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Toxicological information

Dermal absorption

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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, GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 428 (Skin Absorption: In Vitro Method)
Version / remarks:
April 2004
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: MDIPA-Esterquat C16-18 and C18 unsatd.
- Physical state: solid
- Analytical purity: 100%
Radiolabelling:
yes

Test animals

Species:
human
Sex:
female

Administration / exposure

Type of coverage:
open
Vehicle:
water
Duration of exposure:
24 h
Doses:
101 g/L, 0.311 g/L
No. of animals per group:
at least 5 human skin discs from at least 3 different donors/concentration
Details on study design:
DOSE PREPARATION
- Method for preparation of dose suspensions:
A paste formulation of the test item (containing 100 g/kg) fortified with [14C]-test item was prepared: A weighed 1.0010 g portion of the test item was ground and subsequently spiked with 4.4497 g of the [14C]-test item stock solution (3.34 MBq/mL). This mixture was mixed with a mortar and pestle. Afterwards 4.5525 g of [14C]-test item stock solution (3.34 MBq/mL) was added. This mixture (1.0010 g test item and 9.0022 g [14C]-test item) was mixed with a mortar and pestle. Afterwards this mixture transferred to a suitable vial which was warmed in a waterbath (40 ± 2°C) under continuously stirring. The total concentration of test item was 101 g/kg.
The aqueous dilution containing 0.311 g test item/L of was prepared by dissolution of appropriate amount of [14C]-test item in milli-Q water.
The formulations were stored at room temperature in the dark and was used within one day.

APPLICATION OF DOSE:
VEHICLE
- Amount(s) applied (volume or weight with unit): 6.4 μL

REMOVAL OF TEST SUBSTANCE
- at the end of exposure

SAMPLE COLLECTION
- Collection of residual substance: The skin was cleaned using five cotton swabs dampened with 3% Teepol (multipurpose detergent) in water, followed by one dry cotton swab.
- Tape strippings: maximum of 20 times with D-Squame stripping discs and a D-Squame pressure instrument; tape stripping was discontinued when the epidermis was disrupted

SAMPLE PREPARATION
The skin strips were digested in Solvable for at least 4 hours in an incubator set at 60°C. The skin samples were digested with 6N NaOH for at least 16 hours in an incubator set at 60°C. Aliquots (250 μL) of the digests were neutralized with 125 μL HCl (37%). The fluid in the receptor compartment was collected and the cell was rinsed with ethanol:MQ 1:1 (v:v).


Aliquots of all collected samples including the swab extraction samples, the skin digest, the receptor
fluid in the cell, and the rinsing solution, were diluted with Ultima Gold cocktail and analyzed using
LSC. The stripping extraction samples were added to Hionic Fluor cocktail and analyzed using LSC.

ANALYSIS
- Method type(s) for identification: LSC
Details on in vitro test system (if applicable):
SKIN PREPARATION
- Source of skin:, Biopredic International, Rennes, France; Production of skin discs was performed on fresh skin obtained from cosmetic surgery
- Type of skin: Human Split-Thickness Skin (0.2 – 0.4/0.5 mm), dermatomed breast skin
- Membrane integrity check: skin integrity was tested by permeation of tritiated water

PRINCIPLES OF ASSAY
- Receptor fluid: PBS buffer pH 7.4
- Flow-through system: yes; flow rate 1.5 mL/h
- Test temperature: skin surface temperature 32±1ºC

Results and discussion

Total recovery:
- Total recovery: 100 ± 6% (101 g/L), 97 ± 3% (0.311 g/L)
- Recovery of applied dose acceptable: yes
Percutaneous absorptionopen allclose all
Dose:
101 g/L
Parameter:
percentage
Absorption:
0.3 %
Remarks on result:
other: 24 h; (Dose: 101 g/L) (corresponding to 2 ± 0.8 µg/cm²)
Dose:
0.311 g/L
Parameter:
percentage
Absorption:
0.9 %
Remarks on result:
other: 24 h, (Dose: 0.311 g/L) (corresponding to 0.03 ± 0.02 µg/cm²)

Any other information on results incl. tables

 

Formulation

(dose level)

Paste formulation
(101 g/L)

Aqueous dilution

(0.311 g/L)

Skin samples

n=7

n=5

Number of donors

n=5

n=4

%

μg/cm²

%

μg/cm²

mean

SD

mean

SD

mean

SD

mean

SD

DERMAL ABSORPTION PARAMETERS

Lag time (h)

0

NA

NA

0

NA

NA

Maximum flux (µg/cm2/h)

0.068

0.020

0.0014

0.0002

SURFACE COMPARTMENT

 

 

 

 

 

 

 

 

Total skin swabs 24 h

99

6

537

33

84

9

3

0.3

Material remaining in donor chamber

0.09

0.02

0.5

0.08

1.0

0.9

0.03

0.03

Total % non-absorbed1)

99

6

538

33

85

9

3

0.3

SKIN COMPARTMENT

Stratum corneum

0.9

0.9

5

5

11

6

0.3

0.2

Stratum corneum

(excluding tape strips 1&2)

0.7

0.8

4

4

6

4

0.2

0.1

Skin

(excluding stratum corneum)

0.2

0.1

0.8

0.7

0.4

0.5

0.01

0.02

Total % at dose site (excluding tape strips 1&2)

0.9

0.9

5

5

7

4

0.2

0.1

RECEPTOR COMPARTMENT

Receptor fluid

0.2

0.04

0.8

0.2

0.5

0.1

0.01

0.004

Receptor fluid terminal

0.004

0.002

0.02

0.01

0.02

0.009

0.001

0.0003

Receptor chamber

0.004

0.001

0.02

0.008

0.007

0.004

0.0002

0.0001

Total % directly absorbed2)

0.2

0.04

0.9

0.2

0.5

0.1

0.01

0.004

OVERALL ABSORPTION

Systemically bioavailable fraction3)

0.3

0.2

2

0.8

0.9

0.6

0.03

0.02

Potential systemically bioavailable4)4)fraction5)

1

0.9

6

5

7

4

0.2

0.1

Total % recovery

100

6

544

33

97

3

3

0.09

 

SD = standard deviation

1)Total % non-absorbed = % in total skin swabs 24h + material remaining in donor chamber

2)Total % directly absorbed = % receptor fluid + receptor fluid terminal + receptor chamber

3)Systemically bioavailable fraction = % receptor fluid + receptor fluid chamber + receptor fluid terminal+ skin (excl. stratum

corneum)

4)Potential systemically bioavailable fraction = % receptor fluid + receptor fluid chamber + receptor fluid terminal + skin +

stratum corneum (excl. tape strips 1&2)

Applicant's summary and conclusion

Conclusions:
In this in vitro dermal absorption study usind human skin, the systemically bioavailable fraction of MDIPA-Esterquat C16-18 and C18 unsatd. (methyl 14C-radio labelled) was 0.3 ± 0.2% (2 ± 0.8 μg/cm²) for the paste formulation (101 g/L) and 0.9 ± 0.6% (0.03 ± 0.02 μg/cm²) for the aqueous dilution (0.311 g/L).
The potentially systemically bioavailable fraction of the test item was 1 ± 0.9% (6 ± 5 μg/cm²) for the paste formulation and 7 ± 4 (0.2 ± 0.1 μg/cm²) for the aqueous dilution.
Executive summary:

In this dermal absorption study according to OECD guideline 428 (April 2004) the dermal absorption of C14-labelled MDIPA-Esterquat C16-18 and C18 unsatd. (methyl 14C-radio labelled) was investigated using human skin in vitro.

Both a paste formulation of the test item (101 g/L) and an aqueous dilution (0.311 g/L) were tested. One group of 7 human skin discs (5 different donors) was exposed to a paste formulation, and one group of 5 human skin discs (3 different donors) was exposed to an aqueous dilution for 24 hours under non-occlusion conditions.

The integrity of each skin disc was checked by determination of the permeation of tritiated water and was within the acceptability criteria (Kp  4.5E-03 cm/h).

The average total recovery of radioactivity was 100 ± 6% for the skin discs exposed to the paste formulation and 97 ± 3% for skin discs exposed to the aqueous dilution.

The in vitro systemically bioavailable fraction (% receptor fluid + receptor fluid chamber + receptor fluid terminal+ skin (excl. stratum corneum) of MDIPA-Esterquat C16-18 and C18 unsatd. was 0.3 ± 0.2% (2 ± 0.8 μg/cm²) for the paste formulation (101 g/L) and 0.9 ± 0.6% (0.03 ± 0.02 μg/cm²) for the aqueous dilution (0.311 g/L).