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Administrative data

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-10-11 - 2019-04-23
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
other: SCCP,Dermal absorption, 2006
Deviations:
not specified
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Phenyl diamidophosphate
EC Number:
231-218-6
EC Name:
Phenyl diamidophosphate
Cas Number:
7450-69-3
Molecular formula:
C6H9N2O2P
IUPAC Name:
[(diaminophosphoryl)oxy]benzene
Test material form:
solid: crystalline
Details on test material:
Name PPDA
Composition phosphoric acid phenylester diamide

CAS No. 7450-69-3
EINECS-No. 231-218-6
Molecular formula C6H9N2O2P
Molecular weight 172.1 g/mol
Purity 97.77% (HPLC)
Specific details on test material used for the study:
Name: PPDA-suspension

Description: PPDA in a mixture of esters of saturated and unsaturated aliphatic acids
Active Ingredient: PPDA
Content: 5.19 %

Further ingredients: 0.26 % phenol, 0.03 % bisproduct, 0.15 % NH4Cl
Radiolabelling:
no

Test animals

Species:
other: human skin from surgery
Details on test animals or test system and environmental conditions:
For the permeation study the human skin of two donors which was der-matomized to a mean thickness of 500 ± 100 µm was used.
The skin samples were excised during surgical operations. The skin was not being removed to provide samples for these in vitro investigations. The hospital has the prior consent of the patients that the tissue can be used for scientific research.

Administration / exposure

Duration of exposure:
24 hours
Details on in vitro test system (if applicable):
For the permeation study the human skin of two donors which was dermatomized to a mean
thickness of 500 ± 100 µm was used. The thickness of the skin was measured according to SOP M 055. The skin samples were excised during surgical operations. The skin was not being removed to provide samples for these in vitro investigations. The hospital has the prior consent of the patients that the tissue can be used for scientific research.

Results and discussion

Total recovery:
The overall recovered amount PPDA at the end of the experiments ranged be-tween 98 to 101 %.
Percutaneous absorption
Key result
Time point:
24 h
Dose:
13000 to 13800 µg Phenyl phosphorodiamidate per square centimeter skin
Parameter:
percentage
Absorption:
0.92 %

Any other information on results incl. tables

Permeation coefficients, lag time and cumulative transport of Phenyl phosphorodiamidate over a time period of 24 h through all skins from test item PPDA-suspension.

Skin No.
Papp[E-08 cms-1]
Cumulative transport after 24 h
Lag time [h]
Mean
[10-8]
SD
[10-8]
CV [%]
Mean
[µg·cm-2]
SD
[µg·cm-2]
CV [%]

0880-01-0717

1.62

0.44

27.35

78.43

22.13

28.21

11.37

0897-01-1017

1.54

0.70

45.63

73.32

30.94

42.20

11.06

Recovery of Phenyl phosphorodiamidate in the different skin compartments and in the acceptor after 24 h. Arithmetic mean values (n=3) and the standard deviation are shown.

Comparison ofPhenyl phosphorodiamidatein skin fractions from test itemPPDA-suspension
Skin no.
0897-01-1017
0880-01-0717
-
Mean [%]
CV [%]
Mean [%]
CV [%]
Applied amount

100

n.a.

100

n.a.

Surface (sum TF+Wa+SC1+2)

100.52

2.95

96.90

6.23

Amount in swab

100.15

3.01

96.36

6.41

Amount in
Stratum corneum (SC1+2)

0.37

12.49

0.54

58.37

Amount in
Stratum corneum (SC3-20)

0.20

28.04

0.84

38.00

Amount in the Cryo-cuts (K-S)

0.12

38.49

0.12

71.08

Amount in acceptor (end)

0.60

28.79

0.53

38.46

Sum absorbed +
non absorbed

101.44

3.14

98.39

5.85

Fraction absorbed

0.92

29.82

1.49

40.64

Applicant's summary and conclusion

Conclusions:
The applied amount in this dermal permeation and penetration study was about 13000 to 13800 µg Phenyl phosphorodiamidate per square centimeter skin. As summarized in the table above the highest amount Phenyl phosphorodiamidate has been recovered from the surface of the skin (97 to 101 % of amount applied). Only a small amount of PPDA was found in the acceptor medium (0.53 to 0.60 %), stratum corneum (0.20 to 0.84 %) and deeper skin layers (0.12 %). The overall recovered amount PPDA at the end of the experiments ranged between 98 to 101 %.
Executive summary:

In the present study an in vitro examination of the permeation and penetration properties of Phenyl phosphorodiamidate (PPDA) - suspended in a mixture of esters of saturated and unsaturated aliphatic acids - through human skin was performed. This test preparation (the formulated material containing the test substance that is applied to the skin) is the same as that to which humans or other potential target species may be exposed.

 

The reference substance was

·        Phenyl phosphorodiamidate

The test item which was examined is:

·        PPDA-suspension

 

The analytical method for Phenyl phosphorodiamidate was transferred from sponsor and adapted. For the quantitative analysis of the test substance the following validation parameters was measured: selectivity, system suitability, calibration curve and LLOQ.

 

The amount of Phenyl phosphorodiamidate which was absorbed into human organism was determined using human excised skin as anin vitromodel for dermal absorption. The permeated amount of PPDA was quantified over a time period of 24 hours by withdrawing samples from the acceptor compartment of Franz diffusion cells.

 

After the permeation experiment the amount of PPDA taken up into the skin was determined. For this penetration study the stratum corneum was stripped off by the so called “tape stripping technology”. The strips were collected in two samples (2 + 18 strips). The deeper skin layers were sliced in parallel sections using a cryo microtome. The skin slices were collected in one sample.

The used skin was qualified by performing a permeation study with caffeine over a period of 48 hours. The analyte caffeine was quantified by a method developed and validated at Across Barriers. The permeation data were compared with previous data explored at Across Barriers.

The applied amount was about 13000 to 13800 µg Phenyl phosphorodiamidate per square centimeter skin. As summarized in the table above the highest amount Phenyl phosphorodiamidate has been recovered from the surface of the skin (97 to 101 % of amount applied). Only a small amount of PPDA was found in the acceptor medium (0.53 to 0.60 %), stratum corneum (0.20 to 0.84 %) and deeper skin layers (0.12 %). The overall recovered amount PPDA at the end of the experiments ranged between 98 to 101 %.

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