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Toxicological information

Toxicity to reproduction: other studies

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Administrative data

Endpoint:
toxicity to reproduction: other studies
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
10 May 2006 to 09 August 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, meets generally accepted scientific standards and methods are well-described

Data source

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

Materials and methods

Test guideline
Qualifier:
no guideline required
Principles of method if other than guideline:
No guideline for dose range-finding study to set dose levels for a guideline 2-generation study.
GLP compliance:
yes
Type of method:
in vivo

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Each animal was evaluated by a laboratory veterinarian, or a trained animal/toxicology technician under the direct supervision of a laboratory veterinarian, to determine the general health status and acceptability for study purposes upon arrival at the laboratory (fully accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International - AAALAC International). TEST ANIMALS- Charles River: - Age at study initiation: 6 wks- Fasting period before study: No- Housing: he animals were housed two or three per cage in stainless steel cages, in rooms designed to maintain adequate conditions - Diet (e.g. ad libitum): Certified Rodent Diet #5002 (PMI Nutrition International, St. Louis, Missouri) in meal form, ad libitum - Water (e.g. ad libitum): municipal water supply ad libitum- Acclimation period: minimum 1-weekENVIRONMENTAL CONDITIONS- Temperature (°C): 22+/-1C - Humidity (%): 40-70% - Air changes (per hr): 12-15 - Photoperiod (hrs dark / hrs light): 12-h light:dark

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
polyethylene glycol
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: All dosing solutions were prepared by mixing the test material in PEG 400 at concentrations of 6.25, 18.75, 37.5, or 75 mg/ml VEHICLE (PEG 400)- Concentration in vehicle: 6.25, 18.75, 37.5, or 75 mg/ml
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Dose confirmation analyses of all dose solutions were determined pre-exposure. The homogeneity of the low- and the high-dose solutions was determined concurrent with the dose confirmation. The method for analyzing the test material in PEG 400 was gas chromatography-mass spectrometry (GC/MS) with internal and external standards.
Duration of treatment / exposure:
90 days
Frequency of treatment:
once daily
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:0, 25, 75, 150 or 300 mg/kg/day Basis:nominal conc.
Remarks:
Doses / Concentrations:0, 22.8, 74.8, 146, 302 mg/kg/dayBasis:analytical conc.
No. of animals per sex per dose:
8
Control animals:
yes, concurrent vehicle
Details on study design:
A cage-side examination was conducted twice daily, preferably at the same time each day, designed to detect significant clinical abnormalities that are clearly visible upon a limited examination, and to monitor the general health of the animals. In addition, all animals were observed for morbidity, mortality, and the availability of feed and water at least twice daily. Clinical examinations were conducted on all animals at least once daily. Animals were observed approximately one hour after dosing. All rats will be weighed pre-exposure, twice during the first week and weekly throughout the study.Feed consumed was determined twice during the first week and weekly for all animals by weighing feed containers at the start and end of a measurement cycle. A complete necropsy was conducted on all animals include an examination of the external tissues and all orifices. Weights of the liver and kidneys will be recorded, and organ:body weight ratios calculated. Histologic examination will be conducted on all control and high-dose rats and all animals that die or are sacrificed in a moribund condition. Examination of tissues from the remaining groups will be limited to those tissues that demonstrate treatment-related histologic effects at the high dose and relevant gross lesions.
Statistics:
Statistical AnalysesBody weights, feed consumption and organ weights (absolute and relative) will first be evaluated by Bartlett's test (alpha = 0.01) for equality of variances. Based upon the outcome of Bartlett's test, either a parametric or nonparametric analysis of variance (ANOVA) will be performed. If the ANOVA is significant at alpha = 0.05, a Dunnett's test (alpha = 0.05) or the Wilcoxon Rank-Sum (alpha = 0.05) test with Bonferroni's correction will be performed. Both the Dunnett's test and Bonferroni's correction correct for multiple comparisons to the control to keep the experiment-wise error rate at 0.05. Both will be reported at the experiment-wise alpha level. Feed consumption values will be excluded from analysis if the feed has been spilled or scratched. Statistical outliers (alpha = 0.02) will be identified by the sequential method of Grubbs (1969). Outliers will only be excluded from analysis for documented, scientifically sound reasons.If deemed necessary, more statistical tests will be performed. Because numerous measurements will be statistically compared in the same group of animals, the overall false positive rate (Type I errors) will be greater than the nominal alpha levels. Therefore, the final interpretation of the data will consider statistical analyses along with other factors, such as dose-response relationships and whether the results are consistent with other biological and pathological findings and historical control values.

Results and discussion

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
ca. 75 mg/kg bw/day
Sex:
male
Basis for effect level:
other: based on the occurrence of a single rat with slight hepatocellular vacuolization
Dose descriptor:
NOEL
Effect level:
ca. 25 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: based on effects observed at higher dose levels

Any other information on results incl. tables

Administration of CS-1135 at dose levels of 75, 150, and 300 mg/kg/day resulted in toxicity following 90-days of exposure.  Seven animals did not survive to their scheduled necropsies.  Four of these deaths were attributed to gavage error.  In three high-dose rats, CS-1135 was interpreted to be contributory to the cause of death.  Mean body weights of males in all dose levels were slightly lower than controls by 3-10%; however, only the body weight decrement of males given 300 mg/kg/day was interpreted to be treatment related.  High-dose males had a lower mean final body weight (9%) that was consistent with their in-life body weights, along with higher relative kidney (10%), and liver weights (15%).  Females in the high-dose group had a higher mean relative (15%) liver weight compared to controls that was statistically identified and interpreted to be treatment related.

 
Lesions occurred in the nonglandular and glandular portions of the stomach in numerous males and females given 300 mg/kg/day and fewer males and females given
150 mg/kg/day.
  Degenerative lesions consisted of erosions/ulcers and/or multiple foci of necrosis and inflammation involving the glandular mucosa and were noted in one male and a few females given 300 mg/kg/day.  Subacute to chronic inflammation occurred in the submucosa of the glandular stomach of males and females given 300 mg/kg/day.  The inflammation was focal or multifocal in distribution and varied in severity from very slight to severe.  Similar inflammatory changes were also observed in the majority of males given 150 mg/kg/day and were focal in distribution, very slight in degree, and were also interpreted to be treatment related.  Diffuse hyperplasia of the nonglandular stomach was noted in male and female rats given 150 or 300 mg/kg/day and was dose-related in incidence and severity (slight to moderate).  This effect was interpreted to be a protective change secondary to irritation (necrosis and inflammation) induced by CS-1135 and/or its break down products (i.e., formaldehyde).  A variable number of males treated with 75, 150, or 300 mg/kg/day and one female given 300 mg/kg/day had very slight to moderate multifocal vacuolation of hepatocytes that was consistent with fatty change.  The vaculation was dose related and interpreted to be treatment related.  Two males and one female given 300 mg/kg/day had either focal or multifocal hepatocellular necrosis.  This alteration was very slight in degree and was localized to a limited region of only one of the three liver lobes histologically examined.  Although the necrosis may be treatment related, it was interpreted to be of minimal toxicologic significance due to the distribution and limited parenchyma affected.

Applicant's summary and conclusion