Bicyclo[3.1.1]hept-2-ene-2-ethanol, 6,6-dimethyl-, 2-acetate, (1R,5S)-

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 November 2021 to 04 August 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

other: Unaudited results

Title:

Unnamed

Year:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

(1R,5S)-2-(6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl) ethyl acetate

EC Number:

800-940-9

Cas Number:

35836-72-7

Molecular formula:

C13H20O2

IUPAC Name:

(1R,5S)-2-(6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl) ethyl acetate

impurity 1

Reference substance name:

Non identified impurities

Molecular formula:

Not applicable

IUPAC Name:

Non identified impurities

Test material form:

liquid

Details on test material:

Batch No.: 1000099828
Purity: 99.5%
Name of test material (as cited in study report): NOPYL ACETATE
Physical state: colourless - slightly amber liquid
Storage conditions: +2°C to +8°C, under nitrogen and protected from light
Expiry date: 19 October 2022

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: DRT / 1000099828
- Appearance: Colorless-slightly amber liquid
- Expiration date of the lot/batch: 19 October 2022
- Purity : 99.5%

STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Refrigerated (2 to 8°C), protected from humidity and light, stored under nitrogen and used within seven days of opening

Test animals

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl:CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Ltd
- Age at study initiation: a minimum of 10 weeks of age at mating
- Weight at study initiation: a minimum of 200 g at mating
- Housing: One female per cage. Cages comprised of a polycarbonate body, changed at appropriate intervals. Solid (polycarbonate) bottom cages were used during the acclimatization and gestation periods.
- Diet: SDS VRF1 Certified, pelleted diet (Availability: Non-restricted)
- Water: Potable water from the public supply via polycarbonate bottles with sipper tubes. Bottles were changed at appropriate intervals (Availability: Non-restricted)
- Acclimation period: Minimum of 3 days from arrival on Day 2 after mating to commencement of treatment on Day 6 after mating

ENVIRONMENTAL CONDITIONS
- Temperature: Maintained within the range of 20-24ºC
- Humidity: Maintained within the range of 40-70%
- Air changes: Filtered, not recirculated
- Photoperiod: 12 hours light / 12 hours dark

IN-LIFE DATES: From 4 November 2021 To: 23 November 2021

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% Methylcellulose

Details on exposure:

DETAILS ON ROUTE OF ADMINISTRATION:
Oral gavage using a suitably graduated syringe and a rubber catheter inserted via the mouth.

Rationale for route of administration: The oral (gavage) route of administration was chosen to simulate the conditions of possible human exposure.

PREPARATION OF DOSING SOLUTIONS:
Method of preparation: Starting with the lowest concentration, approximately 50% of the final volume of vehicle (1% methylcellulose) was added to the test item and magnetically stirred until uniformly mixed. The mixture was made up to the required volume with vehicle then magnetically stirred until homogeneous. Suspensions at the required concentrations were prepared by dilution of individual weighing of the test item. Detailed records of compound usage were maintained. The amount of test item necessary to prepare the formulations and the amount actually used were determined on each occasion. The difference between these amounts was checked before the formulations were dispensed.
Frequency of preparation: Weekly
Storage of formulation: Refrigerated (2-8 °C)

VEHICLE
- Concentration in vehicle: 20, 50 and 100 mg/mL
- Dose volume: 5 mL/kg bw/day for all groups

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

ANALYSIS of STABILITY:
The homogeneity and stability of formulations during storage were determined as part of another study, Labcorp Study Number 8458047, which demonstrated that prepared formulations in the concentration range of 20 to 100 mg/mL in the vehicle were stable for up to 15 days following refrigerated storage (2 to 8°C), and for one day following ambient storage (15 to 25°C).

FORMULATION ANALYSIS:
Samples of each formulation prepared for administration on the first and last preparation of treatment were analyzed for achieved concentration of the test item.

Details on mating procedure:

Method: Natural mating with Crl:CD(SD) rats of established fertility at the supplier’s facility. Males and females were not related.
Day 0 of gestation = When positive evidence of mating detected
Delivery to Labcorp: On Day 2 after mating

Duration of treatment / exposure:

Females were treated from Day 6 to Day 20 after mating.

Frequency of treatment:

Once daily at approximately the same time each day.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Group 2

Doses / concentrations 2

Dose / conc.:

250 mg/kg bw/day (nominal)

Remarks:

Group 3

Doses / concentrations 3

Dose / conc.:

500 mg/kg bw/day (nominal)

Remarks:

Group 4

No. of animals per sex per dose:

22

Control animals:

yes, concurrent vehicle

Details on study design:

DOSE SELECTION RATIONALE
The dose levels for investigation have been selected in conjunction with the Sponsor and based on the results of a preliminary embryo-fetal development study Labcorp Study No. 8458048. In that study dose levels of 200, 500 and 800 mg/kg bw/day were investigated. The Maximum Tolerated Dose was exceeded at 800 mg/kg bw/day and on Day 8 after mating animals were euthanised after showing body weight loss and clinical signs of decreased activity, piloerection, swaying or uncoordinated movement, hunched posture, irregular breathing, cold to the touch or partially closed eye lids were observed and body weight loss was evident in all females. Bodyweight loss was evident on GD 6 to 9 in three out four pregnant females and one non- pregnant female treated at 500 mg/kg bw/day. All pregnant animals subsequently showed good recovery with no effects of treatment being apparent for body weight gain to termination on GD 21 and overall body weight gain (GD 6 to 21) was only slightly lower than Control. Gravid uterine weight, when compared to Control, was low for females at 500 mg/kg bw/day and food consumption was lower than Control on GD 6 to 9 and GD 18 to 21 for females at 500 mg/kg bw/day. The absolute liver weight for females that received 500 mg/kg bw/day was high, being 21% higher than Control. Male, female and overall mean fetal weights were low in animals dosed at 500 mg/kg bw/day when compared with Control (-15 %) and mean placental weight was also slightly lower than observed for the control group.

Therefore, the dose of 500 mg/kg bw/day was considered to be toxic enough to be used as the high dose for the main study and the subsequent lower doses were separated by a factor of 2 and 2.5 respectively to assess any dose relationship.

Examinations

Maternal examinations:

MORTALITY: Yes
- Animals were killed for reasons of animal welfare where necessary.
A complete necropsy was performed in all cases.

CAGE SIDE OBSERVATIONS: Yes
- Animals were inspected visually at least twice daily for evidence of ill-health or reaction to treatment. Only signs which are indicative of ill-health were routinely recorded as part of this twice daily health check. Those signs which were not indicative of ill-health were routinely be recorded, as appropriate, as part of the detailed physical examination check or the scheduled pre and post dose checks.

DETAILED CLINICAL OBSERVATIONS: Yes
- Detailed observations were recorded daily during the treatment period at the following times in relation to dose administration: Pre-dose observation; One to two hours after completion of dosing; As late as possible in the working day.
- A detailed physical examination was performed on each animal on Day after arrival, GD 5, 12, 18 and 21.

BODY WEIGHT: Yes
- The weight of each adult was recorded on Day after arrival, GD 6, 9, 12, 15, 18 and 21 (GD 0 body weights was provided by the supplier).

FOOD CONSUMPTION : Yes
- The weight of food supplied to each animal was recorded on Days 3-6, 6-9, 9-12, 12-15, 15-18 and 18-21 after mating.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice: Animals surviving until the end of the scheduled study period were killed on Day 21 after mating, by carbon dioxide asphyxiation.
- All adult animals were subject to a detailed necropsy. After a review of the history of each animal, a full macroscopic examination of the tissues was performed. All external features and orifices were examined visually. Any abnormality in the appearance or size of any organ and tissue (external and cut surface) was recorded and the required tissue samples preserved in appropriate fixative.The gravid uterine and the liver were weighed and preserved in 10% Neutral Buffered Formalin.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
For females surviving to Day 21 after mating only, the following uterine content was recorded:
Gravid uterine weight (including cervix and ovaries).

For each ovary/uterine horn, the following were recorded for all animals (including those prematurely sacrificed, where possible):
- Number of corpora lutea: Yes
- Number of implantation sites: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Number of fetuses (live and dead): Yes

For apparently non-pregnant animals and for apparently empty uterine horns, the absence or number of uterine implantation sites was confirmed.

Blood sampling:

For all adults (excluding premature deaths): Yes
- Volume collected : 1.0 mL
- For thyroid hormone analysis (T3, T4 and TSH)

Fetal examinations:

Examination of all viable fetuses and placentae: dissected from the uterus, individually weighed and sexed. Ano-genital distance was recorded. Examined externally with particular attention paid to external genital organs of male fetuses. 50% of fetuses in each litter were examined for visceral abnormalities by fresh microdissection (Modified Staples technique) and subsequently fixed in Bouins solution. 50% of fetuses in each litter were sex confirmed internally, eviscerated and fixed in Industrial Methylated Spirit.

For Bouin’s fixed fetuses : Heads were removed post- fixation and were processed by Wilsons free-hand serial sectioning. Torsos were retained in Bouins solution.
Industrial Methylated Spirit fixed fetuses were processed and stained with Alizarin Red.

Statistics:

The following data types were analyzed at each timepoint separately:
Body weight, using absolute weights and gains over appropriate study periods,
Gravid uterine weight and adjusted body weight,
Food consumption, over appropriate study periods,
C-section litter data (corpora lutea, implantations, pre/post implantation loss, live young and sex ratio - percentage male),
Placental, litter and fetal weights.

For categorical data, the proportion of animals were analyzed for each treated group versus the control group : Group 1 vs 2, 3 and 4.
For continuous data, Bartlett’s test were first applied to test the homogeneity of variance between the groups. Using tests dependent on the outcome of Bartlett’s test, treated groups were then compared with the control group, incorporating adjustment for multiple comparisons where necessary.

Indices:

A - Pre-implantation loss (%) = [(Number of corpora lutea – Number of implantations) / Number of corpora lutea] x 100

// B - Post-implantation loss (%)= [(Number of implantations – Number of live fetuses) / Number of implantations] x 100

Historical control data:

Historical Control data were routinely supplied for selected observations where this information was considered to assist interpretation of study data, and normally include both fetal and litter incidences.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Some females receiving 500 mg/kg bw/day were swaying, with an unsteady gait and hunched posture on GD 7-10 and piloerection was observed in in one animal per day at 250 mg/kg bw/day and in one to seven animals per day in females receiving 500 mg/kg bw/day on GD 6-11.
There was no treatment related change in the appearance or behavior of animals receiving 100 mg/kg bw/day.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Two animals treated at 500 mg/kg bw/day (No’s 71 and 75) were euthanized for welfare reasons on GD 7 or 8. The animals had decreased activity, piloerection, an abnormal gait, were swaying and coordinated and were cold to the touch. Both animals had lost weight following the start of treatment, 28g for No. 71 and 19g for No. 75, and there were no findings during the macroscopic examination.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Animals receiving 500 mg/kg bw/day had body weight loss (-4g) on GD 6-9, following the start of treatment. Thereafter, on GD 9-12, body weight gain for these animals was significantly higher than the control (1.27X), and body weight gain was similar to the control on GD 12-21. Overall body weight gain (GD 6-21) was subsequently slightly low (0.91X). However, following the initial body weight loss on GD 6-9, absolute bodyweights were significantly lower from GD 9-21 when compared to controls.



Adjusted body weight and adjusted body weight change were significantly low for animals receiving 500 mg/kg bw/day, at 0.95X and 0.77X of control. The gravid uterine weight of these females was unaffected by treatment.



Body weight gain, adjusted body weight and gravid uterine weight for animals receiving 100 or 250 mg/kg bw/day was unaffected by treatment.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Animals treated at 500 mg/kg bw/day had significant low food consumption on GD 6-9, at 0.68X of the control. Food consumption for these animals was similar to the control thereafter and overall food consumption (Day 6-21) was similar to control.

Food consumption for animals receiving 100 or 250 mg/kg bw/day was unaffected by treatment.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute Liver weights were significantly higher for animals treated at 250 or 500 mg/kg bw/day, at 1.15X or 1.28X of control, respectively. The liver weight of animals receiving 100 mg/kg bw/day was unaffected by treatment.
Thyroids and Parathyroid weights were unaffected by treatment at any dose level.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no macroscopic findings considered to be attributable to treatment at 100, 250 or 500 mg/kg bw/day. All macroscopic findings were considered spontaneous and/or incidental because they occurred at a low incidence, were randomly distributed across groups (including concurrent
controls), and/or were as expected for animals of Sprague Dawley rats of this age.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Minimal hypertrophy of the follicular cells was observed within the thyroid glands of two
females receiving 250 mg/kg bw/day and three females receiving 500 mg/kg bw/day. All other microscopic findings were considered spontaneous and/or incidental because they
occurred at a low incidence, were randomly distributed across groups and/or their severity
was as expected for Sprague Dawley rats of this age. Therefore, they were considered not test
article-related.

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in number of pregnant:

effects observed, non-treatment-related

Description (incidence and severity):

Six females were not pregnant: one control (No. 2), three at 100 mg/kg bw/day (No. 30, 32 and 38), one at 250 mg/kg bw/day (No. 50) and one at 500 mg/kg bw/day (No. 74), and two females at 500 mg/kg bw/day were euthanized early (No’s 71 and 75). Reproductive assessment is therefore based on 21 litters at 0 or 250 mg/kg bw/day and 19 litters at 100 or 500 mg/kg bw/day.

Effect levels (maternal animals)

Key result

Remarks on result:

other: Study is ongoing

Maternal abnormalities

1

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

other: Liver

Description (incidence and severity):

Higher than control absolute mean liver weights were noted for the females receiving 100,
250 or 500 mg/kg bw/day and attained statistical significance for the females receiving 250 or
500 mg/kg bw/day.

2

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

thyroid gland

Description (incidence and severity):

Minimal hypertrophy of the follicular cells was observed within the thyroid glands of two
females receiving 250 mg/kg bw/day and three females receiving 500 mg/kg bw/day. The
short period of administration could explain the low incidence and severity of this finding.
The results of the thyroid hormone analysis could help to understand the relationship with
treatment of the microscopic changes observed within the thyroid glands.

Results (fetuses)

Fetal body weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Male, female and overall fetal weight was significantly low for females at 500 mg/kg bw/day, at 0.89X, 0.91X and 0.90X of control, respectively. Male fetal weight was also slight low at 250 mg/kg bw/day, at 0.96X of control.
Male, female and overall fetal weight were unaffected by maternal treatment at 100 mg/kg bw/day.

Placental and total litter weight were unaffected by maternal treatment at any dose level.

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

The number of corpora lutea, implantations, resorptions, pre- and post-implantation losses, number of male and female fetuses and sex ratio was similar in all groups and embryofetal survival was unaffected by maternal treatment at any dose level.

Changes in sex ratio:

no effects observed

Description (incidence and severity):

The number of corpora lutea, implantations, resorptions, pre- and post-implantation losses, number of male and female fetuses and sex ratio was similar in all groups and embryofetal survival was unaffected by maternal treatment at any dose level.

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

Placental and total litter weight were unaffected by maternal treatment at any dose level.

Anogenital distance of all rodent fetuses:

not examined

Changes in postnatal survival:

not examined

External malformations:

not examined

Skeletal malformations:

not examined

Visceral malformations:

effects observed, treatment-related

Description (incidence and severity):

The major abnormalities of heart dextrocardia, ventricular septum membranous defect, ascending aorta/pulmonary trunk partially fused and whole-body complete situs invertus and the minor abnormalities of accessory lung lobe absent and lungs (left and right) single lobed were found in one fetus of one female that received 500 mg/kg bw/day (No. 82).



Ureter dilated (left or bilateral) was found in one fetus at 100 mg/kg bw/day, three fetuses (three litters affected) at 250 mg/kg bw/day and three fetuses (two litters affected) at 500 mg/kg bw/day.



Subclavian artery right arises from aortic arch was found one fetus at 250 mg/kg bw/day and one fetus at 500 mg/kg bw/day.



Renal papilla left absent was found in one fetus at 500 mg/ kg bw/day.



Abdominal cavity hemorrhage was found in one fetus at 100 mg/kg bw/day, one fetus at 250 mg/kg bw/day and in three fetuses from a single litter at 500 mg/kg bw/day.



All other findings are considered incidental and are not attributed to treatment.

Effect levels (fetuses)

Key result

Remarks on result:

other: Study is ongoing

Fetal abnormalities

1

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

other: Abdominal cavity

Description (incidence and severity):

Abdominal cavity hemorrhage was found in one fetus at 100 mg/kg bw/day, one fetus at 250 mg/kg bw/day and in three fetuses from a single litter at 500 mg/kg bw/day.

2

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

visceral/soft tissue: urinary

Description (incidence and severity):

Ureter dilated (left or bilateral) was found in one fetus at 100 mg/kg bw/day, three fetuses (three litters affected) at 250 mg/kg bw/day and three fetuses (two litters affected) at 500 mg/kg bw/day. Renal papilla left absent was found in one fetus at 500 mg/ kg bw/day.

3

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

other: heart and lung

Description (incidence and severity):

The major abnormalities of heart dextrocardia, ventricular septum membranous defect, ascending aorta/pulmonary trunk partially fused and whole-body complete situs invertus and the minor abnormalities of accessory lung lobe absent and lungs (left and right) single lobed were found in one fetus of one female that received 500 mg/kg bw/day (No. 82). Subclavian artery right arises from aortic arch was found one fetus at 250 mg/kg bw/day and one fetus at 500 mg/kg bw/day.

Overall developmental toxicity

Key result

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

The study is ongoing. Audited and additional results (thyroid hormones, liver histopathology and HCD) are awaited before drawing the final conclusion.

Executive summary:

In a study conducted according to OECD guideline 414 and in GLP conditions, three groups of 22 females received Nopyl acetate at doses of 100, 250 or 500 mg/kg bw/day by oral gavage administration, from Day 6 to 20 after mating. A similarly constituted Control group received the vehicle, 1% methylcellulose, over the same period.

Animals were killed on Day 21 after mating for reproductive assessment and fetal examination.

Clinical observations, body weight and food consumption were recorded. Adult females were examined macroscopically at necropsy on Day 21 after mating and the gravid uterus weight recorded. All fetuses were examined macroscopically at necropsy and subsequently by detailed internal visceral examination of the head or skeletal examination.

 

Preliminary results

Maternal data:

Two animals treated at 500 mg/kg bw/day (No’s 71 and 75) were euthanized for welfare reasons on GD 7 or 8. The animals had decreased activity, piloerection, an abnormal gait, were swaying and coordinated and were cold to the touch. Both animals had lost weight following the start of treatment, 28g for No. 71 and 19g for No. 75, and there were no findings during the macroscopic examination.   

Some females receiving 500 mg/kg bw/day were swaying, with an unsteady gait and hunched posture on GD 7-10 and piloerection was observed in in one animal per day at 250 mg/kg bw/day and in one to seven animals per day in females receiving 500 mg/kg bw/day on GD 6-11. There was no treatment related change in the appearance or behavior of animals receiving 100 mg/kg bw/day.

Animals receiving 500 mg/kg bw/day had body weight loss (-4g) on GD 6-9, following the start of treatment. Thereafter, on GD 9-12, body weight gain for these animals was significantly higher than the control (1.27X), and body weight gain was similar to the control on GD 12-21. Overall body weight gain (GD 6-21) was subsequently slightly low (0.91X). However, following the initial body weight loss on GD 6-9, absolute bodyweights were significantly lower from GD 9-21 when compared to controls. Adjusted body weight and adjusted body weight change were significantly low for animals receiving 500 mg/kg bw/day, at 0.95X and 0.77X of control. The gravid uterine weight of these females was unaffected by treatment. Body weight gain, adjusted body weight and gravid uterine weight for animals receiving 100 or 250 mg/kg bw/day was unaffected by treatment. 

Animals treated at 500 mg/kg bw/day had significant low food consumption on GD 6-9, at 0.68X of the control. Food consumption for these animals was similar to the control thereafter and overall food consumption (Day 6-21) was similar to control. Food consumption for animals receiving 100 or 250 mg/kg bw/day was unaffected by treatment.

Six females were not pregnant: one control (No. 2), three at 100 mg/kg bw/day (No. 30, 32 and 38) one at 250 mg/kg bw/day (No. 50) and one at 500 mg/kg bw/day (No. 74), and two females at 500 mg/kg bw/day were euthanized early (No’s 71 and 75).  Reproductive assessment is therefore based on 21 litters at 0 or 250 mg/kg bw/day and 19 litters at 100 or 500 mg/kg bw/day. 

No test article-related deaths or macroscopic changes occurred. Statistically significant lower terminal body weight was observed in females receiving 500 mg/kg bw/day. Higher than control, absolute mean liver weights were noted for the females receiving 100, 250 or 500 mg/kg bw/day and attained statistical significance for the females receiving 250 or 500 mg/kg bw/day (at 1.15X or 1.28X of control, respectively). The liver weight of animals receiving 100 mg/kg bw/day was unaffected by treatment. 

 

Fetal data

The number of copora lutea, implantations, resorptions, pre- and post-implantation losses, number of male and female fetuses and sex ratio was similar in all groups and embryofetal survival was unaffected by maternal treatment at any dose level.

Male, female and overall fetal weight was significantly low for females at 500 mg/kg bw/day, at 0.89X, 0.91X and 0.90X of control, respectively.   Male fetal weight was also slight low at 250 mg/kg bw/day, at 0.96X of control. Male, female and overall fetal weight were unaffected by maternal treatment at 100 mg/kg bw/day. Placental and total litter weight were unaffected by maternal treatment at any dose level.  

The major abnormalities of heart dextrocardia, ventricular septum membranous defect, ascending aorta/pulmonary trunk partially fused and whole-body complete situs invertus and the minor abnormalities of accessory lung lobe absent and lungs (left and right) single lobed were found in one fetus of one female that received 500 mg/kg bw/day (No. 82). Ureter dilated (left or bilateral) was found in one fetus at 100 mg/kg bw/day, three fetuses (three litters affected) at 250 mg/kg bw/day and three fetuses (two litters affected) at 500 mg/kg bw/day. Subclavian artery right arises from aortic arch was found one fetus at 250 mg/kg bw/day and one fetus at 500 mg/kg bw/day. Renal papilla left absent was found in one fetus at 500 mg/ kg bw/day. Abdominal cavity hemorrhage was found in one fetus at 100 mg/kg bw/day, one fetus at 250 mg/kg bw/day and in three fetuses from a single litter at 500 mg/kg bw/day. All other findings are considered incidental and are not attributed to treatment.  

The study is ongoing. Audited and additional results (thyroid hormones, liver histopathology and HCD) are awaited before drawing the final conclusion.