2-Propenamide, N-[4-[[(4,6-dimethyl-2-pyrimidinyl)amino]sulfonyl]phenyl]-2-methyl-

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics, other

Type of information:

other: Review

Adequacy of study:

key study

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Review of toxicokinetics based on available information (Reliability 2)

Justification for type of information:

All available information on the test substance was used to assess the potential toxicokinetics, based on the REACH Guidance on Toxicokinetics (Reach Guidance 7c).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Objective of study:

toxicokinetics

Test guideline

Qualifier:

no guideline required

Test material

Test material information

Constituent 1

Reference substance name:

N-{4-[(4,6-dimethylpyrimidin-2-yl)sulfamoyl]phenyl}-2-methylprop-2-enamide

EC Number:

611-915-5

Cas Number:

59941-98-9

Molecular formula:

C16 H18 N4 O3 S

IUPAC Name:

N-{4-[(4,6-dimethylpyrimidin-2-yl)sulfamoyl]phenyl}-2-methylprop-2-enamide

Test material form:

solid: particulate/powder

Remarks:

white crystalline

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on distribution in tissues:

After exposure, a substance can enter the body via the lungs, the gastrointestinal tract, and the skin. Since different parameters are relevant depending on the route of exposure, the three routes will be addressed individually.
After oral administration, in general, a compound needs to be dissolved before it can be taken up from the gastrointestinal tract1. Although the water solubility of V123109 is limited with 0.0881 g/L at 20°C, the substance will dissolve to some extent into the gastrointestinal fluids. The substance has a moderate molecular weight (appr. 346 g/mol), therefore uptake via passive diffusion (passage of small water-soluble molecules through aqueous pores or carriage across membranes with the bulk passage of water) is not expected to contribute significantly to the uptake. V123109 has a moderate partition coefficient (log Pow = 1.0 at pH 7), which implies that this substance will dissolve to some extent in lipids and it will therefore cross epithelia by passive diffusion.
Based on the data of a hydrolysis study, V123109 is expected to be stable in the environment, however stability might be influenced in the stomach and gastro-intestinal tract due to higher temperature. No data are available on the dissociation constant(s) of V123109, therefore it is unclear in which state (ionized or not ionized) the substance will be present under physiological circumstances (in the stomach or intestinal tracts) with low to neutral pH circumstances.
Considering all this data, there are no indications that oral absorption of V123109 is highly limited: its water solubility, its moderate molecular size, and its ability to dissolve in lipids will favour systemic uptake. Therefore, for risk assessment purposes oral absorption of V123109 is set at 100%2. The oral toxicity data do not provide reason to deviate from the proposed oral absorption factor.
Once absorbed, distribution of the test substance throughout the body is expected based on its water solubility and moderate molecular weight. Absorbed V123109 is expected to be excreted mainly via urine3. Based on its moderate partition coefficient, V123109 is not expected to significantly accumulate in adipose tissue, which is further indicated by its water solubility and moderate molecular size. Therefore bioaccumulation is not expected to be high.
V123109 has a very low vapour pressure (4.5 * 10-9 Pa at 25ºC), which indicates that exposure to the substance as a vapour is unlikely. V123109 is a crystalline powder. Since 90% of the particles is smaller than 97.678 μm, the largest part of the substance has the potential to be inhaled. Furthermore, 50% is smaller than 12.541 μm, which means that at least 50% of the substance may reach the thoracic region and the alveolar region of the respiratory tract. If these particles reach these regions, V123109 is likely to dissolve in the mucus lining the respiratory tract and to get absorbed. Since V123109 will dissolve in water and lipids to some extent, uptake through respiratory epithelium will take place. Therefore it is concluded that for risk assessment purposes the inhalation absorption of V123109 is set at 100%.
As V123109 is a powder, uptake through the skin is unlikely to occur unless it is dissolved in a body fluid (sweat). The water solubility of V123109 is moderate, which is sufficient to partition from the stratum corneum into the epidermis. Its ability to dissolve in lipids will favour easy crossing of epidermal barriers. Its moderate molecular size is not expected to hamper uptake through dermal epithelium. According to the guidance2, a default value of 100% skin absorption is generally used unless molecular mass is above 500 and log Pow is outside the range [-1, 4].
Since the substance has a molecular weight of 346 g/mol and a log Pow of 1.0, it does not meet either criteria and the dermal absorption of V123109 for risk assessment purposes is thus set at 100%. The dermal toxicity data do not provide reason to deviate from the proposed dermal absorption factor.

Applicant's summary and conclusion

Conclusions:

A toxicokinetic assessment was performed based on the available data of the substance. Based on the physical/chemical properties of the substance, absorption factors for this substance are derived to be 100% (oral), 100% (inhalation) and 100% (dermal) for risk assessment purposes. The bioaccumulation potential is expected to be low.