Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 March 2016 to 05 April 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Version / remarks:

OECD Guidelines for Testing of Chemicals, No. 407 (03 October 2008)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

Version / remarks:

Directive 96/54/EC B.7 (OJL 248 1996), Commission Regulation (EC) No 440/2008 of 30 May 2008, B.7. (Official
Journal L 142, 31/05/2008).

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

EC Number:

600-273-1

Cas Number:

102089-74-7

Molecular formula:

C13H19NO3

IUPAC Name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Test material form:

solid: particulate/powder

Test animals

Species:

rat

Strain:

Wistar

Details on species / strain selection:

Species and strain: Crl:WI rats
Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, D-97633
Housing conditions: SPF at the supplier, standard laboratory conditions during the study
Justification of species/strain: The rat is regarded as suitable species for toxicology studies. Wistar rat as a rodent is one of the standard strains for repeat-dose toxicity studies
Number of groups: 4 groups; one control and 3 test item-treated groups
Number of animals: 20 male and 20 female rats plus a sufficient number of spare animals
Age of animals: Young adult rats, approximately 6-7 weeks old at onset of treatment
Body weight: Not exceeding ±20% of the mean weight for each sex at onset of treatment males: 229 - 260 g, females: 171 - 194 g
Acclimation period: 5 days

Sex:

male/female

Details on test animals or test system and environmental conditions:

Husbandry
Animal health: Only healthy animals were used for the test. The staff Veterinarian certified the health status prior to acceptance for use in the study.
Animal room: 243
Cage type: Type II and/or III polycarbonate
Bedding: Laboratory bedding, Lignocel 3/4-S (produced by J. Rettenmaier & Söhne GmbH + Co.KG, D-73494 Rosenberg, Germany) and nest building material (ARBOCEL crinklets natural produced by J. Rettenmaier & Söhne GmbH +Co KG) were available to animals during the study. Details of bedding and the nest building material quality are archived with the study raw data.
Illumination: Artificial light, from 6 a.m. to 6 p.m.
Temperature: 20.1-24.2°C
Relative humidity: 33-57 %
Ventilation: 15-20 air exchanges per hour
Housing/Enrichment: Rodents were group-housed (2 or 3 animals/sex/cage), to allow social interaction, and with deep wood sawdust bedding.
The temperature and relative humidity were measured continuously and recorded twice daily during the study and acclimation period.

Diet and water supply
The animals were provided with ssniff® SM R/M "Autoclavable complete diet for rats and mice – breeding and maintenance" produced by ssniff Spezialdiäten GmbH, D-59494 Soest Germany, ad libitum, and tap water from municipal supply, as for human consumption from 500 ml bottle, ad libitum.
The supplier provided analytical certificate for the batch used during the experiment (Batch No.: 540 5117 Expiry date: July 2016) which is archived with the study raw data.
The quality control analysis of the water is performed once every three months and microbiological assessment is performed monthly, by Veszprém County Institute of State Public Health and Medical Officer Service (ÁNTSZ, H-8201 Veszprém, József A.u.36, Hungary). Copies of the relevant Certificates of Analysis are retained in the archive at CiToxLAB Hungary Ltd.
The diet and drinking water are routinely analysed and are considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Animal assignment to the study and randomisation
Each animal was identified by a number unique within the study, written with indelible ink on the tail and cross-referenced to the Animal Master File at CiToxLAB Hungary Ltd.
The animal number consists of 4 digits, the first digit being the group number, the second is 0 for the males and 5 for the females, and the last 2 shows the animal number within the group, as indicated in the table below:
Gr. No. Group Designation Animal Identity Numbers
Males Females
1 Control 1001-1005 1501-1505
2 Low Dose 2001-2005 2501-2505
3 Mid Dose 3001-3005 3501-3505
4 High Dose 4001-4005 4501-4505
The cages were identified by cards holding information at least about study code, sex,
dose group, cage number and individual animal numbers.
During the acclimation period, the animals were assigned to their respective dose groups by randomization based on body weights. Animals were randomly allocated to the control and dose groups based on the most recent actual body weight; the software PROVANTIS v.9 was used in order to verify homogeneity/variation among/within groups. Males and females were randomized separately.

Administration / exposure

Route of administration:

oral: gavage

Details on route of administration:

The dose levels were set by the Sponsor in consultation with the Study Director, based on available data and information from previous experimental work, including the results of a preliminary dose range finding study conducted at CiToxLAB Hungary Ltd. with the test item [CiToxLAB study code 15/356-100PE].
The oral gavage was selected by the Sponsor as oral route is the intended route of administration in humans.

Vehicle:

methylcellulose

Remarks:

1% methylcellulose solution was selected for formulation in the acute oral toxicity study (15/356-001P) and for the dose range finding toxicity study (15/356-100PE); therefore this vehicle was selected for this study in agreement with the Sponsor.

Details on oral exposure:

Dosing procedure
Dose formulations were administered daily starting from Day 0 for 28 consecutive days by oral gavage, using a bulb tipped gastric feeding tube attached to a syringe. A constant dose volume of 5 mL/kg was administered to all animals.
The actual volume to be administered was calculated and adjusted based on most recent individual body weight.
Control animals were treated concurrently with the vehicle only. Animals were not treated on the day of necropsy.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

28 consecutive days

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

30 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

750 mg/kg bw/day (nominal)

No. of animals per sex per dose:

5 females and 5 males per dose

Control animals:

yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:

Clinical observations and neurological assessment
Animals were inspected for signs of morbidity and mortality twice daily (at the beginning and end of each day).

General clinical observations were made at least daily with the exception of Day 28, when only a detailed observation was performed.

Detailed clinical observations were made on all animals outside the home cage in a standard arena at least prior to the first treatment (to allow for within-subject comparisons) and weekly thereafter, in the morning hours (am).

More detailed examinations were made once before the first exposure (to allow for within-subject comparisons), then at least weekly, in the morning or before treatment. These observations were made outside the home cage in a standard arena, at similar times as practical. The animals were monitored for changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions, and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern), or 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), difficult or prolonged parturition or bizarre behaviour (e.g. self-mutilation, walking backwards); special attention were directed towards the observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

During the last week of treatment, each animal were subjected to the functional observation battery, including qualitative assessment of the grip strength, and to
measurements of the landing foot splay and fore/hind grip strength.

To measure the landing foot splay, the hind paws of the rat were painted with ink and the rat was dropped from a horizontal position onto the appropriate record sheet covering the examination table. The distance between the two resulting ink spots was measured. The fore paws of the rat were painted for any possible additional measurements.

Fore/hind grip strength measurements were conducted using a grip strength meter, an instrument designed to quantify objectively rodent muscular strength, in order to identify and assess quantitatively any potential effect of test item. The rats were held appropriately such that the fore limbs are allowed to grip the support bar and gently pulled back until they release the bar; the device measures the maximum grip strength. This was performed 3 times for each animal on the respective test day. The procedure was repeated with the hind limbs with the appropriate grip support. The results were tabulated with individual and mean data.

Sensory reactivity to different type of stimuli (e.g. auditory, visual and proprioceptive), assessment of grip strength and motor activity (automated) were conducted and the general physical condition and behaviour of animals were tested. A modified Irwin test was performed.

The parameters evaluated included the following: body position, locomotor activity, respiration rate, respiration type, piloerection, head searching compulsive biting or licking, circling, upright walking, retropulsion, jumping, exophthalmos, twitches, clonic convulsions, tonic convulsions, tremor, startle, transfer arousal, spatial locomotion, gait, posture, limb position, finger approach, finger withdrawal, touch escape response, diarrhoea, diuresis, visual placing, grip strength, body tone, corneal reflex, pinna, toe pinch, grasping reflex, positional struggle, skin, mucous membrane colour, salivation, palpebral closure, lachrymation, limb tone, abdominal tone, tail pinch, righting reflex, and/or vocalisation.

Sacrifice and pathology:

CLINICAL PATHOLOGY
Blood samples for clinical pathology evaluation (haematology, coagulation, and clinical biochemistry) were collected immediately prior to the scheduled necropsy, by heart puncture under pentobarbital anaesthesia (on Day 28).

After an overnight period of food deprivation of animals, 3 blood samples were collected, for haematology (in tubes with K3-EDTA as anticoagulant, 1.6 mg/mL blood), for blood clotting times (in tubes with sodium citrate as anticoagulant) and one to obtain serum (in tubes with no anticoagulant) for clinical chemistry.

Haematology
The following parameters will be evaluated in the surviving animals:
PARAMETERS (UNITS) METHODS
RBC Red Blood Cell (erythrocyte) count, (1012/L) M/μL Automatic laser cell count
WBC White Blood Cell (leukocyte) count, (109/L) K/μL Automatic laser cell count
Hgb Haemoglobin concentration, (g/dL) Determination of cyan-methemoglobin absorbance
Hct Haematocrit (relative volume of erythrocytes) (%) Computed by equipment
MCV Mean Corpuscular (erythrocyte) Volume (fL) Laser cell volume determination
MCH Mean Corpuscular (erythrocyte) Haemoglobin, (pg) Computed by equipment
MCHC Mean Corpuscular (erythrocyte) Computed by equipment
Haemoglobin Concentration, (g/dL)
RDW Red Cell (erythrocyte) volume (%) Distribution Width, Laser detection
Plt Platelet (thrombocyte) count (109/L) K/μL Automatic laser cell count
MPV Mean Platelet Thrombocyte volume (fL) Cell volume determination by laser
RETIC % Reticulocyte count (%) Comparative value based on laser light detection
NE % Neutrophil (%) Cell differentiation based on myeloperoxidase activity
LY % Lymphocyte (%) Cell differentiation based on myeloperoxidase activity
MO % Monocyte (%) Cell differentiation based on myeloperoxidase activity
BA % Basophil (%) Cell differentiation based on myeloperoxidase activity
EO % Eosinophil (%) Cell differentiation based on myeloperoxidase activity
LUC % Large Unstained Cells (%) Cell differentiation based on

Coagulation
PARAMETERS (UNITS) METHODS
APTT Activated Partial ThromboplastinTime (sec) Micronized silica method
PT Prothrombin Time (sec) Quick method (Biggs, R., and R.G. MacFarlane(1962) Human
Blood Coag.and its Disorders, Oxford)

Clinical chemistry
The following parameters will be evaluated in the surviving animals:
PARAMETERS (UNITS) METHODS
Glucose Blood sugar concentration (mmol/L) Colorimetric test (540 nm)
T-BIL Total Bilirubin concentration (μmol/L) End-point colorimetric (dual-wavelength) test (400 & 460nm)
Urea Urea concentration (mmol/L) Colorimetric test (670 nm)
Chol. Cholesterol concentration (mmol/L) Colorimetric test (540 nm)
Creat. Creatinine concentration (μmol/L) Two-point rate test (670 nm)
Phos. Phosphorus concentration (mmol/L) Colorimetric test (680 nm)
Na+ Sodium concentration (mmol/L) Potentiometric test
K+ Potassium concentration (mmol/L) Potentiometric test
Ca++Calcium concentration (mmol/L) Colorimetric test (680 nm)
Cl- Chloride concentration (mmol/L) Potentiometric test
Tot. Prot. Total Protein concentration (g/L) Colorimetric test (540 nm)
Alb. Albumin concentration (g/L) Colorimetric test (630 nm)
AST/GOT Aspartate Aminotransferase activity (U/L) Multiple-point rate test (340 nm)
ALT/GPT Alanine Aminotransferase activity (U/L) Multiple-point rate test (340 nm)
ALKP Alkaline. Phosphatase – activity (U/L) Multiple-point rate test (400 nm)
GGT Gamma Glutamyltransferase -activity (U/L) γ-Glutamyl-p-nitroanilid e+ Glycylglycine. Increase in p-nitroaniline-monitored at 400nm

PATHOLOGY EVALUATION

Terminal procedures
Gross necropsy will be performed on each animal irrespective of the date of death, including the animals found dead or euthanised preterminally in extremis. Terminally surviving animals will be euthanised under pentobarbital anaesthesia by exsanguination.

Macroscopic evaluation
After exsanguination the external appearance will be examined, cranium, thoracic and abdominal cavities will be opened and the appearance of the tissues and organs will be observed macroscopically. Any abnormality will be recorded with details of the location, colour, shape and size, as appropriate.

Organ weight measurements
The following organs will be trimmed of fat and weighed in surviving animals:

With precision of at least 0.01g:
Brain
Seminal vesicles with coagulating glands
Epididymides
Heart
Spleen
Kidneys
Testes
Liver
Thymus
Prostate
Uterus including cervix

With precision of at least 0.001g:
Adrenals
Ovaries
Thyroids with parathyroids
Pituitary

Paired organs will be weighed together. Absolute organ weights will be measured, and relative organ weights to the body and brain weights will be calculated and reported.

Tissue preservation and microscopic evaluation


Histopathology
On completion of the macroscopic examination the following tissues and organs will be retained from all animals.

Gross findings Lungs with bronchi 5 Skeletal muscle (quadriceps)
Adrenals Lymph node 6 Small intestine 8
Animal identification 1 Ovary Spinal cord11
Aorta10 Oviduct Spleen
Brain 2 Pancreas Sternum with marrow
Epididymis Pituitary Stomach
Eye with the optic nerve 7 Prostate Testis
Oesophagus Salivary gland (including mandibular, Thymus
Femur with marrow sublingual and parotid glands) Thyroid with parathyroid gland7
Heart 3 Tongue
Kidney Sciatic nerve Trachea
Large intestine 4 Seminal vesicle with coagulating gland Urinary bladder
Extraorbital lachrymal gland Uterus 9
Harderian gland Skin, subcutis with mammary gland (inguinal) Vagina
Liver12
1. Fixation and preservation only.
2. 7 section according to the STP recommendations.
3. Section including both ventricles and atria, septum with papillary muscle.
4. Caecum, colon and rectum.
5. Lungs of euthanized animals will be infused with formalin; 3 lobes, left, right cranial, right caudal.
6. Mandibular and mesenteric.
7. If applicable, parathyroids and optic nerves will be examined histologically only if present in routine sections.
8. Duodenum, ileum and jejunum with Peyer’s patches.
9. Horns, body and cervix.
10. Aorta thoracic and abdominal
11. Transverse sections, 3 levels -cervical, thoracic and lumbar.
12. Liver, 3 lobes, left lateral, right medial, caudate

The eyes with the optic nerve and the testes with epididymides were preserved in modified Davidson’s fixative; all other organs in 10% buffered formalin solution.

The retained tissues and organs were embedded in paraffin wax, sections were cut at 4-6μ by microtome and transferred to slides. Tissue sections were stained with haematoxylin-eosin/phloxine and examined by light microscope.

Full histopathology was performed only in Groups 1 (Control) and 4 (High main dose), at the request of the Sponsor.

Other examinations:

Body weight measurement
Body weight was recorded with a precision of 1 g at randomisation, on Day 0, prior to start of treatment, then at least weekly, including on Day 27 (last treatment day) and prior to necropsy (fasted) on Day 28.

Food consumption measurement
The determination of food consumption was performed once a week. The remaining, non-consumed food was weighed at least weekly from Day 7 with a precision of 1 g. Weekly food consumption was calculated.

Examination of vaginal smears
Prior to necropsy, the oestrus cycle of all females was determined by taking vaginal smears, which were prepared and stained with 1% aqueous methylene blue solution. The smears were examined with a light microscope, in order to provide information regarding the stage of oestrus cycle at the time of sacrifice and assist in histological evaluation of oestrogen sensitive tissues.

Statistics:

Group mean and standard deviation was calculated for numerical data. The statistical evaluation of the numerical data was performed with the program package SPSS PC+4.0 (SPSS Hungary Kft, Budapest). Evaluation was made by comparing the data for each of the Groups 2 to 4, respectively, against the control Group 1. The heterogeneity of variance between groups was checked by Bartlett's homogeneity of variance test. Where no significant heterogeneity was detected, a one-way analysis of variance was carried out. If the obtained result was positive, Duncan's Multiple Range test was used to assess the significance of inter-group differences. Where significant heterogeneity was found, the normal distribution of data was examined by Kolmogorov-Smirnov test. In case of abnormal distribution, the non-parametric method of Kruskal-Wallis One-Way analysis of variance was applied. If there was a positive result, the inter-group comparisons were performed using Mann-Whitney Utest. For comparison of Recovery groups T test was used. The mean and standard deviations values, the frequency of clinical observations, macroscopic and microscopic findings were calculated as applicable.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

All animals were clinically normal and there were no toxicologically significant or test-item related findings during the study.

Mortality:

no mortality observed

Description (incidence):

No animal mortality occurred during this study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no effects on bodyweight at any dose levels.
The mean body weights of males and females were comparable to the control throughout the treatment period. The overall body weight gains (Days 0-27) of males and females were similar to the controls.
Only minor differences to control were recorded in body weight gain, e.g. a lower body weight gain value in the high dose males between Days 21-27 (p<0.05) and a higher body weight gain value in high dose females between Days 0-7 (p<0.05). These small differences had no consequences on body weights and were not considered to reflect an adverse effect of treatment.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Administration of the test item did not cause any adverse effect on the food consumption of the animals.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Haematology parameters evaluated at the completion of the 28-day treatment period did not show signs of toxicity. Variations were noted in a few parameters in the treated animals, on two occasions attaining statistical significance.
In males, the Mean Corpuscular (erythrocyte) Haemoglobin Concentration (MCHC) was statistically (p<0.05) lower in the low dose group than the control.
In females, the Neutrophil percentage (NEU%) was statistically (p<0.05) higher in the low dose group than the control.
Although the differences were statistically significant, they were not dose-related, showed no consistent gender response and were within the normal historical control ranges.

In females, the PTT (Prothrombin Time (sec)) was statistically (p<0.01) lower in the high dose group than the control, however it was within the normal historical control range.

Clinical biochemistry findings:

not examined

Description (incidence and severity):

Significant increase compared to control was observed in Albumin concentration (Alb) and in Albumin/globulin ratio (A/G) in the male mid dose (p<0.05) and high dose (p<0.01). The value for the Albumin concentration was out of the historical control range. These changes are considered to be treatment related, but are not a clear sign of an adverse effect.

Significant increase compared to control was observed in Cholesterol concentration (Chol) in the female high dose (p<0.01), however it was within the normal historical control range. This change is not considered to be a clear toxic effect of the test item.

There were other parameters where the difference attained statistical significance but no dose response was observed (such as Chloride concentration in male low dose, Bile acids in female low dose and Glucose concentration in female mid dose) or the values were within the historical control range (such as Alanine Aminotransferase activity, Total Protein concentration and Calcium concentration in male high dose) and they were considered to be not treatment related.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

There were no toxicologically significant changes in the animal behaviour, general physical condition, in the reactions to different type of stimuli or motor activity in the control or treated groups.

There was no test item related effect of treatment noted during the assessment of foot splay or grip strength.

When compared to the control, the grip strength for the hind limb in females in all treatment doses was statistically (p<0.05 or 0.01) higher. However, there was no dosedependence and all values were within the normal range; it was not considered to represent a test item related effect.

In the foot splay test statistically (p<0.05) lower values were obtained in the male low and mid doses, without any dose-response when compared to the control. However, these were regarded as variations ascribed to individual variability and not attributed to the test item administration in the conditions of this study.

Compared to control, no test item-related differences, or dose, or gender related responses, were noted in the animals throughout all the dose groups when subjected tothe modified Irwin test. The behaviour of a

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Enlarged livers were found with dose-response relationship in treated groups in both sexes, up to over 40% above control in high dose males. The liver weight data related to body weight as well as related to brain weight compared to controls showed a consistent increase.

The increase is clearly statistically significant in the mid and high doses in males, and in the high dose in females when compared to the control. A similar trend in the low dose males is relatively small and is not considered to represent a clear adverse effect.

Kidneys in males were also enlarged, up to about 40% above control in high dose males, attaining statistical significance in the mid and high doses as summarized in the table and figure below:

The effects on livers and kidneys are considered to be test item treatment related and are more severe in males.

In males there were other organs where the weight difference attained statistical significance but no dose response was observed (such as prostate gland in low dose, thyroid glands in high dose) or the weights were within the historical control range (such as adrenal glands in low, mid and high dose).

Gross pathological findings:

no effects observed

Description (incidence and severity):

No macroscopic observations were recorded up to a dose level of 750 mg/kg bw on Day 28

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test item related microscopic findings were observed in the liver and kidney at a dose
level of 750 mg/kg bw (samples for the mid and low dose were not examined at the
request of the Sponsor).
Liver
Minimal to slight centrilobular hepatocellular hypertrophy was seen in 5/5 males and 5/5 females. These changes corresponded with increase of the liver weights and were considered to be a non-adverse adaptive response. The clinical chemistry data also had no indication of any clearly adverse effects in the liver.

Kidney
Test item related changes were present only in the males. Slight accumulation of eosinophilic cytoplasmic droplets of the cortical tubules was noted in 5/5 male rats. These droplets appeared similar to those which were seen with H&E stain as normal pattern in control males, however were larger, varying size and accumulated. In addition, minimal or slight unilateral/bilateral multifocal tubule degeneration was occurred in the renal cortex of 3/5 males. These alterations correlated with increased kidney weights brain related.

Other effects:

no effects observed

Description (incidence and severity):

EXAMINATION OF VAGINAL SMEARS
There were no test item related changes in the animal oestrus cycle evaluated prior to necropsy and the animals showed the normal distribution of the oestrus phases.

Effect levels

Key result

Dose descriptor:

dose level:

Effect level:

750 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Remarks on result:

other: The NOAEL of the test material administered by oral gavage to Wistar rats for 28 consecutive days cannot be estimated without histopathological examination of the lower doses which was not performed at request of the Sponsor.

Target system / organ toxicity

Critical effects observed:

yes

Lowest effective dose / conc.:

750 mg/kg bw/day (nominal)

System:

urinary

Organ:

kidney

Treatment related:

yes

Any other information on results incl. tables

A NOAEL could not be determined due to methodological limitiations.The NOAEL of the test material could not be estimated without histopathological examination of the lower doses which was not performed at request of the sponsor.

Applicant's summary and conclusion

Conclusions:

In summary, daily administration of N-Boc-D-phenylglycinol by oral gavage to Wistar rats for 28 consecutive days at dose levels up to 750 mg/kg bw/day caused no effects on body weight, food intake or clinical signs. Changes at 750 mg/kg bw/day included increased albumin in males, and increase of liver weights with centrilobular hepatocellular hypertrophy in livers in both sexes; similar weight changes were seen in mid dose males. These hepatic finding were considered to be adaptive rather than adverse. Kidney weights were increased in males at 750 mg/kg bw/day, associated with tubule degeneration and eosinophilic cytoplasmic droplets of the cortical tubules; similar weight changes were seen in mid dose males. The degenerative findings in male kidneys were considered to be adverse.

The NOAEL of N-Boc-D-phenylglycinol administered by oral gavage to Wistar rats for 28 consecutive days cannot be estimated without histopathological examination of the lower doses which was not performed at request of the Sponsor.