2,2'-Methylenebis(4-aminophenol) dihydrochloride

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 428 (Skin Absorption: In Vitro Method)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Type:

Constituent

Details on test material:

SAT 090013
Batch No.: 703
Study No.: 789228

Radiolabelling:

yes

Remarks:

14C

Test animals

Species:

other: dermatomed pig skin

Strain:

other: landrace large white cross pig

Sex:

male/female

Administration / exposure

Type of coverage:

open

Vehicle:

other: water or cream formulations with different developer mixed with hydrogen peroxide or without hydrogen peroxide

Duration of exposure:

The skin surface was washed at 30 min, for each test preparation, to reflect the in use conditions. The skin was again
washed at 24 h post dose as a final wash off before test run termination.
0.5 hours application time, afterwards test substance was rinsed off.

Doses:

The hair dye formulation was applied at an application volume of ca 20 mg/cm2. Therefore the resulted dose of the test substance was approx. 0.2 mg/cm2 skin.

No. of animals per group:

12 samples of pig skin from 4 different animals

Control animals:

no

Results and discussion

Percutaneous absorption

Percutaneous absorption 1

Dose:

0.2 mg/cm2

Parameter:

percentage

Absorption:

0.64 %

Remarks on result:

other: 30 min exposure, amount absorbed and penetrated within 24 h after application

Remarks:

Standard formulation with H2O2

Percutaneous absorption 2

Dose:

0.2 mg/cm2

Parameter:

percentage

Absorption:

0.92 %

Remarks on result:

other: 30 min exposure, amount absorbed and penetrated within 24 h after application

Remarks:

Standard formulation without H2O2

Conversion factor human vs. animal skin:

No data

Applicant's summary and conclusion

Conclusions:

In conclusion, following topical application of [14C]-A155 in hair dye formulation without hydrogen peroxide to pig skin in vitro, the dermal bio-
availability of [14C]-A155 was 0.92% (1.97 μg equiv./cm2) of the applied dose. The majority of the dose was removed by washing the skin.
The mass balance was complete (94.76%) for [14C]-A155 from Test Preparation 1. Following topical application of [14C]-A155 in hair dye formula-
tion with hydrogen peroxide to pig skin in vitro, the dermal bioavailability of [14C]-A155 was 0.64% (1.41 μg equiv./cm2) of the applied dose.
The majority of the dose was removed by washing the skin. The mass balance was complete (100.37%) for [14C]-A155 from Test Preparation 2.

Executive summary:

The test substance, A155, is intended to be used as an ingredient in harr dye formulations. As part of a safety evaluation of this ingredient, this study was required to assess the extent of dermalbioavailability, following topical application of a typical hair colouring formulation with a content of finally 1% (w/w) A155 ([14C]~radiolabelled) to excised dermatomed pig skin. Immediately prior to application, the formulation containing 2% (w/w) A155 was mixed 1:1 (w/w) with developer without hydrogen peroxide (Test Preparation 1) or with developer containing hydrogen peroxide (6%, w/w) (Test Preparation 2). The concentration of A155 in Test Preparations 1 and 2 was ca 1% (w/w). The skin surface was washed 30 min after topical application of each test preparation to reflect the in use conditions. The skin was again washed at 24 h post dose as a final wash off before test run termination.

Previously frozen dermatomed pig skin (12 replicates per test run of 4 individual pigs in total) was mounted into static diffusion cells containing receptor fluid (phosphate buffered saline, ca 10 ml) in the receptor chamber. The skin surface temperature was maintained at ca 32°C throughout the experiment. An electrical resistance barrier integrity test was performed and any pig skin sample exhibiting a resistance <4 kohm was excluded from subsequent dermal bioavailability measurements. The hair dye formulation was applied at an application volume of ca 20 mg/cm2 , to dermatomed pig skin mounted into static diffusion cells in vitro. Dermal bioavailability was assessed by collecting receptor fluid aliquots at 0.5, 1,2,4,6 and 24 h post dose. At 30 min post dose, for both test preparations, exposure was terminated by washing the skin surface with a dilute shampoo solution and drying the skin surface with

tissue paper (tissue swabs). At 24 h post dose, the washing procedure was repeated. The skin was then removed from the static diffusion cells, dried and divided into exposed and unexposed. The stratum comeum was removed from the exposed skin with 20 successive tape strips. The remaining exposed skin was solubilised with Solvable® tissue solubiliser. After the 24 h receptor fluid aliquot was taken, the receptor fluid in the receptor chamber was removed into a bulk: receptor fluid vial and stored at ca ~20°C. All sampies were analysed by liquid scintillation counting.

For hair dye formulation, containing 1 % (w/w) A155 in the absence of hydrogen peroxide applied to dermatomed pig skin in vitro, most of the applied dose of (90.50%) was removed by washing at 30 min post dose. At 24 h post dose, the total dislodgeable dose was 91.86% of the applied dose. The total unabsorbed dose was 91.88% of the applied dose. The stratum corneum (dermal adsorption) retained 1.96% ofthe applied dose. The percutaneous penetration and dermal bioavailability were 0.01 % (0.03 µg equiv./cm2) and 0.92% (1.97 µg equiv./cm2) of the applied dose, respectively. The mass balance was complete with 94.76% (CV: 6.48%) ofthe applied dose recovered.

For hair dye formulation, containing 1 % (w/w) A155 in the presence of hydrogenperoxide applied to dermatomed pig skin in vitro, most of the applied dose (96.78%) was removed by washing at 30 min post dose. At 24 h post dose, the total dislodgeable dose was 97.77% of the applied dose. The total unabsorbed dose was 97.78% ofthe applied dose. The stratum corneum (dermal adsorption) retained 1.95% of the applied dose. The percutaneous penetration and dermal bioavailability were 0.01 % (0.01 µlg equiv./cm ) and 0.64% (1.41 µg equiv./cm2) of the applied dose, respectively. The mass balance was complete with 100.37% (CV: 8.38%) of the applied dose recovered.

In conclusion, following topical application of radiodiluted [14C]-A155 in a typical hair dye formulation without hydrogen peroxide to pig skin in vitro, the dermal bioavailability of [14C]-A155 was 0.92% (1.97 µg equiv./cm2) of the applied dose. The majority of the dose was removed by washing the skin. The mass balance was complete (94.76%) for [14C]-A155 from Test Preparation 1.

Following topical application of radiodiluted [14C]-A155 in a typical hair dye formulation with hydrogen peroxide to pig skin in vitro, the dermal bioavailability of [14C]-A155 was 0.64% (1.41µg equiv./cm2) of the applied dose. The majority ofthe dose was removed by washing the skin. The mass balance was complete (100.37%) for [14C]-A155 from Test Preparation 2.