Reactive Orange 16

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

other: read across from similar substance

Adequacy of study:

key study

Study period:

21. Dec. 1987 to 21. March 1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP compliant

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Objective of study:

excretion

metabolism

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.7485 (Metabolism and Pharmacokinetics)

Version / remarks:

Tier 1

Deviations:

yes

Remarks:

exhalation determined in separate study

Principles of method if other than guideline:

Determination of radioactivity in the excreta of rats. Identification of metabolites in the excreta.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Acid Blue 040 - Similar Substance 02

IUPAC Name:

Acid Blue 040 - Similar Substance 02

Radiolabelling:

yes

Remarks:

bisphenyl-U-14C

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hoechst AG
- Age at study initiation: -
- Weight at study initiation: 230 g
- Fasting period before study: -
- Housing: 2 per cage
- Individual metabolism cages: no
- Diet: Altromin 1321 ad libitum
- Water: tap ad libitum
- Acclimation period: 1 to 2 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 23°C
- Humidity (%): 30 - 70%
- Air changes (per hr): -
- Photoperiod (hrs dark / hrs light): -

IN-LIFE DATES: From: 21. Dec. 1987 To: 24 Dec. 1987

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 mg/kg bw
- concentration (if solution): 1.836 mg/g

Duration and frequency of treatment / exposure:

single dose

Doses / concentrations

Remarks:

Doses / Concentrations:
10 mg/kg body weight (nominal), 9.94 mg/kg bw actual dose

No. of animals per sex per dose / concentration:

5 males

Control animals:

no

Positive control reference chemical:

-

Details on study design:

TS was dissolved in bidistilled water (5 minutes ultrasound ) to a final concentration of 1.836 mg/g

Details on dosing and sampling:

- Tissues and body fluids sampled: urine, faeces
- Time and frequency of sampling: 0-24 h, 24-48 h, 48-72 h after dosing
- From how many animals: pooled from all animals
- Method type(s) for identification: Liquid scintillation counting, HPLC-UV, HPLC-14C, TSP-HPLC-MS
- Limits of detection and quantification:
- Other:


TREATMENT FOR CLEAVAGE OF CONJUGATES (if applicable):
- acetylation
- enzyme cleavage with beta-glucoronidase/arylsulfatase

Statistics:

-

Results and discussion

Preliminary studies:

NA

Toxicokinetic / pharmacokinetic studies

Details on absorption:

see kinetic study HOE 89.0388

Details on distribution in tissues:

see kinetic study HOE 89.0388

Details on excretion:

More than 90% were excreted within the first 24 hours. Excretion mainly via feces.
85% excretion via feces
15% excretion via urine
no unchanged test item excreted

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

Urine: 6 metabolites were separated, two main metabolites identified.
1. 8% of total radioactivity: sulfate-ester
2. 4% of total radioactivity: N-acetylate

Feces:
All extractable metabolites identified. About 17% of the radioactivity remained unextracted
1. 76% of total radioactivity: sulfate-ester amount decreased over time
2. N-acetylate increased over time

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results
The test item was almost completely metabolized. The majority of the metabolites were excreted via feces.

Executive summary:

The proposed degradation pathway is given in Figure 2.

This means that reductive cleavage of the azo groups is the main metabolization step in the rat. The resulting amine is excreted mainly in the feces either directly or after N-acetylation.

Remarkable is the very high excretion rate of the metabolites via feces. Usually such behavior is caused by one of the following acts:

- almost total absorption of the test substance and subsequent biliary excretion of the metabolites

- degradation of the test substance by the intestinal flora

- abiotic hydrolysis of the test substance in the gastro intestinal tract

In this case, the last possibility can be excluded, as the hydrolysis experiments showed products different from those identified as metabolites in the excreta.

The fact that the metabolite pattern in feces is nearly identical with that in urine gives strong evidence that biliary excretion dominates for the test item. However, determination of the absorption rate was done in a further study.