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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
19 Feb 1998 - 30 March 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study with acceptable restrictions (no analytical purity reported).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Version / remarks:
adopted in 1995
Deviations:
yes
Remarks:
no analytical purity reported
Qualifier:
according to guideline
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
Deviations:
yes
Remarks:
no analytical purity reported
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom, UK

Test material

Constituent 1
Reference substance name:
647028-25-9
Cas Number:
647028-25-9
IUPAC Name:
647028-25-9
Details on test material:
- Name of test material (as cited in study report): Only trade name given
- Physical state: straw coloured liquid
- Analytical purity: not reported
- Storage condition of test material: room temperature in the dark
- Stability under test conditions: formulations were stable for at least thirteen days

Test animals

Species:
rat
Strain:
other: Sprague-Dawley Crl:CD®BR
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Limited, Margate, Kent, UK
- Age at study initiation: 5 to 6 weeks
- Weight at study initiation: 127 – 161 g (males) and 117 – 152 g (females)
- Housing: 5 animals of the same sex per cage in polypropylene grid-floor cages
- Diet: Rat and Mouse SQC Expanded Diet No.1, pelleted, ad libitum
- Water: ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2
- Humidity (%): 55 ± 15
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
arachis oil
Remarks:
BP
Details on oral exposure:
VEHICLE
- Concentration in vehicle: 75 mg/mL, 250 mg/mL, 500 mg/mL
- Amount of vehicle (if gavage): 2 mL/kg/day
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The concentration of test item in the test material formulations was determined by gas chromatography (GC) by means of an external standard technique. The prepared formulations were within ± 10% of the nominal concentration.
Duration of treatment / exposure:
28 days
Frequency of treatment:
once daily, 7 days/week
Doses / concentrations
Remarks:
Doses / Concentrations:
150, 500 and 1000 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: immediately before dosing and one and five hours after dosing during the working week and immediately before dosing and one hour after dosing at weekends.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded on day 0 (the day before the start of treatment) and on days 7, 14, 21, and 28. Body weights were also recorded at terminal kill.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at end of the study (Day 28)
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: all animals from each test and control group
- Parameters examined: Haemoglobin, Erythrocyte count, Haematocrit, Erythrocyte indices (mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration), total leucocyte count, differential leucocyte count (neutrophils, lymphocytes, monocytes, eosinophils, basophils), platelet count, reticulocyte count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at end of the study (Day 28)
- Animals fasted: No
- How many animals: all animals from each test and control group
- Parameters examined: urea, glucose, total protein, albumin, albumin/Globulin ratio, calcium, inorganic phosphorus, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, sodium, potassium, chloride, total cholesterol, total bilirubin

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to the start of treatment and on days 2, 8, 15 and 23.
- Dose groups that were examined: all animals
- Battery of functions tested: sensory reactivity (grasp response, vocalisation, toe pinch, tail pinch, finger approach, touch escape, pupil reflex, startle reflex, blink reflex)/ grip strength (forelimb/hindlimb) / motor activity

BEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to the start of treatment and on days 2, 8, 15 and 23.
- Dose groups that were examined: all animals
- Parameters observed: gait, tremors, twiches, convulsions, bizarre/abnormal/stereotypic behaviour, pilo-erection, exophthalmia, lachrymation, hyper/hypothermia, skin colour, respiration, palpebral closure, urination, defecation, transfer arousal, tail elevation.


Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes. Adrenals, aorta (thoracic), bone and bone marrow (femur including stifle joint), bone and bone marrow (sternum), muscle (skeletal), oesophagus, ovaries, pancreas, pituitary, brain (including cerebrum, cerebellum and pons), caecum, colon duodenum, epididymides, eyes, gross lesions, heart, ileum, jejunum, kidneys, liver, lungs (with bronchi), lymph nodes (cervical and mesenteric), prostate, rectum, salivary glands (submaxillary), sciatic nerve, seminal vesicles, skin (hind limb), spinal cord (cervical), spleen, stomach, testes, thymus, thyroid/parathyroid, trachea, urinary bladder, uterus.
Other examinations:
Organ weights: adrenals, kidneys, testes, brain, liver, thymus, epididymes, ovaries, heart, spleen
Statistics:
Haematological, blood chemical, organ weight (absolute and relative to terminal body weight), weekly body weight gain and quantitative functional performance and sensory reactivity data were considered for dose response relationships by linear regression analysis followed by one way analysis of variance (ANOVA) including Levene’s test for homogeneity of variance. Where variances were shown to be homogeneous pair wise comparisons were conducted by means of Dunnett’s test. Where Levene’s test showed unequal variances the data were analysed using non-parametric methods: Kruskal-Wallis ANOVA and Mann Whitney “U” test.

The haematology variable basophils was not analysed since consistently greater than 30% of the data were recorded as the same value.

Probability values (p) are presented as follows:

p< 0.001***
p < 0.01**
p< 0.05*
p ≥0.05 (not significant)


Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
1000 and 500 mg/kg/day: statistically significant reduction in body weight in males during Week 1 (non adverse)
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
500 and 1000 mg/kg/day: statistical significant increase in platelet cound and reduction in mean corpuscular haemoglobin concentration respectively (no adverse)
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
1000 mg/kg/day (males): statistically significant increase in total and asymptotic motor activity. Females from the same treatment group showed a statistically significant decrease in asymptotic activity (non adverse)
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
500 mg/kg/day: statistically significant reduction in absolute epididymides weight (non adverse)
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
150 mg/kg/day (males and females) and 1000 mg/kg/day: dark foci on the lungs (no adverse)
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
1000 mg/kg/day: 3 males showed globular accumulations of eosinophilic material in the proximal tubular epithelium (non adverse)
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
No mortality occurred during the study period. No clinical signs of toxicity were observed in test or control animals throughout the study. However, noisy respiration was observed in one treated male animal (1000 mg/kg/day group) and one treated female animal (500 mg/kg/day group) one hour after dosing on day 2. These isolated and transient observations showed no convincing dose-relationship and were considered to be of no toxicological importance.
One treated female (1000 mg/kg/day) showed fur loss from day 21 onwards and a control female developed a scab on the head from day 25. Since such findings are occasionally reported in group housed rats, they are considered to be incidental.

BODY WEIGHT AND WEIGHT GAIN
No adverse effect on body weight was noted. Nevertheless a statistically significant reduction in body weight gain was apparent for 1000 and 500 mg/kg/day males during week 1 of the study. The dose relationship was not credible and the intergroup differences were considered to be a result of slightly higher than usual control group body weights gains.

HAEMATOLOGY
No treatment-related changed in the haematological parameters were measured.
Males treated with 1000 mg/kg/day showed a statistically significant reduction (p< 0.05) in mean corpuscular haemoglobin concentration when compared to controls. Under these conditions and in absence of any other haematological changes, the intergroup difference was considered to be accidental
A statistically significant (p < 0.05) increase in platelet count was detected but this was confined to 500 mg/kg/day males and was considered to be incidental.

FUNCTIONAL PERFORMANCE TESTS
Males treated with 1000 mg/kg/day showed a statistically significant increase in total and asymptotic motor activity while females from the same treatment group displayed a statistically significant decrease in asymptotic activity. In the absence of any other evidence to suggest neurotoxicity or other toxicologically significant effects of treatment, these isolated intergroup differences were considered to be accidental and of no toxicological significance.

ORGAN WEIGHTS
No treatment-related effect on body weight was noted. Males treated with 500 mg/kg/day showed a statistically significant reduction in absolute epididymides weight when compared with control but, in the absence of a convincing dose-response relationship, the intergroup difference was considered to be incidental and of no toxicological importance.

GROSS PATHOLOGY
Necropsy revealed no substance-related findings. One male and female animal treated with 150 mg/kg/day and a female animal treated with 1000 mg/kg/day dark foci on the lungs were indentified. These findings showed non dose-related response and where considered to be of non toxicological importance.

HISTOPATHOLOGY: NON-NEOPLASTIC
Three males treated with 1000 mg/kg/day demonstrated globular accumulations of eosinophilic material in the proximal tubular epithelium which should be regarded as a possible effect of treatment. The authors considered this finding consistent with the appearance of hydrocarbon nephropathy, which results from the excessive accumulation of α2-microglobulin in renal proximal tubular epithelium of adult male rats, which does not represent a hazard to human health.

Effect levels

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion