Ethanone, 1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)thio]-

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:

Sept to Nov 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

469-300-0

EC Name:

-

Cas Number:

63675-73-0

Molecular formula:

Hill Empirical Formula: C16H16O3S CAS Empirical Formula: C16H16O3S

IUPAC Name:

1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)sulfanyl]ethan-1-one

Test material form:

solid: particulate/powder

Details on test material:

Lot no: 151105Purity - 101.39%

Test animals

Species:

rat

Strain:

other: Crl:WI(Han)

Details on species / strain selection:

A sufficient number Crl:WI(Han) rats were obtained from Charles River UK Limited, Kent, UK, in order to provide 35 healthy animals of each sex.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALSSource: Crl:WI(Han) rats from Charles River UK Ltd, Kent, UKAge & weight: at the start of treatment, preliminary & main study animals were approx 34 and 43 days. Preliminary study males weighhed from 108.7 to 143.1g and the females weighted from 91.8 to 116.3g. Main study males weighed from 128.0 to 201.3g and the females weighed from 134.6 to 159.7g.Housing: Aminals assigned to preliminary study were housed in groups of five and animals assigned to the main study were housed individually.Diet: SQC Rat and Mouse Maintenance Diet No. 1, expanded at least once dailyWater: Ad libitum supply of mains water Acclimation: 5 days for preliminary study and 2 weeks for main study.ENVIRONMENTAL CONDITIONS Temperature: 19 to 25 CHumidity: 40 to 70%Photoperiod: 12 hours light (0600 to 1800) and 12 hour dark cycle.

Administration / exposure

Route of administration:

oral: gavage

Details on route of administration:

Orally by gavage administration. Dosed once daily for a minimum of either 5 (preliminary study) or 28 (main study) days, excluding the day of necropsy. Dose volume was 10 mL/kg. Individual dose volumes were based on individual body weight.

Vehicle:

methylcellulose

Details on oral exposure:

Method of administration: Oral (gavage)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

High Performance Liquid Chromatography with UV detection. Determined once for the first batch of test article used on the study at concentrations of 10 and 100 mglml during Weeks 1 and 4.

Duration of treatment / exposure:

Test duration: 28 days

Frequency of treatment:

Dosing regime: 7 days/week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Control

Doses / concentrations 2

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

100 mg/kg bw/day Male: 5, Female: 5300 mg/kg bw/day Male: 5, Female: 51000 mg/kg bw/day Male: 5, Female: 5

Control animals:

yes, concurrent no treatment

Details on study design:

OECD 407 has set a limit dose of 1000mg/kg/day and this was chosen as the highest dose level for the preliminary phase in the studay. The low and intermediate doses were selected to allow a 2 fold increase between dose levels, so that a suitable high dose could be selected for the main study.The dose levels for the main study were selected based on the findings from the preliminary study. There were no post dosing observations or effects on body weight and /or food consumption durind the preliminary phase, and dose levels of 100, 300 and 1000 mg/kg/day were therefore selected for the main study

Examinations

Observations and examinations performed and frequency:

POST DOSE OBSERVATIONSDaily: On return to home cage and at 0.5, 1, 2 and 4 hours post-dose. PHYSICAL EXAMINATIONSWeeklyNEUROLOGICAL OBSERVATIONSAll main study animals were subject 10 a battery of behavioural tests and observations before the initiation of treatment and once weekly thereafter. Additional open field tests were included in Week 4. The motor activity of each animal was determined in Week 4.BODY WEIGHTPreliminary study: Recorded before treatment on the first day of dosing, at daily intervals and before necropsy. Main study: Recorded pre-treatment, before treatment on the first day of dosing, at weekly intervals and before necropsy. FOOD CONSUMPTION Preliminary study: Consumption was recorded daily as g/animal/day. Main study: Consumption was recorded weekly as g/animal/week.HAEMATOLOGYSamples (2 x 0.5 mL (EDTA. trisodium citrate}) were taken from all main study animals at the end of Week 4 from the lateral caudal vein after an overnight period without food, following completion of the Week 4 neurological observations.BONE MARROW SMEARSBone marrow smears were prepared at necropsy. They were fixed in methanol but not examined. CLINICAL CHEMISTRYSamples (1 x 0.6 mL (lithium heparin nominal]) were taken from all main study animals at the end of Week 4 from the lateral caudal vein after an overnight period without food, following completion of the Week 4 neurological observations.URINALYSISUrine samples were collected overnight from all animals in Week 4, following completion of the Week 4 neurological observations. Food and water were removed during collection.

Sacrifice and pathology:

NECROPSYAll main study animals were subject to necropsy. Preliminary study animals were killed and discarded without necropsy. Necropsies were carried out in cage order after an overnight period without food. Each animal was given an intraperitoneal injection of sodium pentobarbitone. Once a suitable deep plane of anaesthesia had been established, the animal was exsanguinated by the severing of major blood vessels.Protocol specified tissues from control and high dose animals were examined microscopically by the Study Pathologist.

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

There were no clinical signs noted during the preliminary study. In the main study,one female dosed at 300 mg/kg/day and one female dosed at1000 mg/kg/day presented with tremors in Weeks 4 and 5 (necropsy week) of study. However, as only two animals had tremors and in the absence of any accompanyingsigns, these are considered not to be treatment-related. All other clinical observations (damaged/missing tail and thinning fur), were notconsidered important because they are typical of those signs commonly observed in rats of this strain and age.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No treatment related differences in treated animals compared to controls. Small differences between groups, occasionally achieving statistical significance, were inconsistent between the groups and / or sexes and are considered to be due to individual animal variation.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

There were no changes in the blood chemistry to suggest an effect of Beta Ketosulfide.Differences in treated animals compared to controls, occasionally achieving statistical significance, were small, inconsistent between males and females, and are considered not treatment-related.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

There was no effect of Beta Ketosulfide on behavioural parameters assessed during functional observation battery testing. Although there were a greater number of rears in female animals assigned to Group 4 (dosed at 1000 mg/kg/day) in Week 2, compared to controls, the number of rears for both groups were comparable to pretreatment values; on both occasions the differences b etween the groups achieved a statistical significance of p<0.05, however this observation was not considered to be treatment-related.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Liver weights in males and females dosed at 1000 mg/kg/day were 10% higher than their respective control. There were no differences in liver weights for animals dosed at 100 or 300 mg/kg/day, compared to controls.There were no other differences in organ weights between treated animals and control animals.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Most tissues were macroscopically unremarkable and the findings seen were generally consistent with the usual pattern of findings in rats of this strain and age. There were nomacroscopic findings suggestive of effects of Beta Ketosulfide.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

Microscopic findings were generally infrequent, of a minor nature and consistent with theusual pattern of findings in rats of this strain and age. There were no microscopic findingsin treated animals due to effects of Beta Ketosulfide.

Histopathological findings: neoplastic:

not examined

Details on results:

Clinical observations: There were no unscheduled deaths.No effect observed on body weight, food consumption, functional observation battery, locomotor activity or clinical pathology parameters (haematology, blood chemistry or urinalysis).Laboratory findings:Most tissues were macroscopically unremarkable and the findings seen were generally consistent with the usual pattern of findings in rats of this strain and age. There were no macroscopic findings suggestive of effects of Beta Ketosulfide.Microscopic findings were generally infrequent, of a minor nature and consistent with the usual pattern of findings in rats of this strain and age. There were no microscopic findings in treated animals due to effects of Beta Ketosulfide.Effects in organs:Liver weights in males and females dosed at 1000 mg/kg/day were 10% higher than their respective control. There were no differences in liver weights for animals dosed at 100 or 300 mg/kg/day, compared to controls.There were no other differences in organ weights between treated animals and control animals. The increase in liver weight seen at 1000 mg/kg/day was considered to be non-adverse as there were no histopathological findings and no changes in enzyme parameters.

Effect levels

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: no treatment related adverse effects observed upto the limit dose

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Not classified for Specific Target Organ Toxicity- the classification criteria in Annex I of (EC) 1272/2008 were not met.

Executive summary:

The objective of the study was to determine the toxicity of the test article, Beta Ketosulfide, following oral (gavage) administration of the rat for 28days.A five day preliminary study was conducted prior to the start of the main study in order to assess the dose levels selected for this study.

 

In the preliminary study, the toxicity of Beta Ketosulfide was evaluated in Crl:WI(Han) rats (five animals/sex in Groups 1 to 3), when administered as daily oral (gavage) doses of 250, 500 or 1000mg Beta Ketosulfide/ kg of body weight (mg/kg) for at least five days.

In the main study, the toxicity of Beta Ketosulfide was evaluated in Crl:Wl(Han) rats (five animals/sex in Groups 1 to 4),when administered as daily oral (gavage) doses of 0,100, 300 or 1000mg Beta Ketosulfide/ kg of body weight (mg/kg) for at least 28days.

.

There were no unscheduled deaths during either the preliminary or main study. There were no effects of Beta Ketosulfide on clinical condition, body weight gain, food consumption, functional observation battery, locomotor activity or clinical pathology parameters.

 

Higher liver weights (10%) were recorded for male and female animals dosed at 1000 mg/kg/day, compared to controls; there were no significant differences in liver weights for other treated groups compared to controls and there were no correlative histopathologic changes.  There were no significant differences between treated animals and controls for other organ weights.

In conclusion,Beta Ketosulfide administered to rats for 28 day at dose levels of 100, 300 and 1000 mg/kg/day was well tolerated. The only treatment-related change was10% higher liver weight in male and female animals dosed at1000mg/kg/day, compared to controls. This change was judged to be non-adverse. From the data collected in this study, the no observed adverse effect level (NOAEL) is considered to be1000 mg/kg/day.