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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:
13-3-1989 to 6-4-1989
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
dosing from GD6 to 17
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
sodium;(4-amino-1-hydroxy-1-phosphonobutyl)-hydroxyphosphinate
Cas Number:
121268-17-5
Molecular formula:
C4H12NaNO7P2 · 3 H2O
IUPAC Name:
sodium;(4-amino-1-hydroxy-1-phosphonobutyl)-hydroxyphosphinate
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Lot Number: L-670,452-00SY-008
Puritv: 98.6% by titration
Factor: 1.33

Test animals

Species:
rat
Strain:
Sprague-Dawley
Remarks:
Crl CD (SD) BR
Details on test animals or test system and environmental conditions:
Source: Charles River Breeding Laboratories, Wilmington, Massachusetts Age at Initiation:
Approximately 12 weeks
Weight Range at Initiation: 203-281 grams
Identification Method: Ear notches

Environmental Conditions:
a. Housing:
Females were housed singly in wire mesh bottom cages;
room temperature at 20• to 27•c; room lights were set
with a timer for a 12-hour light and 12-hour dark cycle.
b. Diet:
The rats had free access to Purina Certified Rodent
Chow 1!5002 and tap water.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Remarks:
deinonised
Details on exposure:
Preparation of Test Article:
Solutions of MK-0217 in vehicle were prepared daily.
Control Article: Deionized water
Dosing Volume: 5 ml/kg based on most recent body weight.
Concentrations 1,2 and 5 mg/ml
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Drug Assays and Stability:
Samples of the dosing solutions were collected during
the first and second weeks of dosing and were assayed
for concentration. All dosing samples for the 25.0 and
10.0 mg/kg/day groups were within acceptable limits (not
less than 90% of desired concentration). The first week
sample of the 5.0 mg/kg/day group was also within
acceptable limits but the analysis of sample for the
second week of this dose group did not achieve the
desired concentration being 54.9% (duplicate 54. 7%) of
the desired concentration). This is considered an
individual dilution error in the 5.0 mg/kg/day group on
a single day of dosing and not a systematic error in
drug preparation. The compound has been shown to be
stable in this vehicle under the conditions of the study.
Details on mating procedure:
Each female was housed with 1 untreated male of the
same strain. Females were selected for study when daily
examination revealed the presence of copulatory plugs
below the cage floor. The day of finding the plug(s)
was considered Day 0 of gestation.
Duration of treatment / exposure:
Dosing through Gestation Days 6 to 17
Frequency of treatment:
Daily
Doses / concentrationsopen allclose all
Dose / conc.:
5 mg/kg bw/day (actual dose received)
Dose / conc.:
10 mg/kg bw/day (actual dose received)
Dose / conc.:
25 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
25 (twenty five)
Control animals:
yes, concurrent vehicle
Details on study design:
Females were assigned to the following groups based on
a computer-generated list of random permutations of 5*:
Treatment Groups Number of Females Per Group
Control 25
MK-0217 at:
5.0 mg/kg/day 25
10.0 mg/kg/day 25
25.0 mg/kg/day 25

*The fifth group was comprised of substitution animals.

Examinations

Maternal examinations:
Physical Signs:
Females were observed for physical signs once daily on Day
0 and during Days 6-20 of gestation and 1-5 hours post
dosing.

Maternal Body Weights:
Recorded on Days 0, 6, 8, 10, 12, 14, 16, 18 and 20 of
gestation.

Food Consumption:
Measured for all animals on Days 3-5, 6-8, 9-11, 12-14,
15-17 and 18-20 of gestation.

Necropsy:
A gross examination of thoracic, pelvic and abdominal
viscera was done on all sacrificed females.
Ovaries and uterine content:
All females were sacrificed on Day 20 of gestation by C0
2
asphyxiation. The uterus of each female was examined to
determine reproductive status (pregnant or non-pregnant).
The number of corpora lutea was counted.
Fetal examinations:
Females sacrificed on Day 20 of gestation were assigned a
code number so that litters could be examined without
knowledge of treatment groups. The order of examination was
determined by
a
computer-generated list of random
permutations of 4.
Implants were counted, classified as
live fetus, dead fetus or resorption.
All fetuses were
weighed and examined externally. Every third fetus in each
litter and all externally malformed and dead fetus were
given a visceral examination by dissection. The heads of
these fetuses were fixed in Bouin's solution and later
examined by free-hand coronal sections.
All fetuses were
fixed, cleared, and stained with alizarin red for subsequent
skeletal examination.
Statistics:
Statistical analyses were based on analysis of variance or
covariance using a least significant different procedure
after normalizing for nonparametric data by a rankit method
. Results were considered to be statistically significant if P ~ 0.05.
Indices:
Maternal body weight changes between Days 6 and 18, 18
and 20, and 6 and 20 of gestation (adjusted for Day 6
body weight where appropriate)
 03Z4QL
 
-10-
b. Percent preimplantation loss (litter mean)
c. Implants per pregnant female
d. (Resorptions + dead fetuses)/implants (litter mean)
e. Live fetus per pregnant female
f. Live fetal weight (litter mean, adjusted for time of
sacrifice)
g. Fetuses per litter with incomplete ossification of any
site.
h. Fetuses per
litter affected with hypoplastic
rib.
i.
Fetuses per litter with
incomplete ossification
of
pelvic bone.
j.
Fetuses per litter with
incomplete ossification of
sternebra.
k. Number of litters affected with incomplete ossification.
1. Average number of ossified sacrocaudal vertebrae per
fetus per litter.
m. Total number of live fetuses per litter.
n. Average female fetal weight per litter.
o. Average male fetal weight per litter.
Historical control data:
Not reported

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
First signs of rales were noted on Day 15 of gestation.
They were observed in 7/25 animals in the 25 .Q mg/kg/day
group, 5/25 on a single day and 2/25 animals for 2 days. It
 is unlikely that the rales observed in these animals are
related to treatment as rales were not observed 1 to 5 hours
post dosing and were not observed in a previous oral range­
finding study in pregnant rats given MK-0217
at 25.0 mg/kg/day on Day 6 through 16 of gestation. There
were no other treatment-related signs.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
There were no deaths or abortions during the study.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
During the treatment period (Days 6-18 of gestation) there
were significant (P ~ 0.05) dose-related decreases in mean
materoal body weight gain compared to controls of 9. 5'% and
25.0'% in the 10.0 and 25.0 mg/kg/day dose groups,
respectively. There were no significant effects of
treatment on mean materoal body weight gain in the post
dosing period of Days 18 to 20 of gestation. From Days 6 to
20 of gestation the 10.0 and 25.0 mg/kg/day groups had a
significant (P ~ 0.05) decrease in mean materoal body weight
gain of 8.4 and 21'%, respectively. The mean materoal body
weight gains of the 5.0 mg/kg/day group were not
significantly different from controls.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
In the 25.0 mg/kg/day group average materoal food
consumption was decreased 18.5'% on Days 9-11 of gestation,
17.9'% on Days 12-14 of gestation, 10.3'% on Days 15-17 of
gestation and 12.9'% on Days 18-20 of gestation. In the 10.0
mg/kg/day group food consumption was slightly decreased by
9. 7% on Days 18-20 of gestation.
These decreases in food average consumption are considered treatment related. There
was no effect of treatment on food consumption in the 5.0
mg/kg/day group.
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
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
One female (#89-0384) in the 25.0 mg/kg/day group had
distended intestines which is considered treatment-related
as it has been observed in a previous 3-month oral toxicity
study (TT #89-008-0) in rats dosed at 30 mg/kg/day. There
were no other treatment-related findings.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not specified

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 pregnancy duration:
no effects observed
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Changes in number of pregnant:
no effects observed
Other effects:
not specified
Details on maternal toxic effects:
During the treatment period (Days 6-18 of gestation) there were significant (P ~ 0.05) dose-related decreases in mean materoal body weight gain compared to controls of 9. 5'% and 25.0'% in the 10.0 and 25.0 mg/kg/day dose groups, respectively. From Days 6 to 20 of gestation the 10.0 and 25.0 mg/kg/day groups had a significant (P ~ 0.05) decrease in mean materoal body weight gain of 8.4 and 21'%, respectively.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
5 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
body weight and weight gain

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
There was a significant (P ~ 0.05) treatment-related
decrease in mean male live fetal weight of 6.6% in the 25.0
mg/kg/day group. There was a slight but not statistically
significant decrease (5.5%) in mean female live fetal weight
in the 25.0 mg/kg/day group which is also considered
treatment-related. One litter (Female #89-0384) in the 25.0
mg/kg/day group had a severe depression in live fetal
weight.
The mean live fetal weight of this litter was
decreased 50.2% in males (53.4% below control weights) and
55.9% in females (58.3% below control weights) below the
mean live fetal weight for this dose group. This female had
signs of maternal toxicity and gross findings at necropsy as
discussed below. There were no effects of treatment on mean
fetal weights in the 5.0 and 10.0 mg/kg/day group.
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): not examined
Reduction in number of live offspring:
not examined
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
not examined
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
There were no treatment-related effects observed on
external or visceral examination. One fetus in the 10.0
mg/kg/day group (#89-0359-03) had multiple cranial facial
malformations (micrognathia, cleft lip and palate,
aglossia). One fetus in the 25.0 mg/kg/day group had a tail
malformation. The findings in these 2 fetuses are
considered single incidental events not related to
treatment.
Skeletal malformations:
effects observed, treatment-related
Description (incidence and severity):
There was a slight but not statistically significant increase in the numbers of fetuses/litter with hypoplastic
rib in the 25.0 mg/kg/day group which is considered treatment related.
There was an increased incidence of fetuses with wavy rib in the 5.0 mg/kg/day group (7 fetuses
in treated group vs. 1 in control). Six of the 7 fetuses with wavy rib were in 1 litter (#89-0340) which had he highest number of sites of incomplete ossification for
the dose group and were at the low end of the fetal weight range for this group. The increased number of wavy rib in
this litter is considered to be associated with decreased skeletal maturity due to lower fetal weight.
There is no dose response for wavy rib and this increase in the 5.0 mg/kg/day group is not considered treatment related. Two
fetuses from 1 litter (#89-0398) in 25.0 mg/kg/day group had vertebral malformations (1 cervical vertebral malformation
and 1 missing vertebra) which are considered unrelated to treatment. There were no other treatment-related effects on
skeletal malformations or variations.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
One fetus in the 5.0 and 25.0 mg/kg/day group had a distended ureter.
This common variation is not considered treatment related.
One fetus in the control group had a ventricular septal defect in the heart and one
25.0 mg/kg/day fetus had a cerebral ventricular enlarge-
ment. This single malformation in the treated group is
considered a single incidental finding and not treatment
related.
Other effects:
not specified

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
5 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
fetal/pup body weight changes
skeletal malformations

Fetal abnormalities

Key result
Abnormalities:
effects observed, treatment-related
Localisation:
skeletal: skull
skeletal: sternum
skeletal: vertebra
skeletal: pelvic girdle
Description (incidence and severity):
54.2% and 56% of litter with sites of incomplete ossificaiton at 10 and 25 mg/kg/day respectively.
10.5% and 16% of fetuses with sites of incomplete ossificaiton at 10 and 25 mg/kg/day respectively.
11% fetuses with incomplete ossified sternebra at 25mg/kg/day
7.5% of fetuses with ossified sacrocaudal vertebra at 25 mg/kg/day.

Overall developmental toxicity

Key result
Developmental effects observed:
yes
Lowest effective dose / conc.:
10 mg/kg bw/day (actual dose received)
Treatment related:
yes
Relation to maternal toxicity:
developmental effects occurring together with maternal toxicity effects, but not as a secondary non-specific consequence of maternal toxicity effects
Dose response relationship:
yes
Relevant for humans:
yes

Any other information on results incl. tables

Details on Maternal Toxicity (decreased weight gain ), laparotomy data and summary of fetal abnomalities are appended as attachments.

Applicant's summary and conclusion

Conclusions:
In the 10.0 and 25.0 mg/kg/day groups maternal toxicity was
evidenced by decreases in mean maternal body weight gain and
mean food consumption during the treatment period of Days 6-17
of gestation. Developmental toxicity was observed in the 25.0
mg/kg/day group as evidenced by decreased fetal weights,
increased numbers of litters and fetuses with sites of
incomplete ossification as well as increased number of sites of
incomplete ossification and hypoplastic rib.
Developmental toxicity was evidenced in the 10.0 mg/kg/day group by increases
in the number of litters and fetuses with sites of incomplete ossification as
well as number of sites of incomplete ossification.
There was no treatment-related maternal or developmental
toxicity at the 5.0 mg/kg/day dose.
The NOAEL for developmental toxicity is 5 mg/kg bw/day and the NOAEL for Maternal Toxicity (body weight reduction) is 5 mg/kg bw/day