3-[(2,2-Dimethyl-1,2-azasilolidin-1-yl)(dimethyl)silyl]-1-propanamine

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

CAS No.:388606-32-4
Batch No.: YH00701
Chemical name: 1-[(3-Aminopropyl)dimethylsilyl]-2,2dimethyl-1-aza-2-silacyclopentan
Purpose: industrial chemical
Colour: colourless to yellowish
Physical state: liquid
Storage: at room temperature, protected from light and humidity
Safety precautions: Routine hygienic procedures were sufficient
to assure personnel health and safety

Test animals

Species:

rat

Strain:

other: HSDBr1:WH Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species: Hsd:Wistar rats (HsdBrl:WH,Full-Barrier)
Supplier: Harlan Winkelmann GmbH, D-33178 Borchen
Health status: The animals were derived ft'om a controlled full barrier maintained breeding system (spf). No special findings during the adaptation period; females nulliparous, non-pregnant.
Number and Sex: 5 female and 5 male rats were evaluated at each dose level;Totally 20 females, 20 males,
Body weight at the commencement of the study:
Females: 137 - 184 g, (mean: 161 g, ± 20%= 129-193 g); Males: 140 - 164 g, (mean: 153 g, ± 20%= 122-183 g)
Age at the commencement of the study: 7-9 weeks
The animals were barrier maintained (semi-barrier) in an air conditioned room
Temperature: 22 ± 3 °C
ReI. humidity: 55 ± 10%
Artificial light sequence being 12 hours light, 12 hours dark
Air change: 10 x / hour
Feeding ad libitum, Altromin 1324 maintenance diet for rats and mice, totally-pathogen-free (TPF)
Free access to tap water (drinking water, municipal residue control, microbiol. controlled periodically)
The animals were kept in Macrolon cages on Altromin saw fiber bedding
Adequate acclimatization period

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

The animals were dosed with the test item on 7 days per week for a period of 28 days by gavage, using a stomach tube. Totally 28 doses were
administered per animal and group. Volume of application: The different doses were applied according to bodyweight at a volume of 5mL/kg bw.
The animals in the control group were handled in an identical manner to the test group subjects and received the vehicle in the identical volume.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

FAAS method was used to quantify the Si content.

AAS measurements with calibration ranges of 5 to 200 mg test item/l


Analytical Results:
Mean Recovery Rate of the Test Item in the Fortification Samples:
106 % of nominal (n = 6; SD = 5 %)
Mean Recovery Rate of the Test Item Concentration in the Stability
Samples:
LD: not detennined as below LOQ
HD: 108 % of nominal (n= 2; SD = 2 %)
Mean Recovery Rate of the Test Item Concentration in the
Homogeneity Samples:
LD: not determined as below LOQ
HD: 110 % of nominal (n=2; SD = 0.4 %)
Mean Recovery Rate of the Test Item Concentration in the Test
Samples:
LD: not determined as below LOQ
MD: 106 % of nominal (n=4; SD = 4 %)
HD: 110 % of nominal (n=4; SD = 2 %)

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 5, 50 and 200 mg/kg bw
Basis:

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

Three test groups and one control group were used. According to the results of the findings of a preliminary study the following doses were administered:
Low Dose, LD: 5 mg test item/kg bw
Medium Dose, MD: 50 mg test item/kg bw
High Dose, HD: 200 mg test item/kg bw
Control, C: Corn Oil
The highest dose level was chosen with the aim of inducing toxic effects but not death or severe suffering. Thereafter, a descending sequence of dose
levels was selected with a view to demonstrate any dosage related response and no-observed-adverse effects at the lowest dose level (NOAEL).

Positive control:

not applicable

Examinations

Observations and examinations performed and frequency:

The animals were weighed prior to first application (day 0) and once a week thereafter (day 7, 14,21,27). The total and weekly mean weight gain for each group was calculated. The weights de-termined on the day of sacrifice were used for the calculation of the relative organ weights.

Food consumption was calculated weekly (day 7, 14, 21, 27) with determination of food supply and residual. The total mean and daily food consumption was determined for each group.

The observation period was 28 days. General clinical observations were made at least once a day, preferably at the same time each day. The health condition of the animals was recorded. At least twice daily, all animals were observed for morbidity and mortality. Cageside observations included spontaneous activity, lethargy, recumbent position, convulsions, tremors, apnoe, asphyxia, vocalisa-tion, diarrhoea, changes in the skin and fur, eyes and mucous membranes (salivation, discharge), piloerection and pupil size. Once before the first exposure and in the final week, detailed clinical observations were made in all animals with specific emphasis on locomotion and behaviour. These observations were made outside the home cage at the same time.

Once before the first exposure and in the fourth exposure week sensory reactivity to stimuli of differ-ent types (e.g. auditory, visual and proprioceptive stimuli, and motor activity assessment) was con-ducted. The functional observational battery was oriented according to the method described by Moser et aI., 1991 (Moser Ye., K.L. McDanie1, P.M. Phillips, Rat Strain and Stock Comparisons Using a Functional Observational Battery, Toxicol. Appl. Pharmacol. 108,267-283, 1991).
The examination began with a brief home cage observation, describing the posture, palpebral closure, and the presence of convulsions or tremors. The rat's reactivity to removal from the cage and han-dling were then rated and the observer noted presence of salivation, lacrimation, and pi1oerection. Next the rat was placed on an open field (on a table surrounded by a 10 cm cardboard rim) for 3 min. during which time the arousa11eve1 (alertness) and gait characteristics were recorded. The number of rears, supported (using the cardboard rim as support) and unsupported (unassisted), were counted separately. In addition, feca1 bo1uses and pools of urine were counted. The presence of convulsions and tremors was again noted. Reactions to the approach of a pencil, touch on the rump, and tail pinch using forceps were noted. The pupillary response was tested with the aid of a red light using a pen1ight stimulus. F1exion reflex, equilibrium, grasping reflex (together with grip strength), righting reflexes and auditory startle were tested. Finally the rectal body temperature was taken.

The withdrawal of blood was performed by puncture of the abdominal aorta of the anaesthesized animals after overnight fasting. This was part of the procedure of killing the animals on the day of necropsy. The blood was collected into small tubes containing EDTA for haematology, citrat for clotting tests and plain tubes for clinical biochemistry.

The urine was collected into plain tubes by puncture of the urine bladder as a part of the necropsy.

Haematological and clinical parameters observed:
Haematocrit (Hct) ,Haemoglobin (Hb),Erythrocyte count (RBC),Tota1 1eucocyte count (WBC) Platelet count ,APTT/PTT, Differentia11eucocyte count, AST (GOT) aspartate aminotransferase, ALT (GPT) alanine aminotransferase, Alkaline Phosphatase (AP), Cholesterol (Cho1), Total Protein (TP)
Glucose (GLU), Urea, Creatinine (CREA), Albumin (ALB), Na, K

Urine:
Specific gravity, pH, Leucocytes, Nitrite, Protein, Glucose, Ketones, Urobilinogen, Bilirubin, Blood

Sacrifice and pathology:

All animals in the study were subj ected to a full, detailed gross necropsy which included careful examination of the external surface of the body, all orifices and the cranial, thoracic and abdominal cavities and their contents.

The wet weight was taken from the following tissues immediately after preparation: liver, kidneys, adrenals, testes, epididymides, thymus, spleen, brain, heart.
The relative organ weight was calculated in relation to the bodyweights determined on the day of sacrifice and was expressed in %.

The following tissues were preserved in buffered (sodium dihydrogen orthophosphate/disodium hy-drogen orthophosphate) 10 % formalin solution from all animals of all groups. It is the most appro-priate fixation medium for both the type of tissue and the intended subsequent histopathological ex-amination: all gross lesions, brain (representative regions including cerebrum, cerebellum and pons), spinal cord, liver, kidneys, adrenals, stomach, small and large intestines (including Peyer's patches, Lymphnodes acc. to application), thymus, thyroid, spleen, lung and trachea, heart, gonads, accessory sex organs (e.g. uterus, prostate, vesicula seminalis), urinary bladder, lymph nodes (Lymphocentrum mandibulare; Lnn axillares), peripheral nerve, bone marrow.

Full histopathology was carried out on the preserved organs and tissues of all animals in the Control and High Dose groups. Additionally Liver and Stomach were evaluated from all animals in Low dose group and medium dose group.

Statistics:

For statistical analysis one-way analysis of variance (ANOVA) was carried out, followed by Student's Hest to reveal any differences between controland test groups.
For parameters indicating no compound related alterations and/or showing a high degree of variation (both in control and test groups) no statistical evaluation was carried out. Therefore, biological relevance was discussed. In the evaluation of laboratory parameters all values within a range of the mean - value ± the two fold standard deviation (x ± 2s) are considered to be "normal" values within a "normal" population.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

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):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

Beside the values in both HD groups, the mean weight gain in all groups was almost as high, as ex-pected according to the standard growth curve for this strain.. Individually diminished weight gains are due to the daily treatment associated with mechanical manipulation and therefore with increased stress for the animals.
Reduced weight gain was observed for both HD groups, compared to the controls, reaching statistical significance for the males. Beside one male HD animal, all animals showed normal food intake and no significant reduction in food consumption was found (on the 95% confidential level). A slight reduction in food consumption in the male HD group was observed.
The most relevant changes recorded upon necropsy were yellowish discolouration of liver in two animals of female HD group. Upon histopathology the following findings were noted: Several treat-ment-related changes were noted in the liver. Minimal to mild periportal inflammatory cell infiltra-tion was noted at 50 and 200 mg/kg bw in both sexes with a dose-relationship. Focal leukocytic infil-tration, often associated with degenerating hepatocytes, was evident in all groups including control, with a slightly greater severity in occasional treated groups. Minimal to mild single cell necrosis was noted in all treated groups of both sexes, being slightly more marked in the females. Minimal or moderate mitotic increase was noted in three females given 200 mg/kg bw. Mild centriacinar mi-crovacuolation was noted in one male and one female receiving 200 mg/kg bw and accounted for the yellowish discoloration seen grossly in the female.
In the nonglandular stomach, ulceration in one male and erosion/vesicle formation in one female were noted at 200 mg/kg bw. Both findings were accompanied by acanthosis with hyperkeratosis and inflammation with oedema. Minimal follicular epithelial hypertrophy in the thyroids was noted in four control males and one treated male. Its significance is unclear but a link with the vehicle is pos-sible. This change is not considered to be related to the test item. All other changes seen in protocol organs were consistent with the common background in rats of this age. Incidences were similar in both controls and animals given the test item.

Effect levels

Dose descriptor:

NOAEL

Effect level:

5 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: clinical chemistry

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Considering the reported data of this toxicity study it can be stated, that the Low Dose of 5 mg/kg BW is the no observed adverse effect dose level (NOAEL) of the test item dissolved in Corn Oil after a total of 28 applications by gavage over a period of 28 days. Clear dose dependency was observed in the findings, with a decrease in the severity of the findings evident from the High Dose to the Low Dose.

Executive summary:

 

In this Repeated Dose, 28-day Oral Toxicity Study performed according to First Addendum to OECD Guidelines for Testing of Chemicals, Section 4, No. 407, "Repeated Dose 28-day Oral Toxicity Study in Rodents" adopted 27 July, 1995 and Directive 96/54 EECB.T,the test item 1-Propanamine, 3-[(2 ,2-dimethyl-1-aza-2-silacyclopent-1-yl)dimethylsilyl]- dissolved in Corn Oil as vehicle was orally administered in graduated doses to three groups of 5 male and 5 female rats (HSDBr1:WH Wistar) by gavage, using a stomach tube. A total of 28 applications per animal were administered.

The following doses were chosen:

Low Dose: 5 mg/kg BW

Medium Dose: 50 mg/kg BW

High Dose: 200 mg/kg BW

The volume of application was 5 ml/kg BW. All rats treated with the test item Silazan 88700 VP survived throughout the test period without showing severe clinical-toxic effects. All animals were sacrificed on day 28.

Beside the values in both HD groups, the mean weight gain in all groups was almost as high, as expected according to the standard growth curve for this strain.. Individually diminished weight gains are due to the daily treatment associated with mechanical manipulation and therefore with increased stress for the animals.

Reduced weight gain was observed for both HD groups, compared to the controls, reaching statistical significance for the males. Beside one male HD animal, all animals showed normal food intake and no significant reduction in food consumption was found (on the 95% confidential level). A slight reduction in food consumption in the male HD group was observed.

The most relevant changes recorded upon necropsy were yellowish discolouration of liver in two animals of female HD group. Upon histopathology the following findings were noted: Several treatment-related changes were noted in the liver. Minimal to mild periportal inflammatory cell infiltration was noted at 50 and 200 mg/kg bw in both sexes with a dose-relationship. Focal leukocytic infiltration, often associated with degenerating hepatocytes, was evident in all groups including control, with a slightly greater severity in occasional treated groups. Minimal to mild single cell necrosis was noted in all treated groups of both sexes, being slightly more marked in the females. Minimal or moderate mitotic increase was noted in three females given 200 mg/kg bw. Mild centriacinar microvacuolation was noted in one male and one female receiving 200 mg/kg bw and accounted for the yellowish discoloration seen grossly in the female.

In the nonglandular stomach, ulceration in one male and erosion/vesicle formation in one female were noted at 200 mg/kg bw. Both findings were accompanied by acanthosis with hyperkeratosis and inflammation with oedema. Minimal follicular epithelial hypertrophy in the thyroids was noted in four control males and one treated male. Its significance is unclear but a link with the vehicle is possible. This change is not considered to be related to the test item. All other changes seen in protocol organs were consistent with the common background in rats of this age. Incidences were similar in both controls and animals given the test item.

 

Based on this discussion the following is concluded for histopathology: It can be concluded that the oral administration of the test item was associated with findings in the liver and stomach. Changes in the liver were noted at 50 and 200 mg/kg bw in both sexes, consisting primarily of periportal inflammatory cell infiltration and single cell necrosis at both dose levels, with centriacinar microvacuolation and mitotic increase (females only) at 200 mg/kg bw. Changes, possibly indicative of mild irritation (ulceration and erosion), were noted in the nonglandular stomach at 200 mg/kg bw in one animal of each sex. Upon the assessment of organ weights the most dominant findings were the increased values for the organ weights of brain, testes and epididymides in HD groups, corresponding to the weight development of these groups, but without morphological correlation (histopathological findings). Also for the findings concerning the kidneys (increased absolute and relative values for the females in the HD group) and spleen (increased relative values for the males and females in the HD group) no correlation in histopathology is given.

In the assessment of the haematology parameters (Het, Hb, RBC, WBC) no severe changes or dose-response was observed. With the exception of single borderline values, almost all individual and mean values were within the expected ranges. Single deviations were considered to be incidential and not toxicologically relevant.

With the exception of the Glucose values, the determination of clinical chemical parameters revealed that most mean and individual values were within the expected range. Statistically significant differences were found between some dose groups and the corresponding Control groups both in male and female animals. As none of the mean and individual values per se showed marked pathological deviations, significant differences in general represent variation within a normal range and are of no toxicological relevance. Some individual deviations may also be explained by technical reasons (e.g. problems while blood sampling) or individual, incidental disturbance. Some deviations are discussed.Although no deviation per se, slight increase is observed for the ALT values of the female BD (as compared to the corresponding control), which corresponds to the histopathological findings. Although no significant differences are found, there is clear indication about substance related increase of the AP values in female BD (compared to the control) corresponding to the histopathological results for that group. Considering the findings for the liver enzymes and the histopathological liver results, the increase of CBOL values in the female BD group indicate a clinical cholestasis. Chemicals impair bile formation by a variety of different mechanisms at different sites but compounds that produce cholestasis do not necessarily act by a single mechanism at one site. Most chemicals that cause cholestasis are excreted in bile.

 

 

Considering the reported data of this toxicity study it can be stated, that the Low Dose of 5 mg/kg BW is the no observed adverse effect dose level (NOAEL) of the test item dissolved in Corn Oil after a total of 28 applications by gavage over a period of 28 days. Clear dose dependency was observed in the findings, with a decrease in the severity of the findings evident from the High Dose to the Low Dose.