Ethylenebis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate]

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Apr. 18, 1989 to Aug. 29, 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Objective of study:

absorption

distribution

excretion

Qualifier:

according to guideline

Guideline:

other: US Food and Drug Administration, Bureau of Food, 1982

Deviations:

not specified

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

1984

Deviations:

yes

Remarks:

- No metabolism studied (only absorption, distribution, and excretion tested)

GLP compliance:

yes

Radiolabelling:

yes

Remarks:

Both labelled and unlabelled substances were used.

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: BRL Biological Research Laboratories Ltd. Wölferstrasse 4 CH-4414 Fuellinsdorf/Swltzerland.
- Weight at study initiation: 156-176g.
- Fasting period before study: Prior to dosing with 14C-IRGANOX 245 (14C-TK 12627), rats were fasted overnight.
- Housing: Groups of 2-3 rats in Makrolon cages with standard soft wood bedding during at least 2 days (Test 1 and 2). Animals of Test 2 were held individually in Makrolon cages with a stainless steel grill floor. During the metabolism studies (Test 1) rats were held individually in all-glass metabolism cages. Metabolism cages were ventilated with about 600 mL air per minute.
- Individual metabolism cages: yes.
- Diet (e.g. ad libitum): Pelleted 343-Kliba rat maintenance diet (Klingentalmushle AG, CH-4303 Kaiseraugst/Switzerland), ad libitum.
- Water (e.g. ad libitum): Tap water, ad libitum.
- Acclimation period: At least 5 days to laboratory environment incl. 3 days to metabolism cages (Test 1) or 2 days to Makrolon cages (Test 2).

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3.
- Humidity (%): 40-70.
- Air changes (per hr): 10-15.
- Photoperiod (hrs dark / hrs light): 12 / 12.

Route of administration:

oral: gavage

Vehicle:

other: 0.5% carboxymethylcellulose in 0.9% NaCl.

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The original viscous radioactive material was quantitatively transferred and made up to 10 mL with acetone. The addition of 1 mL chloroform to the suspension obtained did not result in a better dissolution of the radioactive material. The organic solvents were evaporated at room temperature under a gentle stream of nitrogen and the residue taken up in 50 ml of chloroform.
A clear solution (stock solution I) was obtained. As determined by liquid scintillation counting (LSC) stock solution I contained 182.01 mg of 14C-IRGANOX 245 (14C-TK 12627) with a specific radioactivity of 47.78 µCi/mg.
Based on the target dose levels and intended specific radioactivity, the following stock solutions were prepared:

Stock Solution C (Groups 1 and 3 ):
Low target dose level: 1 mg/kg (spec. radioactivity: 50 µCi/mg)
An aliquot of stock solution I, i.e. 3.0 mL corresponding to about 10.92 mg 14CIRGANOX 245 (14C-TK 12627) were made up to 10 mL with chloroform. As determined by LSC and based on a specific radioactivity of 47.78 µCi/mg, this stock solution (stock solution C) contained 11.11 mg of 14C-IRGAN0X 245 (14C-TK 12627).

Stock Solution D (Groups 2 and 4 ):
High target dose level: 10 mg/kg (spec. radioactivity: 5 µCi/mg)
Due to the specific radioactivity of about 5 µCi/mg intended for the high target dose level, an aliquot of stock solution C (spec. radioactivity: 47.78 µCi/mg) was diluted about 10 times. For this purpose, a weighed aliquot of 48.08 mg unlabelled IRGANOX 245 (TK 12627) was placed into a volumetric flask and made up to 5 mL with stock solution C. This stock solution (stock solution D) contained 53.88 mg of 14C-IRGAN0X 245 (14C-TK 12627) with a final specific radioactivity of 5.15 µCi/mg.

Formulation: Based on the average body weight of the rats, intended target dose levels of 1 mg/kg or 10 mg/kg and an excess of about 10%, appropriate aliquots (160-170 µL) of the respective stock solutions were evaporated at room temperature under a gentle stream of nitrogen, taken up in about 170-180 mg CREMOPHOR EL (BASF, Ludwigshafen/FRG) thoroughly mixed with 170-180 µL acetone and the solutions stored at -20°C until administration. Before administration, each solution was made up with 0.5% CMC (carboxymethylcellulose) in 0.9% NaCl to 1.0 mL/100 g body weight and thereafter directly administered.

VEHICLE
- Justification for use and choice of vehicle (if other than water): No Data.
- Concentration in vehicle: Refer to above description on preparation of dosing solution.
- Amount of vehicle (if gavage): 0.5% carboxymethylcellulose and 0.9% NaCl.

HOMOGENEITY AND STABILITY OF TEST MATERIAL: The test article proved to be sufficiently stable as shown by TLC-analysis of the radioactivity in the formulation after the administration of the high dose level (purity ≥99.2%, mean of two determinations) as compared to the radioactivity in the stock solution (purity ≥ 98.3%).

Duration and frequency of treatment / exposure:

Single administration.

Dose / conc.:

1 mg/kg bw/day

Dose / conc.:

10 mg/kg bw/day

No. of animals per sex per dose / concentration:

5/group (males only).

Control animals:

yes, historical

Positive control reference chemical:

Not available.

Details on study design:

- Dose selection rationale: No data.
- Rationale for animal assignment (if not random): Since the study was performed in various separate experiments, animal numbers were given randomly at each batch.

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)

- Tissues and body fluids sampled:
For Experiment 1 (balance study): Urine, faeces, blood, heart, lung, liver, stomach, spleen, kidney, muscle, bones (femur), brain, fat, pancreas, intestinal tract with contents, adrenal glands, testicles, thyroid gland, skin (back region) and residual carcass. The content of the stomach was added to the carcass.
For Experiment 2 (balance study): Blood, urine, faeces, cage wash, intestinal tract/carcass/bones, organs/tissues, blood/plasma.

- Time and frequency of sampling:
For Experiment 1 (balance study): Urine/feces: Urine was taken 8, 24, 48, 72, 96, 120, 144, and 168 hours after the administration. Additionally, at sampling intervals of 8 and 24 hours metabolism cages were rinsed with a small amount of bidistilled water (about 2 mL) to remove droplets of urine. Feces were collected at room temperature 24, 48, 72, 96, 120, 144, and 168 hours after administration.
Blood/organ/tisues/intestinal tract/carcass: After 168 hours, animals were killed and blood was collected and organs and tissues were taken.
Cage wash: At the end of the study, the cages were washed first with water and liquid soap followed by acetone.
For Experiment 2 (balance study): Blood: Blood samples (100-200 microlitres) were withdrawn retroorbitally from the individual rats 0 (prior to dosing), 0.25, 0.5, 1, 2, 4, 8, 12, 24, 48, 72, 96, 120, 144 and 168 hours after the administration.
Organs/tissues/blood/plasma: The radioactivity in organs and tissues was determined after digestion of subsamples with tissue solubilizer. The radioactivity in blood and plasma was determined by digestion of subsamples followed by liquid scintillation counting.
Urine: The radioactivity in all urine samples was determined by liquid scintillation counting of subsamples. Thereafter, the rest of the urine was stored at -20°C.
Feces: To check for volatile radioactivity, a selected sample of feces was divided in two aliquots. One aliquot was homogenized wet by addition of water (about 2+l, w/w), the other aliquot was homogenized after lyophilization. Radioactivity of the respective homogenates was determined by combustion of subsamples. Since similar amounts of radioactivity were recovered in the lyophilized feces as compared to the wet feces, all feces samples were lyophilized. Feces was homogenized in a Waring Blendor (Bender & Hobein, Zürich/Switzerland) equipped with a mini-beaker (12-37 mL working volume) and a cross-knife of 26 mm diameter. In case of too small amounts, feces was directly homogenized in a mortar.
Cage Wash: Solid materials (feed, feces, etc) were homogenized by means of an Ultra-Turrax (Bender & Hobein, Zürich/Switzerland).

Statistics:

No data.

Preliminary studies:

Not applicable.

Details on absorption:

The test article was absorbed in considerable amounts from the gastro-intestlnal tract. Absorption at both dose levels was rapid since the maximal blood/plasma values were reached one hour after administration.

Details on distribution in tissues:

Low dose level: 1.023 mg/kg:
At 168 hours, highest residual radioactivity levels were found in the excretory organs kidney (0.320 µg/g) and liver (0.150 µg/g). Lower but still significant amounts were found in blood (0.009 µg/g), plasma (0.009 µg/g), intestinal tract (0.009 µg/g), muscle (0.007 µg/g), skin back region (0.006 µg/g) and carcass (0.004 µg/g). In stomach and in femur, residual radioactivity levels were about the limit of quantification. In all other organs/tissues, radioactivity levels were at or below the limit of quantification.

High dose level: 10.312 mg/kg:
Again at 168 hours, highest residual radioactivity levels were found in kidney (1.033 µg/g) and liver (0.807 µg/g). In blood (0.073 µg/g), plasma (0.061 µg/g), intestinal tract (0.073 µg/g), skin back region (0.052 µg/g), muscle (0.051 µg/g), carcass (0.040 µg/g) and femur (0.027 µg/g), radioactivity levels amounted to about 1.2 to 5.2 fold the limit of quantification. In all other organs/tissues, radioactivity levels were below or about the limit of quantification. As compared to the low dose level, at about 10 times higher dose levels radioactivity levels increased about 7 - 12 fold in most organs/tissues. In the excretory organs kidney and liver, residual radioactivity levels increased only about 3.2 and 5.4 times, respectively, reflecting an efficient elimination of the test article.

Details on excretion:

Total excretion of radioactivity via the urine represented, on average, 35.01% and 33.49% of the radioactivity administered for the low and high dose level, respectively. Already 24 hours (low dose level) and 48 hours (high dose level) after the administration, urinary excretion accounted for 28.97% and 30.79% at the low and high dose levels, respectively.
Excretion via the feces accounted, on average, for 57.30% (low dose level) and 54.22% (high dose level). Again, the major amount (44.47% and 48.77%) was excreted within the first 24 hours (low dose level) and 48 hours (high dose level), respectively.
Additional radioactivity (1.48%) resulting from excretion via urine and feces was found in the cage wash at both dose levels. Total excreted radioactivity accounted, on average, for 93.79% and 89.20% at the low and high dose level, respectively.
Low amounts of radioactivity were found at 168 hours after the administration in organs/tissues (0.53 % to 1.24 %), intestinal tract (0.07% to 0.09%), blood (0.04% to 0.05%) and residual carcass (0.33% to 0.38%). Recoveries of radioactivity accounted, on average, for 95.56% and 90.23% of the radioactivity administered at the low dose and high dose levels, respectively. Based on the amounts of radioactivity recovered, excretion via expired air can not be excluded.
In conclusion, after single oral administration of 14C-test substance to male rats, the test article was absorbed in considerable amounts based on urinary excretion and thereafter rapidly excreted within the used dose range.

Test no.:

#2

Toxicokinetic parameters:

Cmax: 0.818 µg/g at 1 hr (plasma; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 0.036 µg/g at 48 hrs (plasma; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 2.2 fold the limit of quantification at 168 hrs (plasma; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

Cmax: 0.528 µg/g at 1 hr (blood; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 0.031 µg/g at 48 hrs (blood; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 0.012 µg/g at 168 hrs (blood; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

Cmax: 12.947 µg/g at 1 hr (plasma; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 0.338 µg/g at 48 hrs (plasma; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 2 fold the limit of quantification at 168 hrs (plasma; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

Cmax: 7.874 µg/g at 1 hr (blood; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 0.286 µg/g at 48 hrs (blood; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

C(time): 2.4 fold limit of quantification at 168 hrs (blood; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

half-life 1st: 3.0 hrs (plasma; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

half-life 1st: 2.9 hrs (blood; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

half-life 1st: 7.2 hrs (plasma; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

half-life 1st: 8.6 hrs (blood; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

AUC: 9.69 µg/g x h (plasma; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

AUC: 6.97 µg/g x h (blood; dose of 1 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

AUC: 176.35 µg/g x h (plasma; dose of 10 mg/kg)

Test no.:

#2

Toxicokinetic parameters:

AUC: 125.52 µg/g x h (blood; dose of 10 mg/kg)

Metabolites identified:

not measured

Details on metabolites:

Not determined.

The pharmacokinetic study with 14C-labeled test material has shown that after single oral administration to male rats, the test article was absorbed in considerable amounts from the gastro-intestinal tract and thereafter rapidly excreted within the used dose range. Based on urinary excretion, the amount of absorbed radioactivity accounted for a minimum of 35.01 % and 33.49% for the low and high dose level, respectively. Excretion via the feces amounted, on average, to 57.30% (low dose level) and 54.22% (high dose level). Absorption at both dose levels was rapid since the maximal blood/plasma values were reached one hour after administration. The highest blood/plasma levels and AUC-values Increased about 15-16 and 18 fold, respectively, at about 10 times higher dose levels. These results indicate that the process of absorption was not saturated at the high dose level and that the test article was more efficiently absorbed at 10 mg/kg as compared to 1 mg/kg. Radioactivity from plasma and blood was eliminated with half-lives ranging from 2.9 hours to 8.6 hours at both dose levels. Taking into account the lower concentrations in blood as compared to the ones in plasma, these results indicate that residual radioactivity in blood was not associated with blood cells. At both dose levels, highest residual radioactivity levels at 168 hours after the administration were found in kidney and liver. These results support the function of these organs as excretory organs for the test substance. At 10 fold higher dose levels, residual radioactivity levels at 168 hours in the excretory organs kidney and liver increased only about 3.2 to 5.4 times, respectively. Taking into account the higher absorption of the test article at the higher dose level, the results implicate a more efficient elimination of the test article at 168 hours after administration of the high dose level as compared to the low dose level.

Reference 2

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From Mar. 3, 1982 to Apr. 30, 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Objective of study:

absorption

distribution

excretion

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

- Reliability scoring based on 1984 guideline

Deviations:

yes

Remarks:

1 to 6 rats/group were used instead of 4 rats/group. Metabolism was not studied; however, the study objective was to investigate absorption, distribution, and excretion;

GLP compliance:

yes

Remarks:

Signed Quality of Assurance statement not included in the final study report.

Radiolabelling:

yes

Remarks:

Labelled and unlabelled substances were used.

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Duration and frequency of treatment / exposure:

Single administration.

Dose / conc.:

1 mg/kg bw/day (nominal)

Dose / conc.:

10 mg/kg bw/day (nominal)

No. of animals per sex per dose / concentration:

Test 1: n=5.
Test 2: n=6.
Test 3: n=6.
Test 4: n=6.
Test 5: n=1.

Control animals:

other: The control rats of each test group were treated with the same dose of non-labelled test substance.

Preliminary studies:

Not available.

Details on absorption:

The specific radioactivities in the blood of the rats passed through a maximum in the time interval 0.5 to 1 h following intubation. Afterwards there was no continuous decrease of these values with time, but a kind of a second maximum could be observed in the period 4 to 12 h following intubation. On the average, these findings resulted in a rapid increase of specific radioactivity in the blood up to a maximum at 1 h following intubation.

Details on distribution in tissues:

Results from autoradiographic investigation:
After 3 hr, most of the radioactivity was found in the different parts of the gastro-intestinal tract, but absorption had already occurred leading to distribution of radioactivity nearly over the whole organism of the rat with the highest density of radioactivity in liver, kidneys, lung, heart and in the background of the eyeball which might be attributed to the Harderian or a lacrimal gland.
After 8 hr, most of the radioactivity was detected in the lower parts of the gastro-intestinal tract as well as in liver, kidneys, lung, heart and in the area of the glands in the background of the eyeball.
After 24 hr, the distribution of radioactivity was still very similar to that observed 16 h before showing that the process of faecal excretion was going on at this time.
After 72 hr, the radioactivity density in the rat's organism had decreased very much compared to the autoradiograms taken earlier. Radioactivity was detected in the rectum in the form of faeces pellets, but also in the liver and the renal cortex. All other parts of the body seemed to be free of radioactivity under the exposure conditions used, especially the radioactivity in the area of the glands in the background of the eyeball did not impress by a high density of radioactivity anymore. This impression was confirmed by the autoradiograms of whole-body slices taken from the rat killed at 168 h.

There were no indications on the basis of the autoradiograms for a special affinity of the intubated radioactivity to other organs and tissue, for instance the adrenals, the thyroid gland, the thymus, the brain, the gonads, the bones etc. All the radioactivity residues seen in the autoradiograms of whole body slices taken up to 24 h after test substance intubation had been eliminated up to 168 h after test substance intubation below the limit of detection of the technique used except of persisting radioactivity residues in liver and renal cortex.

Details on excretion:

The excretion of the test substance and/or its biotransformation products with urine and faeces amounted on average to about 95% of the given radioactivity up to 168 h after administration. The ratio of radioactivity found in urine and faeces after peroral administration of the test substance was about 1:1. On the average already at 72 h after administration of the test substance the process of renal and faecal excretion had been accomplished. The extent of renal and faecal excretion as well as the ratio of radioactivity found in urine and faeces were independent on dose of the test substance within the dosage range of 1 to 10 mg/kg body weight. Both renal and faecal excretion of radioactivity seemed to be accelerated to some extent in the time intervals up to 72 h after administration of the test substance in the lower dose of 1 mg/kg body weight compared to the higher dose of 10 mg/kg body weight. A shoulder in the blood level vs. time curve during the elimination phase indicated biliary excretion of the test substance and/or its biotransformation products followed by a re-absorption from the intestine as a possible mechanism of elimination. Exhalation of 14C-labelled carbon dioxide could be neglected as a consequence of biotransformation of test material in male rats.

Test no.:

#1

Toxicokinetic parameters:

other: Not determined.

Metabolites identified:

not measured

Details on metabolites:

Not determined.

Test substance was rapidly absorbed from the gastro-intestinal tract of male rats passing through a maximum at about 1 h after single peroral test substance administration. The absorption quote could be determined to about 46 to 48% of the perorally given dose based on the radioactivity amounts in urine, organs and tissues as well as residual carcasses of the rats. This quote might even be higher because there are strong indications for the assumption that part of the absorbed test substance and/or its biotransformation products was excreted with bile into the intestine. From the blood level vs. time curves for the rats it could also be concluded that enterohepatlc circulation might be of importance for the biokinetics of test substance and/or its biotransformation products.

Following a single peroral administration of test substance to male rats radioactivity was almost completely excreted within 72 hours, the ratio between radioactivity amounts in urine and faeces being about 1:1. Rate and extent of renal and faecal excretion of radioactivity seemed to be independent on dose of test substance within the dosage range tested (1 to 10 mg/kg body weight). Exhalation of radioactivity could be neglected as a possible mechanism of elimination. Distribution of the absorbed radioactivity took place almost over all parts of the organism preferring especially liver and kidneys (renal cortex) which exhibited the highest radioactivity residues at each time of investigation. A particular feature in the biokinetics of test substance and/or its biotransformation products was a relatively high residue concentration in the tissues of the background of the eyeballs comprising the Harderian and lacrimal glands. The eyeballs themselves as well as the brain, the gonads, the adrenals, the thyroid gland, the thymus, the bones etc. did not impose by enrichment of radioactivity amounts. Based on informations of autoradiograms of whole body slices it could be observed that no part of the organism including liver, kidneys as well as Harderian and lacrimal glands cumulated the radioactivity perorally administered as test substance.

Finally, test substance may be characterised by a rapid absorption from the gastro-intestlnal tract after peroral administration with an absorption quote of at least about 50% followed by a nearly complete elimination including enterohepatic circulation within 168 h after intubation leaving only small residues in the different parts of the organism, based upon an almost linear dependance on dose in the dose range 1 to 10 mg/kg body weight.

Reference 3

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Jun. 20, 1990 to Aug. 5, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline available

Principles of method if other than guideline:

No OECD guideline available with which to compare the study design. Details of the study methods, dose preparation, animal husbandry, observations and results are well described.

GLP compliance:

yes

Radiolabelling:

yes

Species:

pig

Strain:

other: Troll Miniature

Sex:

male

Type of coverage:

occlusive

Vehicle:

other: Vaseline

Duration of exposure:

24 hours

Doses:

- Nominal doses: 2 or 20 mg/kg bw

No. of animals per group:

2/treatment group; 1 in control group

Control animals:

yes

Remarks:

vehicle only

Dose:

2 or 20 mg/kg bw

Parameter:

percentage

Absorption:

ca. 0.5 %

Remarks on result:

other: 24 hour

Remarks:

reported to be 0.53%

Conversion factor human vs. animal skin:

Not reported

From the miniature pigs in animal group A (low dose administration) in the mean 0.17 % of the radioactivity administered were excreted during 168 h. From the animals of animal group B (high dose administration) 0.03 % of the total radioactivity administered were excreted during 168 h. The nominal amount weighed for radioactivity determination was 1 ml.

With faeces from Animal Al 0.01 % and from animal A2 less than 0.005 % of the radioactivity administered have been excreted. From Animals Bl and B2 the amount of test substance excreted was always below the limit of detection. Thus elimination of radioactivity with faeces was negligible. The nominal amount weighed of faeces samples for determination of radioactivity was 0.75 g. From animal group B (high dose) only the sample obtained 48 h pa from animal B2 was above the limit of detection. This sample contained 0.164 kBq and coresponded to 0.0005 % of the total administered radioactivity.

Conclusions:

In the mean of all four animals the sum of the percentage of radioactivity, recovered in all biological samples, was below 0.5 % of the administered radioactivity. Because the % of test material in the residual carcass ofthe miniature pigs could not be determined, the percentage in carcass was approximated from a rat study. Therefrom in the mean 0.53 % of the total administered test item was totally absorbed by the animals via the dermal route.

Executive summary:

To investigate the absorption, distribution and elimination of dermally applied test material two animal groups of troll miniature pigs have been used. Animal group A received a low dose of about 19 mg test item and animal group B received a high dose of about 195 mg. The test substance was administered dermally for 24 hours. Urine and feces were collected from 0-168 h in 24 h intervals. With animal group A an average of 0.17 % of the administered radioactivity was eliminated in urine and less than 0.01 % in feces. With animal group B only 0.03 % was eliminated in urine and radioactivity in feces was always below the limit of detection. With both animal groups the major part of elimination of radioactivity in urine occurred during the first 48 h after administration of the test substance. Residues of the test item in organs and tissues were found in liver, kidney, adrenals, thyroid and

subcutaneous fat of the application area. The highest residues were found in liver (2-4 ng equiv./g with animal group A and 5-22 ng equiv./g with animal group B), subcutaneous fat of the application area (21-23 ng equiv./g with animal group A and 11 ng equiv./g with animal B2) and adrenals (1-3 ng equiv./g with animal group A and 16 ng equiv./g with animal Bl). The recovery of radioactivity in terms of radioactivity balances was 91 % for animal group A and 91.8 % for animal group B. Most of the radioactivity was recovered with the bandage, 90.2 % with animal group A and 91.6 % with animal group B. The blood and plasma level profiles showed with all animals only few samples above the limit of detection. Therefore a kinetic analysis of the blood and plasma level profiles could not be performed. The values were always below 2 ng equiv./g with animal group A and below 5 ng equiv./g with animal group B. In the mean of all four animals the sum of the percentage of radioactivity, recovered in all biological samples, was below 0.5 % of the administered radioactivity. Because the % of test material in the residual carcass ofthe miniature pigs could not be determined, the percentage in carcass was approximated from a rat study. Therefrom in the mean 0.53 % of the total administered test item was totally absorbed by the animals via the dermal route.

Additional information

Toxicokinetic properties were investigated using 14C-labelled substance both in vivo and in vitro. The substance is rapidly taken up after ingestion and undergoes enzymatic ester hydrolysis in liver. Conjugates of the metabolite 3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate are eliminated with approximately equal ratio in urine and feces and elimination is basically complete within 72h. After dermal application of radiolabelled material, presence of urinary metabolites indicated that low amounts (less than 1%) penetrate the skin. There is no indication of bioaccumulation of the substance.