Dimethylamine

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: acceptable well-documented publication, which meets basic scientific principles

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Additive Impairment of the Barrier Function and Irritation by Biogenic Amines and Sodium Lauryl Sulphate: A Controlled in vivo Tandem Irritation Study

Author:

Fluhr, J.W., Kelterer, D., Fuchs, S., Kaatz, M., Grieshaber, R., Kleesz, P., and Elsner, P.

Year:

2005

Bibliographic source:

Skin Pharmacol Physiol 2005;18:88–97

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: Frosch PJ, Kligman AM: The soap chamber test: A new method for assessing the irritancy of soaps. J Am Acad Dermatol 1979;1:35–41.

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Pinnagoda J, Tupker RA, Agner T, Serup J: Guidelines for transepidermal water loss (TEWL) measurement: A report from the Standardization Group of the European Society of Contact Dermatitis. Contact Dermatitis 1990; 22:164–178.

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Rogiers V: EEMCO guidance for the assessment of transepidermal water loss in cosmetic sciences. Skin Pharmacol Appl Skin Physiol 2001;14:117–128

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Fullerton A, Fischer T, Lahti A, Wilhelm KP, Takiwaki H, Serup J: Guidelines for measurement of skin colour and erythema: A report from the Standardization Group of the European Society of Contact Dermatitis. Contact Dermatitis 1996;35:1–10

Test guideline 5

Qualifier:

according to guideline

Guideline:

other: Parra JL, Paye M: EEMCO Guidance for the in vivo assessment of skin surface pH. Skin Pharmacol Appl Skin Physiol 2003;16:188–202

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dimethylamine

EC Number:

204-697-4

EC Name:

Dimethylamine

Cas Number:

124-40-3

Molecular formula:

C2H7N

IUPAC Name:

N-methylmethanamine

Details on test material:

DMA [NH(CH3)2; CAS No. 124-40-3; synonym: N-methylmethanamine],
purchased from Merck Schuchardt, Ottobrunn, Germany
Solutions of all compounds (DMA 1.0%, TMA 1.5%) in distilled water with a pH of 7.2 were prepared

Radiolabelling:

no

Test animals

Species:

human

Strain:

other: not applicable

Sex:

male/female

Details on test animals or test system and environmental conditions:

The study was performed in a single-blinded, randomized manner under standardized laboratory conditions using air-conditioning with a room temperature between 20 and 22°C and a relative humidity between 30 and 40%.
20 healthy, non-preselected Caucasian volunteers (11 males and 9 females; aged 19–46 years, median age 28.3 years) without any skin or other systemic diseases were included. During the study period, the subjects were allowed to shower as usual, but they were instructed to avoid any application of detergents, emollients and moisturizers on their backs as well as natural or artificial UV exposure.

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: distilled water

Duration of exposure:

30 min, then 3 hours later again 30 min exposure, this treatment was performed on 4 consecutive days

Doses:

(0.01, 0.1, 1, 1.5 and 2% in pilot study)
1 % in this study

No. of animals per group:

not applicable

Control animals:

no

Remarks:

not applicable, because humans

Details on study design:

The application areas were located on the clinically normal skin of the paravertebral mid back. According to the number of different treatment options (see below), 14 test areas with a space of 3 cm between each test chamber were marked with a permanent marker, resulting in 4 vertical rows.

The test areas were randomized among the volunteers in order to avoid an anatomical selection bias. Aliquots of 50 ml of the freshly prepared aqueous irritants were applied to each test area by an occlusive epicutaneous patch test system (Large Finn Chambers® on Scanpor®, 12 mm diameter with filter discs, Epitest Ltd., Hyrlä, Finland). Patches were removed after 30 min. The exposed areas were rinsed with 10 ml of tap water and carefully dried with a paper tissue without rubbing. After a 3-hour interval, a second exposure with one of the irritants, according to the different treatment options, was performed. Using this scheme of application, each test site was repeatedly treated for 4 days.

Details on in vitro test system (if applicable):

not applicable

Results and discussion

Signs and symptoms of toxicity:

no effects

Dermal irritation:

no effects

Percutaneous absorption

Remarks on result:

other: The human volunteer study revealed no irritating effects of DMA on skin; possible processes at barrier are discussed in detail in this publication.

Any other information on results incl. tables

One day of treatment with detergents or biogenic amines did not result in irritation in any of the test sites.

All biogenic amines tested caused barrier disruption. The ranking order was TMA/TMA > DMA/DMA > AM/AM. The sequential irritation of the biogenic amines with SLS (AM/SLS, DMA/SLS and TMA/SLS) resulted in an increase in the barrier disruption starting for all three groups already on day 3, but this barrier disruption was less prominent than SLS/SLS alone.

The irritation was assessed measuring the redness.

The biogenic amines without the combination with SLS (AA/ AA, DMA/DMA, TMA/TMA) did not induce a significant irritation measured by Chromameter a* values. However, the combination with SLS depicted a significant increase in redness values for AM/SLS (only for day 5) and TMA/SLS (from day 3 on), while such an increase in the combination with DMA/SLS was not detectable

The biogenic amines in combination with SLS showed all an increase of the stratum corneum pH, e.g. AM/SLS on day 5, DMA/ SLS and TMA/SLS already on day 4.

The values assessed with the visual score were overall very low.

Applicant's summary and conclusion

Conclusions:

The highest irritative potential could be detected, as expected, by the double application of SLS/SLS followed by NaOH/SLS. Next we ranked TMA/SLS, followed by AA/SLS > AM/SLS > DMA/SLS.
Biogenic amines induce a permeability barrier disruption after 3 days of application in a tandem repeated irritation test model. This effect was paralleled with the onset of inflammatory signs and an increase in pH. The sequential application of SLS further increased these effects, and the initiation of both barrier disruption and inflammation occurred earlier.

Executive summary:

In the present study, we were able to show for the first time that biogenic amines cause disruption of the permeability barrier. However, the application of each of the three biogenic amines did not reveal a significant irritation or increase in SC pH. This dichotomy of usually related parameters of barrier disruption and induction of irritation might be based on the fact that the amines disturbed the intercellular barrier-lipid processing but did not induce a pH change and a subsequent increase in pH. Sequential application of SLS further enhanced the barrier disruption induced by the biogenic amines. The only exception was the irritation parameter Chroma a*, where no significant increase of redness could be observed. The TMA/SLS irritation and barrier disruption was slightly more prominent than those induced by AM/SLS and DMA/SLS, which can be explained by the higher concentration (1.5 vs. 1.0%). Since these results are detectable in all analysed parameters, we assume that the described features may be consistent properties of biogenic amines.

We assume that the mechanism by which the biogenic amines induce a barrier disruption and inflammatory reaction are different from that of SLS.

The contact with both classes of irritants however did not show overadditive effects.