Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1981
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not done under GLP (1981), however it has been performed according to state of the art methods (e.g. 7-point calibration and method validation) and is therefore considered reliable, relevant and adequate.
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1981
Report date:
1981

Materials and methods

Objective of study:
absorption
metabolism
Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
- Name of test material (as cited in study report): diphenyl sulphone
- Substance type: white powder
- Physical state: solid
- Analytical purity: at least 99,5%
- Impurities (identity and concentrations): See confidential details on test material
- Composition of test material, percentage of components: See confidential details on test material
- Isomers composition: not applicable
- Purity test date:See confidential details on test material
- Lot/batch No.: Y00903-002-001
- Expiration date of the lot/batch: ee confidential details on test material
- Stability under test conditions: no significant degradation had occured under test conditions
- Storage condition of test material: stored in the dark at room temperature
Radiolabelling:
no

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River (UK) Ltd, Margate, Kent
- Age at study initiation: 41 days
- Weight at study initiation: 136-195g for males; 95-159g for females
- Fasting period before study: not applicable
- Housing: in groups of 5 by sex in stainless steel grid cages over cardboard lines trays
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): with exception of periods of blood and urine collection, animals were allowed free access at all times
- Water (e.g. ad libitum): with exception of periods of blood and urine collection, animals were allowed free access at all times
- Acclimation period: 19 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/- 3°C
- Humidity (%): 40-70%
- Air changes (per hr): at least 12 changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

IN-LIFE DATES: From: 16 September 1980 To: 16-22 December 1980

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly intervals
- Mixing appropriate amounts with (Type of food): powdered diet (rat and mouse No 1, Modified, BP Nutrition Ltd., Stepfield, Witham, Essex)
- Storage temperature of food: room temperature

VEHICLE
- Justification for use and choice of vehicle (if other than water): not applicable

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
Homogeneity and stability of the test article in the powdered diet were determined prior to the study. The test article was shown to mix homogeneously in the speicfied diet and test diets were found to be stable over a 14-day period (HLE-report No. 2486-72/203).
Routine analysis of test diets for achieved concentration was performed on diets prepared prior to the start of treatment and again during weeks 4,8 and 13 of treatment. On each occasion triplicate samples of each batch of diet prepared, together with triplicate samples of the control diet provided were analysed for test article concentration
Duration and frequency of treatment / exposure:
The test diets were available continuously for 13 weeks with the exception of 16 hours periods of deprivation associated with the collection of blood and urine samples.
Doses / concentrations
Remarks:
Doses / Concentrations:
100ppm, 200ppm, 2000ppm
No. of animals per sex per dose / concentration:
ABSORPTION: 5 males and 5 females per dose; plasma samples were pooled per group and per sex.
METABOLISM: 6 males and 6 females per dose; liver samples were investigated individually.
Control animals:
yes
Positive control reference chemical:
Not applicable
Details on study design:
- Dose selection rationale: The dietary concentrations, which were selected by the study sponsor in the light of results from a 4 week feeding study
- Rationale for animal assignment (if not random): blood samples were collected from the 5 males and 5 females wiht the highest identification Nos. in each group; liver samples were collected from the 6 males and 6 females wiht the highest identification Nos. in each group.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption)
- Tissues and body fluids sampled: plasma
- Time and frequency of sampling: samples taken during week 1 and 12 of treatment
- Other: validation demonstrated linearity (7-point calibration) with correlation of 0.9920-0.9987; recovery for standards of 1.82 µg/ml demonstrated stability in plasma stored at -20°C for 11 weeks; at lower levels of 0.49 and 0.25 µg/ml some loss of diphenylsuphone under storage was apparent.

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : liver
- Time and frequency of sampling: after necropsy
- From how many animals: 48 animals (samples not pooled) 6 males and 6 females per dose (0, 100, 200 and 2000 ppm)
- Method type(s) for identification: colorimetric method: the absorbance of each solution was measured at 412 nm; The rate of aminopyrine N-demethylation (APDM) was followed by determining the formaldehyde production.
- Limits of detection and quantification: a standard formaldehyde curve of was prepared containing the following concentrations: 7.70, 3.85, 1.93, 0.96, 0.48 and 0.24 µg/ml

TREATMENT FOR CLEAVAGE OF CONJUGATES (if applicable): not applicable
Statistics:
Evaluation of APDM activity was performed using analysis of variance followed bu Students 't' test. Group mean differences for selected biochemical parameters were evaluated using the Kruskal-Wallis test and Wilcoxon rank sum test. The significance of the incidence of selected pathological findings was assessed using the Chi squared method with Yate's correction.

Results and discussion

Main ADME resultsopen allclose all
Type:
absorption
Results:
absorption at all dose levels in week 1 and 12; no dose proportionality established at highest dose
Type:
metabolism
Results:
Aminopyrine N-demethylase (APDM) activities on liver was increased at 2000 ppm. There was no effect on APDM activity at 100 or 200 ppm.

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Diphenyl sulphone was not found in the plasma of control animals at either investigation. Plasma diphenyl sulphone levels in treated animals showed a positive but non linear relationship with dose (see Table 1, furhter provided).
The plasma diphenyl sulphone levels attained by group 2 and 3 animals during week 1 were comparable with corresponding values during week 12. No sex difference in absorption was seen in either group on both occasions.
Group 4 animals showed that plasma levels of diphenylsulphone levels of the males fell from week 1 to 12, whilst that of the femals rose from week 1 to 12. The plasma concentration shown by females was approximately 4 times higher than that of the males on the latter occasion.
Details on distribution in tissues:
Not determined
Details on excretion:
Not determined
Toxicokinetic parameters
Test no.:
#1
Toxicokinetic parameters:
other: pooled plasma concentration

Metabolite characterisation studies

Metabolites identified:
no

Any other information on results incl. tables

The mean APDM levels of female controls was about half that of male controls (see Table 2).

A statistically significant increase in mean APDM activity was demonstrated for animals of both sexes receiving 2000 ppm diphenyl sulphone when compared to control values.

APDM activity was unaffected in animals given 100 or 200 ppm diphenyl sulphone.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): bioaccumulation potential cannot be judged based on study results
ABSORPTION:
Diphenyl sulphone was not found in the plasma of control animals at either investigation. Plasma diphenyl sulphone levels in treated animals showed a positive but not linear relationship with dose.
The plasma diphenylsulphone levels attained by group 2 and 3 animals during week 1 were comparable with corresponding values during week 12. No sex difference in absorption was seen in either group on both occasions.
Group 4 animals of both sexes showed similar plasma levels of diphenylsulphone during week 1. However, during week 12 the plasma diphenylsulphone level of the males fell, whilst that of the females rose. Consequently the plasma concentration shown by females was approximately 4 times higher than that of the males on the latter occasion.

METABOLISM:
A significant increase in mean APDM activities was apparant for rats of both sexes given 2000 ppm diphenylsulphone when compared to corresponding control values (p=<.01). There was no effect on APDM activity in rats given 100 or 200 ppm diphenylsulphone.
The level of APDM activity in female controls was about half that of male controls.
Executive summary:

Plasma samples (5animals/sex/group) were collected from 100, 200 and 2000 ppm diphenyl sulphone dosed treatment groups, including control groups, after 1 and 12 weeks of treatment (this study was part of the 90 -day toxicity study in rats). These samples were then stored at –20° C whilst a reverse phase HPLC method was developed and validated . Pooled samples were then analysed for test article using this analytical procedure. The plasma diphenyl sulphone levels of treated animals showed a positive but non-linear correlation with dose. Circulating levels of diphenyl sulphone were comparable at the week 1 and 12 investigations for the 100 and 200 ppm dosed group. However, during week 12 group 2000 ppm dosed males showed a fall in plasma level when compared to week 1, whilst the plasma diphenyl sulphone level of 2000 ppm dosed females rose against the week 1 value. Consequently, on this occasion the plasma concentration shown by females was some four times higher than that of the males.

Aminopyrine N-demethylase (APDM) activities were determined on individual liver samples (6 animals/sex/group) at the termination of the study using a colorimetric method supplied by the sponsor. A significant increase in mean APDM activities was apparent for rats of both sexes given 2000 ppm diphenylsulphone when compared to corresponding contro1 values (p<.01). There was no effect on APDM activity in rats given 100 or 200 ppm diphenylsulphone. The level of APDM activity in female controls was about half that of male controls.