Barbital sodium

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

One, not reliable study investigating toxicity of male reproductive organs in rats is available. The direct toxic effect of barbital sodium on the testis was not proved. Data on fertility are not sufficient for classification. 

Link to relevant study records

Reference

Endpoint:

reproductive toxicity, other

Type of information:

experimental study

Adequacy of study:

other information

Study period:

1965

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: documentation not sufficient, key information missing

Qualifier:

no guideline followed

GLP compliance:

no

Specific details on test material used for the study:

purchased from Merck

Species:

rat

Strain:

Wistar

Details on species / strain selection:

CFTRI inbred Wistar strain

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: CFTRI

- Age at study initiation: 40 days old
- Weight at study initiation: Males: 80-90 g
- Fasting period before study: no information
- Housing: no information
- Diet: CFTRI rat feed ad libitum
- Water: ad libitum
- Acclimation period: no information

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 26±1°C
- Humidity (%): no information
- Air changes (per hr): no information
- Photoperiod (hrs dark / hrs light): no information
IN-LIFE DATES: From: To: no information

Route of administration:

subcutaneous

Vehicle:

water

Details on exposure:

Barbital sodium in a dose of 15 mg/100 g body weight in 1 mL of distilled water was administered subcutaneously. The controls received 1 mL of distilled water.

Details on mating procedure:

no mating procedure

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

20 days

Frequency of treatment:

twice a day

Dose / conc.:

300 mg/kg bw/day

Remarks:

2 x 150 mg/kg bw

No. of animals per sex per dose:

controls: 10 male rats
barbital sodium treatment: 15 male rats

Control animals:

yes, concurrent no treatment

Parental animals: Observations and examinations:

Initial and final body weight was observed. The animals were autopsied without anaesthesia on 21st day of the study.

Postmortem examinations (parental animals):

Male reproductory organs of albino rats were examined. Testes, epididymis, vas deferens, seminal vesicle, ventral prostate, adrenal and thymus were dissected out, weighted to the nearest mg, fixed in Bouin's fluid, sectioned at 10 µm thick and stained in Harris' haematoxylin-eosin, Heidenhain's iron haematoxylin and Mallory's triple stains.

Clinical signs:

not examined

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Barbital sodium treatment did not affect the body weight.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Barbital sodium treatment affects the structure of the testis, but not its weight. In the controls, the seminiferous tubules are large, and closely packed with many sperms in their lumen. The seminiferous epithelium exhibits various stages of meiosis and spermiosis. In the barbital sodium-treated animals, the seminiferous tubules shrink considerably and are lined by highly vacuolated degenerating seminiferous epithelium with pycnotic nuclei. The sperms are still present in their lumen. The intertubular spaces are wide with well-developed Leydig cells.

Dose descriptor:

dose level:

Effect level:

6 000 mg/kg bw (total dose)

Based on:

test mat.

Sex:

male

Basis for effect level:

organ weights and organ / body weight ratios

histopathology: non-neoplastic

Conclusions:

The barbital sodium treatment causes degeneration of seminiferous epithelium of the testis without affecting the Leydig cells or the accessory organs. The direct toxic effect of barbital sodium on the testis is not proved here.

Executive summary:

The effect of barbital sodium on male reproductive organs was examined in Wistar rats. Barbital sodium in a dose of 15 mg/100 g body weight in 1 mL of distilled water was administered subcutaneously. The controls received 1 mL of distilled water.

Initial and final body weight was examined. The animals were autopsied without anaesthesia on 21st day of the study. Male reproductory organs of albino rats were examined. Testes, epididymis, vas deferens, seminal vesicle, ventral prostate, adrenal and thymus were dissected out, weighted to the nearest mg, fixed in Bouin's fluid, sectioned at 10 µm thick and stained in Harris' haematoxylin-eosin, Heidenhain's iron haematoxylin and Mallory's triple stains.

Barbital sodium treatment did not affect the body weight. In the barbital sodium-treated rats, there was significant increase (P=<0.01) in the weights of seminal vesicles and ventral prostate. There is no change in the weight of adrenals and testes. There is increase in the weight of epididymis and vas deferens, which is not significant. There is decrease in the weight of thymus, which is also not significant.

Barbital sodium treatment affects the structure of the testis, but not its weight. In the controls, the seminiferous tubules are large, and closely packed with many sperms in their lumen. The seminiferous epithelium exhibits various stages of meiosis and spermiosis. In the barbital sodium-treated animals, the seminiferous tubules shrink considerably and are lined by highly vacuolated degenerating seminiferous epithelium with pycnotic nuclei. The sperms are still present in their lumen. The intertubular spaces are wide with well-developed Leydig cells.

Effects on developmental toxicity

Description of key information

Five out of seven evaluated studies on developmental toxicity were considered reliable with restriction (Klim 2), while one study was reported without enough details to assess the quality of the study (conference abstract) and one had significant methodological deficiencies (not reliable). All Klim. 2 studies available showed that repeated doses of barbital (dose levels between 65-330 mg/kg bw) may result in abortion or resorption of the rat and mouse embryo. Malformations were not observed in four studies with rats but in one study with mice. Malformations, including exencephaly, hydrocephalus, spina bifida, cleft palate, and umbilical hernia were observed in mice in a dose dependent manner. These effects were observed below the LOEL (120 mg/kg bw) of repeated dose toxicity in mice (Waalkes and Ward 1989). One conference abstract reports on species susceptibility with regard to teratogenic effects of sodium barbital. No teratogenic effects were found in sodium barbital treated rats (100-400 mg/kg bw) and sodium barbital treated rabbits (50 mg/kg bw). When sodium barbital was administered to pregnant albino mice at dose levels of 65-330 mg/kg bw, the incidence of congenital malformations and fetal resorption was significantly. The dose levels used were in excess of the doses usually employed by clinicians. Barbiturates are GABA Modulators used as hypnotics and sedatives to induce sleep or to reduce psychological excitement or anxiety. The pharmacological effect as sedative causes lethargy and increased sleep duration and may trigger reduced food intake. Resorption or abortion of the rat and mouse embryo seem to be secondary to primary pharmacological effects. However, malformations observed in mice upon treatment with sodium barbital suggest a potential teratogenic effect. According to these results a classification for reproductive toxicity in Category 2 based on GHS criteria (H361d) is recommended.

Link to relevant study records

Reference

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

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

Specific details on test material used for the study:

sodium 5,5-diethylbarbiturate

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.

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.

Dose / conc.:

65 mg/kg bw/day

Dose / conc.:

115 mg/kg bw/day

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.

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.

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

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)

Dose descriptor:

LOEL

Effect level:

65 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

total litter losses by resorption

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

Dose descriptor:

LOAEL

Effect level:

65 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

external malformations

Abnormalities:

effects observed, treatment-related

Localisation:

external: limb

external: umbilicus

other: Hydrocephalus, Stunting

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

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.