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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05.08.1997 to 22.04.1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Test animals

Species:
rat
Strain:
other: Alpk APfSD (Wistar derived)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Zeneca Pharmaceuticals
- Age at study initiation: 28 days
- Weight at study initiation: 159g (males); 133g (females)
- Fasting period before study: No
- Housing: Four per cage in multiple rat racks.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: One week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 3
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 05.08.1997 To: 22.04.1998

Administration / exposure

Route of administration:
oral: feed
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: No data


DIET PREPARATION
- Rate of preparation of diet (frequency): The experimental diets were made in 30 kg batches from premixes prepared bymixing the appropriate amount of Dequest 2066A with up to 7 lots of 1 kg batches of milled diet. The premixes were then added to the appropriate amount of diet and mixed thoroughly.
- Mixing appropriate amounts with (Type of food): Milled CTL diet (no further information)
- Storage temperature of food:

Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples of diet from the control and 1000 ppm groups were analysed pre-study and once during the study for achieved concentration of Dequest 2066A. The homogeneity of Dequest 2066A in CTL diet was determined by analysing samples from the high dose level. The chemical stability of Dequest 2066A in diet was determined at this dose level over a period of up to 36 days.
Duration of treatment / exposure:
90 days
Frequency of treatment:
continuous
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 100, 1000, 10000ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
8.2, 82.5 and 841.9mg/kg (males) and 9.2, 92.3 and 902.6mg/kg (females) (expressed as salt)
Basis:
other: Calculated intakes from food consumption data
No. of animals per sex per dose:
12
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: Doses were selected by the Sponsor based on previous toxicity data.
- Rationale for animal assignment (if not random): Random
- Rationale for selecting satellite groups: No satellite groups
- Post-exposure recovery period in satellite groups: No post-exposure recovery period in any group.
Positive control:
None

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations included: significant changes in clinical condition or behaviour.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At the same time as body weight measurements.


BODY WEIGHT: Yes
- Time schedule for examinations: immediately before start of treatment and then on the same day of each week until termination,


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Recorded continuously throughout the study for each cage of rats.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/rat/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes


FOOD EFFICIENCY:
- Food utilisation value per cage was calculated as the bodyweight gained by the rats in the cage per 100 g of food eaten.


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: all examined pre-treatment, and those of high dose and control groups during the week prior to termination.


HAEMATOLOGY: Yes
- Time schedule for collection of blood: At termination.
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: All surviving animals.
- Parameters checked in table [No.1] were examined.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At termination.
- Animals fasted: No
- How many animals: All surviving animals.
- Parameters checked in table [No.1] were examined.


URINALYSIS: Yes
- Time schedule for collection of urine: In the week prior to termination over a period of 16-18 hours.
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes, during collection.
- Parameters checked in table [No.1] were examined.


NEUROBEHAVIOURAL EXAMINATION: No


Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see table 2)
HISTOPATHOLOGY: Yes (see table 2)
Statistics:
Body weights: analysis of covariance (males and females separately).
Food consumption and food utilisation: analysis of variance (males and females separately).
Haematology, clinical chemistry and urine analysis: analysis of variance (male and female data analysed together).
Organ weights: analysis of variance.
Least squares mean for each group were calculated. Unbiased estimates of differences from control were provided by the difference between each treatment group least-squares mean and the control group least-squares mean. Each treatment group least-squares mean was compared with the control group least-squares mean using a two-sided Student's t-test, based on the error mean square in the analysis.

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:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY: There were no deaths or treatment-related clinical signs of toxicity.


BODY WEIGHT AND WEIGHT GAIN: The group mean bodyweights for the male rats in the 1000 ppm group diverged slightly from controls in the first few weeks of the study. The differences were not statistically significant, and were mainly due to a reduction in one animal. Overall, there was no treatment-related effect on body weight gain.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): The group mean food consumption for males in the 1000 ppm group was slightly below control values during weeks 7-13. The difference was mainly due to one female, and was not considered of toxicological significance.


FOOD EFFICIENCY: No treatment-related effect.


OPHTHALMOSCOPIC EXAMINATION: No effects on the appearance of the eyes.


HAEMATOLOGY: There was an increase in red blood cell levels in males and females at 10000 ppm. Mean cell volume and mean cell haemoglobin were also decreased at this dose.  Haemoglobin and mean cell haemaglobin concentration were significantly decreased in females at top dose. Total iron binding capacity in the serum of males only were increased and the total serum iron decreased in females only.  All changes described were statistically significant. Perls' staining for iron complexes showed decreases in the spleens of both sexes.  Thus, the findings noted in these haematological parameters and serum iron and binding capacity are likely to result from a perturbation of iron homeostasis, which is supported by the reduction of staining in the spleen.The effects are therefore due to the iron binding characteristics of Dequest 2066A, which is a chelating agent. All of these observations are considered to be without toxicological significance.


CLINICAL CHEMISTRY: Plasma albumin was statistically significantly increased in males at 1000 ppm.  This increase was not dose-related and therefore considered treatment-related. Plasma creatine kinase activity and postassium levels were statistically significantly increased in females at 10000 ppm. These changes were small in magnitude and not considered toxicologically relevant. 


URINALYSIS: No effects.


ORGAN WEIGHTS: There was a small but statistically significant decrease in the group mean liver weight (absolute) of male rats in the 10000 ppm group. The effect was not considered of toxicological relevance.


GROSS PATHOLOGY: No findings.


HISTOPATHOLOGY: Reduced pigmentation for age in spleens of male and female rats in the 10000 ppm group. Perl' staining indicated marked reduction in positive staining (for iron complexes) for age in males and a marked  or slight reduction in positive staining for age in females receiving 10000ppm. There was a reduced incidence of microlithiasis in kidneys of females at all dose levels. These findings were considered not to be of toxicological significance.


OTHER: no effect on density of cortical bone.  total bone density and that of trabecular bone was increased in both females and males at highest dose.  No effects seen at other doses.

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
82.5 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: Expressed as dose of salt
Dose descriptor:
NOAEL
Effect level:
92.3 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: Expressed as dose of salt

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 3 Selected haematology and clinical chemistry

Dietary concentrations (ppm)

0

100

1000

1000

0

100

1000

10000

male

female

Number of animals/group

12

12

12

12

12

12

12

12

Haematology

 

 

 

 

 

 

 

 

Haemoglobin (g/dl)

 14.9

 15.0

 14.8

 14.5

 14.9

15.1 

14.9 

14.2* 

Haematocrit

 0.465

 0.467

0.462 

0.459 

 0.452

0.457 

0.452 

0.438 

Red blood cell count (x10**12/l)

 8.75

8.77 

8.75 

9.49** 

 8.22

8.34 

8.13 

8.65* 

Mean cell volume (fl)

 53.1

 53.3

52.8 

49.6** 

 55.1

54.9 

55.7 

50.8** 

Mean cell haemoglobin (pg)

 17.0

17.2 

17.0 

15.4** 

 18.2

18.2 

18.9 

16.5** 

Mean cell haemoglobin concentration (g/dl)

32.0

32.2

32.1

31.6

33.1

33.1

33.0

32.4**

Blood chemistry

 

 

 

 

 

 

 

 

Plasma creatinine kinase (IU/l)

 129.4

141.0 

126.5 

151.1 

 123.1

121.4 

133.1 

155.1* 

Plasma potassium (mmol/l)

 4.80

4.94 

5.18 

5.06 

 5.00

5.13 

5.14 

5.67* 

* P0.05   ** P0.01



Applicant's summary and conclusion

Conclusions:
In a good quality 90-day feeding study (reliability score 1) conducted to OECD 408 and GLP, the NOAEL for Dequest 2066A was 1000 ppm (equivalent to 82.5 and 92.3 mg/kg bw/day of the salt in males and female, respectively).
Executive summary:

In a good quality 90-day feeding study (reliability score 1) conducted to OECD 408 and GLP, groups of 12 male and 12 female Wistar-derived rats were fed diets containing 0 (control), 100, 1000 or 10000 ppm (equivalent to 8.2, 82.5 and 841.9 mg/kg bw/day in males and 9.2, 92.3 and 902.6 mg/kg for females) Dequest 2066A for 90 consecutive days. Clinical observations, bodyweights and food consumption were measured. Ophthalmoscopic and haematology examinations, clinical chemistry and urinalysis were conducted. At the end of the exposure period all animals were killed and a full microscopic examination conducted. Bone mineral density was evaluated for bone collected at termination. There were no deaths and the majority of parameters were unaffected by the treatment. Minor changes in certain haematological parameters (red blood cell count was significantly increased, mean cell volume and mean cell haemoglobin concentration were significantly decreased) were noted at the highest dose. There was also a decreased incidence in Perls' staining of the spleen. Bone density was significantly increased in both sexes in the highest dose group, and the incidence of microlithiasis in the kidney was reduced at all dose levels. These changes are indicative of the influence of Dequest 2066A on calcium homeostasis, however, without causing any changes in calcium plasma levels. Therefore, the changes were not considered to be of toxicological significance, and the NOAEL was 1000 ppm (equivalent to to 82.5 and 92.3 mg/kg bw/day of the salt in males and female, respectively).