N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Well documented study pre-dating OECD protocolls and GLP requirements. However, slight shortcomings regards documentation (e.g. lighting conditions, test substance purity, analytical verification of administered dose) justify a Klimisch 2 rating (reliable with restrictions).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1973

Report date:

1973

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

study pre-dates OECD protocol but follows the same scientific principles and methodology

Deviations:

no

GLP compliance:

no

Remarks:

study pre-dates GLP guideline

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide

EC Number:

245-950-9

EC Name:

N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide

Cas Number:

23949-66-8

Molecular formula:

C18H20N2O3

IUPAC Name:

N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)ethanediamide

Test material form:

solid: crystalline

Details on test material:

Tradeneame: Sanduvor VSU
Batch: 2205
Manufacturing date: 15.11.1972

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

160 SPF-rats of the Sprague-Dawley strain were randomly devided into 4 groups (as control and three test groups) of 20 males and 20 females each and uniquely numbered for further identification. Animals were kept individually in makrolon cages. The temperature in the animal room was kept at 25 ±0.5 °C and relative humidity was controlled to 50 ±5 %.

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: NAFAG mouse and rat feed, No. 194

Details on oral exposure:

The test substance was mixed with NAFAG mouse and rat feed No 194 in portions of 5 kg, using a Turbula mixer (supplier: Bachofen in Basel, Switzerland). Control animals received pure NAFAG mouse and rat feed No 194 without addition of test substance.
Test and control animals received feed and water ad libitum. Feed consumption and body wight of animals were recorded once weekly. Water consumtion was monitored throughout the study but turned out to be obsolete during the course of the study as no differences between control and test animals were noted.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

continuous; the test substance was supplied by feed ad libitum

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 1600, 4000 and 10000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

20 males and 20 females per dose group and control

Control animals:

yes, concurrent no treatment

Positive control:

none

Examinations

Observations and examinations performed and frequency:

Clinical Chemistry:
Following 4, 8 and 13 weeks of exposure, blood samples were taken from 5 males and 5 females of each dose group from the sublingual vene and these samples investgiated for the following parameters:
- BUN (blood urea nitrogen) according to method of W. Marsch et al., Clin. Chem. 11, 624 (1965) using a Technicon AutoAnalyzer micro method [mg%]
- FBS (fasting blood sugar) according to method of W.S. Hoffmann, J. Biol. Chem. 120, 51 (1937) using a Technicon AutoAnalyzer micro method [mg%]
- SAP (serum alakaline phosphatase)according to method of W. Marsch et al., Clin. Chem. 5, 119 (1959) using a Technicon AutoAnalyzer micro method in [IU]
- SGPT (serum glutamic pyruvat transaminase) according to Boehringer test comination 15978 [IU]
Hämatological examinations:
Following 4, 8 and 13 weeks of exposure, the following examinations from 5 males and 5 females of each dose groupwere performed:
- hämatokrit (HCT) with a coulter counter [%RBC in full blood]
- erythrocytes (RBC) with a coulter counter [million cells/mm3]
- total leokocytes (WBC) with a coulter counter [thousand cells/mm3]
- hämoglobin (HGB) with the Merckotest (Merch Darmstadt) [as hämoglobin cyanide in g/100 ml blood]
- differenciate leukocytes (microscopic) [%WBC] as
* neutrophile leucocytes
* lymphocytes
* monocytes
* eosinophiles
* basophiles
- absolute indices: average erythrocyte volume (MCV) and average hämoglobin concentration per cell (MCHC)

Urinanalysis:
Following the 6th and 12th week of exposureurine of 5 males and 5 females per dose was collected and the following parameters were investigated:
- pH
- pecific weight (refractive, using a TS-meter)
- proteine (using albustix reagent tabs)
- glucose (using Clinistix reagens)
- ketones (according to Libbrecht)
- pigments (benzidin method)
- urinary sediment was checked for the following parameters:
* Erythrocytes (RBC)
* Leucocytes (WBC)
* Epithelial cells (EPC)
* Uric acid crystals (Uric AC)
*calcium oxalate crystals (CA-OXA)
* Triple phosphate (TRIPHO)
* Amorphe urates (AM URA)

Sacrifice and pathology:

At the end of exposure period (after 13 weeks) 5 males and 5 females of each dose group, which were not used before for other examinations, were sacrificed and the following organs have been investigated macroscopically (organ weight relative to body weight): Thyroids, adrenal glands, pituitary glands, brain, heart, lungs, thymus, spleen, liver, kidneys, uterus/prostate, seminal vesicle.
Following macroscopic examination the organs were examined histologically.

Statistics:

The Student t-test method was applied for assessing relevance of changes versus control.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

No clinical signs or mortality were observed. At all dose levels no differences in body weight gain compared to controls were observed. Very slight reduction in food consumption of females (not observed in males) did not affect body weight gain and was considered non-significant. As a result, food efficiency of males was normal and slightly increased for females. Water consumption was comparable in all dose groups to controls.
In the 4th week of exposure males showed a slightly increased medium cell volume (MCV) values and slight increase of red blood cells but still within normal ranges. To investigate whether these effects are substance specific, the experiment was repeated only with male rats (controls and 10000 ppm dose group only) but the effect could not be reproduced. Thus, the effect on males regarding red blood cells and MCV values were considered incidental. The clinical chemistry parameters (BUN, SAP and SGPT) revealed no differences between dose groups and controls. fasting blood sugar values (FBS) were slightly increased in all groups inclucing controls but still within normal range and thus this effect was not considered substance specific. Urinanalyses revealed no specific findings, as specific weight and pH were normal, Acetone and glucose were negativ and blood pigments were not found. In some urine samples (from dose groups and controls) proteines were found (non-dose-dependent), which is often found in rats and therefore not considered treatment specific. Significant deviations (p < 0.05) of absolute and relative organ weights of thyroid, brain, kidneys, adrenal glands and lungs were minor and could be explained by lower standard deviation in dose groups compared to controls. All these deviations were also within biological variability and non-dose specific and therefore were not considered treatment related. No other effects on organ weight were observed.
Finally, also gross pathology and histopatholology showed no treatment related findings.

Effect levels

1

Dose descriptor:

NOEL

Effect level:

10 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: In absence of any treatment specific effects the NOEL was set to the highest dose level tested.

2

Key result

Dose descriptor:

NOEL

Effect level:

ca. 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: In absence of any treatment specific effects the NOEL was set to the highest dose level tested.

3

Dose descriptor:

NOEL

Effect level:

521.47 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: In absence of any treatment specific effects the NOAEL was set to the highest dose level tested.

Remarks on result:

other: as average of all males, considering measured food consumption (19125 mg) and body weight over the exposure period

4

Dose descriptor:

NOEL

Effect level:

663.66 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: In absence of any treatment specific effects the NOEL was set to the highest dose level tested.

Remarks on result:

other: as average of all females, considering measured food consumption (15500 mg) and body weight over the exposure period

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In this 90 day feeding study with N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide no treatement related effects were seen in all dose groups (1600, 4000 and 10000 ppm) and thus the "No Observed Effect Level" (NOEL) was set at the highest dose group tested (10.000 ppm) which is equivalent to 521.47 mg/kg bw/d in males and 663.66 mg/kg bw/d in females (ca. 600 mg/kg bw/d males/females).

Executive summary:

The test substance N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide was investigated in a 90-day (13 wk) feeding study in Sprague-Dawley rats. 20 Males and 20 females were used per dose group (0, 1600, 4000, 10000 ppm). Development of body weight was normal in all groups and only a very slight food consumption reduction in females was noted which had no effect on body weight development. Unspecific variations in haematological parameters during exposure of males did normalize at the end of the exposure period and therefore were considered incidental. This was supported by a repetition experiment with another group of males (dose groups 0 and 10000 ppm), in which these haematological variations could not be reproduced. Effects on clinical chemistry parameters were not seen and also urine-analysis did not reveal any findings of significance. Pathological microscopy also did not reveal any effects on organ tissue.

In conclusion, up to 10.000 ppm, which is equivalent to 521.47 mg/kg bw/d in males and 663.66 mg/kg bw/d in females (ca. 600 mg/kg bw/d males/females), no effects were seen and thus this was considered the No-Observed-Effect-Level (NOEL) in this study.