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Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptabel well documented publication which meets basic scientific principles

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Unnamed
Year:
1986
Reference Type:
review article or handbook
Title:
Isomaltulose (Palatinose ®): a review of biological and toxicological studies
Author:
Lina, B.A.R. et al.
Year:
2002
Bibliographic source:
Food and Chemical Toxicology 40:1375-1381

Materials and methods

Principles of method if other than guideline:
Rats were exposed daily to isomaltulose over a time period of 26 weeks to evaluate the subchronic toxic potential.
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
6-O-α-D-glucopyranosyl-D-fructose
EC Number:
237-282-1
EC Name:
6-O-α-D-glucopyranosyl-D-fructose
Cas Number:
13718-94-0
Molecular formula:
C12H22O11
IUPAC Name:
6-O-alpha-D-glucopyranosyl-D-fructose
Details on test material:
- Name of test material (as cited in study report): Isomaltulose (6-O-(α-D-glucopyranosyl)-D-fructofuranose, Palatinose ®)
- Analytical purity: no data
- Lot/batch No.: 1909

Test animals

Species:
rat
Strain:
other: Sprague-Dawley SPF (Crj: CD)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Age at study initiation: approx. 5 weeks
- Weight at study initiation: females: 94-118 g; males: 111-130 g
- Housing: individually in metal cages
- Diet: commercial solid feed CE-2 (Japan CLEA), ad libitum
- Water: tap water, ad libitum
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 ± 1
- Humidity (%): 55 ± 5

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
The amount of sample needed daily was weighed out and completely dissolved by adding an appropriate amount of distilled water and stirring in a approx. 60 °C water bath. Concentrations of 20, 40 and 60% (w/v) were then prepared by adding distilled water. The solutions were cooled to room temperature for use and applied within 4 hours after preparation.

VEHICLE
- Concentration in vehicle: 20, 40 and 60% (w/v)
- Amount of vehicle (if gavage): 0.5 mL/100 g bw
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
26 weeks (183 days for females; 184 days for males)
Frequency of treatment:
once daily
Doses / concentrations
Remarks:
Doses / Concentrations:
1500, 3000 and 4500 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
15
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: The maximum dose of the test substance was set at 7.5 mL/kg of 60% (w/v) aqueous solution using the results of acute toxicity tests previously conducted by the authors and sample dissolution preliminary experiments.

Examinations

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

BODY WEIGHT: Yes
- Time schedule for examinations: once a week up to week 13 of administration and once every two weeks thereafter for each animal

FOOD CONSUMPTION: Yes
- Time schedule for examinations: once a week up to week 13 of administration and once every two weeks thereafter for each individual

WATER INTAKE (if drinking water study): Yes
- Time schedule for examinations: The water intake was measured as amount per animal per day by randomly selecting five animals from each group in week, 1, 4, 13 and 26 after start of test substance administration.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: in week 5 and 26
- Dose groups that were examined: all dose groups (5 randomly selected animals from each dose group)

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Blood samples were collected in week 26 on the day before the final test substance administration
- How many animals: each animal
- Parameters examined: erythrocyte count, hemoglobin concentration, hematocrit value, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean cospuscular hemoglobin concentration (MCHC), leukocyte count, platelet count and leukocyte differentials

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the time of autopsy
- How many animals: each animal
- Parameters examined: total protein, albumin, total cholesterol, calcium, glucose, urea nitrogen, uric acid, creatinine, alkaline phosphatase, LDH, GPT, GOT, total bilirubin and inorganic phosphorus

URINALYSIS: Yes
- Time schedule for collection of urine: samples were collected in week 1, 4, 13 and 26 from five randomly selected animals from each group
- Metabolism cages used for collection of urine: Yes
- Parameters examined: specific gravity, pH, occult blood, total protein, glucose, ketones, urobilinogen and bilirubin

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
The following organs were weighed: brain, heart, lungs, liver, kidneys, spleen, thyroid, pituitary, adrenals, thymus, submaxillary glands, ovaries, uterus, prostate, testes, seminalvesicles.

HISTOPATHOLOGY: Yes (control and high dose group)
The following orans and tissues were stained with hematoxylin-eosin and examined histopathologically: site of the lesion, brain, heart, aorta, lungs, liver, spleen, pancreas, kidneys, urinary bladder, stomach, esophagus, duodenom, ileum, colon, testes, seminal vesicles, epididides, prostate, ovaries, uterus, mammary glands, submaxillary gland, pituitary, thyroid, adrenals, femoral bone marrow, thymus, mesenteric lymph nodes, eyeballs (including lacrimal glands) and skin
Statistics:
Mean and standard deviations; Student t-test (P <0.05)

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):
3000 mg/kg bw/day, females: slightly accelerated weight gain (non adverse)
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
all dose groups: reduced food intake (non adverse)
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
Description (incidence and severity):
changes in hemoglobin concentration, platelet count, hematocrit value, MCH (not dose-dependent, non adverse)
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
changes in Ca, alkaline phosphatase activity, LDH, urea nitrogen, uric acid, creatinine, bilirubin, GOT, glucose, inorganic phosphorus; changes either not dose-dependent or do not markedly exceed the range of physiological fluctuations (non adverse)
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
all doses, females: decrease in relative heart weight; 4500 mg/kg bw, males: increased liver weight; 3000 mg/kg bw: decreased relative lung, uterus and submaxillary gland weights in females and increased relative thyroid weight in males (non adverse)
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
Two females and males of the control group, one male of the 1500 mg/kg bw/day group, two females of the 3000 mg/kg bw/day group and one female and three males of the 4500 mg/kg bw/day group died of rupture of the esophagus showing pulmonary congestion, edema or hemorrhages, due to an erroneous manipulation during administration. There were no other deaths and no test-substance related symptoms could be found in any of the animals.

BODY WEIGHT AND WEIGHT GAIN
Other than slightly accelerated weight gain in females of the 3000 mg/kg bw/day group compared to the control animals in week 9, 11 and 13, no acceleration or inhibition of weight gain could be found in either males or females during the 26 weeks of the test substance administration.

FEED INTAKE
Decreased feed intake was noted from week 23 and from week 13 in males receiving 1500 and 3000 mg/kg bw/day, respectively. In the 4500 mg/kg bw/day group decreased feed intake was observed for females in week 19 and 23 and for males starting at week 11.
The reduced feed intake might be due to the intake of additional energy by daily gavage of the test item.

WATER INTAKE
There were no changes in water intake in any of the dose groups.

OPHTHALMOSCOPIC EXAMINATION
No changes could be observed in the cornea, iris or conjunctivae in any dose group. The ocular fundus findings did not reveal any changes considered to be test substance-related.

HAEMATOLOGY
Increases in hemoglobin concentration were noted in in females receiving 4500 mg/kg bw/day and in males receiving 3000 mg/kg bw/day. A decrease in platelet count was noted in females of the 1500 mg/kg bw/day group and in males of the 3000 mg/kg bw/day group. Hematocrit values were increased in males of the 3000 mg/kg bw/day group. A tendency to increase in mean corpuscular hemoglobin (MCH) in males administered 4500 mg/kg bw/day was found. However, these findings were not considered test substance-related.

CLINICAL CHEMISTRY
Calcium concentration, alkaline phosphatase activity and LDH activity of females and urea nitrogen concentration of males tended to decrease dose-dependently. In addition a dose-dependent decrease in uric acid and creatinine concentration was noted in males and females exposed to the test substance. Decreases in urea nitrogen and bilirubin concentrations in females of the 1500 mg/kg bw/day group, decreases in GOT activity of females of the 4500 mg/kg bw/day group, increases in alkaline phosphatase activity of males receiving 3000 mg/kg bw/day and increases in glucose and inorganic phosphorus concentration of males administered 4500 mg/kg bw/day were determined. However none of these changes markedly exceeded the range of physiological fluctuation.

URINALYSIS
Ketones became positive in week 4, 13, 26 in males of each group, including the control animals. Animals with positive results for bilirubin were found sporadically from week 1 of administration. However, no dose-response relationship was observed for the positive findings in ketones and bilirubin. No further abnormalities in examined parameters could be found in any of the dose groups.

ORGAN WEIGHTS
Slight decreases were noted in the relative weight of heart in females exposed to the test substance compared to the control animals. In females of the 3000 mg/kg bw/day group relative weight of lungs, uterus and submaxillary glands was slightly decreased. Slight sporadic increases were determined in the relative weight of the thyroid in males of the 3000 mg/kg bw/day group and in the relative weight of the liver and absolute weight of the adrenals in males administered 4500 mg/kg bw/day.

GROSS PATHOLOGY and HISTOPATHOLOGY: NON-NEOPLASTIC
Histopathology was restricted to animals of the control and high dose group.
Tiny fatty droplets were seen primarily in the peripheral hepatocyte of the lobules in male and female rats. Rarely, slight hyperplasia of the bile duct was noted. In the kidney, formation of vacuoles in the epithelial cells of the straight part of the proximal tubules was observed occasionally in females and rarely in males, respectively. Occasionally small grouping of foam cells in the alveoli were noted. Calcification was seen in the tunica media of the arteries in the lung. In the pancreas, fibrosis of the islet of Langerhans and deposition of hemosiderin were seen in males. However, no differences between the administration and control group was determined regarding the histopathological findings in liver, kidney, lungs and pancreas. In addition, although there was slight myocardial fibrosis in males of the administration groups, there was not great difference from the control goup.

In general, there were no abnormal findings believed to have been caused by the test substance administration in the pathological examination.

Effect levels

Dose descriptor:
NOAEL
Effect level:
>= 4 500 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse effects were noted up to the highest dose tested.

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion