Ethanone, 2,2-dichloro-1-(2,3-dihydro-3-methyl-4H-1,4-benzoxazin-4-yl)-

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Biological phase April 1987 to May 1987; analytical phase May 1987 to July 1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Near-guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The dermal absorption of CGA154281 was determined over a 10 and 24 hour exposure period.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

2,2-dichloro-1-[(3R)-3-methyl-3,4-dihydro-2H-1,4-benzoxazin-4-yl]ethan-1-one; 2,2-dichloro-1-[(3S)-3-methyl-3,4-dihydro-2H-1,4-benzoxazin-4-yl]ethan-1-one

EC Number:

619-372-6

Cas Number:

98730-04-2

Molecular formula:

C11H11Cl2NO2

IUPAC Name:

2,2-dichloro-1-[(3R)-3-methyl-3,4-dihydro-2H-1,4-benzoxazin-4-yl]ethan-1-one; 2,2-dichloro-1-[(3S)-3-methyl-3,4-dihydro-2H-1,4-benzoxazin-4-yl]ethan-1-one

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

other: Sprague Dawley CD®BR

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Portage, Michigan, USA
- Age at study initiation: approximately 50-54 days
- Weight at study initiation: 200-300 g
- Further details in IUCLID 7.1.1 Report no. 82016 (CGA154281/0240)

Administration / exposure

Type of coverage:

other: nonocclusive

Vehicle:

unchanged (no vehicle)

Duration of exposure:

Single

Doses:

1, 10mg/rat

No. of animals per group:

16

Control animals:

no

Details on study design:

DOSE PREPARATION
- Method for preparation of dose suspensions: the low dose was prepared by mixing 15.7 mg of 14C-CGA154281, 46.6 mg of blank formulant (EC) and 500 mg of non-labelled metolachlor, then suspending the mixture in 25 mL water. The high dose was prepared by mixing 31.5 mg of 14C-CGA154281, 31.5 mg of blank formulant (EC) and 1000 mg of non-labelled metolachlor, then suspending the mixture in 10 mL water. These suspensions simulate a typical metoachlor 7.8 EC formulation containing 2.8% 14C-CGA154281.
- Application: 50 µL of 1.0 mg/rat or 100 µL of 10.0 mg/rat were applied with a displacement pipette and spread over the apprication area. After 5-10 minutes the entire area was enclosed by a nonocclusive covering.

TEST SITE
- Area of exposure: 10 cm2 (4.0 x 2.5 cm)
- Type of cover / wrap if used: a Stomahesive bandage was used to form a wall around the edge of the application area. After dosing, aluminium foil was glued onto the Stomahesive across the diameter of the dose area, to support filter paper that was then glued onto the Stomahesive; this enclosed the entire application area.
- Time intervals for shavings or clippings: on the day prior to dose application

SITE PROTECTION: yes, on the day of dosing, rear leg hobbles were fitted to prevent disturbance of the application site

REMOVAL OF TEST SUBSTANCE
- Washing procedures and type of cleansing agent: the treated skin area was washed twice with a detergent solution and rinsed with deionised water. Each washing was done with a sterile gauze square which was then placed in 50 mL of methanol.
- Time after start of exposure: 2, 4, 10 or 24 hours after application

SAMPLE COLLECTION
- Collection of blood: yes, at termination. Blood was collected at termination from the inferior vena cava.
- Collection of urine and faeces: a single continuous collection of urine and faeces from dose application until termination. Metabolism cages were washed with equal amounts of methanol and deionised water (approximately 500 mL total volume).
- Collection of expired air: no
- Skin from the application site was excised

SAMPLE PREPARATION
- Storage procedure:
- Preparation details: cage wash, bandage rinse, soap rinse, water rinse, paper rinse, aluminium foil rinse, solubilised skin and urine were aliquoted directly. Carcasses were ground with a Hobart food cutter and homogenised. Faeces were homogenised with dry ice and a micromill. Paper, gauze squares, faeces, blood and carcass homogenates were combusted using a Harvey Oxidizer.

ANALYSIS
- Method type(s) for identification (Liquid scintillation counting): the scintillation cocktail used for directly aliquoted samples was Scint-A. Combusted samples were assayed and counted in Oxosol-14C. Combustion efficiencies were determined using 14C-benzoic acid standard. All counting was by a Beckman Model LS-3801 and efficiencies determined by external standardisation.

Results and discussion

Signs and symptoms of toxicity:

no effects

Remarks:

(see cross-reference to other study)

Dermal irritation:

no effects

Remarks:

(see cross-reference to other study)

Total recovery:

10-hour exposure: total 14C recovery the 2, 4, and 10 hour time points ranged from 100.3 - 106.3% for the low dose level and 102.2% - 106.5% for the high dose level.
24-hour exposure: total 14C recovery mean values were 98.8% for the low dose level and 97.9% for the high dose level.

Percutaneous absorption

Percutaneous absorption 1

Dose:

1.0 mg/rat

Parameter:

percentage

Absorption:

49.4 %

Remarks on result:

other: 10 hrs

Percutaneous absorption 2

Dose:

1.0 mg/rat

Parameter:

percentage

Absorption:

55.7 %

Remarks on result:

other: 24 hrs

Percutaneous absorption 3

Dose:

10.0 mg/rat

Parameter:

percentage

Absorption:

25.4 %

Remarks on result:

other: 10 hrs

Percutaneous absorption 4

Dose:

10.0 mg/rat

Parameter:

percentage

Absorption:

27.5 %

Remarks on result:

other: 24 hrs

Any other information on results incl. tables

The actual doses were 0.88 mg/rat and 8.3 mg/rat equivalent to 0.088 and 0.83 mg/sq.cm for the 1.0 and 10.0 mg/rat dose levels respectively.

Total ¹⁴C mean recoveries ranged from 98.8-106.3% for the low dose level, and 97.9-106.5% for the high dose level. After a 10-hour exposure period, the total amount absorbed (excreta, blood, carcass, washed skin) was 49.4% and 25.4% for the low and high dosage levels, respectively. After a 24-hour exposure period, the total amount absorbed (excreta, blood, carcass, and washed skin) was 55.7% for the low dose level and 27.5% for the high dose level. The extra 14-hour exposure period between 10 and 24 hours did not significantly increase the amount of absorption of CGA154281. The rate of absorption of ¹⁴C-CGA154281 is inversely related to the dosage level. For all dosage levels, 3-33% was excreted in either a 10 or 24 hour period. The main route of excretion was via the urine. For both dosage levels, excretion values progressively increased from two to twenty-four hours.

The % of dose absorbed, unabsorbed and remaining in the skin after a soap and water rinse in animals treated with¹⁴C- CGA154281 at 1.0 mg/rat to 10 cm²of skin.

	2 hours (n=4)	4 hour (n=4)	10 hours (n=4)	24 hours (n=4)
Blood	0.01	0.07	0.14	0.09
Carcass	11.48	5.25	10.09	7.49
Urine	0.69	1.31	16.95	31.71
Faeces	0.00	0.00	0.07	2.24
	12.18	6.63	27.25	41.53
Skin I	27.59	21.60	22.14	14.18
Skin II	0.00	0.00	0.00	0.00
Total skin	27.59	21.60	22.14	14.18
Absorbed^1	39.77	28.23	49.39	55.71
Bandage	0.51	0.47	0.39	0.85
Foil rinse	0.09	0.12	0.09	0.25
Paper rinse	0.52	1.03	2.10	2.99
Paper	0.03	0.03	0.15	0.07
Soap rinse	57.38	61.42	43.16	32.39
Water rinse	5.52	5.88	4.29	3.06
Gauze A	1.81	1.91	1.33	0.90
Gauze B	0.10	0.08	0.09	0.05
Cage wash	0.52	1.10	1.19	2.49
Unabsorbed^2	66.48	72.04	52.79	43.05
Total^14C recovered	106.25	100.27	102.18	98.76

¹Summation of the blood, carcass, urine, faeces, skin I and skin II

²Summation of the bandage, foil rinse, paper rinse, paper, soap rinse, water rinse, gauze A, gauze B and cage wash

The % of dose absorbed, unabsorbed and remaining in the skin after a soap and water rinse in animals treated with¹⁴C- CGA154281 at 10.0 mg/rat to 10 cm²of skin.

	2 hours (n=4)	4 hour (n=4)	10 hours (n=4)	24 hours (n=4)
Blood	0.01	0.02	0.04	0.04
Carcass	0.83	1.73	2.17	3.59
Urine	0.74	0.94	4.53	10.17
Faeces	0.00	0.00	0.01	0.48
	1.58	2.69	6.75	14.28
Skin I	11.09	16.22	16.55	11.15
Skin II	4.63	4.82	2.13	2.08
Total skin	15.72	21.04	18.68	13.23
Absorbed^1	17.30	23.73	25.43	27.51
Bandage	1.10	0.39	1.24	0.72
Foil rinse	0.02	0.03	0.27	0.08
Paper rinse	0.11	0.18	0.26	0.49
Paper	0.01	0.01	0.01	0.02
Soap rinse	80.16	75.46	69.11	63.80
Water rinse	2.54	3.98	3.63	2.56
Gauze A	2.60	2.22	1.71	1.88
Gauze B	0.05	0.26	0.05	0.04
Cage wash	0.10	0.20	0.45	0.82
Unabsorbed^2	86.69	82.73	76.73	70.41
Total^14C recovered	103.99	106.46	102.16	97.92

¹Summation of the blood, carcass, urine, faeces, skin I and skin II

²Summation of the bandage, foil rinse, paper rinse, paper, soap rinse, water rinse, gauze A, gauze B and cage wash

Applicant's summary and conclusion

Conclusions:

The rate of absorption of 14C-CGA154281 is inversely related to the dosage level. For all dosage levels, 3-33% was excreted in either a 10 or 24 hour period. The main route of excretion was via the urine.

Executive summary:

A single dermal dose of 14C-CGA154281 was administered to two groups of 16 male Sprague Dawley CD BR rats, at dose levels of 1.0 or 10.0 mg/rat. Urine and faecal samples were collected. Four animals from each dose level were killed at 2, 4, 10 and 24 hours after application of the test material. After the appropriate exposure time, the test material was removed by washing.

Total 14C mean recoveries ranged from 98.8-106.3% for the low dose level, and 97.9-106.5% for the high dose level. After a 10-hour exposure period, the total amount absorbed (excreta, blood, carcass, washed skin) was 49.4% and 25.4% for the low and high dosage levels, respectively. After a 24-hour exposure period, the total amount absorbed (excreta, blood, carcass, and washed skin) was 55.7% for the low dose level and 27.5% for the high dose level. The extra 14-hour exposure period between 10 and 24 hours did not significantly increase the amount of absorption of CGA154281. The rate of absorption of 14C-CGA154281 is inversely related to the dosage level. For all dosage levels, 3-33% was excreted in either a 10 or 24 hour period. The main route of excretion was via the urine. For both dosage levels, excretion values progressively increased from two to twenty-four hours.