect is not incorporated (FIG. 22). Thereby, especially in the region up to SPF 20, the light enhancing effect of UVA was observed, and it became clear that the reciprocity law was established. Therefore, we have established that UVA has a light enhancing effect on the erythema response.

By the way, the verification of the light enhancement effect of UVA has been promoted.
Can be presumed to be influenced by the ratio of UVA to UVB in the transmitted UV spectrum. Therefore, in order to verify this, first, 32
The transmitted UVA intensity value and the EUI value in the range of 0 to 400 nm (Σ
EE (λ) I (λ)), and then the measured SPF
The theoretical value (α _Th ) at the bottom of each light enhancement effect coefficient of each of the 20 or less sunscreen agents is calculated. Here, the transmission U
The reason why the EUI value is used instead of the VB amount is that the EUI value is almost equal to the transmitted UVB amount. Each α _Th is calculated from the ratio between the theoretical value and the measured value of the erythema UV intensity and the measured UVA intensity using the equation (13). Therefore, transmission UV
FIG. 23 shows the relationship between the ratio of the A intensity value / EUI value (ΣEE (λ) I (λ)) and the theoretical value (α _Th ) at the bottom of the light enhancement effect coefficient. As a result, with increasing ratio of transmitted UVA, α
Is increasing. That is, the light enhancement by UVA is U
It can be said that it is affected by the ratio between VA and UVB. When the ratio of UVB, which has a strong biological effect, is high, the center of the erythema reaction is UVB, and when the ratio of UVB is low, the light enhancing effect of UVA is seen. The following relational expression is determined from the relation in FIG.

Α _TH = 1 (x ≦ 23) α _TH = (x−23) ^0.032 (23 <x ≦ 175) α _TH = 1.175 (175 <x) (14) where x = UVA / EUI Using the formulas (14) and (13), the final EUI theoretical value (EUI _UL ) including the effect of the UVA / UVB ratio on the light enhancement effect of UVA is calculated, and all the sunscreen agents are calculated. Was again verified (FIG. 24). As a result, the final theoretical value of EUI (EUI _UL ) for all sunscreen agents was determined by reciprocity curve and SPF
Highly correlated with the value. Thus, we could more clearly show the existence of a photoenhancing effect of UVA on the erythemal response.

A curve satisfying the "reciprocity rule" is shown by a dotted line in FIG. As a result, within SPF 20, "Reciprocity law"
Is satisfied, but it is found that the “reciprocity law” does not hold in a region where the SPF is 20 or more. As far as the erythema reaction of human skin is concerned, the "reciprocity rule", which is the basic principle of the light reaction, is satisfied within a certain period of time, but not more. Instead, it was possible that another law with biological effects might hold. Therefore, only a calculation program in which “reciprocity law” and “reciprocity irregularity” are considered can predict the SPF value with high accuracy.

FIG. 25 shows an SP according to a second embodiment of the present invention.
Personal computer 26 used for F measurement device
It is a flowchart showing the process of FIG. For a sample having an application amount of 2.0 mg / cm ^2, the measurement data I (λ) is taken in from the detector 24 (step a), the EUI is calculated according to the equation (8), and the IUI is calculated in the range of 290 to 400 nm.
The UVA intensity is calculated by taking the sum of (λ) (step b). From the value of UVA / EUI, α _TH according to equation (13)
Is calculated (step c), and the final theoretical value EUI _UL of the EUI is calculated from the values of α _TH , UVA and EUI according to EUI _UL = EUI × α _TH ^UVA (step d). It is determined whether the value of EUI _UL is 75 or more (step e), and when the value of EUI _UL is 75 or more (S
PF <18), the SPF value is calculated by the formula SPF = 1350 / EUI _UL based on the formula (10) representing the reciprocity law (step f). When the EUI _UL is not 75 or more, the SPF value is calculated by the following empirical formula (step g).

SPF = (log (1 / EUI _UL ) +2.9227) /0.0581 FIG. 26 shows a part of the measurement results. In vitro measured by the apparatus of the present invention particularly in a high SPF region
It is noted that the SPF value is very close to the in vivo SPF value.

[0055]

As described above, according to the present invention, i
The SPF value showing a high correlation with the n vivo SPF value is i
It is obtained in n vitro using a common formula independent of the dosage form.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overview of a solar simulator as a light source.

FIG. 2 is a diagram illustrating an overview of a spectroradiometer on a detection side.

FIG. 3 is a diagram illustrating a positional relationship among an irradiation nozzle, a light receiving unit, and a sample.

FIG. 4 shows a spectrum of irradiation light of a solar simulator,
It is a figure showing an example of the spectrum of transmitted light.

FIG. 5: Inv for powder foundation
It is a figure showing the correlation of an IVO SPF value and EUI.

FIG. 6: i for W / O Liquid Foundation
It is a figure showing the correlation of n vivo SPF value and EUI.

FIG. 7 in vivo about O / W sunscreen
FIG. 6 is a diagram showing a correlation between an SPF value and an EUI.

FIG. 8: In vivo for oily foundation
FIG. 6 is a diagram showing a correlation between an SPF value and an EUI.

FIG. 9 is a diagram showing a correlation between an in vivo SPF value and an EUI for an oily foundation that does not pass UV-A.

FIG. 10 is a diagram showing a relationship between a UV-A amount and a light enhancement effect coefficient.

FIG. 11 is a diagram illustrating a relationship between EUI and a base α of a light enhancement effect coefficient.

FIG. 12 shows in vivo SPF values and E according to the present invention.
It is a figure showing the correlation with UI.

FIG. 13 is a diagram illustrating an in-vivo method according to the first embodiment of the present invention.
It is a flowchart showing the procedure of ro SPF measurement.

FIG. 14 shows in in various types of sunscreen agents.
FIG. 4 is a diagram illustrating a relationship between a Vivo SPF value and an EUI.

FIG. 15: Typical 2 with the same SPF value and the same dosage form
FIG. 3 is a diagram showing transmission UV spectra of two sunscreen agents.

FIG. 16 is a diagram in which each measurement point in FIG. 14 is distinguished according to the magnitude of UVA intensity.

FIG. 17 is a diagram showing a measurement result of a sample adjusted for verification of a light enhancement effect.

FIG. 18 shows in vivo in the sample of FIG.
It is a figure showing the relation between SPF and EUI.

FIG. 19 is a diagram showing the relationship between UVA intensity and light enhancement effect.

FIG. 20 is a diagram showing a relationship between an in vivo SPF value and EUI _TH incorporating a light enhancement effect.

FIG. 21. In in sunscreens of various dosage forms
It is a figure which shows the relationship between a Vivo SPF value and EUI _TH .

FIG. 22: In in sunscreens of various dosage forms
FIG. 4 is a diagram illustrating a relationship between a Vivo SPF value and an EUI.

FIG. 23 is a diagram showing the relationship between UVA / EUI and α _TH .

FIG. 24 shows various types of sunscreen agents in
FIG. 4 is a diagram illustrating a relationship between a Vivo SPF value and EUI _UL .

FIG. 25 is a diagram illustrating an in-vitro according to the second embodiment of the present invention
It is a flowchart showing the procedure of ro SPF measurement.

FIG. 26 is a diagram showing a measurement result in the second example of the present invention.

[Explanation of symbols]

10 ... solar simulator 16 ... irradiation nozzle 18 ... spectrometer radiometer 20 ... receiving portion 24 ... detector 26 ... personal computer 28 ... sample 30 ... transpore ^TM Tape

Continuation of front page (72) Inventor Harumi Odagiri 1050 Nippa-cho, Kohoku-ku, Yokohama-shi, Kanagawa Shiseido Co., Ltd. First Research Center (56) References Soc. Cosmet. Chem. 1989; 40, p127-133 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01N 33/00 JICST file (JOIS) WPI / L ( QUESTEL) Practical file (PATOLIS) Patent file (PATOLIS)

Claims (11)

(57) [Claims] 1.) a) measuring the intensity of ultraviolet light transmitted through a sample in a plurality of wavelength sections; b) multiplying the measured intensity of each wavelength section by an erythema coefficient for each wavelength section, and taking the sum thereof. C) calculating the transmitted UV-A intensity by taking the sum of the intensities in each wavelength section belonging to the UV-A wavelength range; and d) calculating the light from the transmitted UV-A intensity. F) multiplying the light enhancement effect coefficient by the erythema-inducing UV intensity to calculate a final erythema-inducing UV intensity; g) calculating an SPF value from the final erythema-inducing UV intensity A method for measuring an ultraviolet protection effect. 2. In the step d), the light enhancement effect coefficient is an exponential function of the transmitted UV-A intensity.
The described method. 3. The method according to claim 2, wherein the base of the exponential function is determined from the value of the erythema-inducing UV intensity. 4. The method of claim 2, wherein the base of the exponential function is determined from a ratio of the transmitted UV-A intensity to the erythema-inducing UV intensity. 5. In the step g), when the final erythema-inducing UV intensity is not less than a predetermined value, a constant is determined.
5. The method according to claim 4, wherein the SPF value is calculated by dividing by the V intensity, and when the final erythema-inducing UV intensity is equal to or less than the predetermined value, the SPF value is calculated from the final erythema-inducing UV intensity according to a predetermined empirical formula. . 6. The step a) includes applying the sample on a tape member that can transmit ultraviolet light, irradiating the tape member coated with the sample with ultraviolet light having a predetermined intensity distribution, and transmitting the sample through the tape member. The method according to any one of claims 1 to 5, comprising measuring the intensity of the applied ultraviolet light. 7. A means for measuring the intensity of ultraviolet light transmitted through a sample in a plurality of wavelength sections, and multiplying the measured intensity of each wavelength section by an erythema coefficient for each wavelength section to obtain a sum of them. Means for calculating the erythema-inducing UV intensity; means for calculating the transmitted UV-A intensity by summing the intensities in each wavelength section belonging to the UV-A wavelength range; and a light enhancement effect from the transmitted UV-A intensity. Means for calculating a coefficient, means for calculating the final erythema-inducing UV intensity by multiplying the light enhancement effect coefficient by the erythema-inducing UV intensity, and means for calculating an SPF value from the final erythema-inducing UV intensity. A device for measuring an ultraviolet protection effect, characterized in that: 8. The apparatus according to claim 7, wherein said light enhancement effect coefficient calculating means calculates said light enhancement effect coefficient as an exponential function of said transmitted UV-A intensity. 9. The apparatus according to claim 8, wherein the base of the exponential function is determined from the value of the erythema-inducing UV intensity. 10. The base of the exponential function is the erythema-inducing UV
9. The apparatus of claim 8, wherein the apparatus is determined from a ratio of the transmitted UV-A intensity to intensity. 11. The SPF value calculating means calculates an SPF value by dividing a constant by the final erythema-inducing UV intensity when the final erythema-inducing UV intensity is equal to or greater than a predetermined value. 11. The apparatus according to claim 10, wherein when the value is equal to or less than the predetermined value, an SPF value is calculated from the final erythema-inducing UV intensity according to a predetermined experimental formula.