Barbital sodium

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1969

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

THE TERATOGENICITY OF BARBITAL SODIUM IN MICE

Author:

PERSAUD TN and HENDERSON WM

Year:

1969

Bibliographic source:

ARZNEIM FORSCH 19:1309-1310,1969

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Sodium barbital was administered daily i.p. in three dose groups on days one to six of gestation to twenty pregnant albino mice of the Rockefeller strain. Foetuses recovered from pregnancies terminated on the eighteenth day were examined for external and internal gross malformations. The incidence of resorption and foetal death were evaluated. In some cases the skeletal development of the foetus was determined by staining with alizarin red.

GLP compliance:

no

Remarks:

before GLP

Test material

Test material information

Constituent 1

Reference substance name:

Barbital sodium

EC Number:

205-613-9

EC Name:

Barbital sodium

Cas Number:

144-02-5

Molecular formula:

C8H11N2O3.Na

IUPAC Name:

sodium 5,5-diethyl-4,6-dioxo-1,4,5,6-tetrahydropyrimidin-2-olate

Test material form:

not specified

Specific details on test material used for the study:

sodium 5,5-diethylbarbiturate

Test animals

Species:

mouse

Strain:

other: Rockefeller strain

Details on test animals or test system and environmental conditions:

Maintained on standard Purina lab chow and water ad libitum, were housed in individual cages.

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

other: physiological saline

Details on exposure:

Since the dose of 65 mg/kg body weight i.p. did not produce much evidence of teratogenicity it was increased to 115 and 330 mg/kg body weight respectively. Animals of the control group received daily 0.1 ml physiological saline i.p. from days one to six of gestation. Animals of the control group received daily 0.1 ml physiological saline i.p. from days one to six of gestation.

Details on mating procedure:

No details given on mating procedure.
Conception was marked by the appearance of a vaginal mating plug and considered to be day 0.

Duration of treatment / exposure:

From days one to six of gestation.

Frequency of treatment:

daily

Duration of test:

Study was terminated on the eighteenth day.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

65 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

115 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

330 mg/kg bw/day

No. of animals per sex per dose:

65 mg/kg bw: 4 females
115 mg/kg bw: 8 females
330 mg/kg bw: 8 females
control: 11 females

Control animals:

yes, concurrent vehicle

Details on study design:

Sodium barbital (sodium 5,5-diethylbarbiturate) dissolved in physiological saline, 0.05-0.1 ml pH 9.6, was administered daily i.p. on days one to six of gestation to twenty pregnant albino mice of the Rockefeller strain. Conception was marked by the appearance of a vaginal mating plug and considered to be day 0, Since the dose of 65 mg/kg body weight i.p. did not produce much evidence of teratogenicity it was increased to 115 and 330 mg/kg body weight respectively. Animals of the control group received daily 0.1 ml physiological saline i.p. from days one to six of gestation. The pregnant animals, maintained on standard Purina lab chow and water ad libitum, were housed in individual cages. Foetuses recovered from pregnancies terminated on the eighteenth day were examined for external and internal gross malformations. The incidence of resorption and foetal death were evaluated. In some cases the skeletal development of the foetus was determined by staining with alizarin red.

Examinations

Maternal examinations:

One animal in the experimental group 330 mg/kg bw and one animal in the experimental group 115 mg/kg bw died during treatment.

Fetal examinations:

Of the 102 foetuses recovered from treated mothers 61 (59.8%) had malformations. No skeletal abnormalities were observed.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

One animal in the experimental group 330 mg/kg bw and one animal in the experimental group 115 mg/kg bw died during treatment.

Body weight and weight changes:

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:

not examined

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Maternal developmental toxicity

Total litter losses by resorption:

effects observed, treatment-related

Description (incidence and severity):

Death of the conceptus followed by resorption was noted in significant numbers when sodium barbital was given.
65 mg/kg bw: 11.8% (4 resorption sites, 34 implantation sites)
115 mg/kg bw: 26.2% (16 resorption sites, 61 implantation sites)
330 mg/kg bw: 46.0% (23 resorption sites, 46 implantation sites)
control: 1.1% (1 resorption site, 93 implantation sites)

Effect levels (maternal animals)

Dose descriptor:

LOEL

Effect level:

65 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

total litter losses by resorption

Results (fetuses)

External malformations:

effects observed, treatment-related

Description (incidence and severity):

Of the 102 foetuses recovered from treated mothers 61 (59.8%) had malformations.
65 mg/kg bw: 26.7% malformed fetuses (8 malformed fetuses, 22 normal fetuses)
115 mg/kg bw: 71.1% malformed fetuses (32 malformed fetuses, 13 normal fetuses)
330 mg/kg bw: 77.8% malformed fetuses (21 malformed fetuses, 6 normal fetuses)
control: 4.3% malformed fetuses (4 malformed fetuses/stunting, 88 normal fetuses)

Skeletal malformations:

no effects observed

Description (incidence and severity):

No skeletal abnormalities were observed.

Visceral malformations:

not examined

Effect levels (fetuses)

Dose descriptor:

LOAEL

Effect level:

65 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

external malformations

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

external: limb

external: umbilicus

other: Hydrocephalus, Stunting

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

65 mg/kg bw/day

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

Applicant's summary and conclusion

Conclusions:

The teratogenic activity of sodium barbital in pregnant mice of the Rockefeller strain was investigated. A high incidence of foetal resorption and congenital malformations were observed following the i.p. administration of 65/115/330 mg/kg bw of the barbiturate.

Executive summary:

Sodium barbital (sodium 5,5-diethylbarbiturate) dissolved in physiological saline, 0.05-0.1 ml pH 9.6, was administered daily i.p. on days one to six of gestation to twenty pregnant albino mice of the Rockefeller strain. Conception was marked by the appearance of a vaginal mating plug and considered to be day 0. Since the dose of 65 mg/kg body weight i.p. did not produce much evidence of teratogenicity it was increased to 115 and 330 mg/kg body weight respectively. Animals of the control group received daily 0.1 ml physiological saline i.p. from days one to six of gestation. The pregnant animals, maintained on standard Purina lab chow and water ad libitum, were housed in individual cages. Foetuses recovered from pregnancies terminated on the eighteenth day were examined for external and internal gross malformations. The incidence of resorption and foetal death were evaluated. In some cases the skeletal development of the foetus was determined by staining with alizarin red.

One animal in the experimental groups 330 mg/kg bw and 115 mg/kg bw died during treatment. Death of the conceptus followed by resorption was noted in significant numbers when sodium barbital was given (65-330 mg/kg) during the first six days of gestation. As determined from total resorption sites 30.1% of the embryos were killed following treatment. Foetal mortality in the control group was 1.1% of all implantations. Of the 102 foetuses recovered from treated mothers 61 (59.8%) had malformations. No skeletal abnormalities were observed in the few specimens cleared and stained with alizarin red.