3,3'-sulphonyldianiline

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP study performed acc to guideline. The read-across of toxicological data is considered justified because 4,4’-DDS (dapsone) and 3,3’-DDS are structural isomers with identical mol mass, identical elemental composition and identical functional groups. To the best of our knowledge, only Dapsone is used as a pharmaceutical. It is not known whether 3,3’-DDS acts as 4,4’-DDS as a folate synthesis inhibitor in microorganisms.The main toxicological hazard of 4,4’-DDS is the methemoglobin formation. This is due to the aromatic amine substituent of the molecule, which is present in both isomers. It is concluded that the main toxicological hazard of 3.3’-DDS is also methemoglobin formation. Both isomers do not show a structural alert for mutagenicity. The toxicological and ecotoxicological hazard profiles of both isomers are considered to be identical. A read-across 1:1 is considered reasonable and justified due to the very small structural difference of both substances.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dapsone

EC Number:

201-248-4

EC Name:

Dapsone

Cas Number:

80-08-0

Molecular formula:

C12H12N2O2S

IUPAC Name:

4,4'-sulfonyldianiline

Test material form:

other: gel

Details on test material:

Test material is dapsone plus DMGE (diethylene glycol monoethylether (excipient))

Test animals

Species:

rat

Strain:

other: Crl: CD(SD) albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

Age: Six weeks at initiation
Weight: Males 123-175 g, females 131-157 g

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

0.5%

Details on oral exposure:

10 ml/kg application volume
DMGE (excipient) = 180 mg/kg bw
Dapsone at 3, 30 and 100 mg/kg/day

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

90 days

Frequency of treatment:

1/day

No. of animals per sex per dose:

Each 10 males and 10 females,

Details on study design:

The study was performed with 5 groups:
Group 1: Control (vehicle only)
Group 2: 180 mg/kg/day diethylene glycol monoethylether (DMGE)
Group 3: 3 mg /kg/day dapsone
Group 4: 30 mg /kg/day dapsone
Group 5: 100 mg /kg/day dapsone

A satellite group was used for toxicokinetics

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined weekly

OPHTHALMOSCOPIC EXAMINATION: Yes

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on day 85

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on day 85

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Organs weighted: Adrenals, brain, kidneys, liver, ovaries, spleen, teses, thymus
HISTOPATHOLOGY: Yes
Main study animals in grous 1 (vehicle control), 2 (DGME control) and 5 (top dose 100 mg/kg/day) and gross lesions, liver, lungs, kidneys, target organs (spleen), and tumors from animals in groups 3 (3 mg/kg/day and 4 (30 mg/kg/day)

Other examinations:

Toxikokinetics: Samples obtained from three animals and group per time point at days 1 and 90 at 0 (immediately prior treatment), 0.5, 1, 2, 4, 8, 24 hours post-dose. The Cma, Tmax time of last measurable concentration (T last) and AUC 0-24 were determined.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

no mortality; skin discoloration (cyanosis) of mouth, nose, limbs, ears and body in 3/10 males (but no females) at 3 mg/kg/day and in both males and females at 30 mg/kg/day or above. Hypoactivity in both males and females at 30 mg/kg/day or above.

Mortality:

mortality observed, treatment-related

Description (incidence):

no mortality; skin discoloration (cyanosis) of mouth, nose, limbs, ears and body in 3/10 males (but no females) at 3 mg/kg/day and in both males and females at 30 mg/kg/day or above. Hypoactivity in both males and females at 30 mg/kg/day or above.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Significantly reduced in males at 100 mg/kg/day. Day 90 mean weights of group 1 and group 5 males were 561+/-74g and 457+/-25g, respectively. The body weight gains were reduced for all treatment groups relative to controls, differences not significant.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Significantly reduced in males at 100 mg/kg/day

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

At 30 mg/kg/day or above: Increased WBC count, decreased RBC count, decreased hemoglobin, reduced hematocrit (males insignificant trend only), increased mean corpuscular volume and mean corpuscular hemoglobin (males only), and increased prothrombin time.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

At 100 mg/kg/day: Males: increased albumin, bilirubin, BUN, ALT, γ-GT, potassium. Decreased levels of triglycerides and chloride. Females: Increased BUN, ALA, γ-GT, alkaline phosphatase and calcium and reduced chloride.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Increased (200-300% in males, 20-40% in females) spleen weights at 30 mg/kg/day or above . Increased (25%) liver weight in females at 30 mg/kg/day and above

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Enlarged spleen in males at 30 mg/kg/day or above. Small thymus at 30 mg/kg/day or above. Females: Uterine enlargement at 100 mg/kg/day.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Effects on spleen only. Mild splenic congestion and minimal extramedullary hematopoiesis were observed in male animals at 30 mg/kg/day and above. Minimal brown pigmentation of the spleen in males and females at 3 mg/kg/day or above.

Histopathological findings: neoplastic:

no effects observed

Effect levels

Dose descriptor:

NOAEL

Effect level:

>= 3 - < 30 mg/kg bw/day (actual dose received)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: Effects mainly due or secondary to methemoglobin formation

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

NOAEL is 3 mg/kg/day. Target organs are blood and spleen.

Executive summary:

In this 90d gavage study in the rat treatment-related findings were observed at 30 mg/kg/day. The main effects were cyanosis of the skin (dapsone is known to induce methemoglobinemia, and the cyanosis may be secondary to this), hyperactivity, increased WBC count, decreased RBC count, hemoglobin concentration and hematocrit., increased prothrombin time, spleenomegaly (especially in males), mild spleenic congestion, and mild pigmentation of the spleen. These effects were more observed at 100 mg/kg/day. No frank toxicity was observed at 3 mg/kg/day dapsone, although minimal brown pigmentation of the spleen was observed. 3 mg/kg/day is considered as the NOAEL in this study.