1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail. No deficiencies.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Materials and methods

Objective of study:

other: To evaluate the toxicokinetics of 14C PAC in the rat. The fate and disposition of 14C in the rat tissues was followed by whole body autoradiography (WBA).

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

8 male and 8 female CD rats were dosed with 2.56 mg [14C]-labeled PAC by gavage. The distribution of the test substance was studied by WBA analysis. Excretion of radioactivity was followed over 4 days after dosing in urine, faeces and exhaled air. TLC and HPLC analyses were carried out on the urine samples for the detection of possible metabolites.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

EC Number:

224-675-8

EC Name:

1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

Cas Number:

4443-26-9

Molecular formula:

C14H15NO4

IUPAC Name:

6-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)hexanoic acid

Details on test material:

Lot/Batch number: S2015901
Specific activity: 8.87 μCi/mg
Purity: > 98% w/w

Details of label: C14 (carbonyl) labelled phthalic anhydride was reacted with caprolactam, so to obtain C14 labelled PAC.

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: not reported
- Weight at study initiation: males 236-270 g; females 215-246 g

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: ethanol and 10% Tween 80 solution in distilled water

Details on exposure:

Labeled PAC was dissolved in ethanol (51.2 mg in 2 ml) and diluted to 18 ml with a 10% solution of Tween 80 in distilled water.
Concentration in vehicle: 2.56 mg/ml (22.7 μCi/ml).
Total volume administered: 1 ml.

Duration and frequency of treatment / exposure:

Single treatment

Doses / concentrations

Remarks:

Doses / Concentrations:
2.56 mg/animal (22.7 μCi/animal)

No. of animals per sex per dose / concentration:

Male: 8 animals at 2.56 mg/animal = 22.7 μCi/animal
Female: 8 animals at 2.56 mg/animal = 22.7 μCi/animal

Control animals:

not specified

Details on dosing and sampling:

Samples:
Expired air, urine and faeces were collected/sampled as follows:
- Urine: At 8, 24, 72 and 96 hours
- Faeces: At 24, 48, 72 and 96 hours
- Expired air: At 2, 4, 8 and 24 hours.

Observations:
At 4, 8, 24, 48 and 96 hours one male and one female rat were weighed and sacrificed and prepared for whole body autoradiography (WBA). After 96 ours, heart blood was withdrawn from the remaining animals, whose carcasses were prepared for 14C analysis.

Throughout the study 14C activity was determined by liquid scintillation counting. Urine samples were analysed by TLC and HPLC for the detection of metabolites.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:

The 14C was extensively and rapidly absorbed from the gut, then rapidly excreted.

Details on distribution in tissues:

WBA showed similar tissue distribution. The tissues showing the highest levels of 14C were those associated with the major routes of excretion (liver - including bile ducts, kidney, bladder and intestinal tract). Other tissues showing low levels of radioactivity were the lungs, heart, muscle, testis, nasal turbinates, salivary gland and brown fat. After 24 hours only low levels of radioactivity remained, being confined to the liver, kidney and intestine At 48 and 96 hours all the organs and tissues are at background levels indicating that there is not accumulation or retention of the chemical.

Details on excretion:

The major route of excretion was in the urine, with approximately 90 - 92 % (males - females) of the dose accounted for in 96 hours with the majority excreted in the first 24 hours. Excretion via the faeces in 96 hours accounted for another 8 - 5 % (males - females) of the dose. The majority of the faecal 14C was in the first 24 hours in the male rats and in the 24 -72 hour period in the female rats. No exhalation of 14C CO2 was detected and no radioactivity was detected in samples of circulating blood. Only 1-2% of the administered dose was present in the carcase after 96 hours.

Metabolite characterisation studies

Metabolites identified:

no

Details on metabolites:

Chromatographic analysis (HPLC and TLC) of urine showed there to be at least six products of metabolism of which two accounted for approximately 80% of total urinary 14C. There did not appear to be any parent material present. The identity of the metabolism products was not established but they appeared to be the same as the test substance’s degradation products in urine (cfr. Section A6.2.3).

Any other information on results incl. tables

Mean 14C recovery (%) from rats dosed by gavage with labeled 6 -(phthalimido)hexanoic acid

	CO2	Urine					Faeces					Cage wash	Blood	Carcass	Total recovery
	Day 1	Day 1	Day 2	Day 3	Day 4	Total	Day 1	Day 2	Day 3	Day 4	Total
Males	0.00*	88	1.6	0.29	0.14	90	7.15	0.51	0.06	0.03	7.75	0.18	0.00*	1.24	99.03
Females	0.00*	80	9.4	1.73	0.45	92	0.11	0.60	4.66	0.10	5.47	0.26	0.00*	1.28	98.97

14C recovery (%) from rats dosed by gavage with labeled 6 -(phthalimido)hexanoic acid -- WBA results

	Sacrifice time (h)	CO2	Total Urine	Total Faeces	Cage wash	Total recovery
Males	4	0.00*	32.48	0.03	5.37	37.88
	8	0.00*	58.29	8.22	5.82	72.33
	24	0.00*	94.21	4.78	2.04	101.03
	48	0.00*	91.72	4.70	0.69	97.11
	96	0.00*	107.41	5.83	0.43	113.67
Females	4	0.00*	21.58	0.24	3.07	24.89
	8	0.00*	53.40	0.04	9.16	62.60
	24	0.00*	88.77	8.64	1.10	98.51
	48	0.00*	70.66	2.75	0.060.35	73.76
	96^1	0.00*	53.01	2.10	4.660.23	55.34

Applicant's summary and conclusion

Conclusions:

PAC is rapidly absorbed from the gut and rapidly excreted via the urine. No tissue retention was observed. PAC completely metabolised before the excretion.

Executive summary:

8 male and 8 female CD rats were dosed with 2.56 mg [14C]-labeled PAC by gavage. The distribution of the test substance was studied by WBA analysis. Excretion of radioactivity was followed over 4 days after dosing in urine, faeces and exhaled air. TLC and HPLC analyses were carried out on the urine samples for the detection of possible metabolites.

Rapid absorption and excretion of the test substance were observed. Urine was the main excretion route with 90-92% of the total dose excreted within 96 hours. 8-5% of the radioactivity were excreted via faeces within the first 24 hours. No radioactivity was detected in the exhaled air. After 96 hours only 1-2% of the administered radioactivity was detected in the carcass, mainly present in tissue related to the excretion routes. No parent compound was detected in the metabolite analysis of excreted urine. At least six metabolites were detected, of which two accounted for approximately 80% of total urinary¹⁴C.