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Administrative data

Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Aug 07, 2018 - Aug 21, 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test type:
acute toxic class method
Limit test:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
(4-butoxy-2,3-difluorophenyl)boronic acid
EC Number:
692-793-0
Cas Number:
156487-12-6
Molecular formula:
C10H13BF2O2
IUPAC Name:
(4-butoxy-2,3-difluorophenyl)boronic acid
Test material form:
solid

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: F. Winkelmann, 33178 Borchen
- Age at study initiation: about 9 weeks
- Weight at study initiation: 166 g (range from 155 to 182 g).
- Fasting period before study: yes, overnight (17 hours before - 4 h after treatment)
- Housing: the rats were housed in an air-conditioned room of ca. 25 m² in the Institute of Toxicology in Macrolon cages type III with a shelter, placed on mobile racks. Animals were kept on conventional softwool granulate as bedding which was changed 2x per week.
- Diet: Provimi Kliba 3433.0, ad libitum
- Water: tap water from Makrolon drinking bottles, ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.7 – 23.2
- Humidity (%): 43.2 – 58.5
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
methylcellulose
Details on oral exposure:
VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg bw
Directly before the preparation the test metariel was solved in the vehicle using a shaking device (Vortex Genie) and and Ultra Turrax device.

The vehicle chosen was Methocel(R) K4M Premium solution

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw
Doses:
2000 mg/kg bw
No. of animals per sex per dose:
3
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
The behaviour and general condition of all animals was monitored for at least 6 h after administration of the test material and then checked daily. All animals were weighed before treatment and on days 2, 4, 6, 8, 11, 13, and 15 of the experimental part.
- Necropsy of survivors performed: yes, At the end of the experimental part, all surviving rats were sacrificed by an air carbon dioxide mixture and exsanguination after opening the abdominal vessels (Vena cava caudalis, Aorta abdominalis). All rats (survivors and rats found dead) were subjected to a gross pathological investigation and macroscopic findings were noted manually on a necropsy record sheet.
Statistics:
Body weight data were recorded with the PC software "akudat", the statistical evaluation of the body weight were carried out with the software "Tox 511A", the body weight development of each rat and group was determined. The group mean value was calculated for each measurement.

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 300 - < 2 000 mg/kg bw
Based on:
test mat.
Mortality:
Three out of six rats treated with 2000 mg/kg died on day 2 and 3 after the last observation. No mortality was seen after treatment with 300 mg/kg during the course of this study.
Clinical signs:
observations of tremors
other: locomotor disturbance, dyspnea and tremor
Body weight:
lower than 10% body weight loss
Remarks:
Five out of six rats treated with 2000 mg/kg showed a decrease of the body weight on day 2. The body weight development of the surviving rats treated with 2000 mg/kg after day 2 was inconspicuous until experimental day 15. The body weight development of the rats treated with 300 mg/kg was inconspicuous throughout the study.
Gross pathology:
Necropsy revealed no findings in animals dosed with 300 mg/kg. Three out of six rats (no. 4,5,6) dosed with 2000 mg/kg showed macroscopic lesions as follows. All three rats showed dark-red discolorations in the fundus mucosa of the stomach (no histology correlate). In the intestines, multifocal to diffuse red discolorations were noted (no histology correlate); a firm content was found in the cecum (no histology correlate). Animal 4 showed dark-red discolorations in the thymus (acute hemorrhages). Animal no. 5 had a smaller spleen (marked lymphoid depletion) and animal no. 6 dark-red discolored kidneys (no histology correlate) and a wet abdominal fur (reddish fluid).
Other findings:
Histopathology examination of selected organs from rats dosed with 2000 mg/kg showed lesions in the urinary bladder, the hemo-lymphoid system (bone marrow, thymus, spleen), the liver, the small intestines and the lung. In the urinary bladder of all three rats (no. 4, 5, 6) dosed with 2000 mg/kg, moderate erosions of the mucosa (urothel) or a mild cytoplasmic vacuolation of the urothelium were seen. In addition, moderate submucosal located granulocytic infiltrates and acute focal hemorrhages were found. In the bone marrow, a moderate to marked decreased cellularity was seen. In the thymus of animal no. 4, severe lymphoid necrosis and acute hemorrhages were noted. The spleen showed marked to severe lymphoid depletion and lymphoid necrosis in all three animals. In the liver, a mild cytoplasmic vacuolation of periportal hepatocytes was found in all three rats. Animal no. 5 and 6 showed multifocal mucosa ulcerations and granulocytic infiltrates in the small intestines. All three rats showed lungs with acute blood congestion (most likely an agonal change).

Any other information on results incl. tables

 


The body weight development of rats is given in the following table:
































































































































































































Animal No.



Sex



Dose
[mg/kg]



Body weight in g on day



Body weight gain in g



1



2



4



6



8



11



13



15



Day 1 to 15



1



Female



2000



161



155



165



176



174



190



188



199



+38



2



Female



2000



171



166



175



185



194



201



205



216



+45



3



Female



2000



171



177



178



186



194



202



204



210



+39



4*



Female



2000



157



152



-



-



-



-



-



-



-



5**



Female



2000



163



158



-



-



-



-



-



-



-



6**



Female



2000



158



151



-



-



-



-



-



-



-



7



Female



300



162



175



177



184



182



191



190



197



+35



8



Female



300



182



194



203



204



211



213



216



223



+41



9



Female



300



169



184



189



197



197



199



205



208



+39



10



Female



300



165



180



184



181



190



193



197



201



+36



11



Female



300



173



188



190



195



199



203



201



208



+35



12



Female



300



155



171



175



176



181



183



188



193



+38



* died on day 3 after last observation; body weightpost mortem: animal no. 4: 147 g


** died on day 2 after last observation; body weight post mortem: animal no. 5: 152 g, animal no. 6: 146 g

Applicant's summary and conclusion

Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
Under the conditions of the present study, the LD50 value for the test item is expected to be between 300 - 2000 mg/kg after single oral administration in rats