In vitro prediction of sunscreen PFA values
View Patent ↗An in vitro method for the prediction of in vivo UVA protection by a composition with sunscreen properties. The method includes the steps of: determining in vivo SPF; determining in vitro SPF based on the sunscreen's absorbance spectrum in the UV region; normalizing the absorbence spectrum based on integration area of UVA1; and calculating the PFA-PPD in vitro.
1. A method for predicting the PFA value of a sunscreen composition comprising the steps of:
determining in vivo SPF;
determining in vitro SPF based on an absorbance spectrum in a UV region for said sunscreen composition; and
calculating the PFA-PPD in vitro based on an integration area of a UVA1 region.
2. The method of claim 1 , further comprising, after the step of determining in vitro SPF, the step of normalizing said absorbance spectrum.
3. The method of claim 1 , wherein said step of determining in vitro SPF is conducted on a substrate selected from the group consisting of surgical tape, polyvinyl chloride film, and synthetic skin substitute material.
4. The method of claim 1 , wherein said step of determining in vitro SPF is conducted on a substrate formed of a synthetic skin substitute material.
5. The method of claim 1 , wherein said step of determining in vitro SPF comprises a sunscreen composition applied to a substrate in an application dose of 2 mg/cm 2 .
6. The method of claim 3 , wherein said step of determining in vitro SPF comprises a sunscreen composition applied to said substrate in an application dose of 2 mg/cm 2 .
7. The method of claim 4 , wherein said step of determining in vitro SPF comprises a sunscreen composition applied to said substrate in an application dose of 2 mg/cm 2 .
8. The method of claim 1 , wherein said PFA-PPD in vitro is calculated using an equation:
PFA
-
PPD
in
vitro
=
∫
340
nm
400
nm
E
(
λ
)
·
S
(
λ
)
∫
340
nm
400
nm
E
(
λ
)
·
S
(
λ
)
/
10
[
A
(
λ
)
·
C
]
wherein E(λ) is an irradiance at a wavelength λ of a light spectrum used, S(λ) is an effectiveness of a biological endpoint at a wavelength λ, A(λ) is an absorbance, and C is a constant factor for an adjustment of the light spectrum.
9. The method of claim 2 , wherein said absorbance spectrum is normalized using an equation:
SPF
in
vivo
=
SPF
in
vitro
=
∫
290
nm
400
nm
E
(
λ
)
·
S
(
λ
)
∫
290
nm
400
nm
E
(
λ
)
·
S
(
λ
)
/
10
[
A
(
λ
)
·
C
]
wherein E(λ) is an irradiance at a wavelength λ of a light spectrum used, S(λ) is an effectiveness of a biological endpoint at a wavelength λ, A(λ) is an absorbance, and C is a constant factor for an adjustment of the light spectrum.