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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:
weight of evidence
Study period:
1990-04-27 to 1991-01-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report date:
1991

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)
Version / remarks:
1981
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
4-(trans-4-propylcyclohexyl)acetophenone
EC Number:
406-700-6
EC Name:
4-(trans-4-propylcyclohexyl)acetophenone
Cas Number:
78531-61-0
Molecular formula:
Hill formula: C17H24O CAS formula: C17H24O
IUPAC Name:
1-[4-(4-propylcyclohexyl)phenyl]ethan-1-one

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Females nulliparous and non-pregnant: not specified
- Age at study initiation: 9 weeks
- Weight at study initiation: males: 316 g (295 - 336); females: 193 g (181 - 208) g
- Fasting period before study: not specified
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: not specified

ENVIRONMENTAL CONDITIONS
- Temperature: 22 - 28 °C
- Humidity: 26-45 %
- Air changes: not specified
- Photoperiod: not specified

To provide similar climate and lighting conditions for all rats, the position of the cages was changed once a week according to a rotation schedule.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
methylcellulose
Remarks:
0,5 % Methylcellulose in aqua / Tween 80 mixture (5 g Methocel(R) K4M Premium + 5 g Tween 80 ad 1 L)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle: well tolerated
- Concentration in vehicle: according to dose levels: 12.5, 25, 50 g/L
- Amount of vehicle: 20 mL / kg bw
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
Test duration: 28 days
Frequency of treatment:
Dosing regime: 7 days/week
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Remarks:
vehicle control
Dose / conc.:
250 mg/kg bw/day (actual dose received)
Dose / conc.:
500 mg/kg bw/day (actual dose received)
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
5 per sex per dose group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: 1000 mg/kg are recommended as highest dose for a 4-weektoxicity-study in the OECD-guidelines. According to a dose range finding study the low dose was expected not to produce any adverse effects.
- Rationale for animal assignment: random
- Fasting period before blood sampling for clinical biochemistry: not specified
Positive control:
not applicable

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Not specified

BODY WEIGHT: Yes
- Time schedule for examinations: twice daily

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY: No

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: twice weekly

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to start of the treatment and in study weeks 1 and 4
- Dose groups that were examined: all animals

HAEMATOLOGY: Yes
- Time schedule for collection of blood: study week 4
- Anaesthetic used for blood collection: Yes (halothane)
- Animals fasted: Not specified
- How many animals: all animals
- Parameters checked: Erythrocyte count; Leukocyte count; Hemoglobin; Packed cell volume; Platelet count; Reticulocyte count; Differential blood cell count; Absolute number of segmented neutrophilic granulocytes; Absolute number of lymphocytes; mean corpuscular volume; Mean corpuscular hemoglobin content; Mean corpuscular hemoglobin concentration

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: study week 4
- Animals fasted: Not specified
- How many animals: all animals
- Parameters checked: Electrolytes (Sodium, Potassium, Calcium, Chloride, Inorganic phosphorus); Substrates (Glucose, Urea); Creatinine, Bilirubin, Cholesterol, Triglycerides, Enzymes (Alanine aminotransferase; Alkaline Aminotransferase; Aspartate aminotransferase); Proteins (total; Albumin)

URINALYSIS: Yes
- Time schedule for collection of urine: overnight, for 18 h without feed
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked: pH value; protein; glucose; Urobilinogen; Bilirubin; Blood; Sediment

NEUROBEHAVIOURAL EXAMINATION: No


IMMUNOLOGY: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes
Statistics:
Body weight gain, food consumption, water consumption, organ weights, the clinico-chemical serum parameters and the hematological parameters hematocrit, hemoglobin and numbers of erythrocytes and leucocytes of the dose groups were compared with those of the control (separately for each sex and time) using the multiple two-sided t-test according to DUNNETT (1955). Different group sizes or variance nonhomogeneity between the dose groups and the control were considered by correcting the critical t-values according to DUNNETT (1964), and in case of variance nonhomogeneity by WELCH'S correction of the degrees of freedom (cf. WINER, 1970, pp. 36 - 39). In cases of very low group sizes or extreme variance nonhomogeneity no statistical comparison was performed. For evaluation of the hematology parameters reticulocytes, eosinophilic, basophilic, juvenile/ bandform neutrophilic granulocytes and the leucocytes (which were not classified
further) the procedure of STOCKY and VOLLMAR (1976) (which is based on a linear rank test acc. to KRAUTH, 1971) with the two sided alternative was used. The parameters segmented neutrophilic granulocytes (SE) and lymphocytes (LY) were evaluated together acc. to UNKELBACH (1980), using the same procedure for the values SE/(SE +LY) .

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Except for dose-dependent burrowing in the litter and salivation, there were no differences to the controls in appearance and behavior of the rats from groups 2 and 3. The same reaction was seen in rats of group 4, some of which showed petechial bleedings at the tail. Burrowing in the litter for a short time and salivation directly after treatment are an indication of bad taste of the test material.
Mortality:
no mortality observed
Description (incidence):
No rat died in the course of the study.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean body weight gain in group 2 corresponded to that of the controls. In group 3, near the end of the study, moderately reduced body weight gain was seen in both sexes. In group 4, body weight gain was clearly reduced throughout the study.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Decreased food consumption was mainly seen in group 4 in the first two weeks of treatment.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Water consumption in group 2 essentially corresponded to that of the controls. At the end of the study, moderately increased water consumption was seen in group 3, while a clear increase occurred in group 4.
Ophthalmological findings:
no effects observed
Description (incidence and severity):
As a finding, which is characteristic of young rats of this strain, rests of the membrana pupillaris persistens were seen in treated and untreated rats with the same frequency.
Haematological findings:
no effects observed
Description (incidence and severity):
The mean values for the hematological parameters corresponded to those of the controls. A slight, but significant decrease of hemoglobin values was indicated in females of the 500 mg/kg group and 1000 mg/kg bw/d group. A slight decrease in erythrocyte numbers was also seen. However, these deviations did not exceed the normal range.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
A significant dose-dependent increase in serum creatinine was found in the males and females of groups 3 and 4. Further, a dose-dependent decrease in serum cholesterol values was found, which was significant in all treated groups, except for the males of group 2. Only in the males of group 4 a significant increase in alkaline phosphatase activity was observed. Sporadically mean values occurred which were significantly different from the corresponding control values. However, these deviations did not exceed the normal range and were thus without toxicological relevance.
Urinalysis findings:
not specified
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
There was a dose-dependent increase in liver weights in all treated groups. The differences to the controls achieved statistical significance only on the basis of the body weight related data, due to decreased body weight gain of the rats. There was also a dose-dependent effect on the thymus, which was significantly lighter in all groups, except the low dose males. The adrenals were heavier in the dosed as compared to the control rats with statistical significance only in the high dose group. A similar effect was recorded for the prostate of the high dose males.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Adrenal size increased: 500 mg/kg bw/d 1 male and 1 females respectively; 1000 mg/kg bw/d 3 males and 1 female
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
The following organ alterations attributable to the test item were found:
Adrenals: Hyperplasia of the adrenal cortex (500 mg/ kg bw/d : 1 m, 2 f; 1000 mg/kg bw/d: 3 m, 1 f)
Thymus: In only one of the 5 females of the 1000 mg/kg group atrophy was diagnosed.
Liver: No alterations attributable to treatment with the test item were found. Thus there was no morphological correlate to the increased weight of this organ.
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed

Effect levels

Key result
Dose descriptor:
NOEL
Effect level:
250 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
food consumption and compound intake
histopathology: non-neoplastic
organ weights and organ / body weight ratios
Remarks on result:
other: Since it was not possible to derive a "no observed adverse effect level" on the basis of this study, a second study was performed.

Target system / organ toxicity

Key result
Critical effects observed:
no

Applicant's summary and conclusion

Conclusions:
Based on this subacute oral toxicity study a no observed adverse effect level could be derived.
Executive summary:

The test item was given via oral gavage to groups of 10 rats in daily doses of 250, 500, and 1000 mg/kg bw/d for a period of 4 weeks. All rats survived the treatment. Treatment and dose-related findings such as reduced food consumption and body weight gain and increased water consumption are frequently found in this kind of rat study. In addition, dose-dependent serum creatinine increase and serum cholesterol decrease, and increased liver weight were found and may be indicative of functional impairment of kidneys and liver. Since, however, these organs were perfectly normal histologically, no irreversible damage was induced in these organs by any of the doses tested. This also applies to all the other organs including thymus and adrenals, which reacted to the treatment by decrease or increase, respectiveley, of their weights.