Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1977
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1978
Report Date:
1977

Materials and methods

Objective of study:
metabolism
Test guideline
Qualifier:
no guideline followed
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source: Toluene-2-sulphonamide (m.p. 153ºC) was synthesized from toluene (Vogel, 1956).
- [Me-14C] Toluene-2-sulphonamide (1.7 µCi/mg), containing 0.05% of the 4-isomer, was obtained during the synthesis of [3-14C]saccharin (Ball, Renwick & Williams, 1977).

RADIOLABELLING INFORMATION (if applicable)
- Specific activity: 1.7 µCi/mg

FORM AS APPLIED IN THE TEST: animals were given [Me-14C]toluene-2-sulphonamide (6 pCi; 20 mg/kg in 20% ethanol in water (1 ml) or 10 pCi; 125 mg/kg suspended in 1% sodium carboxymethylcellulose or 12 pCi; 200 mg/kg in propylene glycol-water, 1 : 1, v/v (1 ml)).
Radiolabelling:
yes

Test animals

Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source:
- Age at study initiation:
- Weight at study initiation: 200-250 g
- Housing:
- Diet (e.g. ad libitum):
- Water (e.g. ad libitum):
- Acclimation period:

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

IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: 20% EtOH in water, 1% sodium carboxymethylcellulose or propylene glycol - water (1:1 v/v)
Duration and frequency of treatment / exposure:
Single dose
Doses / concentrationsopen allclose all
Dose / conc.:
20 mg/kg bw/day (nominal)
Dose / conc.:
125 mg/kg bw/day (nominal)
Dose / conc.:
200 mg/kg bw/day (nominal)
No. of animals per sex per dose:
3 females per dose
Control animals:
yes, concurrent no treatment
Details on dosing and sampling:
METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled: urine, faeces
- Time and frequency of sampling: Urine and faeces were collected daily and analysed for 14C content.
- From how many animals: 3 (samples pooled)
- Method type(s) for identification: TLC , GC, GC-MS; confirmation: NMR, UV-Vis, IR

- Preparation: The 0-48 h pooled urine (90 ml; after 200 mg/kg) was adjusted to pH 5 and incubated for 5 days with ketodase (40 000 units) and glucuronidase / sulphatase (3000 units of sulphatase) at 37ºC. TLC (solvent 1: chloroform-methanol-aq. NH, soln. (sp. gr. 0.88) (100 : 50 : 11.5,
by vol.)) showed that during this time band A and part of band C (RF = 0.48) were slowly lost, whilst bands D and E showed corresponding increases. The incubation mixture was freeze dried and all the 14C extracted into methanol (4 x30 ml) which was evaporated under reduced pressure. Bands corresponding to the main 14C metabolites were separated by thick-layer chromatography (solvent 1) and purified by chromatography using the aforementioned solvents. 14C Metabolites were separated by t.l.c. in solvent 1. The proportion of the 14C in each band was determined by scintillation counting. The metabolites in each band were isolated by thick-layer chromatography and characterized.
1. TLC: separation of metabolites was achieved using 20 x 20 cm plates coated with silica gel HF254 (1 mm layer). The 14C bands were removed from the plate and eluted with methanol until the silica contained less than 3% of the radioactivity. The eluate was evaporated to small vol. at 4ºC under reduced pressure.
2. GC: Method 1: A methanol soln. of the compound or metabolite (10 µl) was mixed with MethElute (10 µl). On-column methylation was achieved by injecting 4 µI into a Packard 427 Gas Chromatograph fitted with 2 m glass columns (2 mm i.d.) packed with 3% SE30 on Chromosorb W. Injection and detector blocks were maintained at 280ºC, the oven at 135ºC and the carrier (nitrogen) flow rate was 18 ml/min. / Method 2: A pyridine soln. of the material was mixed with Regisil and heated at 100ºC for 20 min. A portion (2 µl) was injected into a Packard 427 set up as for method 1 but with a column temp. of 175ºC.
3. GC-MS: Samples were derivatized as for GC and injected into a Pye 104 g.l.c. fitted with a 2 m column of 3% OV-1 on diatomite CQ (100-200 mesh) at 195ºC and a helium flow rate of 40 ml/min. Mass spectra of the g.l.c. eluates were recorded using an AEI MS30 Mass Spectrometer at 70 eV.

Results and discussion

Main ADME resultsopen allclose all
Type:
metabolism
Results:
The main metabolite of [Me-14C]toluene-2-sulphonamide in rat and man is 2-sulphamoylbenzyl alcohol with smaller amounts of saccharin, 2-sulphamoylbenzoic acid, N-acetyltoluene-2-sulphonamide, and with little excreted as unchanged compound.
Type:
excretion
Results:
20 mg/kg doses were rapidly eliminated by rats (92% in 24 h), mostly in urine (88%) with little (5%) in the faeces. Larger oral doses were eliminated more slowly but the overall distribution of 14C between urine and faeces was unchanged.

Toxicokinetic / pharmacokinetic studies

Details on excretion:
After oral administration of [Me-14C]toluene-2-sulphonamide an average of 94% of the 14C was recovered, mostly in the urine and with little (5-7%) in the faeces. The urine contained about 78% of the 14C at all dose levels, but the rate of elimination decreased with increase in dose. Thus the 14C in the 0-24 h urine decreased (79, 58 and 36% of dose), while the 24-48 h elimination increased (7, 14 and 33% of dose) with increase in dose (20, 125 and 200 mg/kg respectively).

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
The main metabolite of [Me-14C]toluene-2-sulphonamide in rat and man is 2-sulphamoylbenzyl alcohol with smaller amounts of saccharin, 2-sulphamoylbenzoic acid, N-acetyltoluene-2-sulphonamide, and with little excreted as unchanged compound.
The results presented in this paper confirm that acetylation of the sulphonamide groups of simple alkylbenzene sulphonamides occurs to a small extent. The presence of saccharin as a minor metabolite of toluene-2-sulphonamide in the rat and major metabolite in man suggests that at some stage in the oxidation of toluene-2-sulphonamide to 2-sulphamoylbenzoic acid cyclization occurs and that the extent of this process shows species differences.

Any other information on results incl. tables

Table 1. Elimination of 14C by rat and given [14C]toluene-2-sulphonamide orally

Species

(no., sex)

Dose

Time

(d)

% of dose of 14C in (CL)

mg/kg

µCi/individual

Urine

Faeces

Total

Rat (3F)

20

6

1

79 (72-87)

3.7 (2.0-5.7)

92 ( 83-1 02)

2

7 (4-10)

0.5 (0.5-0.6)

9 (6-13)

7

88 (80-94)

4.5 (2.7-6.4)

104 (93-110)

(cumulative total)

 

 

 

Rat (3F)

125

10

1

58 (54-62)

4.4 (2.4-7.0)

70 (64-75)

2

14 (5-28)

1.3 (0.3-30)

16 (6-32)

7

72 (63-85)

5.9 (2.8-10.5)

87 (74-110)

(cumulative total)

 

 

 

Rat (3F)

200

20

1

36 (22-46)

4.2 (1.7-5.9)

43 (27-55)

2

33 (25-41)

1.9 (0-3.7)

38 (28-49)

7

75 (69-83)

7.0 (5.9-8.9)

90 (85-98)

(cumulative total)

 

 

 

 

Applicant's summary and conclusion

Conclusions:
The test item was eliminated mostly in urine (88%) and a little in faeces (5%), rapidly at low doses and more slowly as the dose increased. The main metabolite in rat and man is 2-sulphamoylbenzyl alcohol with smaller amounts of saccharin, 2-sulphamoylbenzoic acid, N-acetyltoluene-2-sulphonamide, and with little excreted as unchanged compound.
Executive summary:

A study on the metabolism and excretion of the test item (14C-labelled) was performed in female Wistar rats. A single dose of 20, 125 or 200 mg/kg radiolabelled test item was administered via oral gavage to 3 females each and the concentrations of the test item in urine and faeces were determined daily by TLC and GC-MS. The metabolites were identified and quantified. A study in humans (2M, 1F) was conducted in parallel to observe similarities. The 20 mg/kg doses were rapidly eliminated by rats (92% in 24 h), mostly in urine (88%), with little (5%) in the faeces. Larger oral doses were eliminated more slowly but the overall distribution of 14C between urine and faeces was unchanged. The main metabolite of [Me-14C] toluene-2-sulphonamide in rat and man is 2-sulphamoylbenzyl alcohol with smaller amounts of saccharin, 2-sulphamoylbenzoic acid, N-acetyltoluene-2-sulphonamide, and with little excreted as unchanged compound.