Diisononyl adipate

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of 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:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

yes

Remarks:

urine and fecal excretion was not measured

Principles of method if other than guideline:

Yes, see description of method below.

GLP compliance:

yes (incl. QA statement)

Remarks:

Midwest Research institute

Test material

Test material information

Constituent 1

Reference substance name:

Bis(2-ethylhexyl) adipate

EC Number:

203-090-1

EC Name:

Bis(2-ethylhexyl) adipate

Cas Number:

103-23-1

Molecular formula:

C22H42O4

IUPAC Name:

bis(2-ethylhexyl) adipate

Test material form:

liquid

Specific details on test material used for the study:

- Name of test material (as cited in study report): DEHA
- Analytical purity: >99.7%
- Impurities (identity and concentrations): no data

Radiolabelling:

yes

Remarks:

Radiolabeled material was prepared by NEN (Boston), and supplied through the CMA. Lot No. 1679-109, specific activity 32.2 mCi/mmol. Radiochemical purity 98.9% (TLC). HPLC analysis by MRI showed >97%.

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Lab. (Wilmington, Massachusetts).
- Age at study initiation: 50-57 days
- Weight at study initiation: 14-24 gram
- Fasting period before study: 18 hours prior to dosing
- Individual metabolism cages: yes
- Diet: ad libitum
- Water :ad libitum
- Acclimatisaton period: at least 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68-72:
- Humidity (%): 40-60
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

The mice were dosed orally with 14C-DEHA at the low, mid, or high dose (50, 500 and 5000 mg/kg).

Duration and frequency of treatment / exposure:

once

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

50 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

500 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

5 000 mg/kg bw/day

No. of animals per sex per dose / concentration:

hydrolysis and absorption: 6 animals per sex and dose group
hydrolysis and absorption repeat: 3 animals per sex and dose group
preliminary disposition (only males): 2 males per dose group
disposition: 4 animals per sex for the low and high dose group, 8 animals per sex for the high dose group

Control animals:

no

Positive control reference chemical:

no data

Details on study design:

Three groups of four male and four female mice each were treated orally with the low, mid, or high dose levels of 14C-DEHA
(50, 500 and 5000 mg/kg) and were placed in individual glass metabolism cages (Delmar-Rath type).
Expired air, urine, and feces were collected during 0-6, 6-12, and 12-24 hr intervals following dosing.
The expired 14 C02 was trapped with 5-Methol-amine in 2-methoxyethanol. Other volatile products were collected in
methanol:water (50:50).
Urine was collected in containers kept on dry ice. After each collection, the cages were rinsed and the cage washings were measured
and analyzed.
At 24 hr, the mice were anesthesized with ether, blood was withdrawn by cardiac puncture, and the following tissues and organs were
removed, weighed, and assayed for 14-C content: Liver, Spleen, Urinary bladder, Kidneys, Adrenals, Skeletal muscle, Lungs, Testes ,
Retroperitoneal tissue, Brain, Epididymides, GI tract plus contents, Heart, Skin, pancreas, ovaries and uterus.

Portions of blood were centrifuged to separate plasma and red blood cells (RBC's). Bladder contents were removed and the bladder was
washed thoroughly with 0.9% saline. The contents and washings were combined with the final urine samples and analyzed.
Blood and tissues were kept on ice during the necropsy procedures. Sample preparatian and analyses were performed immediately after collection, or the samples were frozen until analyzed. The remaining tissue and excreta were stored frozen.

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : Expired air, urine, and feces, cage washes, and:
blood, Liver, Spleen, Urinary bladder, Kidneys, Adrenals, Skeletal muscle, Lungs, Testes ,
Retroperitoneal tissue, Brain, Epididymides, GI tract plus contents, Heart, Skin, pancreas, and ovaries and uterus.
- Time and frequency of sampling: Expired air, urine, and feces and cage washings during 0-6, 6-12, and 12-24 hr intervals following dosing.
Other tissues at sacrifice after 24 hrs.


METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine, GI-content
- Time and frequency of sampling: 24 hrs
- From how many animals: samples pooled
- Method type(s) for identification: HPLC-MS-MS

Statistics:

The means ± standard errors were calculated for each test group with a programmable calculator. Data were subjected to analysis of variance.
Significant F-ratios were then analyzed by Dunnett's procedure. Significant differences were indicated when p < 0.05.

Results and discussion

Preliminary studies:

A preliminary study in males only:
Absorption
dose mg/kg: 50, 500, 5000
Urine +expired air : 81% 86% 67%

excretion (24 hr)
dose mg/kg: 50, 500, 5000
Urine +expired air+ feces : 94% 101% 75%

Toxicokinetic / pharmacokinetic studies

Details on absorption:

At 24 hr
dose mg/kg: 50, 500, 5000
Urine +expired air: 92-94% 98-100% 67- 76%

Details on distribution in tissues:

Levels in organs were low (< 0.3%) . From all tissues examined the liver and kidneys showed the highest level ( 0.1-0.2% and 0.03-0.086% resp.).
Also in the GI-tract the levels were relatively high, and highest in 5000 mg/kg group (12%).

Details on excretion:

At 24 hr
dose mg/kg: 50, 500, 5000
Urine +expired air+ feces : 97-98% 98-100% 69-81%

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

The GI tract contained the diester, monoester, and the alcohol, and traces of the polar material.
The liver contained primarily the oxidation products.
The urine contained major amounts of the oxidation products and their conjugated derivatives. Although the liver
profiles did not contain appreciable amounts of the less polar metabolites, these products may have been excreted shortly following formation.

Metabolites identified:
MEHA : monoethylhexyladipate
EH: ethylhexanol and EH glucuronide
EHA: ethylhexanoic acid, and EHA glucuronide
DiEHA: ethylhexanedioic acid

Any other information on results incl. tables

Hydrolysis and Absorption: 14C-DEHA and/or its metabolites was rapidly absorbed from the GI tract. The highest 14C levels were found in blood and liver 1 or 3 hr after dosing. In the GI tracts large amounts of the diester (DEHA) , monoester(MEHA)and alcohol (EH) were found. The quantities of DEHA decreased with time while other products increased. The major metabolites in the livers were more polar than EH. In general, only small amounts of DEHA, MEHA and EH were found. The livers of male mice also contained large amounts of an early eluting metabolite which was found in female livers in only small quantities. The extent of the two major metabolites recovered in livers of female mice differed significantly.

 

Disposition:

Preliminary studies with males: after treatment with 50 and 500mg/kg 14C-DEHA, 95-102% was eliminated in urine, feces and expired air within 24 hr. After 5,000 mg/kg, most of the 14C was excreted in 24 hr but ~12% were also recovered in the GI tracts.

Definitive studies with male and female mice (50, 500 and 5,000 mg/kg 14C-DEHA): urinary elimination of 14C was rapid and extensive. About 91% of the low and mid doses were eliminated in urine in 24 hr; only 75% after 5,000 mg/kg. Elimination in feces was 7-8% at the low and mid doses and 4% at the high dose. The latter group showed high recovery in the GI tract. Only 0.8 to 1.2% in males and 1.5 to 3.8% in females were eliminated in the expired air. Respiratory elimination was highest in the female low dose group. Only small amounts were found in blood and tissue 24 and 48 hr after dosing. Adrenals and livers showed the highest levels at low and mid dose, especially in males. After 5,000 mg/kg, blood also contained high 14C levels; blood and liver content of the females were significantly higher than of males. At 48 hr, the skin (both sexes) and the fat (females) showed higher retention of 14C than other tissues.

The high recovery in the GI tract following the high dose (12%) may account for the lower elimination in feces.