Semicarbazide hydrochloride

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1986

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Semicarbazide hydrochloride

EC Number:

209-247-0

EC Name:

Semicarbazide hydrochloride

Cas Number:

563-41-7

Molecular formula:

CH5N3O.ClH

IUPAC Name:

semicarbazide hydrochloride

Specific details on test material used for the study:

SC hydrochloride (Supplier Merck) was dissolved in 1 mL of saline solution at a concentration of 0,9% NaCl and a final pH of 7,2. The animals were weighed at the moment of injection in order to calculate the mg of SC to be added to the mL of saline solution necessary for the dosis indicated by kg of weight.

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

Female rats : Virgin
Weight at the beginning of the study : 200-250g

Food : standard rat died ad libitum
Water :ad libitum

Room temperature : 25+/-2°C

Light cycles : 12 hours light/12 hours dark, automatically regulated

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

other: Saline solution of NaCl

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Virgin female Wistar rats were bred in estrus during the early afternoon and remainded caged with fertile male Wistar rats overnight (4 females to 2 males)
Pregnancy diagnosis was determined by vaginal smears.

Duration of treatment / exposure:

One group is injected with 17 mg/kg/day C throughout gestation
Another group on day 5, 7, 10, 13 or 15 of gestation with 50, 75, 100 or 150 mg/kg SC respectively

Frequency of treatment:

One group is injected with 17 mg/kg/day C throughout gestation
Another group on day 5, 7, 10, 13 or 15 of gestation with 50, 75, 100 or 150 mg/kg SC respectively

No. of animals per sex per dose:

All the experimental (single and coninuous dose) and control animals were divided into 2 groups : A and B.
Group A was made of 190 experimental animals.
Group B was made of 105 experimental pregant animal and 30 controls.

Control animals:

yes, concurrent vehicle

Details on study design:

Control animals received the same volume of saline solution intraperitoneally on a similar schedule i e on the day of gestation corresponding to that of the treated (experimental) animals.
10 pregnants females were used as controls for each of the days (5, 7, 10, 13 or 15) of gestation in which SC was administered.
Another 10 females controls received 1 mL saline solution daily during the whole gestation.

The animals of the group A were sacrified on day 21 of gestation. A midline abdominal incision was performed and both uterine horns were exposed.
Live and dead fetuses were removed and counted together with the number of resoprtions and implantations.
All fetuses were carefully examined for signs of externals malformations and their sex and weight noted down.
The live fetuses were then subdivided at random into 2 subgroups, a and b, in order to carry out a specific study in each of the subgroups.
In subgroup a, organic anomalies were studied. The fetuses were placed in Bouin's fluid, and their internal organs were then examined by sectioning with a razor blade following Wilson's technique..
The fetuses in subgroup b, were used to study the skeleton anomalies. They were fixed in 70% ethanol and then cleared with 1% OHK and stained with alizarin red S.

Group B: all animals from this group were allowed to deliver, and the mortality rate of their offspringwas studied during the first month of life.

Examinations

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: No
- Number of implantations: Yes
- Number resorptions: Yes

Fetal examinations:

- External examinations: Yes
- Soft tissue examinations: No data
- Skeletal examinations: Yes:
- Head examinations: No data
- Internal organs : Yes

Statistics:

The mean +/-SEM values for treated and non-treated (control) fetuses were statistically compared with a 2-tail Student's t test. p<0.05 being the minimum significant value.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

not specified

Dermal irritation (if dermal study):

not specified

Mortality:

mortality observed, treatment-related

Description (incidence):

Some maternal deaths ensued after treatment with the 50, 100 and especially 150 mg/kg SC regimen.

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Maternal developmental toxicity

Number of abortions:

not specified

Pre- and post-implantation loss:

not specified

Total litter losses by resorption:

effects observed, treatment-related

Description (incidence and severity):

There were several degrees of resoprtion rates as well deaths almost every day with all the doses studied.
The resroption rate were directly correlated with the dose; while the number of live fetuses was inversely related to it.
Treatment with SC was most embryotoxic onday 7 abd 10 of gestation, with statistically significant differences in the number of live fetuses with respect to controls with all the doses used.
The administration of SC on day 5 produced a significant decrease in the number od live fetuses only with the 100 mg/kg dose while on day 13 and 15 this occured with the 100 and 150 mg/kg doses.

The percentage of resorptions, expressed as small, medium or large in size and appaearing on the different days of treatment, were for days 5, 7, 10, 13 and 15 : 48, 27, 25, 3 and 0%, for the samll resorptions; 52, 68, 39, 38 and 32% respectively for the medium resorptions and 0, 4, 36, 52 and 68% respectively for the large resorptions.

Early or late resorptions:

not specified

Dead fetuses:

not specified

Changes in pregnancy duration:

not specified

Changes in number of pregnant:

not specified

Other effects:

not specified

Effect levels (maternal animals)

Key result

Dose descriptor:

conc. level:

Effect level:

>= 100 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

mortality

Remarks on result:

other: NA

Maternal abnormalities

Abnormalities:

not examined

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

Fetal weight is significantly decreased with all the doses used when these were admninistered on days 5, 7 or 10 of gestation.
With the 75, 100 and 150 mg/kg doses, fetal weight was significantly decreased on all the days of gestation in which SC was administered.

Reduction in number of live offspring:

effects observed, treatment-related

Changes in postnatal survival:

effects observed, treatment-related

Description (incidence and severity):

SC produced a high mortality rate with high statistical differences as compared to controls on all the days and with all the doses studied.
Mortality was highest when SC was administered on day 10 of gestation (63+/-3% beign the highest value found and corresponding to the 100 mg/kg dose).

External malformations:

not specified

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

The most frequent skeletal lesions found were an incomplete ossification of the skull and sternum, especially when SC was administered during the implantation period.
A small percentage of lesions was also found in the ribs. An incomplete ossification of the limbs also occured.
The malformations found in the fetuses whose mothers were injected with 17 mg/kg/day SC during the entire course of pregnancy were similar to the ones mentioned for the single-dose treatment; although the hemorrhages in the liver and hydronephroses were less frequent.

Visceral malformations:

effects observed, treatment-related

Description (incidence and severity):

The fetuses showed some abnormalities in the brain, especially when the rats were treated during the differentiation period.
These abnormalities were mainly internal hydrocephaly, and in somes cases, exencephaly and meningocele.
Severe hemorrhages in liver and intentines were also observed in the fetuses treated during this period.
A high percentage of hydronephroses appeared in the fetuses, regardless of the period in which their mothers were treated, although the percentage was higher during the developmental period.
A small percentage of anophtalmia on one side, cleft palate or an absence of testes was also observed in the fetuses which came to term.

Other effects:

not specified

Effect levels (fetuses)

Key result

Dose descriptor:

LOEL

Effect level:

< 17 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

skeletal malformations

Remarks on result:

other: NA

Fetal abnormalities

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

external: limb

skeletal: skull

skeletal: sternum

skeletal: rib

Overall developmental toxicity

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

17 mg/kg bw/day (nominal)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects in the absence of maternal toxicity effects

Dose response relationship:

not specified

Relevant for humans:

not specified

Applicant's summary and conclusion

Conclusions:

SC produced a significantly smaller number of live fetuses with respect to controls.
This toxic effect after injection at days 7 and 10 of gestation was highest for all single doses.
The mean of fetal weight decreased with respect to controls with almost all of the SC treatment studied.
The number of implantations and live fetuses was significantly decreased in the rats receiving the continuous treatment.
Most abnormalities in the 21-day-old fetuses wre found in the brain, kidney, intestines and liver; skeletal anomalies were seen in the skull, sternuum and ribs.
SC also produced high postnatal mortality rates during the first month of life with the single doses as well as the continuous treatment.
Thus, SC produced signs of toxicity and/or teratogenic effects in rats with all doses administered.

Executive summary:

In a developmental and teratogenicity toxicity study (published), 5 groups of pregnant Wistar rats were injected intraperitoneally with a single dose of SemiCarbazide (SC) on days 5, 7, 10, 13 or 15 of gestation. The lots in each group received either 50, 75, 100 or 150 mg/kg SC. A sixth group received 17 mg/kg of the drug during ther entire course of pregnancy.

Results indicate that SC has an embryotoxic effect on Wistar rats when it was administered intraperitoneally in single doses of 50, 75, 100 pr 150 mg/kg on the different gestation days studied or in daily injections of 17 mg/kg throughout the entire course of pregnancy.

One of the most notable effect of this substance wasfetal death and resorption, resulting in a significant decrease in the number of live fetuses with respect to controls.

The embryotoxicity of SC as seen from the number of resorbed or dead conceptuses may provide an interesting correlation as to the extent of its teratogenicity.

The dosage levels producing these effects also caused some maternal toxicity. However, some pregnant females who did not show anu overt signs of toxicity had litters with malformed embryos. Thus, the embryotoxic consequences of SC treatment were due to a direct action on the embryo (and not to an indirect effect through the mother).

Intrauterine growth (weight of the 21 -day old fetuses) was decreased with the single dose injections but not with the continuous treatment. The decrease in the number of live fetuses and implantations per litter, however, wss more notable with the coninuous treatment.

Thus from the results foundon the relationship between resorption sizes and days injected, it is possible to infer taht SC acts on intrauterine life, stopping its growth one the drug is administered.

A slight increase in the number of organic lesions when SC was injected during the differentiation period (which corresponds to the teratogenic susceptibility othe rat during these days 9 and 10 of gestation) has been observed. Abnormatlities in the brain, the kidney, intestines and liver ; skeletal aomalies were seen in the skull, sternuum and ribs. SC produced also high postnatal mortality rates during the first month of life with the single doses as well as with the continuous treatment.

Tus, SC produced signs of toxicity and/or teratogenic effects in rats with all doses administered.