N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 May 2003 to 21 October 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Version / remarks:

1995

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

445-890-5

EC Name:

-

Cas Number:

201290-01-9

Molecular formula:

C14H37NO2Si3

IUPAC Name:

7-ethoxy-2,2,7-trimethyl-3-(trimethylsilyl)-8-oxa-3-aza-2,7-disiladecane

Test material form:

liquid

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature in the dark
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: the test substance was used as supplied in suspension in dry corn oil

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: A series of suspensions was prepared by direct dilution of the test substance into the vehicle dry corn oil. All suspensions were prepared freshly each week. Formulations were allowed to warm up to room temperature prior to dosing. Before commencement of treatment, the suitability of the mixing procedures was determined and specimen formulations at concentrations of 2 and 200 mg/ml were analysed to assess the homogeneity and stability of the test formulation. In addition, samples of formulations prepared for use on day 1 were analysed to assess achieved concentrations.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl:CD(SD) IGS BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Ltd., UK
- Females (if applicable) nulliparous and non-pregnant: no data
- Age at study initiation: 6 - 7 weeks old
- Weight at study initiation: 173.6 - 223.8 g (males) and 156.7 - 187.2 g (females). At the start of the treatment individual body weights were within +/-20% of the group mean each sex.
- Fasting period before study: none
- Housing: stainless steel with stainless steel grid floors
- Diet: pelleted SDS Rat and Mouse No. 1 modified Maintenance Diet, ad libitum
- Water: tap water, ad libitum
- Acclimation period: 7 days

DETAILS OF FOOD AND WATER QUALITY: No non-nutrient substance likely to influence the effect of the test substance was present in the diet or the drinking water. Food and water were routinely subjected to regular chemical analysis. Food hoppers and water bottles were changed at appropriate intervals.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 23°C
- Humidity (%): 40 - 70 %
- Air changes (per hr): 15/ hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Details on route of administration:

The animals were dosed at approximately the same time each day, using a suitably graduated syringe and a rubber catheter inserted via the mouth into the stomach.

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: A series of suspensions were prepared by direct dilution of the test substance into the vehicle dry corn oil. All suspensions were prepared freshly each week. Formulations were allowed to warm up to room temperature prior to dosing. Prior to dosing, the formulations were mixed by inversion and magnetically stirred for at least 5 minutes.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Based on a series of suspensions prepared by direct dilution of the test substance into the vehicle dry corn oil.
- Concentration in vehicle: 3, 30, 130 mg/ml
- Amount of vehicle (if gavage): not specified
- Lot/batch no. (if required): no data
- Purity: no data

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Before commencement of treatment, the suitability of the mixing procedures was determined and specimen formulations at concentrations of 2 and 200 mg/ml were analysed to assess the homogeneity and stability of the test formulation. In addition, samples of formulations prepared for use on day 1 were analysed to assess achieved concentrations.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

Once daily, seven days a week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

Dose / conc.:

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

No. of animals per sex per dose:

5 males and 5 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The doses were selected on the basis of a seven day preliminary oral toxicity study, in which animals were dosed at 250, 500 and 1000 mg/kg bw/day. Treatment at a dosage level of 1000 mg/kg bw/day was not tolerated well and adverse clinical signs were observed in all the animals. At 250 and 500 mg/kg bw/day similar clinical signs were observed but they were mainly confined to the first or second days of the treatment. The intermediate (150 mg/kg bw/day) and low (15 mg/kg bw/day) dose levels were selected on the basis of key dosages relative to the EEC labelling requirements.
- Rationale for animal assignment (if not random): random assignment of the animals
- Rationale for selecting satellite groups: no satellite groups were used
- Post-exposure recovery period in satellite groups: not applicable
- Section schedule rationale (if not random): random

Positive control:

Not used

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice each day from arrival to termination. During the treatment period all animals were observed at intervals after dosing
- Cage side observations included: signs of ill health, behavioural changes or reaction to treatment, dead or moribund animals

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: During weeks 1 to 4 a detailed physical examination were carried out to all the animals and convulsions, tremor and abnormalities of gait or behaviour were recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: All rats were weighed one week before commencement of treatment, prior to dosing on day 1 and on days 8, 15, 22 and 28. In addition, the body weights of all animals were recorded prior to necropsy.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Not applicable
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Not applicable

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Not applicable
- Time schedule for examinations:

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on day 29
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: all rats
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on day 29
- Animals fasted: Yes
- How many animals: all the animals
- Parameters checked in table [No.1] were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: During week 4 of the study period, prior to dosage arena based behavioural observations were carried out
- Dose groups that were examined: all animals
- Battery of functions tested: convulsions, tremor and abnormalities of gait or behaviour (during weeks 1-4) and sensory activity, grip strength, and motor activity (during week 4)

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table No. 2)

HISTOPATHOLOGY: Yes (see table No. 2)

Statistics:

- Mantel test for a trend in proportions
- Fisher's exact test for each dose group against the control
- Bartlett's test for variance homogeneity
- Williams' test for a monotonic trend
- means and standard deviations

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Reduced body tone and abnormal gait of animals at 650 mg/kg bw/day from day 1 and persisting throughout the treatment period. Low incidences of post-dose underactive behaviour, limited use of limbs, hunched posture, salivation, unresponsive behaviour, and partially closed eyes in animals at 650 mg/kg bw/day. These post-dose signs were generally noted within 1.5 hours of dosing. One animal at 150 mg/kg bw/day showed post-dose abnormal gait. No signs of reaction to treatment were noted in animals at 15 mg/kg bw/day. None of the observed clinical findings were considered to be attributable to treatment.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Group mean body weight gains for all the treated groups were considered to be unaffected by the treatment. All treated female groups showed lower overall group mean body weight gains compared to controls. However there was no dose-response relationship.

Food efficiency:

no effects observed

Description (incidence and severity):

Food efficiency values for all treated male groups and females receiving 15 or 150 mg/kg bw/day were comparable with controls and was considered to be unaffected by the treatment.

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Mean platelet value for males at 650 mg/kg bw/day was lower than that of the control group. Statistically significant lower mean lymphocyte, basophil, and large unstained cell values for females at 650 mg/kg bw/day were lower compared to control group values. However, the majority of individual values were within the range of the individual concurrent control values for these parameters. Thus, the differences in white blood cell parameters noted for females were not considered to be treatment-related.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant with dose-response relationship higher mean creatinine values were observed for male groups treated with 150 or 650 mg/kg bw/day. However, similar response was not evident in treated females and the mean creatinine values were comparable to the control values. Statistically significant higher mean aspartate aminotransferase value was also noted in males treated with 650 mg/kg bw/day. This response was not observed in the corresponding female group.

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

Two females at 650 mg/kg bw/day and one control male did not show a touch response. Mean hindlimb grip strength for all treated males were lower than the concurrent control; however, no dose-response relationship was observed. Females at 650 mg/kg bw/day showed lower overall mean motor activity in comparison with controls and background data and thus the differences from controls were considered to be attributable to treatment. No effects of treatment on motor activity in males were observed.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

Slightly higher than control body weight-adjusted kidney weights for males treated with 150 and 650 mg/kg bw/day were observed. Similarly, statistically significantly higher than control bodyweight-adjusted spleen weights were noted in males at 650 mg/kg bw/day. However, the microscopic pathology did not show any treatment-related changes in the spleen of males at 650 mg/kg bw/day. Changes in spleen weight were not observed in females. Therefore, this finding in male spleen was not considered to be treatment-related.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No macroscopic changes were observed at necropsy.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Hyaline droplets in the cortical tubule cells were seen in most treated male rats with a trend towards a higher incidence and degree in rats treated with 650 mg/kg bw/day. These lesions were considered to be associated with the slightly higher than control creatinine levels seen for all treated males. Similar effects due to hydrocarbons have not been shown to occur in human kidneys, nor in female rats. Thus, the incidence of these findings in the male treated groups were considered to be treatment-related, but of no toxicological importance with regard to a health risk in humans.

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

behaviour (functional findings)

clinical signs

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

In the key 28-day repeated dose oral toxicity study, conducted according to OECD 407 and GLP, the reported NOAEL value was 150 mg/kg bw/day based on post-dose clinical signs in both sexes and lower motor activity seen in females dosed at 650 mg/kg bw/day.