2-dimethylaminoethyl methacrylate

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Febuary 2014 - 02 July 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

adopted on 21 September 1998

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 424 (Neurotoxicity Study in Rodents)

Version / remarks:

adopted on 21 July 1997

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-dimethylaminoethyl methacrylate

EC Number:

220-688-8

EC Name:

2-dimethylaminoethyl methacrylate

Cas Number:

2867-47-2

Molecular formula:

C8H15NO2

IUPAC Name:

2-(dimethylamino)ethyl methacrylate

Test material form:

liquid

Specific details on test material used for the study:

TEST MATERIAL:
- Name of test material (as cited in study report): Dimethylaminoethyl methacrylate
- Supplier: Evonik Röhm GmbH, D-64293 Darmstadt, Germany
- Substance type: organic
- Physical state at room temperature: liquid
- Storage condition of test material: 4°C, light protected

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Italy S.r.l., San Pietro al Natisone (UD), Italy
- Age at study initiation: (P) Males/females: approximately 47-49 days old
- Weight at study acclimatisation: (P) 86 - 103 g (male and female)
- Fasting period before study:
- Housing: No more than 5 per cage of one sex in clear polysulphone soilid bottomed cages measuring 59.5X38X20 cm (Code 1354 G, suppied by Techniplast Gazzada S.a.r.l., Buguggiate, Varese, Italy). Each cage tray held absorbent material inside suitable bedding bags which were changed at least twice a week.
- Diet: ad libitum, commercially available laboratory rodent diet (4 RF 21, Mucedola S.r.l., Via G. Galilei, 4, 20019, Settimo Milanese (MI), Italy) throughout the sudy, except as indicated during week 13 of treatment, samples of blood were taken under conditions of food deprivation.
- Water: ad libitum, supplied via water bottles
- Acclimation period: approximately 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ±2 °C
- Humidity (%): 55 ±15 %
- Air changes (per hr): 15 - 20 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hrs dark/ 12 hrs light

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The test item was suspended in corn oil to give the required concentrations of 20, 40 and 100 mg/mL. The test-substance preparations were produced daily.
The test substance was administered as an suspension. It was administered orally by gavage at a dose volume of 5 mL/kg body weight.
Control animals received the vehicle alone at the same dose volume. The dose was administered to each animal on the basis of the most recently recorded body weight and the volume administered was recorded for each animal.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Prior to commencement of treatment the proposed formulation procedure was checked by chemical analysis to confirm that the method was
acceptable. Stability over a 24 hour period at room temperature was assessed for content check prior to the start of treatment. Samples of the
formulations prepared at weeks 1 and 13 were analysed to check the concentration and homogeneity. Results of all the analyses were within the limits of acceptance (85-115% for concentration and CV < 10% for homogeneity).

Duration of treatment / exposure:

For a minimum of 13 consecutive weeks followed by a recovery period of 4 weeks (for 5 males and 5 females of groups 1, 4, 5 and 8.
Animals of the main phase were dosed up until the day before necropsy.

Frequency of treatment:

daily, 7 days a week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

200 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

500 mg/kg bw/day (nominal)

No. of animals per sex per dose:

Main groups
Group Treatment (mg/kg/day) number of animals
--------------------------------------------------------------
1 0 15 males and 15 females
2 100 10 males and 10 females
3 200 10 males and 10 females
4 500 15 males and 15 females
----------------------------------------------------------------
Neuropathology groups
----------------------------------------------------------------
5 0 10 males and 10 females
6 100 5 males and 5 females
7 200 5 males and 5 females
8 500 10 males and 10 females
-----------------------------------------------------------------

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The dose levels of 100, 200 and 500 mg/kg/day were defined based on information from previous studies (see chapter 7.8).

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes (Mortality (all groups))
- Time schedule: daily
All observations were recorded for individual animals. Examination of individual animals for signs of reaction to treatment was carried out twice daily
once early in each working day and again in the afternoon. At weekends and on public holiday similar procedure was used except that the final check was carried out at ca. mid-day.

DETAILED CLINICAL OBSERVATIONS AND NEUROTOXICITY: Yes (main groups)
- Time schedule: All clinical signs were recorded for individual animals. Once before commencement of treatment and once daily during the study, each animal was subjected to a detailed clinical examination. Observations were performed at the same time interval each day, the interval was selected taking into consideration the presence of post-dose reactions. The signs “breathing difficulties” was not tabulated due to technical problems.

Once before commencement of treatment and once weekly thereafter during treatment period, the first 10 animals of each sex were given a detailed clinical examination. The same examination was carried out once during Week 4 of the recovery period in the recovery animals. Animals were examined in an open arena for a minimum of three minutes.
Observed parameters, described by an evaluation scale, are indicated below:

Removal (from cage): Easy, Difficult, Very difficult
Handling reactivity: Normal, Slow, Moderate, Marked
Lachrymation: Absent, Slight, Marked
Palpebral closure: Absent, Slight, Moderate, Marked
Salivation: Absent, Slight, Marked
Piloerection: Absent, Present
Rearing: Absent, Intervals of number of times (i.e. 1-3, 4-7, 8-10)
Spasms: Absent, Tonic spasms, Clonic spasms, Tonic-clonic spasms
Myoclonia: Absent, Present
Mobility impairment: Absent, Slight, Moderate, Marked
Arousal (animal activity): Very slow, Slow, Normal, Moderate, Marked
Vocalisation: Absent, Present
Stereotypies: Absent, Present
Unusual respiratory pattern: Absent, Present
Bizarre behaviour: Absent, Present
Urination: Absent, Intervals of number of times (i.e. 1-3, 4-6)
Defecation: Absent, Intervals of number of times (i.e. 1-3, 4-6)
Tremors: Absent, Present
Gait (one of the following options): Normal
Ataxia (Slight, Moderate, Marked)
Hunched (Slightly, Moderately, Severely)
Pronation
Forelimbs drag (Slight, Moderate, Marked)
Hindlimbs drag (Slight, Moderate, Marked)

The test included observation of changes in gait and posture, reactivity to handling, presence of clonic or tonic movements, stereotypies or bizarre behaviour and effects on the autonomic nervous system (e.g. lachrymation, piloerection, unusual respiratory pattern). Changes in fur, skin, eyes, mucous membranes, occurrences of secretions and excretions were also recorded.
An evaluation of sensory reactivity to stimuli of different modalities (e.g.auditory, visual and proprioceptive stimuli), an assessment of grip strengthn and motor activity were also performed in the same animals once before commencement of treatment and once during Weeks 1, 4, and 12 of treatment and Week 4 of recovery.

Motor activity assessment (MA)
The motor activity (MA) was measured by an automated activity recording over a period of 5 minutes.

BODY WEIGHT: Yes (all animals)
- Time schedule for examinations:
Each animal was weighed on the day of allocation to treatment group, on the day that treatment commenced, weekly thereafter and just prior to necropsy.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes (all animals)
The weight of food consumed by each cage of rats was recorded at weekly intervals following allocation. The group mean daily intake per rat was calculated. Food consumption of Groups 5, 6, 7 and 8 was inadvertently recorded on Day 72 (and not on Day 71 as for weekly schedule). Therefore, in the report the food consumed on Day 71 was calculated over a period of 8 days and that for the subsequent week (78) over a 6 day period.

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 data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Both eyes of all animals assigned to the study were examined just prior to the commencement of treatment by means of an ophthalmoscope, and by a slitlamp microscope, after the instillation of 0.5% Tropicamide (Visumidriatic®, Visufarma, Rome, Italy). The eyes of all animals from the high dose and control groups (Main groups) were re-examined during Week 13 of treatment.
- Dose groups that were examined: all animals

Both eyes of all animals assigned to the study were examined just prior to the commencement of treatment by means of an ophthalmoscope, and by
a slit-lamp microscope, after the instillation of 0.5% Tropicamide (Visumidriatic®, Visufarma, Rome, Italy). One animal with non-resolving lesions (No. 27580066) was replaced with a spare animal showing no ocular abnormality, from the batch initially ordered for the study. The eyes of all animals
from high dose and control groups were re-examined during week 13 of treatment.

HAEMATOLOGY: Yes (main groups)
- Time schedule for collection of blood: during week 13 of treatment prior to necropsy
- Anaesthetic used for blood collection: Yes (identity): isofluorane (identity: no data)
- Animals fasted: Yes
- How many animals: 10 male and 10 female animals from each group (main phase groups)
At the end of Week 4 of the recovery period, blood samples were also taken from all surviving animals under identical conditions in order to reevaluate haematology (except coagulation) and clinical chemistry parameters, since potential treatment-related changes were observed at measurements
performed during the treatment period.
- Parameters checked: The blood samples collected were divided into tubes as follows:
EDTA anticoagulant for haematological investigations
Heparin anticoagulant for biochemical tests
Citrate anticoagulant for coagulation tests

The measurements performed on blood samples are listed below:
-Haematology
Haematocrit
Haemoglobin
Red blood cell count
Reticulocyte count
Mean red blood cell volume
Mean corpuscular haemoglobin
Mean corpuscular haemoglobin concentration
White blood cell count
Differential leucocyte count - Neutrophils
- Lymphocytes
- Eosinophils
- Basophils
- Monocytes
- Large unstained cells
Abnormalities of the blood film
Platelets
Prothrombin time

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: during week 13 of treatment
- Animals fasted: Yes
- How many animals: all surviving animals
- Parameters checked: Clinical chemistry
Alkaline phosphatase
Alanine aminotransferase
Aspartate aminotransferase
Gamma-glutamyltransferase
Urea
Creatinine
Glucose
Triglycerides
Phosphorus
Total bilirubin
Total cholesterol
Total protein
Albumin
Globulin
A/G Ratio
Sodium
Potassium
Calcium
Chloride



Necropsy (main groups)
The clinical history of the animal was studied and a detailed post mortem examination was conducted (including examination of the external surface
and orifices). Changes were noted, the requisite organs weighed and the required tissue samples preserved in fixative and processed for
histopathological examination (see sections organ weights to Histopathological examination).

Organ weights (main groups)
From all animals of the main groups (main phase and recovery phase) completing the scheduled test period, the organs indicated in the table1 below were dissected free of fat and weighed. The ratios of organ weight to body weight were calculated for each animal.

Intravascular Perfusion in situ fixation - Neuropathology (Neuropathology groups)
Tissues from all animals of the neuropathology groups (main phase and recovery phase) were fixed in situ using an intravascular perfusion fixation
followed by an additional period of immersion post-fixation. Animals were anesthetised by intraperitoneal injection of penthotal sodium and perfused
using 10% neutral buffered formalin. Central and peripheral nervous system (CNS and PNS) organs/tissues, listed in Annex 2 of Study Protocol - Neuropathology continued the fixation in 10% neutral buffered formalin in order to allow the complete fixation. After fixation sampling of CNS and PNS
organs/tissues was performed and the brain was weighed (data not reported).

Tissues fixed and preserved
Samples of all the tissues listed in table 1 below were fixed and preserved in 10% neutral buffered formalin (except eyes, testes and epididymides which were fixed in Modified Davidson’s fluid and preserved in 70% ethyl alcohol).

Histopathological examination
The tissues required for the histopathological examination are listed in table 1 below. After dehydration and embedding in paraffin wax, sections of
the tissues were cut at 5 micrometre thickness and stained with haematoxylin and eosin.
The examination was as detailed below:
a) Tissues specified in table 1 below from 10 animals/sex in the control and high dose groups killed at the end of the 13 weeks of treatment.
b) All abnormalities in all groups.

The examination was then extended to include, from all other animals killed after 13 weeks of treatment and 4 weeks of recovery, liver and stomach in
which treatment-related changes were observed at the high dose level.

Histopathological examination - Neuropathology (Neuropathology groups)

Preparation of samples of CNS e PNS was performed following the indication reported in “Current Pathology Techniques” Symposium Review: Advances and Issues in Neuropathology – Toxicologic Pathology, 36: 871-889 2008. CNS and PNS samples were embedded in paraffin wax, sectioned at 4 mm and stained with haematoxylin and eosin and with special stain such as Cresyl violet, specific for neurons, and Luxol Fast Blue, specific for myelin.
The examination was as detailed below:
i Tissues specified in Table 2 of Study Protocol - Neuropathology (see below) from 5 animals/sex in the control and high dose groups killed
at the end of the 13 weeks of treatment (Neuropathology animals).

Table1: of study protocol (main groups)
---------------------------

Organs / Tissues Weight Fixation Microscopic
Preservation Examination
------------------------------------------------------------------------------------------------------
Abnormalities x x
Adrenal glands x x x
Aorta x x
Bone marrow (from sternum) x x
Brain (7 sections) x x x
Caecum x x
Colon x x
Duodenum x x
Epididymides x x x
Eyes x *
Femur with joint x *
Heart x x x
Ileum x x
Jejunum (including Peyer’s patches) x x
Kidneys x x x
Liver x x x
Lungs (including mainstem bronchi) x x
Lymph nodes - cervical x x
Lymph nodes - mesenteric x x
Mammary area x x
Oesophagus x x
Ovaries x x x
Oviducts (a) x
Pancreas x x
Parathyroid glands (b) x x
Pituitary gland x x
Prostate gland x x
Rectum x x
Salivary glands x x
Sciatic nerve x x
Seminal vesicles x *
Skeletal muscle x *
Skin x x
Spinal column x
Spinal cord (cervical, thoracic, lumbar) x x
Spleen x x x
Stomach x x
Testes x x x
Thymus (where present) x x x
Thyroid x x
Trachea x x
Urinary bladder x x
Uterus - cervix x x x
-----------------------------------------------------------------------------------------------------------
*: not examined as no signs of toxicity or target organ involvement were observed
a: weighed and preserved with ovaries
b: preserved with thyroid gland

Table 2 of Study Protocol
(Neuropathology Groups)

Organs / Tissues Weight Fixation Preservation Microscopic Examination
----------------------------------------------------------------------------------------------------------------
Brain (Cerebellum, Frontal Lobe,
Hippocampus, Midbrain, Medulla x x x
Oblongata, Parietal Lobe, Pons)

Diaphragm (transversal and longitudinal) x x Cervical ganglia (Ganglion Dorsal
Root Cervical and Ganglion x x Dorsal Root Lumbar)
Eyes with optic nerves x x
Gasserian ganglia (Ganglion
Gasserian) x x
Skeletal muscle x x
Lumbar ganglia (Nerve Root Dorsal
Cervical,
Nerve Root Dorsal Lumbar, x x
Nerve Root Ventral Lumbar,
Nerve Root Ventral Cervical)
Spinal cord (cervical, thoracic, lumbar)
Sciatic nerve (proximal, transversal
and longitudinal) x x
Tibial nerve (Tibial Nerve Distal,
Tibial Nerve Proximal) x x
-----------------------------------------------------------------------------------------------------------------

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 1 section Observation and examinations performed and frequency)
HISTOPATHOLOGY: Yes (see table 1 section Observation and examinations performed and frequency)

Statistics:

For continuous variables the significance of the differences amongst groups was assessed by analysis of variance. Differences between each treated group and the control group were assessed by Dunnett's test using a pooled error variance. The homogeneity of the data was verified by Bartlett's
test before Dunnett's test. If data were found to be inhomogeneous a Modified t test (Cochran and Cox) was applied. The mean values, standard
deviations and statistical analysis were calculated from the actual values in the computer without rounding off. Statistical analysis of histopathology
findings were carried out by means of the non-parametric Kolmogorov-Smirnov test.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

no mortality, no systemic toxicity

Mortality:

no mortality observed

Description (incidence):

no mortality, no systemic toxicity

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant body weight increases were observed in the high dose
females of the main groups during the last month of the treatment period
and during the recovery period.
No toxicological significance was attributed to these differences. No changes
were observed in the males.
Body weight gain was comparable between treated and control groups.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Statistically significant food consumption increases were observed in the high
dose females from the second month of the treatment period up to Week 12
as it appeared to be due to a reduced food intake in the controls.
No toxicological significance was attributed to this difference as it appeared
to be due to a reduced food intake in the controls.
No changes were observed in the males.

Food efficiency:

not specified

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Lymphocytosis and monocytosis were recorded in many animals treated with
200 and 500 mg/kg/day.The other statistically significant changes recorded between control and
treated animals were of low severity and/or not dose-related, therefore considered
of no toxicological significance.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Increase of phosphorus was recorded in a number of males from all treated
groups (approximately 26%, with no dose-relation) and in females dosed
with 200 and 500 mg/kg/day (31% and 67%, respectively). In addition, urea
was increased in animals of both sexes dosed with 500 mg/kg/day (21% in
males and 43% in females). Due to the low severity and the absence of other
related changes (e.g. kidneys markers, calcium), the above findings were not
considered adverse. Some other statistically significant differences were recorded between control
and treated animals, such as: decrease of creatinine in males receiving 200 and
500 mg/kg/day (11% and 13%, respectively), decrease of alkaline phosphatase
(29%) and alanine aminotransferase (24%) and increase of albumin (5%) in
females dosed with 200 mg/kg/day, decrease of sodium (1%) in females receiving
500 mg/kg/day. Due to the absence of dose-relation, the low magnitude
and/or the direction of changes, the above findings were considered of no toxicological importance

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Slight increases, significant at statistical analysis, in the absolute weights of
kidneys (+11% and 24%) and liver (+15% and 17%) were observed at the
end of the treatment period in the females dosed at 200 and 500 mg/kg/day.
The relative weights of the kidneys were significantly increased in male and
female animals dosed at 500 mg/kg/day (+12% and 16%, respectively) and in
the females dosed at 200 mg/kg/day (+9%). The relative weight of the liver
was also slightly increased in the females dosed at 200 and 500 mg/kg/day
(+12% and +11%).
No toxicological relevance was attributed to the changes observed in the
weight of kidneys as they were low and not supported by any macroscopic or
microscopic findings.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

The only relevant change observed at post mortem examination was thickening
and oedematous consistency of the non-glandular region of the stomach
in high dose male no. 97120076. On microscopy, it correlated with marked ulceration of the non-glandular region of the stomach.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Treatment-related changes were noted in the liver and stomach of males and
females. Three males and three females of the high dose group showed changes in the
stomach.

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY

No mortality occurred during the study.

Convulsions were occasionally observed in 1 male from the mid-dose (200
mg/kg/day) and 1 female from the low dose (100 mg/kg/day). More frequent
episodes of convulsions were seen in the high dose males (2/15 from Group
4, 1/10 from Group 8) and high dose females (8/15 from Group 4, 4/10
from Group 8), either prior or after the daily administration. Convulsions
were occasionally associated to salivation in some of these animals. Single
episodes of ataxia, breathing difficulties or red discharge from mouth were
also observed in individual animals.

No clinical signs were observed during the 4 week recovery period.


WEEKLY DETAILED CLINICAL SIGNS (Removal from cage and Open field measurements)

No changes of note were found at the weekly clinical examination which included an evaluation of neurotoxicity during treatment and recovery periods.


NEUROTOXICITY ASSESSMENT (Functional Tests and Motor activity)

No differences between treated animals and controls which could be considered treatment-related were observed at functional tests (sensory reactivity, landing footsplay, grip strength) and motor activity measurements performed during treatment and recovery periods.


BODY WEIGHT AND WEIGHT GAIN

Statistically significant body weight increases were observed in the high dose
females of the main groups during the last month of the treatment period
and during the recovery period.
No toxicological significance was attributed to these differences. No changes
were observed in the males.
Body weight gain was comparable between treated and control groups.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)

Statistically significant food consumption increases were observed in the high
dose females from the second month of the treatment period up to Week 12
as it appeared to be due to a reduced food intake in the controls.
No toxicological significance was attributed to this difference as it appeared
to be due to a reduced food intake in the controls.
No changes were observed in the males.


FOOD EFFICIENCY

No data


OPHTHALMOSCOPIC EXAMINATION

No findings were seen at the ophthalmic examination.


HAEMATOLOGY

Treatment Phase

Lymphocytosis and monocytosis were recorded at the end of treatment in many animals treated with 200 and 500 mg/kg/day.

Recovery Phase

Lymphocytosis and monocytosis were still observed in the females and in one male at the end of recovery.


COAGULATION

No changes were recorded.


CLINICAL CHEMISTRY

Treatment Phase

Increase of phosphorus was recorded in a number of males from all treated
groups (approximately 26%, with no dose-relation) and in females dosed
with 200 and 500 mg/kg/day (31% and 67%, respectively). In addition, urea
was increased in animals of both sexes dosed with 500 mg/kg/day (21% in
males and 43% in females). Due to the low severity and the absence of other
related changes (e.g. kidneys markers, calcium), the above findings were not
considered adverse.
Some other statistically significant differences were recorded between control
and treated animals, such as: decrease of creatinine in males receiving 200 and
500 mg/kg/day (11% and 13%, respectively), decrease of alkaline phosphatase
(29%) and alanine aminotransferase (24%) and increase of albumin (5%) in
females dosed with 200 mg/kg/day, decrease of sodium (1%) in females receiving
500 mg/kg/day. Due to the absence of dose-relation, the low magnitude
and/or the direction of changes, the above findings were considered of no toxicological importance

Recovery Phase

Phosphorus was still higher than controls in treated animals (16% in males,
42% in females). As for the dosing phase, this finding was not considered
adverse.
No other relevant changes were recorded.

MACROSCOPIC OBSERVATION

Detailed macroscopic observations have been reported for male and female
animals from all groups.
The only relevant change observed at post mortem examination was thickening
and oedematous consistency of the non-glandular region of the stomach
in high dose male no. 97120076. On microscopy, it correlated with marked ulceration of the non-glandular region of the stomach.

Recovery sacrifice

There were no changes at necropsy indicating an effect of treatment.


MICROSCOPIC OBSERVATION

Treatment-related changes were noted in the liver and stomach of males and
females.
In the liver, the size and distribution within the tissue of hepatocytic vacuolation
differed between the control and high dose animals. All ten male controls
had macrovesicular vacuolation randomly scattered through the tissue. Such
finding occurred only in one high dose male (no. 97120076), whereas three
high dose males showed microvesicular, periportal hepatocytic vacuolation.
Male low-dose group showed scattered macrovesicular vacuolation in all ten
animals, in the intermediate dose group only 7 out of 10 males exhibited
this finding. Female control group contained only one animal (no. 97120017)
with hepatocytic vacuolation. In contrast, eight high dose females showed
microvesicular, periportal vacuolation. The female low dose group had 5 out
of 10 animals with microvesicular vacuolation, while in the intermediate dose
group they were 7 out of 10.
The liver changes noted among control and treated groups are considered to
reflect physiological and nutritional condition of the animals. They do not
indicate a damage of the liver.
Three males and three females of the high dose group showed changes in the
stomach. Male no. 97120076 had mucosal ulceration and male no. 97120090
squamous hyperplasia, both in the non-glandular region of the stomach. Male
no. 97120088 had erosion in the glandular region of the stomach. Female
nos. 97120079, 97120085 and 97120087 had squamous hyperplasia in the
non-glandular region of the stomach. These changes observed in the stomach could be considered to be related to the gavage procedure. Examination of
the stomach of males and females in the low and intermediate dose groups
did not show any such finding.
The other sporadic lesions reported in control and treated animals were
considered to be an expression of spontaneous and/or incidental pathology,
commonly seen in this species and age under our experimental conditions.

Recovery sacrifice

The size, tissue distribution, incidence and grade of severity of hepatocytic
vacuolation were similar in control and treated males and females, indicating
full reversibility of the observed differences.
There were no findings in the stomach of treated males and females following
the recovery period.
Microscopic examination (Neuropathology groups)
There were no pathological changes indicating an effect of the treatment
with the test item. The examined tissues contained normally distributed
anatomical structures such as neurons with neuronal processes, myelin sheaths,
supporting glial cells, connective tissue, muscle fibers and blood vessels.
A few findings observed in treated or control animals represented incidental
background pathology.

Effect levels

Key result

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

500 mg/kg bw/day (nominal)

Based on:

test mat.

Remarks:

suspended in corn oil

Sex:

male/female

Basis for effect level:

other: no effects observed

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

On the basis of the above results, only minor signs of possible treatment-related effects of the test
item, Dimethylaminoethyl methacrylate (convulsions / salivation, lymphocytosis
and monocytosis) were observed during the in vivo phase in male and
female rats at the dose levels of 200 and 500 mg/kg/day, when administered
by oral gavage for 13 consecutive weeks at the dosages of 100, 200 and 500
mg/kg/day. None of them was considered to be adverse. Changes were also
observed at the post mortem examination in the liver. These were considered
to be adaptive and, therefore, not adverse. Changes observed in the stomach
of treated animals were ascribed to a local irritant effect and, as such, not
systemically adverse.

No changes indicating a neuropathological effect of the treatment with the
test item were observed at any of the dose levels tested.

No significant changes were observed in the animals dosed at 100 mg/kg/day.
Therefore, the No Observed Adverse Effect Level (NOAEL) for this study is
500 mg/kg/Day.

Executive summary:

The oral toxicity of Dimethylaminoethyl methacrylate (CAS 2867 -47 -2, Purity: 99.79%) when given by daily administration to rats, has been investigated over a period of 13 consecutive weeks and recovery from any treatment-related effects during a treatment-free period of 4 weeks. Three groups, each of 10 male and 10 female Sprague Dawley rats, received the test item by gavage at dosages of 100, 200 and 500 mg/kg/day for 13 consecutive weeks. A fourth similarly constituted group received the vehicle alone (corn oil) and acted as a control. Additional five male and 5 female animals were included in separate groups for neuropathology investigations. Control and high dose main and neuropathology groups included each 5 additional animals per sex to be sacrificed after 4 weeks of recovery.

Minor signs of possible treatment-related effects of the test item, Dimethylaminoethyl methacrylate, were observed at in vivo and at post mortem in male and female rats only at the dose levels of 200 and 500 mg/kg/day, when administered by oral gavage for 13 consecutive weeks at the dosages of 100, 200 and 500 mg/kg/day. None of them were considered to be systemically adverse.

No changes indicating a neuropathological effect of the treatment with the test item were observed at any of the dose levels tested.

No significant changes were observed in the animals dosed at 100 mg/kg/day.

Therefore, the high dose of 500 mg/kg/day, when administered daily for 13 consecutive weeks, was considered the No Observed Adverse Effect Level (NOAEL) for systemic long-term toxicity.

This study is acceptable and satisfies the guideline requirement for a 13 week oral toxicity study (OECD 408) in rats.

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