Disodium [2,2'-bi-1H-indole]-3,3'-diolate

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

March 1982 to May 1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

No GLP study, oxidized form of the test item, acceptable, well-documented study report which meets basic scientific principles. The test substance is synthesized and handled as a 15% to 50% aqueous sodium hydroxide solution (pH 13) only under inert gas atmosphere. It is instable in an aqueous phase at neutral pH or as solid material on air and oxidises rapidly to indigo CAS 482-89-3.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Principles of method if other than guideline:

Method as requested by the National Institute of Environmental Health Sciences, USA

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one

EC Number:

207-586-9

EC Name:

2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one

Cas Number:

482-89-3

Molecular formula:

C16H10N2O2

IUPAC Name:

2,2'-biindole-3,3'(1H,1'H)-dione

Constituent 2

Reference substance name:

2-(1,3-dihydro-3-oxo-2H-indazol-2-ylidene)-1,2-dihydro-3H-indol-3-one

IUPAC Name:

2-(1,3-dihydro-3-oxo-2H-indazol-2-ylidene)-1,2-dihydro-3H-indol-3-one

Details on test material:

- Name of test material (as cited in study report): CI Vat Blue #1: Indigo
- Molecular formula (if other than submission substance): C16H10N2O2
- Molecular weight (if other than submission substance): 262.3
- Smiles notation (if other than submission substance): O=C3c4ccccc4NC3=C2Nc1ccccc1C2=O
- InChl (if other than submission substance): InChI=1/C16H10N2O2/c19-15-9-5-1-3-7-11(9)17-13(15)14-16(20)10-6-2-4-8-12(10)18-14/h1-8,17-18H
- Structural formula attached as image file (if other than submission substance): see 7.1.1
- Substance type: active substance
- Physical state: blue solid
- Analytical purity: essentially pure
- Lot/batch No. unlabeled: #A1A Eastman Kodak
- Purity test date: 19. October 1981
- Lot/batch No. labeled: 1555-105 New England Nuclear
- Radiochemical purity (if radiolabelling): ca. 70%
- Specific activity (if radiolabelling): 13.4 mCi/mmol
- Radioactivity: 5.88 mCi
- Locations of the label (if radiolabelling): [phenyl-14C(U)]-

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Kingston, NY
- Age at study initiation: adult
- Housing: singly
- Individual metabolism cages: yes
- Diet: Purina Rat Chow ad libitum
- Water: furnished water ad libitum
- Acclimation period: at least 2 weeks

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: 1. ointment from PEG 1540+PEG 400+propylene glycol; 2. unchanged

Duration of exposure:

168 and 192 hours

Doses:

Dermal 1: 3.7 mg/kg bw
Dermal 2: 1.5 mg/kg bw

No. of animals per group:

3

Control animals:

no

Details on study design:

Dose selection as requested by NIEHS

DOSE PREPARATION / APPLICATION
Dermal 1:
Vehicle: ointment
Composition: 9 g PEG 1540, 6 g PEG 400, 3 g propylene glycol
Concentration: 28 mg ointment + 2 mg labeled indigo (2.53 x 10E8 DPM)
Dosage: 1 cm² ointment: 3.7 mg/kg bw

Dermal 2:
applied as dry powder: 0.5 mg (6.3 x 10E7 DPM)
Dosage: 1 cm² dry powder: 1.5 mg/kg bw

TEST SITE
- Preparation of test site: clipping of fur on the back 20 to 24 hours prior treatment
- Area of exposure: 1 cm²
- Type of cover / wrap if used: occlusive hardback waxed paper + adhesive tape
- Time intervals for shavings or clipplings: 20 to 24 hours

SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: occlusive hardback waxed paper + adhesive tape glued to the animals' skin covered with elastic bandage also glued to the animals' skin

SAMPLE COLLECTION
- Tissues and body fluids sampled: urine, faeces, blood (plasma and red blood cells), selected tissues (see attached table)
- Time and frequency of sampling: see attached tables
- Time of sacrifice:
- Dermal 1: 192 hours
- Dermal 2: 1 rat - 168 hours; 2 rats - 192 hours

SAMPLE PREPARATION
- Preparation details: dermal 1: 28 mg ointment (9 g PEG 1540, 6 g PEG 400, 3 g propylene glycol) were molten at 40°C, 2 mg 14C-indigo were added and mixed with spatula
dermal 2: applied unchanged as dry powder

ANALYSIS
- Method type(s) for identification: Liquid scintillation counting; HPLC/scintillation spectrometry

Results and discussion

Signs and symptoms of toxicity:

no effects

Dermal irritation:

no effects

Absorption in different matrices:

see attached table

Total recovery:

dermal 1: 92.4% +/- 4.2%
dermal 2: 75.2% +/- 3.4%

Percutaneous absorption

Percutaneous absorption 1

Dose:

1.18 mg/cm²

Parameter:

percentage

Absorption:

2 %

Remarks on result:

other: 0-72 h

Remarks:

dermal 1: 3.7 mg/kg in ointment

Percutaneous absorption 2

Dose:

0.42 mg/cm²

Parameter:

percentage

Absorption:

0.7 %

Remarks on result:

other: 0-72 h

Remarks:

dermal 2: 1.5 mg/kg dry powder

Conversion factor human vs. animal skin:

no data

Any other information on results incl. tables

NA

Applicant's summary and conclusion

Conclusions:

Very low dermal absorption of indigo. Excretion via urine > feces. Only about 2% of indigo was excreted unchanged..
No potential for bioaccumulation of indigo or its metabolites was observed.

Executive summary:

The toxicokinetic properties of Indigo has been investigated in male rats (Research Triangle Institute: Absorption,
Distribution, Metabolism and Excretion of CI Vat Blue#I; Indigo; RTI/2227/00-04P, September 1983). For this purpose, radioactive labeled (¹⁴C) Indigo (radiochemical purity ca. 70%) was administered as a single intravenous injection (0.23 mg/kg bw), a single oral gavage (3.0; 31; 305 mg/kg bw) and a single dermal application (1.5 and 3.7 mg/kg bw).

The highest tissue levels after oral administration were found in liver and kidneys

Dermal administration: After dermal application of the ointment, 0.8% of the administered radioactivity were found in urine, feces and cage washes; after application of the dry powder, only 0.3% were found, leading to a very limited dermal absorption of indigo.

There were no hints for a possible bioaccumulation of indigo