2-(2-aminoethylamino)ethanol

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Reference 2

Reference Type:

publication

Title:

Toxicokinetic Profile of N-(2-Aminoethyl)ethanolamine in the Female Wistar Rat and Distribution into the Late Gestation Fetus and Milk

Author:

Moore, N.P. et al.

Year:

2012

Bibliographic source:

Birth Defects Research Part B: 95:107–115 (2012)

Materials and methods

Objective of study:

toxicokinetics

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-aminoethylamino)ethanol

EC Number:

203-867-5

EC Name:

2-(2-aminoethylamino)ethanol

Cas Number:

111-41-1

Molecular formula:

C4H12N2O

IUPAC Name:

2-[(2-aminoethyl)amino]ethan-1-ol

Details on test material:

- Name of test material (as cited in study report): AEEA (2-(2-aminoethylamino)ethanol)
- non-radiolabeled AEEA was from BASF, purity 99.8%. Uniformly 14C-radiolabeled AEEA was supplied
by Moravek Biochemicals, Brea, California.
- Analytical purity: Radiolabeled: 98.0 % (ACL-2003-57), Non-Radiolabeled: 99.8 % (BASF reference 01L00492)
- Specific activity: 60 mCi/mmol
- Locations of the label: Uniformly 14C-labeled

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hilltop Lab Animals, Inc. (Scottdale, Pennsylvania)
- Age at study initiation: 11-12 weeks old
- Weight at study initiation: females 249-279 g, females pregnant, 336-397 g (gestational day 18)

- Housing:
- one per cage in glass Rothtype metabolism cages, in rooms designed to maintain adequate
conditions of temperature, humidity and photocycle
- the metabolism cages were designed for the separation and collection of urine, feces, CO2, and expired volatiles
- air was drawn through the metabolism cages at ~ 500 ml/minute.

- Individual metabolism cages: yes

- Diet:
- LabDiet Certified Rodent Diet #5002 (PMI Nutrition International, St. Louis, Missouri) in pelleted form, ad libitum
- animals receiving an oral administration, feed was withdrawn approximately 16-hours prior to the
administration of AEEA and was returned about 4-hours post-dosing

- Water: municipal water, ad libitum
- Acclimation period: 2 days


ENVIRONMENTAL CONDITIONS

- Temperature (°C): 22 +/- 1 °C
- Humidity (%): 40-70 %
- Air changes (per hr): 12-15 times
- Photoperiod (hrs dark / hrs light): 12 hour

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

Oral:

PREPARATION OF DOSING SOLUTIONS:
- the oral dose solution was prepared as a solution in deionized water. Appropriate amounts of
14C-labeled and/or non-radiolabeled AEEA were added to obtain the target doses
of 0.5 or 50 mg AEEA/kg bw.

Radioactivity in the dose solutions was quantified by liquid scintillation spectrometry (LSS) as described below.
The amount of oral dose solution administered was targeted at ~5 g/kg bw. The target radioactivity was ~75 μCi/kg.

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
- the AEEA has been reported to be stable in distilled water for 8 days (Stott et al., 1991).
- concentration of AEEA in the dose solution was analyzed in accordance with the standard operating procedures of
the Analytical Chemistry Laboratory. LSS analysis of aliquots of the 14C-labeled dosing solution taken from various
locations in the solution container were used to confirm the concentration of radioactivity and the homogeneity of
the 14C-AEEA in the dosing solution.


Dermal:

TEST SITE
- Area of exposure: ~12 cm² (4 cm x 3 cm)
- % coverage: 100
- Type of wrap if used: the application site was semi-occluded by covering with Teflon Spectra/Mesh macroporous
filter material



REMOVAL OF TEST SUBSTANCE
- Washing: skin washing 8-hours post application
- rats were fitted with rodent jackets containing dermal inserts

TEST MATERIAL
- the amount of the dermal dose solution applied was ~ 384 μL area
- concentration: target concentration of dose solution 250 mg/mL


USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Duration and frequency of treatment / exposure:

- a single oral administration 14C-AEEA
- a single dermal application 14C-AEEA

Doses / concentrations

Remarks:

Doses / Concentrations:
Oral:
- 3 female Wistar rats, 0.5 mg/kg bw
- 3 female Wistar rats, 50 mg/kg bw
- 3 female Wistar pregnant rats, 50 mg/kg bw (dosed on day 18 of gestation)

- 2 additional pregnant and 2 additional non-pregnant rats dosed at 50 mg/kg bw
(sacrificed at the time of maximum plasma radioactivity (Cmax; 0.5 hours))

Dermal:
- 8 female Wistar rats, 8-hour application of 25 % solution of 14C-AEEA (32 μl/cm² x 12 cm² skin; 480 mg/kg bw)

No. of animals per sex per dose / concentration:

- 3 rats (oral)
- 8 rats (dermal)

Control animals:

no

Positive control reference chemical:

none

Details on study design:

- Dose selection rationale:

The dose levels for this study were selected to provide measurable concentrations of plasma radioactivity
after oral administration or dermal application to rats and were based on previous toxicity studies.
The dose levels of 0.5 and 50 mg/kg bw were chosen to examine oral absorption of AEEA and
are several orders of magnitude lower than reported LD50 (Lockwood and Borrego, 1980).
In the OECD 421 study, the lowest dose was 50 mg/kg bw (Schneider et al., 2003).
The dermal application amount selected (32 μl/cm2 x 12 cm2 skin; 480 mg/kg bw) was equivalent,
on a mg/cm² skin basis, to that applied in a 28 day dermal toxicity study (Stott et al., 1991).

Details on dosing and sampling:

- Tissues and body fluids sampled: urine, faeces, blood, plasma, serum, cage washes, kidney, liver,
carcass, blood (terminal), application-site skin, skin

- Time and frequency of sampling:
- blood: samples of 0.2 ml were collected at the intervals 0.0-, 0.25-, 0.5-, 1-, 2-, 4-, 6-, 8-, 12-, 24-,
36-, and 48-hours post application (the plasma was centrifuged and the radioactivity was counted)
- urine: samples were collected in dry-ice cooled traps at 12-, 24-, 36-, and 48-hours post-administration and examined
for radioactivity (selected samples were additionally analyzed using liquid chromatography (HPLC) to obtain profiles of
radiolabeled metabolites)
- feces: samples were collected at 24-hours intervals and analyzed for radioactivity
- Expired volatiles: air was drawn through a charcoal trap at approx. 500 ml/min. Charcoal was changed at 24-hr intervals
during 48 hours. (trapped radioactivity was desorbed with toluene and analyzed)
- Expired CO2: following the charcoal trap the expired air was passed through a solution containing monoethanolamine and
1-methoxy-2-propanol to trap CO2 and analyzed for radioactivity. The trap was changed at 12-hr intervals during 24 hours.
- Carcass, organs: at termination, the anaesthetized animals were exsanguinized via cardiac puncture. Terminal blood,
kidney, liver, skin, and carcass were collected and analyzed for radioactivity.
- Unborn fetuses were humanely killed and examined with the carcass.

Statistics:

Descriptive statistics were conducted, (i.e., mean and standard deviation. Samples with dpm less than twice the concurrently run background (blanks) were considered to contain insufficient radioactivity to reliably quantify. Non-quantifiable excreta samples (urine/rinse/feces/CO2/expired volatiles) were identified in the tables as NQ and a value of ‘0’ used in calculations. For tissues, when a sample was nonquantifiable, that sample was assigned the quantitation limit (QL) for calculations and displayed as NQ with the quantitation limit in parenthesis. The mean was calculated from actual values and calculated QL values and presented as Mean ± SD, unless greater than ½ of the values are presented as NQ, in which case the mean was expressed as NQ(Mean) ± SD. If all tissue values were NQ the mean was presented as NQ (QL) with SD displayed. Quantitation limits (as a fraction of administered dose) were calculated using a formula. All calculations in the database were conducted using Microsoft Excel spreadsheets and databases in full precision mode (15 digits of accuracy). Certain pharmacokinetic parameters were estimated from the plasma 14C concentration-time course including AUC (area-under-curve), Cmax, ½Cmax, elimination rate constants, half-lives, apparent volume of distribution and clearance, using PK Solutions (Summit Research Services, Montrose, Colorado), a pharmacokinetic computer modeling program or Microsoft Excel. Log-linear regression analysis of the interval 14C-excretion rate data was used to estimate the urinary half-lives of excretion of the radiolabel. Statistical analysis (t-test) of selected datasets was performed with Prism v4.0 (Graphpad Software, Inc., San Diego, California).

Results and discussion

Preliminary studies:

no preliminary study was performed within this study

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Following a single oral administration, 14C-AEEA was rapidly absorbed by female Wistar rats. Maximum plasma levels were noted at 0.5 hrs after dosing in non-pregnant rats given 0.5 or 50 mg/kg bw, and at 1.0 hrs in pregnant rats at 50 mg/kg bw. Maximal plasma concentrations approx. 100-fold higher were noted at 50 mg/kg bw than at the 0.5 mg/kg bw dose. Absorption was >85 %  within 48 hours in all dose groups, based on the recoveredradioactivity in urine, tissue, cage wash, and expired air.

Details on distribution in tissues:

Tissue distribution following oral administration:
At termination, the radioactivity in tissues was low, and there was no statistically significant difference between dose groups, or between pregnant and non-pregnant animals. 

Details on excretion:

Excretion was rapid and occurred mainly via urine, with approx. 85-98 % of the oral dose recovered in the 0-48 hour urine, 5.2-11.5 % in feces, and 0.02-0.03 % in expired volatiles and as 14CO2. In tissues 2.3 to 3.0 % of the administered radioactivity was recovered. The overall recovery ranged between 99 and 107 %.
Some dose-dependency was seen when the amount of administered dose recovered in the urine of the 0.5 mg/kg bw low dose group was 12 % greater than in the 50 mg/kg bw dose group (p< 0.05). 
The total recovery in the low dose group was higher (98 %) than in the high dose groups (85.2 and 86.6 %).

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

Plasma: 
In samples collected at T(max) (time at which maximal plasma levels were noted) from the high dose pregnant and nonpregnant groups only the parent compound AEEA was found.
Urine:
Four components (A-D) were noted in selected urine samples from all oral dose groups. The percentage of the administered dose was approx. as follows:  A 5-10 %  (not identified) B 11-20 % (not identified) C 5-11 %  (N-acetyl-AEEA) D 55-65 % (AEEA).
No substantial differences in metabolic profile were noted between dose level or pregnancy status. Preliminary identification efforts showed that the metabolite D was the  parent compound AEEA, and C was N-acetyl-AEEA. Metabolites A and B were determined not to be ethylenediamine, ethanolamine, or the corresponding acetyl analogs.

Any other information on results incl. tables

The plasma elimination of orally administered 14C-AEEA was biphasic, with alpha and beta elimination t1/2 values of 1.6-1.8 hours and 16.7-17.3 hours, respectively. 
Bioavailability of AEEA was fairly linear with dose, though the low oral dose group also had a higher relative plasma AUC than the high oral dose group (p<0.05). No statistical significant difference was noted between the pregnant and non-pregnant groups.
No significant differences were seen in absorption or distribution between non-pregnant and pregnant rats given 50 mg 14C-AEEA/kg bw by the oral route. 

 

The pharmacokinetic parameters per animal group may be summarized as follows:

		0.5 mg/kg bw oral Non-pregnant	50 mg/kg bw oral Non-pregnant	50 mg/kg bw oral Pregnant	480 mg/kg bw dermal Non-pregnant
Plasma AUC    0-24 hr	[µg-hr/ml]	1.3 ± 0.1	95.0 ± 12.9	117.1 ± 9.7	13.7 ± 0.8
Plasma Absorption	t1/2 [hr]^a	0.1 ± 0.1	0.2 ± 0.1	0.2 ± 0.1	na
Plasma Elimination	t1/2 [hr]^b	1.8 ± 0.1	1.8 ± 0.1	1.6 ± 0.3	na
Plasma Elimination	t1/2 [hr]^c	17.3 ± 0.7	17.1^e± 0.9	16.7 ± 0.7	na
Urine	t1/2 [hr]^d	6.0 ± 0.3	6.1 ± 0.5	7.9 ± 0.3	5.7^g

a        calculated from 0-0.5 hr values

b        calculated from 1-6 hr values        

c        calculated from 8-48 hr values                        

d        calculated from 0-48 hr values

e        n = 2

f         calculated from actual and quantitation limit values        

g        calculated from mean 8-12 and 12-24 hr values

Tissue distribution following oral administration: At termination, the radioactivity in tissues was low, and there was no statistically significant difference between dose groups, or between pregnant and non-pregnant animals. 

Percentage of administered dose retained in tissues

	0.5 mg/kg bw oral Non-pregnant	50 mg/kg bw oral Non-pregnant	50 mg/kg bw oral Pregnant
Carcass	1.68 ± 0.39	1.19 ± 0.07	2.20 ± 0.34
Kidneys	0.29 ± 0.18	0.14 ± 0.06	0.13 ± 0.01
Liver	0.47 ± 0.07	0.33 ± 0.02	0.58 ± 0.09
Skin	0.65 ± 0.29	0.64 ± 0.15	0.42 ± 0.07
Total Tissue	3.09 ± 0.67	2.30 ± 0.09	3.33 ± 0.49

 

Values represent mean and SD (N=3)

Applicant's summary and conclusion

Executive summary:

In a metabolism study AEEA [(98.0 % a.i.), uniformly 14C-labeled] was administered to 3 pregnant or non pregnant female Wistar rats per sex/dose in single doses by gavage at dose levels of 0.5 or 50 mg/kg bw. In addition AEEA was dermally administered for 8 hours to 8 non pregnant rats at a dose level of 480 mg/kg bw.

Following a single oral administration, 14C-AEEA was well absorbed by female Wistar rats, with 85.21 - 98.18 % of the dose recovered in the 0-48 hour urine, 5.16-11.51 % in feces, and 0.02 - 0.03 % in expired volatiles and 14CO2. Some dose-dependency was seen for oral absorption, where the amount of administered dose recovered in the urine of the 0.5 mg/kg bw dose group was 12 % greater than in the 50 mg/kg bw dose group (p< 0.05). The low oral dose group also had higher relative plasma AUC than the high oral dose group (p< 0.05). No significant differences were seen in absorption or distribution between non-pregnant and pregnant rats given 50 mg 14C-AEEA/kg by the oral route. Overall recovery of radioactivity following an 8-hour dermal application of a 25 % solution of 14C-AEEA in water (32μl/cm² x 12 cm²; 480 mg/kg bw) was 90.97 %. Excluding radioactivity recovered from the remote-site skin, the amount of absorbed testmaterial, as measured in excreta, cage wash, tissues and application-site skin was 7.73 ±1.56 %. As was seen following oral administration, the major route of elimination was via the urine, comprising 3.04 ± 3.54 % of the administered dose. The rate of absorption of test material, following oral administration, was quite rapid, with absorption t1/2 values ranging from 0.1-0.2 hours. The plasma elimination of orally administered 14C-AEEA was biphasic, with alpha and beta elimination t1/2 values of 1.6-1.8 hours and 16.7-17.3 hours, respectively. Only parent compound was found in plasma. Four radiolabeled metabolites were observed in urine from all three oral dose groups. These metabolites comprised approximately 5 - 10 (Metabolite A), 11 -20 % (Metabolite B), 5 - 11 % (N-acetyl-AEEA) and 55-65 % (AEEA) of the administered dose. No significant differences in metabolic profile were observed between dose level or pregnancy status.

This metabolism study in the rat is classified as acceptable and satisfies the guideline requirement for a metabolism study according to OECD guideline 417.