N-[3-(dimethylamino)propyl]docosanamide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-03-01 to 2001-04-01

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

DIMAPDO lactate is a surface active chemical with the alkyl moieties being composed of C22 residues.
In recently published articles in peer reviewed journals (see reference list below, and publications cited in the revised OECD guideline 429 (July 2010)) it is clearly demonstrated that for the realistic assessment of the skin sensitization potential of surfactants the LLNA (OECD 429) is much less suitable than the Magnusson & Kligman method (OECD 406) and could lead to confounding results.
In particular, the OECD 429 guideline specifies that “In addition, test substance classes or substances containing functional groups shown to act as potential confounders (Basketter et al., 2009) may necessitate the use of guinea pig tests”.
Consequently, in the evaluation of such surface active substances for sensitising properties, the LLNA is not an appropriate assay and would not represent an optimum use of test animals. The mechanism underlying confounding or false positive result is not fully understood, but it may be that an unspecific, non-immunologically triggered mechanism may be the cause of an increased lymphocyte proliferation.
In contrast to the GPMT, the LLNA focuses on the induction process of skin sensitisation (i.e. lymphocyte proliferation), and does not capture the process of elicitation which checks if the organism had actually been sensitized or not. The design of the LLNA does not allow to assess whether lymphocyte proliferation is a specific response or unspecific (false positive) response.
 
References:
Kreiling, R et al., Food and Chemical Toxicology 46 (2008): 1896-1904: Comparison of the skin sensitizing potential of unsaturated compounds as assessed by the local lymph node assay (LLNA) and the guinea pig maximization test (GPMT)
 
Basketter, D et al., Regulatory Toxicology and Pharmacology 55 (2009): 90-96: Application of a weight of evidence approach to assessing discordant sensitisation data sets: Implications for REACH
 
Garcia, C et al., Regulatory Toxicology and Pharmacology 58 (2010): 301-307: Comparative testing for the identification of skin sensitizing potentials of nonionic sugar lipid surfactants
 
Ball, N et al., Regulatory Toxicology and Pharmacology 60 (2011): 389-400: Evaluating the sensitizing potential of surfactants: integrating data from the local lymph node assay, guinea pig maximization test, and in vitro methods in a weight-of-evidence approach

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

yes

Remarks:

no positve control

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

DIMAPDO lactate is a surface active chemical with the alkyl moieties being composed of C22 residues.
In recently published articles in peer reviewed journals (see field "Justification for type of information") it is clearly demonstrated that for the realistic assessment of the skin sensitization potential of surfactants the LLNA (OECD 429) is much less suitable than the Magnusson & Kligman method (OECD 406) and could lead to confounding results.
In particular, the OECD 429 guideline specifies that “In addition, test substance classes or substances containing functional groups shown to act as potential confounders (Basketter et al., 2009) may necessitate the use of guinea pig tests”.
Consequently, in the evaluation of such surface active substances for sensitising properties, the LLNA is not an appropriate assay and would not represent an optimum use of test animals. The mechanism underlying confounding or false positive result is not fully understood, but it may be that an unspecific, non-immunologically triggered mechanism may be the cause of an increased lymphocyte proliferation.
In contrast to the GPMT, the LLNA focuses on the induction process of skin sensitisation (i.e. lymphocyte proliferation), and does not capture the process of elicitation which checks if the organism had actually been sensitized or not. The design of the LLNA does not allow to assess whether lymphocyte proliferation is a specific response or unspecific (false positive) response.

Test material

Test material information

Constituent 1

Reference substance name:

N-[3-(dimethylamino)propyl]docosanamide;2-hydroxypropanoic acid

Cas Number:

221446-54-4

Molecular formula:

C30H62N2O4

IUPAC Name:

N-[3-(dimethylamino)propyl]docosanamide;2-hydroxypropanoic acid

Details on test material:

- Name of test material: DIMAPDO lactate
- Physical state: solid
- Analytical purity: 99%

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 5 weeks
- Weight at study initiation: 336 g (mean at induction)
- Housing: in groups of 5 animals in aluminum cages (W350 x D400 x H230: Natsume Seisakusho Co., Ltd.)
- Diet (e.g. ad libitum): solid food (RC4: Oriental Yeast Co., Ltd.), ad libitum
- Water (e.g. ad libitum): filtered tap water, ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 2°C
- Humidity (%): 50 ± 10%
- Air changes (per hr): 17
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: for intradermal induction: physiological saline; for epicutaneous induction and challenge 50% ethanol in water

Induction 2

Concentration / amount:

intradermal induction: 0.01%
epicutaneous induction: 30%
challenge: 0.5%, 1%, 3%, 5%, 10%, 30%

Concentration selection based on a preliminary dose range finding study.

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: for intradermal induction: physiological saline; for epicutaneous induction and challenge 50% ethanol in water

Challenge 2

Concentration / amount:

intradermal induction: 0.01%
epicutaneous induction: 30%
challenge: 0.5%, 1%, 3%, 5%, 10%, 30%

Concentration selection based on a preliminary dose range finding study.

No. of animals per dose:

8 (preliminary study); 10 (test group); 5 (control group)

Details on study design:

RANGE FINDING TESTS:
pilot experiment with 8 animals to determine which concentration of the test substance
- led to slight irritation after intradermal application (determination of the maximum compatible dose); concentrations tested: 0.01%, 0.03%, 0.05%, 0.1%, 0.5%, 1% and 5% (w/w)
- led to slight irritation after dermal application; concentrations tested: 0.3%, 0.5%, 1%, 3%, 5% and 10% (w/w)

MAIN STUDY
A. INDUCTION EXPOSURE
Intradermal induction (day 0)
- No. of exposure sites: 2
- Test groups: test substance
- Control group: vehicle
- Site: left and right back
- Frequency of applications: 1
- Concentrations:
0.1 mL FCA (mixed at a ratio of 1+1 in vehicle)
0.1 mL 0.01% test substance (or physiological saline in control)
0.1 mL 0.02% test substance (or physiological saline in control) + FCA (mixed at a ratio of 1+1 in vehicle)

Epicutaneous induction (day 8)
- No. of exposures: 1
- Exposure period: 48 h
- Test groups: test substance
- Control group: vehicle
- Site: back, same region as for intradermal induction
- Frequency of applications: 1
- Concentrations: 30% test substance (or 50% ethanol in water in control)
- Since the test substance is non-irritating, 0.5 g of 10% SDS (vaseline base) was applied on day 7

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 21
- Exposure period: 24 h
- Test groups: 0.05 mL of the test substance soaked in the cloth portion of an adhesive plaster for patch test
- Control group: same as test group
- Site: lateral abdomen
- Concentrations: 0.5%, 1%, 3%, 5%, 10%, 30% test substance (w/w)
- Evaluation (hr after challenge): 3h, 24 h, 48 h

Challenge controls:

yes, vehicle only during induction phase

Positive control substance(s):

no

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.5%, 1%, 3%, 5%, 10%, 30%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.5%, 1%, 3%, 5%, 10%, 30%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0.5%, 1%, 3%, 5%, 10%, 30%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0.5%, 1%, 3%, 5%, 10%, 30%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No

Results 5

Group:

positive control

Remarks on result:

not measured/tested

Any other information on results incl. tables

Reading	Hours after challenge	Group	Dose level	No. with + reactions	Total no. in group	Clinical observations
Additional reading	3	test group	0.5%, 1%, 3%, 5%, 10%, 30%	0	10	No
Additional reading	3	negative control	0.5%, 1%, 3%, 5%, 10%, 30%	0	5	No

No abnormality in the general conditions was observed after induction or challenge during the study period and the animals showed satisfactory body weight increases.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

DIMAPDO lactate is not a dermal sensitizer in this Guinea pig maximisation test.

Executive summary:

In a dermal sensitization study with DIMAPDO lactate 23 young female Albino Hartley guinea pigs (8 preliminary study, 10 in test group, 5 in control group) were tested using the method of Guinea pig maximization test equivalent to OECD Guideline 406 (1992). No positive control was reported.

Concentration selection was based on a preliminary dose range finding study:

intradermal induction: 0.01% in physiological saline

epicutaneous induction: 30% in 50% ethanol in water

challenge: 0.5%, 1%, 3%, 5%, 10%, 30% in 50% ethanol in water

One day prior to epicutaneous induction the sites were pretreated with SDS to create local skin irritation.

There were no signs of erythema or oedema in any dose group 3, 24 and 48 hours after patch removal. Therefore, DIMAPDO lactate is not a dermal sensitizer in this study.