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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15.07. - 07.10.2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report date:
2004

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Qualifier:
according to guideline
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
4-chlororesorcinol
EC Number:
202-462-0
EC Name:
4-chlororesorcinol
Cas Number:
95-88-5
Molecular formula:
C6H5ClO2
IUPAC Name:
4-chlorobenzene-1,3-diol
Test material form:
other:
Remarks:
beige powder
Details on test material:
Molecular weight: 144.65

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Recognized by the international guidelines as the recommended test system.
Sex:
male/female
Details on test animals or test system and environmental conditions:
Age: approx. 6 weeks
Body weight range at acclimatization: males:132.8- 157.0 (mean 148.2 grams); females: 117.2 - 131.9 grams (mean 125.6 grams)
Conditiions:
Standard Laboratory Conditions. Air-conditioned with 10-15 air changes per hour, and continuously monitored environment with target ranges for temperature 22+/-3°C and for relative humidity between 30-70%. 12 hours fluorescent light/12 hours dark, music during the light period.
Accomodation:
In groups of five in Makrolon type-4 cages with wire mesh tops and standardized softwood bedding ('Lignocel' Schill AG, CH-4132 MuttenzlSwitzerland).
Diet:
Pelleted standard Provimi Kliba 3433 (batch no. 34/04) rat maintenance diet (Provimi Kliba AG, CH-4303 Kaiseraugstl Switzerland) was available ad libitum.
Water:
Community tap-water from ltingen was available ad libitum in water bottles.

Administration / exposure

Route of administration:
oral: gavage
Details on route of administration:
dose volume: 10 ml/kg bw
Vehicle:
other: bidistilled water
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
group 1 (vehicle control)
Dose / conc.:
30 mg/kg bw/day (nominal)
Remarks:
group 2
Dose / conc.:
150 mg/kg bw/day (nominal)
Remarks:
group 3
Dose / conc.:
300 mg/kg bw/day (nominal)
Remarks:
group 4
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
Viability/mortality:
Twice daily.

Cageside observations:
Once prior to first administration; twice daily on days 1-3; once daily on days 4-28.

Food consumption:
Once during acclimatization and weekly thereafter, using an on-line electronic recording system consisting of a Mettler balance connected to the RCC computer.

Body weights:
Once during acclimatization and weekly thereafter, using an on-line electronic recording system consisting of a Mettler balance connected to the RCC computer.


Results and discussion

Effect levels

Key result
Dose descriptor:
NOEL
Effect level:
30 mg/kg bw/day (nominal)
Sex:
male/female
Basis for effect level:
behaviour (functional findings)
body weight and weight gain
clinical biochemistry
clinical signs
food consumption and compound intake
gross pathology
haematology
histopathology: non-neoplastic
mortality
organ weights and organ / body weight ratios
urinalysis
water consumption and compound intake
other: T3/T4 level

Target system / organ toxicity

Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
150 mg/kg bw/day (nominal)
System:
urinary
Organ:
kidney
Treatment related:
yes
Dose response relationship:
not specified
Relevant for humans:
not specified

Applicant's summary and conclusion

Conclusions:
Daily administration by gavage of A 012 to Wistar rats at doses of 30, 150 and 300 mg/kg/day for 28 days was well tolerated and did not produce early mortality or effects on food intake and body weight development. However, high dose animals showed a variety of clinical signs, mainly during the first few treatment days (sedation, tremor, recumbency, and ruffled fur) and again during weeks 3 and 4 (tremor, convulsions, abnormal gait, muscle twitchings, and breathing rales). Some mid dose females were affected to a much lesser extent (tremor) during week 4 of treatment.
The macroscopic lesions observed consisting of bilateral pelvic dilation in one group 3 female and one group 4 male could be correlated with unilateral hydronephrosis. In addition, the histopathological investigation (restricted on kidney and thyroid gland) revealed a slight increase in incidence/severity of hyaline droplets in males of group 3, which however, was considered within the historical background range.
The thyroid hormone levels of T3/T4 were not considered influenced.
Based on the results of this study, 30 mg/kg body weight/day of A 012 was established as the no-observed-effect-level (NOEL).
Executive summary:

GENERAL

In this 28-Day Oral (Gavage) Range-Finding Toxicity Study in the Wistar Rat, A 012 was administered by daily gavage to SPF-bred Wistar rats of both sexes at dose levels of 30, 150, and 300 mg/kg body weight/day for a period of 28 days. A control group was treated similarly with the vehicle (H20 bidest.) only. A total of 40 rats was used in this study. The groups comprised 5 animals per sex which were sacrificed after 28 days of treatment. Clinical signs, food consumption and body weights were recorded periodically during acclimatization and the treatment period. At the end of the treatment period, all animals were killed, necropsied and examined post mortem. Histological examinations were restricted on kidneys from all animals. Blood samples were taken from all animals for analysis of their T3/T4 hormone levels.

ANALYTICAL CHEMISTRY

The results indicate homogeneous distribution of the test item in the vehicle, mean concentrations close to the nominal values (97*, 95*, and 99%* in dose groups 2, 3, and 4, respectively.), and stability over a period of 7 days at room temperature.

* Mean values of 2 determinations

MORTALITY I VIABILITY

No deaths occurred during this study.

CLINICAL SIGNS

During the first few treatment days sedation, tremor, recumbency, and ruffied fur were observed in all high dose animals. Additional signs including convulsions, abnormal gait, muscle twitchings, and breathing rales were noted during weeks 3 and 4. Same group 3 females were affected to a much lesser extent (tremor) during week 4 of treatment.

FOOD CONSUMPTION

The overall mean food intake over the entire treatment period did not show relevant differences between controls and treated groups.

BODYWEIGHT

The body weight development in male and female groups was not affected by treatment.

ORGAN WEIGHTS

Neither absolute nor relative mean organ weights were considered influenced by treatment.

HORMONE LEVEL DETERMINATION

T3/T 4 hormone level determination in blood plasma revealed no relevant differences between controls and groups treated with the test item.

MACROSCOPIC / MICROSCOPIC FINDINGS

The macroscopic lesions observed and possibly related to treatment consisted of bilateral pelvic dilation of animal number 31 (group 3 female) and 19 (group 4 male). They could be correlated to pelvic dilation and unilateral hydronephrosis. The histopathological investigation (restricted on kidney and thyroid gland) revealed a slight increase in incidence/severity of hyaline droplets in males of group 3 (4/1.0 in the control group versus 5/1.4 in group 3). There were two cases of slight degree unilateral hydronephrosis (one case in group 4 male and group 3 female each) that went along with contralateral pelvic dilation.