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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 Apr - 25 May 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
adopted in 2018
Deviations:
yes
Remarks:
No histopathological examination of thyroid performed.
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom, Medicines & Healthcare Products Regulatory Agency, UK
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Propylidynetrimethanol, propoxylated
EC Number:
500-041-9
EC Name:
Propylidynetrimethanol, propoxylated
Cas Number:
25723-16-4
Molecular formula:
C3H5(CH2OR)3 R= (C2H3(CH3)O)nH sum of n: >1 - <6.5 mol PO
IUPAC Name:
Propylidynetrimethanol, propoxylated
Test material form:
liquid
Specific details on test material used for the study:
Batch/Lot Number: 1907170614
Expiry: 03 October 2020
Storage Conditions: Ambient room temperature

Test animals

Species:
rat
Strain:
other: Han Wistar RccHan®:WIST
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Envigo RMS (UK) Limited, Shaw’s Farm, Blackthorn, Bicester, Oxon, UK
- Age at study initiation: 9 - 11 weeks
- Weight at study initiation: 177 - 246 g
- Housing: 3 per cage in polycarbonate cages with stainless steel grid tops, solid bottoms and sterilised white wood shavings as bedding material.
- Diet: VRF-1 breeder diet (SDS, Witham, Essex, UK), ad libitum
- Water: Water from public supply, ad libitum
- Acclimation period: From arrival until start of dosing, i.e. a minimum of 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 23
- Humidity (%): 44 - 65
- Air changes (per hr): >= 10
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: 14 Apr To: 07 May 2020

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Dosing solutions were prepared weekly by weighing the required amount of test item and adding the required amount of the vehicle water (w/w). The final concentrations of test item in the vehicle were 10, 30 and 100 mg/mL.

VEHICLE
- Substance: Milli-Q Water (purified in house)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Duplicate top, middle and bottom samples (duplicate middle only for control) were collected for concentration and homogeneity analyses. When only concentration analysis was required, the formulations were only sampled from the middle. Concentration results were considered acceptable if they were within or equal to ± 15% of theoretical concentration. Each individual sample concentration result was considered acceptable if it was within or equal to ± 20%. Homogeneity results were considered acceptable if the relative standard deviation of the mean value at each sampling location was <= 10%. The analyses confirmed the concentration, stability and homogeneity of the dosing formulations.
Details on mating procedure:
- Impregnation procedure: purchased timed pregnant
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy
Duration of treatment / exposure:
Day 6 - 20 of gestation
Frequency of treatment:
daily, 7 days/week
Duration of test:
Until Day 20 of gestation
Doses / concentrationsopen allclose all
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Dose / conc.:
300 mg/kg bw/day (actual dose received)
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
24 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Dose levels were based on the results of a foregoing preliminary prenatal developmental toxicity study in which animals were orally exposed to 100, 300 and 1000 mg/kg bw/day from GD 6 to GD 20 (Charles River, 2020, study no. 490513). In the absence of any maternal toxicity findings, 100, 300 and 1000 mg/kg bw/day were selected as the dose levels for the main study.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily throughout the study for general health/mortality and moribundity.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once during pretreatment on GD 3 and weekly during the dosing period from GD 6.

BODY WEIGHT: Yes
- Time schedule for examinations: GD 0 (provided by the supplier), GD 3, GD 6, GD 9, GD 12, GD 15, GD 18 and GD 21.

FOOD CONSUMPTION: Yes
- Time schedule: GD 3 - 6, GD 6 - 9, GD 9 - 12, GD 12 - 15, GD 15 - 18 and GD 18 - 21

WATER CONSUMPTION: Yes
- Time schedule for examinations: Water consumption was monitored by visual inspection of the water bottles only. No quantitative analysis was performed.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs / tissues examined: Thyroid gland (with parathyroid), ovary, oviduct, uterus/cervix/vagina, placentae
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: Apparent non-pregnant uteri were retained, stained and examined for implantation sites.
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter
Statistics:
Means, standard deviations, percentages, numbers, and/or incidences have been reported, as appropriate by dataset. Inferential statistical tests were conducted at the 5% significance level. All pairwise comparisons were conducted using two sided tests and have been reported at the 1% and 5% levels, unless otherwise noted. Analyses were performed excluding any group with less than 3 observations.
Parametric/Non-parametric: Levene’s test was used to assess the homogeneity of group variances. The groups were compared using an overall one-way ANOVA F-test if Levene’s test was not significant or the Kruskal-Wallis test if it was significant. If the overall F-test or Kruskal Wallis test was found to be significant, then pairwise comparisons were conducted using Dunnett’s or Dunn’s test, respectively.
Non-parametric: The groups were compared using an overall Kruskal-Wallis test. If the overall Kruskal-Wallis test was found to be significant, then the above pairwise comparisons were conducted using Dunn’s test.
Incidence: A Fisher’s exact test was used to conduct pairwise group comparisons of interest.
Indices:
Pregnancy Rate = (No. of animals pregnant / No. of animals mated at the supplier) x 100

Pre-Implantation Loss = [(No. of corpora lutea – No. of implants) / No. of corpora lutea] x 100

Post-Implantation Loss = [(No. of implants – No. of live fetuses) / No. of implants] x 100

Sex Ratio (% males) = (No. male fetuses / Total No. of fetuses) x 100

Litter % of Fetuses with Abnormalities = (No. of fetuses in litter with a given finding / No. of fetuses in litter examined) x 100

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
9/23 animals in the high-dose group showed ploughing of the cage shavings from GD 15 onwards. This was transient and was seen immediately following dose administration only. Abnormal gait and hunched posture were observed in 2/24 animals on GD 7 or GD 8. One of these 2 animals was euthanised on GD 7 and showed decreased respiratory rate, hunched posture, eyes partly closed, uncoordinated and abnormal gait, subdued, cold to touch and head twitches as additional clinical signs. Further minor clinical observations were not treatment-related based on the type and distribution, e.g. fur thinning, and scabbing are commonly observed in rats and were therefore considered normal background findings. Increased activity was seen once in 1 animal of the low-dose group. Based on the single incidence and absence of dose response, this was considered sporadic.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, non-treatment-related
Description (incidence):
One animal of the high-dose group was euthanised on GD 7 after receiving 2 doses due to the onset of adverse clinical signs at 1 - 2 h post dose administration. At necropsy, there were no abnormalities noted. The animal was not pregnant.
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
effects observed, non-treatment-related
Description (incidence and severity):
A significant increase in food consumption in the high-dose group on GD 9 - 15 was observed. This was considered not treatment-related.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Description (incidence and severity):
Water consumption was not analysed quantitatively.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
effects observed, non-treatment-related
Description (incidence and severity):
Maternal thyroid hormone levels (T3, T4 and TSH) on GD 21 were comparable between all groups. Slight intergroup differences did not follow a dose-related pattern and were too small to be considered treatment-related.
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
effects observed, non-treatment-related
Description (incidence and severity):
The mean pre- and post implantation losses were higher in the mid-dose group when compared to the controls. However, as there was no dose relationship, this was considered incidental.
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
effects observed, non-treatment-related
Description (incidence and severity):
4, 4 and 2 animals were found to be not pregnant in the low-, mid- and high-dose groups, respectively. As there was no dose relationship, these non pregnancies were considered sporadic and unrelated to administration of the test substance.
Details on maternal toxic effects:
Additional details on results are provided in the pdf document 'Summary tables' under 'Attached background material'.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Remarks:
maternal
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: no biologically relevant effects observed

Maternal abnormalities

Key result
Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
not examined
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
not examined
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Other effects:
effects observed, non-treatment-related
Description (incidence and severity):
In the high-dose group, the litter mean anogenital distance (AGD) was lower by 12% in male fetuses (2.90 mm vs. 3.28 mm in the controls) and by 16% in female fetuses (1.26 mm vs. 1.50 mm in the controls). However, the differences in absolute values were small, the mean AGD was within the standard deviation for the control group and within the test facility’s control values from similar assessments. Therefore, the AGD was considered to be within normal variation for all groups. There was no evidence of an effect on fetal weights.
Details on embryotoxic / teratogenic effects:
Additional details on results are provided in the pdf document 'Summary tables' under 'Attached background material'.

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Remarks:
development
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no biologically relevant effects observed

Overall developmental toxicity

Key result
Developmental effects observed:
no

Any other information on results incl. tables

Additional details on results are provided in the pdf document 'Summary tables' under 'Attached background material'.

Applicant's summary and conclusion

Conclusions:
Propylidynetrimethanol, propoxylated did not exert any maternal systemic toxicity and had no effect on intrauterine development when administered at doses of up to 1000 mg/kg bw/day by oral gavage to pregnant rats on GD 6 - GD 20. Additional details on results are provided in the pdf document 'Summary tables' under 'Attached background material'.