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Toxicological information

Acute Toxicity: other routes

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Administrative data

Endpoint:
acute toxicity: other routes
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Basic data given
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1965
Report Date:
1965

Materials and methods

Principles of method if other than guideline:
To estimate the intravenous LD50 of the test substance, a solution was administered to two groups of rats by rapid infusion. The mortality and clinical signs were monitored and gross pathology was performed at necropsy.
GLP compliance:
no
Remarks:
performed prior to GLP
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Tris(hydroxymethyl)aminomethane, THAM
- Physical state: White, crystalline solid
- Composition of test material, percentage of components: 36.3 g tris(hydroxymethyl)aminomethane, 1.75 g NaCl, 0.37 g KCl; dissolved in 1000 mL water for injection

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: 200-300 g
- Acclimation period: 14 days

Administration / exposure

Route of administration:
intravenous
Vehicle:
water
Details on exposure:
Animals were injected via the tail vein. Group 1 and 2 received the same doses, but while group 1 animals were all exposed one the same day, the dosing of group 2 animals was spread over several days. An additional control group was included to assess the effect of rapid infusion of large volumes, where the rats were administered physiological saline (0.9 g NaCl/100 mL). The infusion rates and volumes resembled those of the treatment groups.

The rate of administration was established on the basis of the weight of each individual rat, to administer 450 mg/kg bw/minute. Total infusion time was the same for a given dosage level, while infusion volume varied per rat, based on the weight.
Doses:
Group 1: 2000, 2500, 3000, 3500, 4000 and 4500 mg/kg bw (all animals dosed in one day)
Group 2: 2000, 2500, 3000, 3500, 4000 and 4500 mg/kg bw (dosing per animal spread over several days)
No. of animals per sex per dose:
3
Control animals:
other: yes, 4 animals per sex per dose
Details on study design:
- Duration of observation period following administration: Surviving animals were observed for 2 hours post-infusion
- Necropsy of survivors performed: Yes, all animals were necropsied. Specimens of all organs and tissues were fixed in neutral buffered 10% formalin.

Results and discussion

Effect levelsopen allclose all
Sex:
not specified
Dose descriptor:
other: LD50 group 1
Effect level:
3 500 mg/kg bw
Based on:
test mat.
95% CL:
3 280 - 3 830
Sex:
not specified
Dose descriptor:
other: LD50 group 2
Effect level:
3 600 mg/kg bw
Based on:
test mat.
95% CL:
3 280 - 4 040
Mortality:
Group 1: In the 2000, 2500, 3000, 3500, 4000 and 4500 mg/kg bw dose groups, the mortality was 0/6, 0/6, 1/6, 2/6, 5/6 and 6/6, respectively.
Group 2: In the 2000, 2500, 3000, 3500, 4000 and 4500 mg/kg bw dose groups, the mortality was 0/6, 0/6, 1/6, 3/6, 4/6 and 5/6, respectively.

Many of the animals died before the infusion was complete, particularly in the higher dose levels. There was no mortality in the control group.
Clinical signs:
Some of the surviving animals were obviously ill during the infusion, but recovered during the observation period. Some animals were lethargic during the observation period.
Gross pathology:
No gross lesions were observed.
Other findings:
- Histopathology: peracute toxic nephrosis was observed in the kidneys in animals surviving up to 2 hours after the infusion. In rats infused with low doses (2000 and 2500 mg/kg bw), the severity was limited to a moderate degree of pyknosis of the nuclei of isolated segments of the renal tubular epithelium, increasing in severity with the dose. In rats administered from 2500 mg/kg bw, the lesion was characterised by severe pyknosis of the nuclei of swollen renal tubular epithelial cells of varied segments of the cortex. In these animals the cytoplasm of affected cells was coagulated, distinctly granular and intensly eosinophilic. The lumens of affected tubules were frequently distended with eosinophilic, amorphous tissue debris and secretions. Affected tubules were observed adjacent to apparently normal tubules. While only a few animals in the 2500 mg/kg bw group had these lesions, the severity and number of affected animals increased with dose, with all rats affected in the highest dose groups. In the highest dose groups little difference was observed between rats that died during infusion and those surviving until sacrifice.

Two rats in the 3000 and one in the 3500 mg/kg bw groups had acute toxic hepatitis, characterised by pyknosis of the nucleus of the hepatocytes and cloudy swelling of the cytoplasm.

- Potential target organs: kidneys

Any other information on results incl. tables

Table 1: mortality per dose level and group

Doses

Number of rats

Both groups

Group 1

Group 2

Mg/kg bw

Mortality total

Mortality per sex

Mortality total

Mortality per sex

2000

0/6

-

0/6

-

2500

0/6

-

0/6

-

3000

1/6

1 female

1/6

1 male

3500

2/6

1 male, 1 female

3/6

1 male, 2 females

4000

5/6

3 males, 2 females

4/6

1 male, 3 females

4500

6/6

3 males, 3 females

5/6

2 males, 3 females

Applicant's summary and conclusion