N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide]

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

no substance purity given, no identification of metabolites, no cannulation of bile-duct

Objective of study:

other: absorbtion and excretion

Qualifier:

no guideline followed

Principles of method if other than guideline:

Absorption and excretion of the test substance was investigated quantitatively by radiotracer technique in a GLP study. Additionally the residues of the test substance and its metabolites were determined in blood and in the faeces free body. The radiolabelled substance was applied orally as well as intravenously on male sprague dawley rats. No metabolic identification was done, time-dependent blood plasma-profile were not determined.

GLP compliance:

yes

Radiolabelling:

yes

Remarks:

14-C labelled test

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: (han: SPRD/ SPF- albino rats), central institute for test animals, Hannover
- Weight at study initiation: 143.3 , 187.8, 151, 147.5, 188.2 g mean weight per group
- Fasting period before study: the day before application food ration was reduced to half of daily intake (8 g vs. 15 g), thereafter animals got normal daily ration, but the first ration was given 8 hrs after application.
- Housing: individual housing
- Individual metabolism cages: yes
- Diet: normal diet mark Gode (Art. No. 253), Dr. Rupprecht Schott Nachf., Hamburg; 15 g / day
- Water: ad libitum
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1
- Humidity (%): 55 ± 5
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

other: oral and intravenous

Vehicle:

other: (oral application: olive oil, intravenous application: propanediol-1,3)

Details on exposure:

oral application:
- Concentration in vehicle: 103.2 µg/g and 2179 µg/g solution for doses of 0.28 and 5.4 mg/kg bw, respectively

intravenous application:
- Concentration in vehicle: 383.8 µg/g solution for dose of 0.22 mg/kg bw

Duration and frequency of treatment / exposure:

single exposure, 72 hrs

Dose / conc.:

5.4 mg/kg bw/day (actual dose received)

Remarks:

test group (14C- labelled test substance); oral application (group I)

Dose / conc.:

0.28 mg/kg bw/day (actual dose received)

Remarks:

test group (14C- labelled test substance), oral application (group II)

Dose / conc.:

0.22 mg/kg bw/day (actual dose received)

Remarks:

test group (14C- labelled test substance); intravenous application (group III)

Dose / conc.:

5.5 mg/kg bw/day (actual dose received)

Remarks:

control group (non-radioactive test substance); oral application (groups 0I und 0II)

Dose / conc.:

0.25 mg/kg bw/day (actual dose received)

Remarks:

control group (non-radioactive test substance); intravenous application (group 0III)

No. of animals per sex per dose / concentration:

4 animals per control group
7 animals per test group

Control animals:

other: male rats administered with non-labelled test substance for oral and intravenous application

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Excretion)
- Tissues and body fluids sampled: urine, faeces, blood, rat bodies bleeded to death and without faeces
- Time and frequency of sampling: (for faeces and urine) 0-6, 6-24, 24- 48, 48- 72 hrs
- Method type(s) for identification: liquid scintilation counter
- Limits of detection: 0.04, 0.8, 0.3, 0.2 ng test substance or metabolites/g sample for urine, faeces, blood and homogenized entire bodies
- other: for determination of the radioactivity in test materials animal materials were mixed and homogenized. Afterwards samples from blood, urine and homogenisates from body were weighed in scintillation measuring glasses. In contrast to this direct taking of samples for faeces probes a lyophilization and pulverization was done. Then test substance was burnt to carbon dioxide and collected in a fixed quantity absorber liquid. After addition of suitable scintillation solution scintillation measurement was done.

Type:

excretion

Results:

by faeces: 101.6 % (high dose, oral application), 102.7 % (low dose, oral application), 88.7 % (intravenous application) of radioactivity after 72 hrs

Type:

excretion

Results:

by urine: 1.7 % (high dose, oral application), 2.2 % (low dose, oral application), 2.0 % (intravenous application) of radioactivity after 72 hrs

Type:

distribution

Results:

in blood: 0.01 % (high dose, oral application), 0.06 % (low dose, oral application), 0.03 % (intravenous application) of radioactivity after 72 hrs

Type:

distribution

Results:

in whole body (after removal of faeces): 0.35 % (oral application, high dose) of radioactivity after 72 hrs

Details on absorption:

By means of the pharmacokinetic results described here no information if substance is absorbed can be given. The test substance could be excreted directly via faeces or excreted via faeces after absorption.

Details on distribution in tissues:

- The residual radioactivities, found after oral and intravenous application of radiolabelled test substance after 72 h in the blood of the rats of test group I, II, and III killed by bleeding to death, were comparatively small and amounted on an average to 0.01, 0.06 and 0.03 % of the applicated radioactivity amounts.
- The residual radioactivities found after oral application of radiolabelled test substance after 72 h in the free of faeces bodies of the killed rats of test group I amounted on an average to 0.35 % of the given radioacitivity amounts.

Details on excretion:

-The radioactivity amounts, orally given to the rats of test group I and II in form of the 14C -labelled test substance, were nearly excreted quantitatively in 72 hrs, favouredly by faeces and only to a smaller extent (on an average up to 1.7 or 2.2 %) on renale way.
- The radioactivity amounts, intravenously given to the rats of test group III in form of radiolabelled test substance were eliminated in 72 hrs on an average to 88.7 % by faeces and to 2.0 % by urine.

- Elimination for intravenous application is considerably slower than via the oral route. Substance is not completely excreted 72 hrs after substance application

Metabolites identified:

not measured

Absorption and elimination of the test substance was investigated quantitatively by radiotracer technique in a GLP study. Additionally the residues of the test substance and its metabolites were determined in blood and in the faeces free body. The radiolabelled substance was applied orally as well as intravenously on male sprague dawley rats (7 per group) with doses of 0.28 and 5.39 mg/kg bw for oral and 0.22 mg/kg bw for intravenous application.

It was shown that the test substance rests only a short time in male rats as well after oral as after intravenous application. After 72 hrs the test substance or its metabolites were nearly quantitatively excreted by faeces. A small share was excreted by the renale way.

By means of the pharmacokinetic results described here no information if substance is absorbed can be given. The test substance could be excreted directly via faeces or excreted via faeces after absorption.

No bioaccumulation potential based on the study results was detected.

Conclusions:

no bioaccumulation potential based on study results

Description of key information

The test substance rests only a short time in male rats as well after oral as after intravenous application. After 72 hours the test substance or its metabolites were nearly quantitatively excreted by feces. A small share was excreted by the renal way. By means of the pharmacokinetic results described here no information if substance is absorbed can be given. The test substance could be excreted directly via feces or excreted via feces after absorption. No bioaccumulation potential based on the study results was detected.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

The test substance is a white solid with low volatility (vapor pressure < 0.1hPa) with a molecular mass of 665 g/mol. Each molecule has two ionisable (phenolate) groups. The water solubility is very low (< 1mg/L). The molecule is very hydrophobic (log Po/w > 6). The high hydrophobicity was confirmed by theoretical calculations (log Po/w = 10, (clogP fragment based approach according to Leo and Hansch)). Due to high lipophilicity, a molecular weight > 500 g/mol the molecule is not favorable for oral absorption and therefore a low bioavailability is assumed. Dermal absorption may be very low due to molecular weight > 500 g/mol (molecule is probably too large for penetration) and due to the high lipophilicity, which results in a slow rate of transfer between the stratum corneum and the epidermis. Furthermore, uptake into the stratum corneum itself may be slow. The very low solubility results in a lower partitioning of the test substance from the stratum corneum into the epidermis.

It is assumed that bioavailability is restricted by the low aqueous solubility of the test compound. Nevertheless, pre-systemic metabolism like hydrolysis of the amide bonds in gastro-intestinal tract or in liver may occur.

Low bioavailability of the oral and dermal route is confirmed by acute oral toxicity studies in rats (LD50 > 7750 mg/kg bw) and in hamster (LD50 > 3000 mg/kg bw). In a dermal study no toxicity at the limit dose (2000 mg/kg bw) was seen. In a subchronic dietary toxicity study in rats and a subchronic dog study no compound related effects were observed.

Absorption and elimination of the test substance was investigated quantitatively by radiotracer technique in a GLP study. Additionally, the residues of the test substance and its metabolites were determined in blood and in the feces- free body. The radiolabeled substance was applied orally as well as intravenously on male Sprague Dawley rats (7 per group) with doses of 0.28 and 5.39 mg/kg bw for oral and 0.22 mg/kg bw for intravenous application. Two percent of radioactivity was excreted by urine, which may correlate with the kidney findings the combined cancer/ chronic study. The remaining radioactivity was excreted by feces.

The very low radioactivity observed at the end of the ADE study (below 0,4 %) suggests a low potential of bioaccumulation.