2-amino-5-bromopyridin-3-ol

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 28 Sep to 05 Oct 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study run to a method comparable with current guidelines and to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-amino-5-bromopyridin-3-ol

EC Number:

689-734-6

Cas Number:

39903-01-0

Molecular formula:

C5H5BrN2O

IUPAC Name:

2-amino-5-bromopyridin-3-ol

Details on test material:

- Purity: 96.2% w/w
- Batch No.: CCS-952/STG-02/00109

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: Approximately 9 weeks.
- Weight at study initiation: all animals within ± 20% of the sex mean.
- Fasting period before study:
- Housing: Group housing of 3 animals per sex in Macrolon cages with sterilized sawdust as bedding material and paper as cage-enrichment.
- Diet (e.g. ad libitum): Free access to pelleted rodent diet.
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: At least 5 days before the start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0ºC (actual range: 20.2 – 22.2ºC)
- Humidity (%): 40-70% (actual range: 43 - 76%)
- Air changes (per hr): Approximately 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day.

IN-LIFE DATES: From: 2010-09-28 To: 2010-10-05

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: polyethylene glycol 400

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency):
- Mixing appropriate amounts with (Type of food):
- Storage temperature of food:

VEHICLE
- Justification for use and choice of vehicle (if other than water): Based on trial formulations performed at NOTOX and on information from the sponsor.
- Concentration in vehicle:
- Amount of vehicle (if gavage):
- Lot/batch no. (if required):
- Purity:

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

7 days

Frequency of treatment:

Once daily for up to 7 consecutive days, approximately the same time each day with a maximum of 6 hours difference between the earliest and latest dose.

Doses / concentrations

Remarks:

Doses / Concentrations:
150, 300 and 600 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

3 males and 3 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
- Rationale for animal assignment (if not random): Dose levels for this 7-day oral gavage study were selected to be 0, 150, 300 and 600 mg/kg, based on the results of the acute oral toxicity study (NOTOX project 494244) and on information from the sponsor.
- Rationale for selecting satellite groups:
- Post-exposure recovery period in satellite groups:
- Section schedule rationale (if not random):

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No data
- Time schedule:
- Cage side observations checked in table [No.?] were included.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At least once daily, detailed clinical observations were made in all animals. The time of onset,
degree and duration was recorded. All symptoms were recorded and graded according to fixed scales:
Maximum grade 1: grade 0 = absent, grade 1 = present
Maximum grade 3 or 4: grade 1 = slight, grade 2 = moderate, grade 3 = severe, grade 4 = very severe

BODY WEIGHT: Yes
- Time schedule for examinations: On Days 1, 4 and 7.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Over Days 1-4 and 4-7.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: Subjective appraisal was maintained during the study, but no quantitative investigation introduced as no effect was suspected.

OPHTHALMOSCOPIC EXAMINATION: No data
- Time schedule for examinations:
- Dose groups that were examined:

HAEMATOLOGY: Yes / No / No data
- Time schedule for collection of blood:
- Anaesthetic used for blood collection: Yes (identity) / No / No data
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked in table [No.?] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Blood samples were collected under anaesthesia using an isoflurane in nitrous oxide/oxygen combination immediately prior to scheduled post mortem examination, between 7.00 and 10.30 a.m. Animals were deprived of food overnight (for a maximum of 20 hours), but water was available. Blood samples were drawn from the retroorbital sinus and collected into tubes prepared with EDTA for haematological parameters (0.5 mL), with citrate for clotting tests (0.45 mL) and Li-heparin treated tubes for clinical biochemistry parameters (0.5 mL). An additional blood sample (0.25 mL) was collected into untreated tubes for determination of bile acids.
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked in table [No.?] were examined.

URINALYSIS: No data
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes / No / No data
- Animals fasted: Yes / No / No data
- Parameters checked in table [No.?] were examined.

NEUROBEHAVIOURAL EXAMINATION: No data
- Time schedule for examinations:
- Dose groups that were examined:
- Battery of functions tested: sensory activity / grip strength / motor activity / other:

OTHER:

Sacrifice and pathology:

Necropsy:
Animals surviving to the end of the observation period were deeply anaesthetized using an isoflurane in nitrous oxide/oxygen combination and subsequently exsanguinated and subjected to a full post mortem examination. Samples of the tissues and organs were collected from all animals at necropsy and fixed in 10% buffered formalin.

Histotechnology:
All organ and tissue samples, as defined under Histopathology (following), were processed, embedded in paraffin wax and cut at a thickness of 2-4 micrometers and stained with haematoxylin and eosin.

Histopathology:
The following slides were examined by a pathologist: all tissues collected at the scheduled sacrifice from all group 1 and 4 animals; all gross lesions. All abnormalities were described and included in the report. An attempt was made to correlate gross observations with microscopic findings.

Other examinations:

Mortality/Viability: At least twice daily.
Organ Weights: The organ weights (and terminal body weight) were recorded from the animals on the scheduled day of necropsy.

Statistics:

None stated

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

Mortality:
No mortality occurred during the study period.

Clinical Signs:
No clinical signs of toxicity were noted during the observation period.
All males at 300 and all males and females at 600 mg/kg showed salivation from Day 3 onwards. This slight degree of salivation is often noted in rats of this age and strain following oral gavage. Therefore salivation was not considered to be of toxicological relevance.

Body Weights:
Body weights of treated animals remained in the same range as controls over the study period.
Slightly reduced body weight gain was noted in males at 300 and 600 mg/kg at the end of the study period. The body weight gain remained within the expected range for these kinds of animals in this kind of study. This finding was therefore not regarded as toxicological relevant.

Food Consumption:
No toxicologically significant changes in food consumption before or after allowance for body weight were noted.

Haematology:
No toxicologically relevant changes occurred in haematological parameters of treated rats.

Clinical Biochemistry:
Higher total bilirubin, cholesterol and triglycerides and lower sodium level were noted in females at 600 mg/kg.
In males lower triglycerides were noted in a dose related response, most prominently at the highest dose level.
The higher glucose level and the lower cholesterol level in males at all dose levels were considered to be caused by the slightly lower glucose level and higher cholesterol level of the control group and therefore not considered to be of toxicological relevance.
Other changes in clinical biochemistry parameters were considered to be in the range expected for these rats and this kind of study.

Macroscopic Examination:
Necropsy did not reveal any toxicologically relevant alterations.
Other necropsy findings were considered to be of no toxicological significance since they occurred in the absence of a treatment-related distribution, and are occasionally seen among rats used in these types of studies. These findings included reduced size of testes and epididymides, nodules in epididymides, foci on thymus and fluid in the uterus.

Organ Weights:
Higher liver weight (absolute and relative) was noted in females at 600 mg/kg. In females at 300 mg/kg/day only a slightly higher liver weight (absolute and relative) was noted.
Other organ weights and organ to body weight ratios among the dose groups were similar to control levels.

Microscopic Examination:
There were no microscopic findings recorded which could be attributed to treatment with the test substance.
All microscopic findings were within the range of background pathology encountered in Wistar rats of this age and strain and occurred at similar incidences and severity in both control and treated rats.

Effect levels

Dose descriptor:

NOAEL

Effect level:

> 600 mg/kg bw/day (actual dose received)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: No toxicologically adverse effects at highest dose level tested

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

From the results presented in this report it was concluded that the test substance has no toxic potential when administered to rats by daily oral gavage for a period of up to 7 consecutive days up to 600 mg/kg.