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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication meeting basic scientific principles

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1980

Materials and methods

Objective of study:
absorption
distribution
excretion
metabolism
Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 417 (Toxicokinetics)
Principles of method if other than guideline:
35S disulfiram (DSF), 7 mg/kg, was administered as a single dose to rats both orally (p.o.) or intraperitoneally (i.p.).
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 35S-disulfiram was prepared by the iodine oxidation of diethyldithiocarbamic acid (DDTC).
In this synthesis, 4 mmole of nonradioactive sodium salt of DDTC (Sigma Chemical Co., St. Louis, Mo., USA) was dissolved in 40 mL of double distilled water. To this mixture, 0.25 mmole (7.5 mCi) of 35S sodium DDTC (Amersham, Arlington Heights) was added. Iodine (2.15 mmole) dissolved in 10 mL of ethanol was then added to the 35S-DDTC solution and stirred briskly. The crystals (35S-DSF) which were formed from the reaction of 35S-DDTC and iodine, were then filtered over a fine glass frit. The crude material obtained was dissolved in 6 mL of ethanol and 1 mL distilled water. The ethanol and distilled water mixture was warmed slowly whit the temperature not exceeding 70ºC, until the crystals were dissolved. After cooling, the 35S-DSF crystals were recollected over a fine clean frit. The yield of 35S-DSF was approximately 60%.
Radiolabelling:
yes
Remarks:
35S-disulfiram

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Madison, Wisc., USA
- Age at study initiation: young adult
- Weight at study initiation: 150-250 g
- Fasting period before study: 24 h prior to drug administration
- Housing: groups of five in stainless steel wire-bottomed cages
- Individual metabolism cages: yes/no
- Diet (ad libitum): Purina Chow
- Water (ad libitum): tap water

ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
other: both, orally or i.p.
Vehicle:
other: The 35S-disulfiram was solubilized in polysorbate 80 and suspended in 0.5% methyl cellulose
Duration and frequency of treatment / exposure:
single dose
Doses / concentrations
Remarks:
Doses / Concentrations:
7 mg/kg either i.p. or p.o.
No. of animals per sex per dose:
3
Control animals:
no
Details on dosing and sampling:
Tissue analysis
Rats were given 35S-DSF in a dose of 7 mg/kg either i.p. or p.o., and then sacrificed by decapitation at 0.5, 2, 4, 6, 12, 24, and 48 hr following drug dosing. Exsanguinated blood was collected in citrate solution to prevent clotting. Tissue samples were removed, rinsed, blotted dry, und weighed. Tissues analyzed were liver, kidney, muscle, spleen, lung, stomach, testes, pancreas, thyroid, adrenals, brain, heart, skin, intestinal tract, and adipose layer. Three animals were used at each time period studied for each route of 35S-DSF administration. Approximately 100-300 mg of tissue sample was digested in a mixture of 0.8 mL of 70% perchloric acid and 0.4 mL of 30% hydrogen peroxide at 70ºC for 1 hr. Samples were allowed to cool to room temperature and then 20 mL of a triton X-100 scintillation cocktail was added. Samples were counted on a Beckman Scintillation counter (Model 1650). Appropriate corrections for quenching were made.

Gastrointestinal Tract Analysis
In a separate study 35S-DSF was given in a dose of 7 mg/kg either i.p. or p.o. and the animals then were immediately placed into stainless steel metabolism cages. The rats then were sacrificed by decapitation at 0.5, 1, 2, 4, 6, 12, 24, and 48 hr following drug administration. The intestinal tract plus contents (minus stomach) was removed and homogenized in a polytron homogenizer with 24 mL of 0.01 g EDTA/1% sodium chloride buffer, pH 8,5, and 6 mL of dimethyl sulfoxide (DMSO).


Breath, Urine, and Faeces Analysis
For the simultaneous collection of breath, urine, and faeces, animals were housed in a modified Roth-Delmar metabolism cage. The chamber was continuously vented with CO2-free air at a constant rate. Carbon disulfide in the expired air was collected by bubbling the air through a double trapping system containing a modified Viles reagent. Nonradioactive CS2 was determined spectrophotometrically. Radioactive CS2, was determined by taking 1 mL aliquots of the trapping solution and placing it in 15 mL of the triton X-100 scintillation cocktail and counted. Urine and faeces were collected in the metabolism cages separately. Aliquots of urine (50-100 mL) and faeces (200-300 mg) were treated similarly to the tissue samples and total radioactivity determined.

Disulfiram Metabolite Studies
Tissue analysis.
The time period at which the greatest radioactivity was found for each route of 35S-DSF administration was determined. One hour after i.p. and 5 hr after p.o. administration were the time periods selected. The 35S-DSF then was administered, and the rats sacrificed by decapitation 1 and 5 hr after dosing. Exsanguinated blood was collected in a citrate solution to prevent clotting. Tissues were excised and 35S-DSF metabolites determined as described previously.
Urine analysis.
A group of rats were given 35S-DSF i.p. and p.o., and immediately placed in stainless steel cages. Urine was collected for 48 hr and 35S-DSF and 35S metabolites determined.

Results and discussion

Main ADME resultsopen allclose all
Type:
absorption
Results:
The 35S DSF was rapidly absorbed by either route.
Type:
distribution
Results:
Kidney, pancreas, liver, and the gastrointestinal tract exhibited the greatest uptake of radioactivity, while the least was found in brain. Preferential tissue uptake was similar with both routes of administration.
Type:
metabolism
Results:
The 35S-DSF was rapidly metabolized to the 35S-diethyldithiocarbamate-glucuronide and 35S inorganic sulfate.
Type:
excretion
Results:
7% of the dose was excreted in the feces. Approximately 12% of the dose was eliminated by the breath as CS2. Most of the radioactivity is eliminated after 48 hr.
Type:
other:
Results:
Approximately 93% of the radioactivity was accounted for 48 hr after p.o. or i.p. 35S administration.

Toxicokinetic / pharmacokinetic studies

Details on distribution in tissues:
Radioactivity in the various tissues investigated peaked between 0.5 and 1 hour after i.p. (Table 1) and between 4 and 6 hr following p.o.35S-DSF administration (Table 2). Greatest uptake after i.p. dosing was found in kidney > pancreas > liver > largo intestine > small intestine > fat, while tissues exhibiting the least uptake were brain < muscle < heart < adrenal gland < testes. Generally, the p.o. route led to an uptake pattern similar that observed after i.p.35S-DSF. Only in the stomach was uptake greater after p.o.35S-DSF as compared to the i.p. route, which is not surprising since the stomach may not have been completely emptied. Furthermore, if uptake into tissues was compared either 1 hr after i.p. or p.o35S-DSF, or 6 hr after i.p. or p.o.35S-DSF, the rank order For each tissue uptake was similar. The dpm/g for each tissue studied after p.o.35S-DSF was found to be approximately 1/2 that observed after i.p. administration, reflecting greater bioavailability after i.p. dosing. After 48 hrs, approximately 93% of the dose of35S-DSF administered could be accounted for regardless of the route of administration.

Total tissue radioactivity 0.5 hr after i.p. 35S-DSF corresponded to approximately 23% of the total dpm administered, whereas 6 hr after p.o. 35S-DSF the tissues accounted for only about 10% of the radioactivity. After p.o. 35S-DSF, radioactivity in the tissues gradually increased, reflecting stomach emptying and drug absorption, and then declined at the same rate as that observed after i.p. administration.
Details on excretion:
Approximately 12% of the dose was eliminated as CS2. After either i.p. or p.o. dosing, radioactive CS2in breath was found within 2 hr. No urine was excreted for the first 4 hr after each route of administration.
After i.p. administration, total radioactivity in the tissues as the percent of35S-DSF administered declined in a biexponential manner, After p.o.35S-DSF, tissue radioactivity gradually increased peaking within 6 hr, The plasma decline was similar after both routes of administration. Radioactivity found in urine during the first 6 hr was less after p.o. than after
i.p. administration. This is due to the i.p. route being absorbed more rapidly und metabolized to water soluble metabolites that are subsequently excreted in the urine.

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
One and 6 hr after i.p. and p.o. dosing respectively, the greatest amount of35S in the tissues was due primarily to35S-DDTC-glucuronide and35S inorganic sulfate. These water soluble metabolites constituted approximately 80% of the radioactivity regardless of the route of administration. An exception to this was the pancreas and fat in which only approximately 19% of the radioactivity was due to the glucuronide and inorganic sulfate after i.p. dosing, while after p.o. administration approximately 50% was due to these water soluble metabolites. Also, more parent35S-DSF was found in fat tissue after i.p. than after oral administration. Greater amounts of35S-DSF also were found in the pancreas and fat after i.p. than after p.o. 35S-DSF.
lncreased35S in the kidney, liver, and intestinal tract appears to be due to water soluble metabolites. Even though the testes, adrenal gland, heart, muscle, and brain have a high blood flow, the rapid metabolism of 35S-DSF precludes the uptake of polar metabolites into tissue.

Any other information on results incl. tables

Table 1. Distribution of35S after i-p.35S-Disulfiram (% of35S-Disulfiram administered)

Tissue

Time (hr) after administration

0.5

1.0

2.0

4.0

6.0

12.0

24.0

48.0

Thyroid

0.0024

0.0028

0.0022

0.0022

0.0019

0.0018

0.0014

0.0017

Adrenals

0.0156

0.0054

0.0060

0.0041

0.0041

0.0025

0.0020

0.0014

Stomach

1.2259

0.3688

0.2521

0.2738

0.2841

0.3237

0.1826

0.1436

Muscle*

8.2965

4.5871

4.1079

3.7431

3.3109

2.1308

1.4491

1.0880

Brain

0.0627

0.0459

0.0459

0.0437

0.0442

0.0296

0.0222

0.0190

Liver

6.4349

2.8972

2.2768

2.3615

1.6110

1.0060

0.5057

0.3260

Testes

0.5389

0.4996

0.3162

0.3095

0.2646

0.1765

0.0972

0.0693

Kidney

1.6317

0.9493

0.6855

0.6102

0.5015

0.3160

0.1705

0.1131

Lung

0.4634

0.3053

0.3542

0.2506

0.2056

0.1227

0.0759

0.0704

Spleen

0.3851

0.1894

0.0979

0.0726

0.0606

0.0456

0.0284

0.0161

Heart

0.0972

0.0744

0.0637

0.0564

0.0479

0.0320

0.0179

0.0144

Blood**

3.8653

2.9395

3.5082

3.3053

2.7393

1.5999

0.9502

0.6005

Total

23.0296

13.0363

11.7166

11.0330

9.0724

5.7771

3.503

2.4658

Rats were given 7 mg/kg35S-disulfiram. i.p. and sacrified at the times indicated. Tissues were excised and radioactivity determined. Each value is the average of three rats.

* based on 40% of body weight

** based on 7% of body weight

 

 

 

Table 2: Distribution of35S after p.o.35S-Disulfiram (% of35S administered)

Tissue

Time (hr) after administration

0.5

1.0

2.0

4.0

6.0

12.0

24.0

48.0

Thyroid

0.0005

0.0005

0.0011

0.0015

0.0013

0.0010

0.0007

-

Adrenals

0.0008

0.0014

0.0029

0.0035

0.0017

0.0015

0.0010

0.0015

Pancreas

0.0537

0.0480

0.0465

0.056 1

0.1214

0.0463

0.0384

0.0268

Stomach

2.2113

0.9214

0.9082

1.1354

0.3621

0.2813

0.1616

0.1446

Muscle*

0.5244

1.3940

2.2860

2.8859

3.2715

1.8280

1.4048

1.0915

Brain

0.0058

0.0114

0.0150

0.0273

0.0405

0.0244

0.0251

0.0196

Liver

0.9807

1.8321

1.4673

2.2578

2.2330

0.9998

0.6483

0.4160

Testes

0.0172

0.0696

0.0989

0.1709

0.2614

0.1268

0.1030

0.0739

Kidney

0.2639

0.4171

0.4626

0.6616

0.7426

0.3501

0.1879

0.1331

Lung

0.0467

3.1392

0.1233

0.1782

0.2264

0.0987

0.0790

0.0539

Spleen

0.0217

0.0301

0.0291

0.0462

0.0670

0.0401

0.0400

0.0232

Heart

0.0224

0.0224

0.0278

0.0427

0.0562

0.0357

0.0226

0.0154

Blood**

0.8803

1.0310

1.4400

2.0520

2.9300

1.7698

1.2116

0.9135

Total

5.0771

5.9182

6.8963

9.5184

10.3169

5.6038

3.9246

2.9123

Rats were given 7 mg/kg35S-disulfiram. i.p. and sacrified at the times indicated. Tissues were excised and radioactivity determined. Each value is the average of three rats.

* based on 40% of body weight

** based on 7% of body weight

Table 3: Distribution and Excretion of Radioactivity after i.p.35S-Disulfiram (% of35S-Disulfiram administered, mean values)

 

 

Time (hr) after administration

 

12

24

48

Diverse tissues

5.78

3.5

2.47

Gastrointestinal tract

10.38 (5)

4.74 (5)

5.25 (4)

Urine

32.6 (5)

48.64 (5)

66.10 (4)

Faeces

-

-

6.75 (3)

Breath

10.34 (5)

10.97 (5)

12.64 (3)

Total

 

 

93.21

Number of rats in parenthesis

 

Table 4: Distribution and Excretion of Radioactivity after p.o.35S-Disulfiram (% of35S-Disulfiram administered, mean values)

 

 

Time (hr) after administration

 

12

24

48

Diverse tissues

5.60

3.92

2.91

Gastrointestinal tract

12.30 (5)

8.86 (5)

5.10 (4)

Urine

45.24 (5)

59.48 (5)

66.82 (4)

Faeces

-

-

6.52 (4)

Breath

8.82 (2)

10.70 (4)

11.00 (4)

Total

 

 

92.36

Number of rats in parenthesis

 

 

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): no bioaccumulation potential based on study results