Dicerium tricarbonate

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 16-JUL-2007 to 31-OCT-2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an international guideline and to GLP.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dicerium tricarbonate

EC Number:

208-655-6

EC Name:

Dicerium tricarbonate

Cas Number:

537-01-9

Molecular formula:

CH2O3.2/3Ce

IUPAC Name:

dicerium tricarbonate

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: approximately 10 weeks old at the beginning of the treatment period
- Weight at study initiation: at the beginning of the treatment period, the animals had a mean body weight of 419 g (range: 392 g to 442 g) for the males and 263 g (range: 239 g to 283 g) for the females
- Fasting period before study: no
- Housing: The males were individually housed, except during pairing, in wire-mesh cages (43.0 x 21.5 x 18.0 cm). The females were individually housed, except during pairing, until late gestation in wire-mesh cages (43.0 x 21.5 x 18.0 cm). The females were individually housed from late gestation, and with their litter during lactation, in polycarbonate cages (43.0 x 21.5 x 20.0 cm).
- Diet: free access to SSNIFF R/M-H pelleted maintenance diet
- Water: free access to bottles containing tap water (filtered with a 0.22 µm filter)
- Acclimation period: the animals were acclimated to the study conditions for a period of 7 days before the beginning of the treatment period.


ENVIRONMENTAL CONDITIONS
- Temperature: 22 +/- 2°C
- Humidity: 50 +/- 20%
- Air changes: about 12 cycles/hour of filtered, non-recycled air
- Photoperiod: 12 hrs dark / 12 hrs light


IN-LIFE DATES: From 14-AUG-2007 to 10-OCT-2007

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 0.5% aqueous methylcellulose solution

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test item was administered as a suspension in the vehicle. The test item was ground to fine powder using a mortar and pestle, suspended in the vehicle in order to achieve the concentrations of 30, 90 and 200 mg/mL and then homogenized using a magnetic stirrer. The test item dosage forms were prepared at a frequency based on stability data (up to 9 days) and were stored at +4°C, protected from light, prior to use.


VEHICLE
- Justification for use and choice of vehicle (if other than water): aqueous suspension, as recommended in the guideline
- Concentration in vehicle: 30, 90 and 200 mg/mL
- Amount of vehicle (if gavage): a constant volume of 5 mL/kg/day was used
- Lot/batch no. (if required): methylcellulose batch No. 017K0052, supplied by Sigma
- Purity: data not available

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

During a pre-study period, the homogeneity, stability and concentration of two dosage forms prepared at the lowest and highest concentrations of the present study (30 and 200 mg/mL) were checked using ICP-OES (Inductively Coupled Plasma/Optical Emission Spectrometry) after validation of the analytical method. The results showed acceptable homogeneity and stability of both concentrations over 9 days at +4°C.

During the study, the concentration of the test item and homogeneity of the dosage forms was determined in samples of each control and test item dosage form prepared for use in weeks 1, 3 and 6. The results showed acceptable homogeneity and concentration of all dosage forms analyzed. Precision (RSD =< 10%) and accuracy (100 +/- 10%) of the method were found to be satisfactory.

Duration of treatment / exposure:

- In males: 15 days before mating, during the mating period (up to 3 weeks), until sacrifice (i.e. at least 4 weeks in total)
- In females: 15 days before mating, during the mating period (up to 3 weeks), during pregnancy, during lactation until day 5 post-partum inclusive

Frequency of treatment:

Each animal was given the appropriate dosage form once a day, at approximately the same time each day, 7 days a week.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 150, 450 and 1000 mg/kg
Basis:
other: nominal conc. corrected from the water content

No. of animals per sex per dose:

10 males and 10 females per group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: on the basis of a previous 14-day toxicity study in the rat in which the dose-levels of 150, 450 and 1000 mg/kg/day elicited no clear treatment-related effects.
- Rationale for animal assignment: during the pre-treatment period, the required number of animals (40 males and 40 females) was selected according to body weight and clinical condition and allocated to the groups (by sex), according to a computerized stratification procedure, so that the average body weight of each group was similar.

Positive control:

not used

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: From arrival, the animals were observed once a day as part of routine examinations. From the start of treatment period, each animal was observed once a day, at approximately the same time for the recording of clinical signs.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on all animals outside the home cage, in a standard arena, once before the beginning of the treatment period and then once a week until the end of the study.
Observations included (but were not limited to) changes in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes (e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded.


BODY WEIGHT: Yes
- Time schedule for examinations: the body weight of each male was recorded on the first day of treatment (day 1), then once a week until sacrifice. The body weight of each female was recorded on the first day of treatment (day 1), then once a week until mated (or until sacrifice) and on days 0, 7, 14 and 20 post-coitum and days 1 and 5 post-partum.


FOOD CONSUMPTION: Yes
The quantity of food consumed by each male was recorded once a week, over a 7 day period, from the first day of treatment until sacrifice. The quantity of food consumed by each female was recorded once a week, over a 7 day period, from the first day of treatment through gestation (days 0-7, 7-14 and 14-20 post-coitum intervals) and lactation (days 1-5 post-partum intervals) until sacrifice. During the pairing period, food consumption was not recorded for males or females.


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: on the day of sacrifice
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: the last five males and females of each group
- The following parameters were determined: Erythrocytes, Hemoglobin, Mean cell volume, Packed cell volum, Mean cell hemoglobin concentration, Mean cell hemoglobin, Thrombocytes, Leucocytes, Differential white cell count with cell morphology (neutrophils, eosinophils, basophils, lymphocytes and Large Unstained Cells), monocytes, Reticulocytes, Prothrombin time, Activated partial thromboplastin time, Fibrinogen.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on the day of sacrifice
- Animals fasted: Yes
- How many animals: the last five males and females of each group
- The following parameters were determined: Sodium, Potassium, Chloride, Calcium, Inorganic phosphorus, Glucose, Urea, Creatinine, Total bilirubin, Total proteins, Albumin, Albumin/globulin ratio, Total cholesterol, Triglycerides, Alkaline phosphatase, Aspartate aminotransferase, Alanine aminotransferase, Lactate dehydrogenase, Bile acids.



URINALYSIS: No


NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: once at the end of the treatment period
- Dose groups that were examined: on the first five males and the first five females from each group
- Battery of functions tested: detailed clinical examination, measurement of reactivity to manipulation or to different stimuli and motor activity


OTHER: MORTALITY AND MORBIDITY: each animal was checked for mortality or signs of morbidity at least twice a day during the treatment period.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes. A complete macroscopic post-mortem examination was performed on all animals. This included examination of the external surfaces, all orifices, the cranial cavity, the external surfaces of the brain, the thoracic, abdominal and pelvic cavities with their associated organs and tissues and the neck with its associated organs and tissues. Special attention was paid to the reproductive organs. The numbers of corpora lutea and implantation sites were also recorded.
HISTOPATHOLOGY: Yes (see table 1)

Statistics:

Mean values were compared by one-way variance analysis and Dunnett test, (mean values being considered as normally distributed, variances being considered as homogeneous). Percentage values were compared by Fisher exact probability test.

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 examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY: there were no treatment-related mortalities or clinical signs.


BODY WEIGHT AND WEIGHT GAIN: Females had lower mean body weight gains during pregnancy and lactation and lower food consumption during lactation but this may be related to the higher number of fetuses/pups in the control group. There were no effects during the pre-mating period and no effects on mean male body weight or food consumption.


HAEMATOLOGY: Males and females treated at 1000 mg/kg/day had a decrease in white blood cell count (approximately 12 %) when compared with controls (See Table 3).


CLINICAL CHEMISTRY: Females treated at 1000 mg/kg/day had a decrease in chloride concentration and an increase in glucose, potassium, inorganic phosphorus and urea concentrations.


NEUROBEHAVIOUR: A majority of animals treated at 1000 mg/kg/day had an increased number of horizontal movements during the 1-hour motor activity test but there were no other effects of treatment observed during the tests performed in the functional observation battery.


HISTOPATHOLOGY: NON-NEOPLASTIC: There was microscopic treatment related in the stomach that consisted of increased incidence and/or severity of submucosal eosinophil infiltration and pyloric gland hyperplasia in rats from both sexes treated at 1000 mg/kg/day and 450 mg/kg/kg. See detailed values in Table 2.
No microscopic treatment related changes were observed in the testes and ovaries.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

450 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: based on systemic effect (laboratory investigations)

2

Dose descriptor:

NOAEL

Effect level:

150 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: Based on microscopic local effects observed in the stomach

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table 2: incidence and grading at microscopic findings in the stomach of rats given Cerium carbonate 99 humide Sex Male  Female Group 1 2 3 4 1 2 3 4 Dose-level (mg/kg/day) 0 150 450 1000 0 150 450 1000 STOMACH - Increased submucosal eosinophil infiltration Grade 1 3 2 4 0 1 1 2 3 Grade 2 0 1 1 4 0 0 0 0 Grade 3 0 0 0 1 0 0 0 0 Total affected 3/5  3/5 5/5  5/5 1/5  1/8 2/6  3/5 - Pyloric glands hyperplasia Grade 1 0 0 5 2 0 0 0 2 Grade 2 0 0 0 2 0 0 0 0 Total affected 0/5  0/5  5/5 4/5 0/5  0/5  0/5 2/5 Table 3: Hematology - concentration in Monocytes Dose (mg/kg/d) 0 150 450 1000 Monocytes (G/L) Males M SD n 0.61 0.104 4 0.44 0.143 4 0.43 0.046 4 0.37 ** 0.053 5 Females M SD n 0.30 0.139 5 0.38 0.073 5 0.40 0.101 5 0.54 * 0.172 5 M : Mean value SD : Standard Deviation N : number of animals * : P0.05 ** : P0.01 Table 4 : Blood biochemistry Sex                                                           Male                                                      Female Dose-level (mg/kg/day)                 0       150      450    1000               0       150     450      1000 Potassium (mmol/L)                    4.11   3.80      4.02    4.12              4.00    4.17    4.16     4.70 Chloride (mmol/L)                   104.2  105.0   103.9 104.7            102.1  101.3  100.8    99.6** Glucose (mmol/L)                    8.13    9.71    8.73     8.53            6.60     7.10    7.41    8.79** In. phosphorus (mmol/L)              2.22    2.16     2.11    2.17             2.12   2.15    2.29    2.39 Urea (mmol/L)                    5.3      5.7       5.2       5.9               6.6      7.4      6.4       7.9 **: p<0.01.

Applicant's summary and conclusion

Conclusions:

Based on the experimental conditions of this study, the NOAEL for parental toxicity was considered to be 450 mg/kg/day in female and male rats based on systemic effects (laboratory investigations), considering that the microscopic findings in the stomach were likely to be related to portal-of-entry irritating effects, due to the high concentrations of the substance given as a bolus by gavage.

Executive summary:

The test item, Cerium carbonate, was administered daily by oral gavage to male and female Sprague-Dawley rats, for 2 weeks before mating, during mating, gestation and until day 5post-partum, at dose-levels of 150, 450 or 1000 mg/kg/day.

There were no adverse effects of treatment at any dose-level on mortality, clinical signs, body weight or food consumption. Animals treated at 1000 mg/kg/day had lower white blood cell counts and females in this group had lower chloride concentration and higher glucose, potassium, inorganic phosphorus and urea levels.
There were no treatment-related organ weights and macroscopic changes in rats treated at 1000 mg/kg/day.
At 450 or 150 mg/kg/day, there were no treatment-related organ weights and macroscopic changes.
There were microscopic treatment related findings in the stomach that consisted of increased incidence and/or severity of submucosal eosinophil infiltration and pyloric gland hyperplasia in rats from both sexes treated at 1000 mg/kg/day and 450 mg/kg/kg. No test item-related microscopic findings were observed at 150 mg/kg/day. However, the microscopic findings in the stomach were likely to be related to portal-of-entry irritating effects, due to the high concentrations of the substance given as a bolus by gavage.No microscopic treatment related changes were observed in the testes and ovaries.
Based on the experimental conditions of this study, the No Observed Adverse Effect Level (NOAEL) for parental toxicity was considered to be 450 mg/kg/day in female and male rats.