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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Dibutylamine hydrochloride
- Physical state: solid
- Analytical purity: 95 %
- Lot/batch No.: JB 126

Test animals

Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Germany
- Age at study initiation: 10 - 12 weeks
- Housing:housed singly
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 30-70%
- Air changes (per hr): 15 times per hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
The test substance solutions were prepared at the beginning of the administration period and thereafter at intervals of 7 days, which took into account the analytical results of the stability verification.
For the preparation of the solutions, appropriate amounts of the test substance was weighed in a beaker, topped up with drinking water and subsequently intensely mixed with a magnetic stirrer.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The results of the analyses of the test substance solutions in drinking water confirmed the correctness of the prepared concentrations. The analytical values of the samples corresponded to the expected values within the limits of the analytical method, i.e. were always above 90% and below 110% of the nominal concentrations.
Details on mating procedure:
The animals were paired by the breeder("time-mated") and supplied on GD 0 (=detection of vaninal plug/sperm).
Duration of treatment / exposure:
Gestation day 6 - 19
Frequency of treatment:
Once daily
Duration of test:
Dams sacrificed on GD20
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 15, 50, 150 mg/kg bw
Basis:

No. of animals per sex per dose:
25 female rats per dose
Control animals:
yes, concurrent vehicle

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: GD 0, 1, 3, 6, 83 10, 13, 15, 17, 19 and 20

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- With the exaption of day 0, the consumption o food was determined on the same days as body weight.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20


Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: dead fetuses
Fetal examinations:
All fetus was weighed, sexed and external tissues ans all orifices were examined macroscopically.
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
Statistics:
DUNNETT-test
FISHER`S EXACT
WILCOXON-test
KRUSKAL-WALLIS test

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Clinical observation:
Test group: NAD
Dose 10 mg/kg b.w.: NAD
Dose 50 mg/lg b.w.: salivation
Dose 150 mg/kg b.w.: slivation; one dam showed distinct clinical signs of maternal toxicity such as abdominal position, convulsion, twitching and hypersensitivity after treatment on just one occasion during the tretment.

Gravidity
24 rats gravid out of 25(rats) at 0, 50 and 150 mg/kg bw; 25/25 at the 15 mg/kg bw

Food consumption:
The average food consumtion of the rats of test groups 1,2 and3 (15, 50 and 150 mg/kg bw/d) was comparable to the control group and did not show any substance-related impairments.

Body weight: no significant effects
Body weight gain:
Body weight gain of the high-dose rats was statistically significantly reduced at initiation of treatment (GD 6-8, about 63% below the concurrent control value) but recovered afterwards. If calculated for the enire treatment phase (GD 6-19), the mean body weight gain of these rats was slightly ans non-signicantly below control (about 5%).
Body weight gain of the dams of test groups 1 and 2 (15 and 50 mg/kg bw/d) was comparable to the concurrent controls. All observable differences in these 2 groups in comparison to the controls are without any biological relevance.

There were no substance-related or spontaneous mortalities in any of the groups.

Hematology:
In the dams on GD 20 the red bood cell conts as well as the menoglobin and hematocit values were slightly, but statictically significantly increased beginning in the 50 mg/kg bw/d dose group.
Clinical Chemistry:
On GD 20, the medians of the alanine aminotransferase (ALT) activity were increased in the dams of the 150 mg/kg bw/d dose group. The inorganic phosphate levels were increased in the dams starting in the 50 mg/kg bw/d dose group. Correspondingly, the calcium levels were increased. This increase showed a statistically weakly significance already in the 15 mg/kg bw/d dose group. However, in this dose group the calcium increase was the only increased parameter in clinical pathology. Because of this exclusiveness, the calcium increase in this dose group was regarded as non-adverse. Beginning in the dams of the 50 mg/kg bw/d dose group the urea as well as the cholesterol values were increased.

Pathology:
Gross lesions: No gross lesions were noted in the dams of any fo the dose groups
Organ weights: Absolute kidney weights were slightly, but significantly increased in the high-dose group (150 mg/kg bw/d). Neither clinical pathological correlates nor any corroborative gross lesions were noted in this dose group, thus this rather marginal increase of kidney weight was not considered as an adverse effect of systemic toxicity.
Uterus weight: The mean gravid uterus weights of the animals of test groups 1, 2 and 3 (15; 50 or 150 mg/kg bw/d) were not influenced by the test substance. The differences between these groups and the control group revealed no dose-dependency and were assessed to be without biological relevance. They reflect the normal degree of variation for rats of the strain used for this study and have to be assessed in association with the fortuitous fluctuations in the mean number of live fetuses/dam in this study
Reproduction data of dams: The conception rate reached 96% in test groups 0, 2 and 3 (0; 50 and 150 mg/kg bw/d) and 100% in test group 1 (15 mg/kg bw/d). There were no test substance-related and/or biologically relevant differences among the test groups in the conception rate, in the mean number of corpora lutea and implantation sites or in the values calculated for the pre- and the postimplantation losses as well as the number of resorptions and viable fetuses. All observed differences are considered to reflect the normal range of fluctuations for animals of this strain and age

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
15 mg/kg bw/day
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
150 mg/kg bw/day
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The sex distribution of the fetuses in test groups 1-3 (15; 50 and 150 mg/kg bw/d) was comparable to the control group.
The mean fetal body weights in test groups 1, 2 and 3 (15; 50 and 150 mg/kg bw/d) were not influenced by test substance and were comparable to the corresponding mean control weights.

External Malformations:
External malformations were recorded for one fetus each in the mid- and high-dose group (50 and 150 mg/kg bw/d). Both fetuses concerned had multiple malformations. The domed head mirrored the hydrocephaly found in this fetus and is therefore no independent finding. Cleft palates are present in the historical control data at a comparable incidence, thus these, findings were considered to be spontaneous in nature and without a relation to dosing. In the treated groups, the total incidences of external malformation were not significantly different from the control group.
No external variations were observed.
No external unclassified observations were seen in any fetuses of any group.

Soft tissue malformations/variations:
The examination of the soft tissues revealed soft tissue malformations in one litter each of test groups 2 and 3 (50 and 150 mg/kg bw/d). Some of these soft tissue malformations are present in the historical control data at comparable incidences and on the whole no specific malformation pattern was obvious. Thus, these individual cases were not considered to be related to the treatment. Malformation incidences showed no statistically significant differences between the test groups and the control.
Three soft tissue variations, i.e. short innominate, uni- or bilateral dilation of the renal pelvis and dilated cerebral ventricle, were detected. These findings were observed in 3 to 4 fetuses of 3 litters in each group including the controls and showed no dose-response relationship. No association to the treatment is assumed.

Skeletal examinations:
One skeletal malformation was noted in one fetus each of test groups 0 and 1 (0 and 15 mg/kg bw/d). Neither statistically significant differences between the test groups nor a dose-response relationship were observed. Based on the rate of affected fetuses per litter, the incidence of skeletal malformations was comparable to the historical control data. No association to the treatment is assumed.
For all test groups, skeletal variations of different bone structures were observed, with or without effects on corresponding cartilages. The observed skeletal variations were related to several parts of fetal skeletons and appeared without a relation to the dose. Based on the rate of affected fetuses per litter, the incidence of skeletal variations was comparable to the historical control data

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Examinations of the Fetuses

Total external malformations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

229

25

224

24

201

24

206

Fetal incidence

N

0.0

0.0

1(0.5%)

1(0.5%)

Litter incidence

N

0.0

0.0

1(4.2%)

1(4.2%)

Affectd fetuses/litter

Mean %

0.0

0.0

0.5

0.4

 

 

 

 

 

 

Total fetal soft tissue malformation

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

109

25

105

24

95

24

98

Fetal incidence

N

0.0

0.0

1(2.1%)

1(1.0%)

Litter incidence

N

0.0

0.0

1(4.2%)

1(4.2%)

Affectd fetuses/litter

Mean %

0.0

0.0

2.1

0.8

 

 

 

 

 

 

Total soft tissue variations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

109

25

105

24

95

24

98

Fetal incidence

N

3 (2.8%)

4 (3.8%)

4(4.2%)

4 (4.1%)

Litter incidence

N

3 (2.8%)

3 (12%)

3 (13%)

3 (13%)

Affectd fetuses/litter

Mean %

2.7

3.3

2.1

0.8

 

 

 

 

 

 

Total skeletal malformations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

120

25

119

24

106

24

108

Fetal incidence

N

1 (0.8%)

1 (0.8%)

0.0

0.0

Litter incidence

N

1 (4.2%)

1 (4.0%)

0.0

0.0

Affectd fetuses/litter

Mean %

0.8

0.8

0.0

0.0

 

 

 

 

 

 

Total skeletal variations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

120

25

119

24

106

24

108

Fetal incidence

N

120 (100%)

119 (100%)

106 (100%)

108 (100%)

Litter incidence

N

24 (100%)

25 (100%)

24 (100%)

24 (100%)

Affectd fetuses/litter

Mean %

100.0

100.0

100.0

100.0

Total fetal malfromations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

229

25

224

24

201

24

206

Fetal incidence

N

1 (0.4%)

1 (0.4%)

2 (1.0%)

1 (0.5%)

Litter incidence

N

1 (4.2%)

1 (4.0%)

1 (4.2%)

1 (4.2%)

Affectd fetuses/litter

Mean %

0.5

0.4

1.0

0.4

 

Total fetal variations

 

Test group 0

0 mg/kg bw/d

Test group 1

15 mg/kg bw/d

Test group 2

50 mg/kg bw/d

Test group 3

150 mg/kg bw/d

Litter

Fetuses

N

N

24

229

25

224

24

201

24

206

Fetal incidence

N

123 (54%)

123 (55%)

110 (55%)

112 (54%)

Litter incidence

N

24 (100%)

25 (100%)

24 (100%)

24 (100%)

Affectd fetuses/litter

Mean %

53.7

55.1

54.7

53.7

mg/kg bw/d = milligram per kilogram body weight per day; N = mumber; % = per cent

 

Applicant's summary and conclusion