Registration Dossier

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:
2007-02-21 to 2007-05-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
After dissolution and disociation in environmental (aqueous)/physiolological media the constituents of tin difluoride become bioavailable and the overall toxicity of the dissociated substance can be described by the toxicity of the individual constituents/ions. Since synergistic effects are not to be expected, the human health and environmental hazard assessment of the assessment entity tin difluoride consists of an individual assessment of the assessment entities tin cation and the fluoride anion. The tin cation and the fluoride anion are considered to represent the overall toxicity of tin difluoride in a manner proportionate to the fluoride and the metal (represented by one of its readily soluble salts). Based on the above information, unrestricted read-across is considered feasible and justified.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.26 (Sub-Chronic Oral Toxicity Test: Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
2007-04-20
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
- Name of test material (as cited in study report): Tin(II)methanesulfonate (Stannous methane sulfonic acid)
- Chemical name: Tin(II)methanesulfonate
- Physical state: solid
- Storage condition of test material: at room temperature, in a tight container, preferably under nitrogen

Test animals

Species:
rat
Strain:
other: Crl:CD (SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories Germany GmbH, Sandhofer Weg 7, 97633 Sulzfeld, Germany
- Age at study initiation: males: 35 days; females: 36 days
- Weight at study initiation: males: 136.3 - 158.8 g; females: 121.2 - 139.3 g
- Housing: the animals were kept singly in MAKROLON cages (type III) with a basal surface of approx. 39 cm x 23 cm and a height of approx. 15 cm
- Bedding: granulated textured wood (Granulat A2, J. Brandenburg, 49424 Goldenstedt, Germany)
- Diet (ad libitum): commercial ssniff® R/M-H V1534 (ssniff Spezialdiäten GmBH, 59494 Soest, Germany)
- Water (ad libitum): drinking water
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22°C ± 3°C (maximum range)
- Relative humidity: 55% ± 15% (maximum range)
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: 0.5% aqueous hydroxypropylmethylcellulose gel
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
The test-tiem-vehicle mixture were freshly prepared every day.
The test item was suspended in the vehicle to the appropriate concentrations and administered at a constant volume.
During the administration period, the test item mixture was stirred to keep the mixture homogenous.
The control animals received the vehicle for 90 days in same manner.
The amount of the test item was adjusted to each animal's current body weight daily until end of test week 6 and weekly thereafter.

ADMINISTRATION VOLUME: 5 mL/kg bw/day

VEHICLE
- Synopharm, 22885 Barsbüttel
- Batch no.: 0403A093
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
For the analysis of the test item-vehicle mixtures, samples of approximately 10 mL were taken at the following times and stored at -20°C or colder until dispatch:
1) At study initiation:
- Analysis of stability and concentration: immediately after preparation of the mixture as well as after 8 and 24 hours storage of the test item preparations at room temperature (3 samples/dose level group).
- Analysis of homogeneity: at the start of administration, during (middle) administration and before administration to the last animal of each dose level group (3 samples/dose level group).
2) At study termination:
- Analysis of concentration: during treatment with the test item always before administration to the last animal/dose level group (1 sample/dose level group).

Results:
The results indicate that the content of tinmethansulfonat (measured as total tin and methansulfonate) in the dosing suspensions correspond reasonably well with the nominal concentrations in the concentration range of 5 to 150 g/L (preliminary test) and 10 to 90 g/L (main test), so that mainenance of the dosing regimen can be concluded (80 - 120% of nominal in the initial and final sampling). In a separate experiment, the dosing suspensions were shown to be stable and homogenous during the application period.
Duration of treatment / exposure:
90 days
Frequency of treatment:
Once daily for 90 days
Doses / concentrationsopen allclose all
Dose / conc.:
50 mg/kg bw/day (actual dose received)
Dose / conc.:
150 mg/kg bw/day (actual dose received)
Dose / conc.:
300 mg/kg bw/day (actual dose received)
Remarks:
males only: as of test day 20
Dose / conc.:
450 mg/kg bw/day (actual dose received)
Remarks:
females: whole testing period; males: until test day 19
No. of animals per sex per dose:
10 males/10 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: the dose levels for this study have been selected in agreement with the study monitor based on the results of the 28-day dose-range-finding study in rats (please refer to Section 7.5.1 Repeated dose toxicity: oral: s_Leuschner_2007_28 days-range-finding study)
Positive control:
none

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once daily for clinical signs; twice daile for mortality
In addition, animals were checked regularly throughout the working day from 7.30 a.m. to 4.30 p.m. On Saturdays and Sundays animals were checked regularly from 8.00 a.m. to 12.00 noon with a final check performed at approximately 4.00 p.m.
- Cage side observationsincluded: skin/fur, eyes, mucous membranes, respiratory and circulatory systems, somatomotor activity and behaviour patterns.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before the first exposure (to allow for within-subject comparisons) and once a week thereafter (1, 2, 4, 8 and 24 hours after administration); in test week 13 these observations were performed prior to any laboratory investigations.
These observations were made outside the home cage in a standard arena and at the same time, each time. Signs noted included changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic acitivty (e.g. lacrimation, pilo-erection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypies (e.g. excessive grooming, repetitive circling) or bizarre behaviour (e.g. self-mutilation, walking backwards) were also recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: at the time of allocation of animals to groups, on the day of commencement of treatment and once a week thereafter always on the same day of the week throughout the experimental period.

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
The quanity of food left by individual animals was recorded on a weekly basis throughout the experimental period. Food intake per rat (g/rat/week) was calculated using the total amount of food given to and left by each rat in each group on completion of a treatment week.
The relative food consumption (in g/kg bw/ day) was determined using the following formula:
Relative food consumption (g/kg bw/day) = (total food given (g) - total food left(g))/ number of animal days* x body weight (kg)
* the term 'animal days' counts one animal day for each animal alive for a whole day; it is assumed that on the day of death an animal does not eat.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: daily by visual appraisal throughout the study

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to the start of aadministration and at study termination
- Dose groups that were examined: all animals
The ocular structures were examined: adnexa oculi, conjunctiva, cornea, anterior chamber, iris (pupil dilated), lens, vitreous body and fundus

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at study termination (on the first day of dissection)
- Anaesthetic used for blood collection: Yes, blood samples were taken from the retrobulbar venous plexus under light ether anaesthesia
- Animals fasted: Yes, overnight
- How many animals: all animals
- Parameters examined: haemoglobin content, erythrocytes, leucocytes, differential blood count (relative), differential blood count (absolute), reticulocytes, platelets, haematocrit value, thromboplastin time, activated partial thromboplastin time, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at study termination (on the first day of dissection) blood samples were taken from the retrobulbar venous plexus under light ether anaesthesia.
- Animals fasted: Yes, overnight
- How many animals: all animals
- Parameters examined: albumin, bilirubin (total), creatinine, glucose, protein (total), triglycerides, urea (in blood), uric acid, celcium, chloride, potassium, sodium, alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase and lactate dehydrogenase

URINALYSIS: Yes
- Time schedule for collection of urine: at study termination; The collection of urine was terminated immediately prior starting the blood withdrawals for the haematological and clinical biochemical examinations at study termination
- Metabolism cages used for collection of urine: Yes, the urine was collected for 16 hours in a URIMAX funnel cage.
- Animals fasted: Yes, overnight
- Parameters examined: volume, pH, specific gravity, protein, glucose, bilirubin, urobilinogen, ketones, haemoglobin, nitrite, epithelial cells, leucocytes, erythrocytes, organisms, further consitiuents (i.e. sperm, casts),crystalluria colour an turbidity

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: in test week 13 approx. 1 - 2 hours after dosing and before any blood sampling for laboratory examiniations
- Dose groups that were examined: all animals
- Battery of functions tested: screening of sensory reactivity to stimuli of different types (e.g. auditory, visual and proprioceptive stimuli) (based on GAD*), as well as the assessment of grip strength (MEYER*) and motor activity assessment were conducted.
1) Observational screening: rightnin reflex, body temperature, salivation, startle response, respiration, mouth breathing, urination, convulsions, pilo-erection, diarrhoea, pupil size, pupil response, lacrimation, impaired gait, stereotypy, toe pinch tail pinch, wire maneuver, hind leg splay, positional passivity, tremors, positive geotropism, limb rotation and auditory function
2) Functional tests: grip strength and locomotor activity
*References:
- GAD, S.C., A. Neuromuscular Screen for USe in Industrial Toxicology. Journal of Toxicology and Environmental Health, 9, 691 - 704 (1982).
- Meyer, O. A., H. A. Tilson, W. C. Byrd and M.T. Riley. A method for the routine assessment of fore- and hind limb grip strength of rats and mice. Neurobehavioral Toxicology, Vol. 1, pp. 233 - 236 (1979)
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
Starting on test day 91 (one day after the last administration) the animals were dissected. The animals were sacrificed under ether anaesthesia by cutting the aorta abdominalis, exsanguinated, weighed, dissected and inspected macroscopically.
All superficial tisseus were examined visually and by palpation and the cranial roof was removed to allow observation of the brain, pituitary gland and cranial nerves. After ventral midline incision and skin reflection, all subcutaneous tissues were examined. The condition of the thoracic viscera was noted with due attention to the thymus, lymph nodes and heart.The abdominal viscera were exmained before and after removal, the urinary bladder was examined externally and by palpation. The gastro-intestinal tract was examined as a whole and the stomach and caecum were incised and examined. The lungs were removed and al pleural surfaces examined under suitable illumination. The liver and the kidneyes were examined. Any abnormalities in the appearance and size of the gonads, adrenals, uterus, intra-abdominal lymph nodes and accessory reproductive organs were recorded.
The weights of the following organs of all animals were determined before fixation: adrenal gland (2), brain, epididymes (2), heart, kidney (2), liver, ovary (2), spleen, testicle (2), thymus and uterus.
Paired organs were weighed individually and identified as left or right.
Organ weights and body weight (at autopsy) of the animals which died or were sacrificed prematurely were recorded but not included into the mean value comparison.

HISTOPATHOLOGY: Yes
The following organs or parts of organs of all animals were fixed: adrenal gland (2), aorta abdominalis, bone marrow (os femoris), brain (3 levels: cerebrum, cerebellum, medulla/pons), epididymis (2), eye with optic nerve (2), gross lesions observed, heart (3 levels: right and left ventricle, septum), large intestine (colon, rectum), small intestine (duodenum, jejunum, ileum, incl. Peyer's pathces), kidney and ureter (2), liver, lungs (with mainstem bronchi and bronchioles (presevered by inflation with fixative and then immersion)), lymph node (1, cervical), lymph node (1, mesenteric), mammary gland, nerve (sciatic), oesophagus, ovary (2), pancreas, pituitary, prostate, salivary glands (mandibular, parotid and sublingual gland), skin (left flank), spinal cord (3 levels: cervical, mid-thoracic, lumbar), spleen, stomach, testicle (2), thymus, thyroid (2)(incl. parathyroids), tissue masses or tumours (including regional lymph nodes), trachea (incl. larynx), urinary bladder, uterus (incl. cervix and oviducts) and vagina
The afore-listed organs of all animals of the control group and 450 mg/kg bw dose group (males only: 300 mg/kg bw as of test day 20) and of all deceased or prematurely sacrificed animals were examined histologically after preparation of paraffin sections and haematoxylin-eosin staining.
In addition, frozen sections of the heart, liver and one kidney were made and stained with scarlet R.
Parathyroids cannot always be identified macroscopically if in the plane of section and in all cases where they were noted as grossly enlarged.
Statistics:
The test item-treated groups were compared statistically with the control group.
The following statistical methods were used:
1) STUDENT's t-test:
- all numerical functional tests/urinalysis
the following limit was used:
p = 0.01 approx. t = 2.8784
(for 18 degress of freedom)
p = 0.01 approx. t = 2.9467
(for 15 degress of freedom)
p = 0.01 approx. t = 2.9768
(for 14 degress of freedom)
2) Multiple t-test based on DUNNETT, C.W. New tables for multiple comparisons with a control Biometrics, 482 - 491 (Spetember 1964):
- body weight/food consumption/haematology/clinical biochemistry/organ weights
(p ≤ 0.01)
the following limits was used:
p = 0.01 approx. t = 3.09
(for 32 to 36 degress of freedom)
3) Exact test of R.A. FISHER:
- histology (p ≤ 0.05)
These statistical procedures were used for all data.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
no effects observed
Behaviour (functional findings):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
but related to decreased body weight
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
- Three of 10 males treated orally with 450 mg/kg bw/day died on test days 8, 11 or 13 and four of 10 females treated orally with 450 mg/ kg bw/day died on test days 38, 48, 67 and 80, respectively. The deaths are considered to be related to the administration of the test item.
- Because of the early deaths in the high dose male group, the dose level of the high dose male group was reduced from 450 to 300 mg/kg bw/day on test day 20.
- None of the male and female rats treated orally with 50 or 150 mg/kg bw/day showed any test item-related clinical signs of systemic toxicity.
- Treatment with 450/300 or 450 mg/kg bw/day, resulted in ataxia, soft faeces and/or pale or pale-reddish faeces for all male and female animals starting on test day 1. Additionally, pilo-erection, pale skin or body parts, laboured breathing, reduced motility, rough fur, inflated abdomen or salivation were noted for several animals. These findings are considered to be related to the administration of the test item.

BODY WEIGHT AND WEIGHT GAIN
- No influence was noted on the body weight of the males and females treated orally with either 50 or 150 mg/kg bw/day.
- The body weight of the male and female animals treated orally with 450/300 or 450 mg/kg bw/day was reduced by maximally 27% for the male and maximally 18% for the female animals compared to the control from test week 1 onwards (statistically significant at p ≤ 0.01 in test week 2 to 13 for the males and in test week 1, 2, 6 and 7 for the females).
- The body weight gain of the male and female animals of the high dose group was reduced. The body weight gain of the male animals (450/300 mg/kg) from start (test week 0) to the end of test week 13 was 145% compared to 210% of the control group. The body weight gain from start to test week 13 for the females (450 mg/kg) was 96% compared to 110% of the control group.
- Body weights at autopsy of the high dosed animals was reduced by 22% for the males and by 11% for the females compared to the control group at dissection (statistically significant at p ≤ 0.01).
- All findings are considered to be test item-related.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- No test item-related influence was noted on the relative and absolute food consumption of the males and females treated orally with 50 or 150 mg/kg bw/day.
- The male animals treated with 450/300 mg/kg bw/day revealed a decrease in relative food consumption by 12% in test week 1 compared to the control group (statistically significant at p ≤ 0.01). This is regarded to be test item-related.
- An increase in relative food consumption by maximally 17% was noted in test weeks 4 to 8 (statistically significant at p ≤ 0.01 in test weeks 7 and 8) for the males treated with 450/300 mg/kg bw/day. The female animals treated with 450 mg/kg bw/day revealed also an increase in relative food consumption by maximally 26% (statistically significant at p ≤ 0.01 in test weeks 7) in test weeks 2 to 8. As the absolute food consumption was not influences and the relative food consumption is related to the reduced body weight, this increase is considered to be due to the reduced body weight.

WATER CONSUMPTION AND COMPOUND INTAKE
- The visual appraisal of the drinking water consumption revealed no differences between the control and the test item-treated animals.

OPHTHALMOSCOPIC EXAMINATION
- The ophthalmological examination revealed no test item-related changes of the eyes and the optic region in any rat of any group at any dose level examined.

HAEMATOLOGY
- the male animals treated orally with 50 or 150 mg/kg bw/day and the female animals treated orally with 50 mg/kg bw/day revealed no test item-related influence.
- treatment with 150 or 450 mg/kg bw/day (females) or 450/300 mg/kg bw/day (males) caused changes in leucocytes, neutrophilic granulocytes (absolute adn relative), absolute unstained cells, absolute lymphocytes and absolute monocytes (please refer to Table 1 in the field "Any other information on results incl. tables" below).
- No test item-related influence was observed for the haemoglobin content, the number oferythrocytes, reticulocytes and platelets, the haematocrit value, the thromboplastin and the activated partial thromboplastin time, the mean corpuscular volume (MCV), the mean corpuscular haemoglobin (MCH) and the mean corpuscular haemoglobin concentration (MCHC).

CLINICAL CHEMISTRY
- No test item-related influence was noted for the male and female animals treated orally with 50 mg/kg bw/day compared to the control group.
- Treatment with 150, 450/300 or 450 mg/kg bw/day caused cahgnes in alanine aminotransferase, alkaline phosphatase, asparate aminotransferase and lactate dehydrogenase (please refer to Table 2 in the field "Any other information on results incl. tables" below).
- No test item related influence was noted on the plasma levels of albumin, bilirubin, cholesterol, creatinine, glucose, protein, triglycrides, urea, uric acid, calcium, chloride, potassium and sodium.

URINALYSIS
- Treatment with 50, 150, 450/300 or 450 mg/kg bw/day, did not lead to any test item-related changes of the urinary status in any rat of any group at any dose level examined compared to the control group.

NEUROBEHAVIOUR
- The functional observation battery did not reveal any test item-related influence on the rats treated orally with 50 or 150 mg/kg bw/day.
- The fore- and hindlimb strength of the rats treated orally with 450/300 or 450 mg/kg bw/day was reduced by 43% for the male and by 45% for the female rats at maximum (statistically not significant) approx. 1 - 2 hours after dosing in test week 13. Statistical significance (at p ≤ 0.01) was reached for the forelimb grip strength of the male animals. These findings are considered to be related to the administration of the test item.
- No influence was noted on spontaneous motility in any animal treated with the test item at any dose level.

ORGAN WEIGHTS
- No test item-related influence was noted for the relative and absolute organ weights of male and female animals treated orally with either 50 or 150 mg and for the females treated orally with 450 mg/kg b.w./day.
- Treatment with 450/300 mg/kg bw/day caused changes in the absolute organ weights of the male animals (please refer to Table 3 in the field "Any other information on results incl. tables" below). These effects are regarded to be related to the reduced body weight. No effects were noted on the relative organ weights of the respective organs.
- Treatment with 450/300 mg/kg bw/day caused an increasse (statistically significant at p ≤ 0.01) in the relative brain, epididymis and gonads weights inthe male animals. These findings are considered to be due to the reduced body weight.

GROSS PATHOLOGY
- No test item-related changes were noted in the animals treated orally with either 50 or 150 mg/kg b.w./day.
- In the 3 males and 4 females treated orally with 450/300 or 450 mg/kg b.w./day that died prematurely macroscopic lesions were noted in the spleen ((severely) reduced in size), stomach (dilated, aerated, (mucosa) red discoloured), intestinal tract (dilated, aerated), prostate (reduced in size), seminal vesicle (reduced in size), liver (several pale spots, black discoloured), lungs (emphysematous, multiple black foci (diameter 2 mm), (right and central upper lobes) red-black discoloured), adrenals (enlarged), thymus ((severely) reduced in size), caecum ((severely) enlarged), pancreas (pale) and kidney (reduced in size).
- Additionally, three high dosed female animals showed a dilated intestinal tract.
- All findings are considered to be test item-related.

HISTOPATHOLOGY: NON-NEOPLASTIC
A moderate to marked reduction of lymphocytes was noted in the spleen, thymus and lymph nodes in five of the 7 rats that died prematurely. These morphological lesions are considered to be related to the administration of the test item. No changes were noted in the remaining high dosed animals.

Effect levels

open allclose all
Dose descriptor:
NOEL
Effect level:
50 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
body weight and weight gain
haematology
clinical biochemistry
gross pathology
histopathology: non-neoplastic
Dose descriptor:
NOAEL
Effect level:
150 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Because there were no effects on organ weight and no pathological/histopathological correlate to the minimal findings on haematology and clinical chemistry in mid dose female animals, the findings observed were regarded as incidental and not adverse.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1:

Changes in haematological parameters compared to the control [%]

Parameter

Females

150 mg/kg

Males

450/300 mg/kg

Females

450 mg/kg

Leucocytes

+40

none

+66**

Neutrophilic granulocytes (absolute)

Neutrophilic granulocytes (relative)

 +26

 

none

+45

+40

+193**

+60

Absolute unstained cells

+110**

none

+171**

Absolute lymphocytes

+42

none

+48

Absolute monocytes

+46

none

+75

** statistically significant at p ≤ 0.01

Table 2:

Changes in biochemical parameters compared to the control [%]

Parameter

Males

150 mg/kg

Females

150 mg/kg

Males

450/300 mg/kg

Females

450 mg/kg

Alanine aminotransferase

none

+22

+88**

+136**

Alkaline phosphatase

none

+40

+12

+43

Aspartate aminotransferase

none

none

+28**

+30**

Lactate dehydrogenase

none

+14

none

+42

Table 3:

Changes in absolute organ weights compared to the control [%]

Organ

Males

450/300 mg/kg

Heart

-17**

Kidney (left)

-13

Kidney (right)

-14**

Liver

-24**

Adrenal (left)

-18

Adrenal (right)

-12

Spleen

-23**

Thymus

-29

Applicant's summary and conclusion

Conclusions:
Under consideration of all changes noted, the no-observed-effect level (NOEL) for systemic changes was 50 mg/kg bw/day, but because there were no effects on organ weight and no pathological/histopathological correlate to the findings in mid dose female animals, the findings observed were regarded as incidental and not adverse, and thus a NOAEL can be established at the mid dose level of 150 mg/kg bw/d.