5-chloro-2-(4-chlorophenoxy)phenol;[DCPP]

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-01-25 to 2008-2008-10-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline studies, GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

(1984)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

429-290-0

EC Name:

-

Cas Number:

3380-30-1

Molecular formula:

C12 H8 Cl2 O2

IUPAC Name:

5-chloro-2-(4-chlorophenoxy)phenol

Details on test material:

Non-labelled compound:
- Name of test material (as cited in study report): DCPP
- Physical state: beige solid
- Analytical purity: 99.94%
- Lot/batch No.: DCS LAB 006 07
- Expiration date: March 31, 2009
- Stability in vehicle: the stability of the test item in the administration vehicle was checked by HPLC at the time of the application separately for each dosing group.
- Storage conditions: room temperature, approximately 20°C

Labelled compound:
- Name of test material (as cited in study report): 14C-DCPP
- Radiochemical purity (if radiolabelling): 99.3%
- Lot/batch No.: CFQ40113 Batch 1
- Specific activity: 4.37 GBq/mmol (118 mCi/mmol) <=> 16.9 MBq/mg (456 μCi/mg); 259 g/mol at this spec. activity
- Storage conditions: -20°C in absence of moisture, light, and air

Radiolabelling:

yes

Test animals

Species:

hamster, Syrian

Strain:

other: LAK:LVG(SYR) BR or HsdHan:AURA

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd, Laboratory Animal Services, Füllinsdorf / Switzerland
- Age at study initiation: 5 to 7 weeks of age (for those animals weighing 80 to 100 g)
- Weight at study initiation: 100 g and 80 g for males and females (single dose), 180 g (males, repeated dose)
- Housing: one day prior to the administration the animals were individually kept in metabolism cages
- Feeding: certified standard diet, ad libitum
- Drinking: tap water, ad libitum
- Acclimatization: yes, at least 5 days

ENVIRONMENTAL CONDITIONS
The animals were kept in rooms maintained at standard conditions, i.e. a temperature of 22±3°C, a relative humidity of 30-70 % and a 12 hours light/dark cycle.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Remarks:

(PEG 300 in water, 70:30 v:v)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS
A concentrated stock solution of the radiolabeled test item was prepared, i.e. about 42 mg 14C-DCPP was dissolved in 2 mL ethyl acetate.

- Application solution Group 1 (LD):
A volume of the stock solution containing 1.9 mg 14C-DCPP was added to 2.6 mg unlabeled DCPP and the solvent of the stock solution removed by a gentle stream of N2. Thereafter the dry test item was totally dissolved in 9.2 mL PEG 300 and 3.8 mL Water. This procedure yield to 14C-DCPP with a final specific radioactivity of 7244 kBq/mg. The new specific radioactivity was determined by liquid scintillation counting (LSC).
The final administration suspension had a concentration of 0.34 mg test item/ml corresponding to 2508 kBq/mL as determined by LSC. The density of the administration solution was determined to be 1.1042 g/mL.

- Application solution Group 2 (HD):
A volume of the stock solution containing 7.6 mg 14C-DCPP was added to 437.5 mg unlabeled DCPP and the solvent of the stock solution removed by a gentle stream of N2. Thereafter the dry test item was totally dissolved in 9.2 mL PEG 300 and 3.8 mL Water. This procedure yield to 14C-DCPP with a final specific radioactivity of 289 kBq/mg. The new specific radioactivity was determined by liquid scintillation counting (LSC).
The final administration suspension had a concentration of 34.2 mg test item/ml corresponding to 9887 kBq/mL as determined by LSC. The density of the administration solution was determined to be 1.1088 g/mL.

- Application solution Group 3 (LD):
A volume of the stock solution containing 0.2 mg 14C-DCPP (16900 kBq/mg) was added to 4.6 mg unlabeled DCPP and the solvent of the stock solution removed by a gentle stream of N2. Thereafter the dry test item was totally dissolved in 10 mL PEG 300 and 4 mL Water. This procedure yield to 14C-DCPP with a final specific radioactivity of 778 kBq/mg. The new specific radioactivity was determined by liquid scintillation counting (LSC).
The final administration suspension had a concentration of 0.34 mg test item/ml corresponding to 267 kBq/mL as determined by LSC. The density of the administration solution was determined to be 1.1042 g/mL.

APPLICATION
The administration solution was orally administered on a target volume of 0.6 mL/100 g bw.

Duration and frequency of treatment / exposure:

- Single administration of 14C-DCPP was performed in male and female hamsters.
- Repeated administration of 14C-DCPP was performed in male hamsters; the animals received 14 applications of radiolabelled test material on consecutive days.

Doses / concentrations

Remarks:

Doses / Concentrations:
2 mg/kg bw (single low dose)
200 mg/kg bw (single high dose)
2 mg/kg bw (repeated low dose)

No. of animals per sex per dose / concentration:

Single dose: 17 ♂ + 8 ♀
Repeated dose: 7 ♂

Control animals:

no

Details on study design:

The fate of DCPP was investigated in the hamster after single and repeated oral administration.
SINGLE DOSE EXPERIMENT
Single administration of 14C-DCPP was performed in male and female hamsters. The dosing was performed at two dose levels, i.e. 2 mg/kg (low dose) and 200 mg/kg body weight (high dose). Excreta were collected in daily intervals and tissues were collected 96 h after administration. Blood and plasma kinetics was investigated after oral administration to male hamsters at the low dose level.
REPEATED DOSE EXPERIMENT
Repeated administration of 14C-DCPP was performed in male hamsters. Animals received 14 applications of radiolabelled test material on consecutive days, at a dose level of 2 mg/kg bw/application.

Details on dosing and sampling:

SAMPLES
Single dose experiment: Urine, faeces, cage wash, blood/plasma, bile, carcass, adrenals, bile fluid, blood, brain, carcass, epididymis, fat (white), femur, heart, kidneys, liver, lungs, muscle, ovaries, pancreas, skin, spleen, testis, thymus, uterus
Repeated dose experiment: Urine, faeces, cage wash, blood/plasma

SAMPLING TIME
Single dose experiment:
Urine: 0-24, 24-48, 48–72, and 72-96 hours after administration.
Feces: 0-24, 24-48, 48–72, and 72-96 hours after administration.
Necropsy at the end of the experiment, i.e. 96 hours after administration.
Repeated dose experiment:
Urine was collected only from 2 animals in daily intervals.
Feces were collected only from 2 animals (as above) in daily intervals.
Blood was sampled immediately before sacrifice:
Animal 1 = 24 hours after 1st dose
Animal 2 = 24 hours after 4th dose
Animal 3 = 24 hours after 7th dose
Animal 4 = 24 hours after 10th dose
Animal 5 = 24 hours after the last dose
Animal 6 = 72 hours after the last dose
Animal 7 = 168 hours after the last dose

The 14C-DCPP related residues in tissues and organs were determined by means of quantitative whole-body autoradiography technique. The excreted radioactivity was determined in urine and feces at daily intervals.

Results and discussion

Main ADME results

Main ADME results 1

Type:

absorption

Results:

Following oral uptake, DCPP was rapidly and almost completely absorbed from the gastrointestinal tract into the systemic circulation.

Main ADME results 2

Type:

excretion

Results:

Excretion was mainly via urine, accounting for 78 to 88% (both sexes). Excretion via feces was lower, accounting for 4.5 to 5.5%.

Main ADME results 3

Type:

distribution

Results:

Less than 2 % of the oral dose remained in tissues, organs, and carcass 96 hours after administration.

Main ADME results 4

Type:

metabolism

Results:

DCPP was extensively metabolized. Parent compound accounted for 5-10% of radioactivity in urine & feces. Glucuronic acid and/or hydroxylated conjugate of DCPP were almost formed and excreted via urine.

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Single dose: After oral administration at the low dose level the radioactivity was rapidly and almost completely absorbed from the gastrointestinal tract into system circulation. The maximum concentration level in blood and plasma was achieved 4 hour after administration.
The amount absorbed was calculated based on the radioactivity determined in urine, cage wash, and residues in tissues and carcass. At least 81/79% of the low dose and 89/79% of the high dose were absorbed from the gastrointestinal tract into systemic circulation, for males/females respectively. The actual extent of absorption may be even higher since the total recovery of the low dose level amounted only for 86% (males) and 84% (females), which is caused by a loss radioactivity in the wire grid of the metabolism cages.
Repeated dose: The orally administered DCPP was almost completely absorbed from the gastro- intestinal tract into the systemic circulation.

Details on distribution in tissues:

Single dose:
For the low dose level, the concentration in tissues and organs were generally low at 96 hours after administration. However all selected tissues and organs showed concentration levels above the LOQ level except in brain (females). Beside the bile fluid the highest concentrations were found in plasma, kidneys liver, and lungs. Lowest concentration was found in brain. Females had significantly lower residue levels as compared to males.
At the high dose level the concentration in tissues and organs were correspondingly higher. Again the highest concentrations were found in bile fluid and plasma, followed by adrenals, kidney, liver, and lung. Also at the high dose level the lowest concentration was found in the brain with level very close to LOQ, indication that DCPP and/or its radiolabelled metabolites are not able to pass the blood/brain barrier. At the high dose level the concentration levels in males and females were comparable.
Repeated dose:
The concentration in tissues and organs showed an almost constant level for all of the selected tissues and organs during the dosing period. The steady state was reached just at the first sampling time point at day 2. The bile bladder revealed a high concentration of radioactivity, i.e. 0.771 ppm at Day 2, indication a biliary excretion of the absorbed DCPP.
The high concentration of radioactivity in the bile fluid caused a high range of variation of the concentration values of the bile bladder. The bile bladder could not be assigned in the whole body sections of animal 3 and 4.
The highest steady state levels were found in blood, kidney cortex and lungs, accounting for 0.305 ppm, 0.224 ppm, and 0.221 ppm DCPP equivalents, respectively. All other tissues and organs showed plateau levels below 0.200 ppm. Lowest plateau levels were found in muscle, thymus, and bone, not exceeding 0.030 ppm. In brain tissue all measured concentrations were below LOQ, indicating that DCPP and/or its radiolabelled metabolites are not able to pass the blood brain barrier.
After the last of 14 daily doses, the concentration levels in tissues and organs decreased with terminal half lives (Day 15-21) of 31 to 54 hours. Within 7 days after last dosing all selected tissues and organs reached concentration levels below LOQ except for liver, kidney and bile bladder.

Details on excretion:

Single dose:
The absorbed radioactivity was predominately excreted with the urine, accounting for 80/78% of the low dose and 88/78% of the high dose for males/females, respectively. Significantly lower amounts were excreted with the faeces, accounting for 5.5/4.6% of the low dose and 5.3/12.6% of the high dose. Ninety-six hours after administration less than 2% of dose remained in the animals for both dose levels.
Repeated dose:
During the dosing period (14 daily doses), a steady state in terms of excretion was reached just 1 day after the first administration. The amount of daily excretion remained nearly constant until the end of dosing, accounting for about 78% and 16% of the daily dose for urine and faeces, respectively. Due to the almost constant excretion profile the systemic absorption seems to be uninfluenced by the multiple-dose regimen.

Toxicokinetic parameters

Toxicokinetic parameters 1

Test no.:

#2

Toxicokinetic parameters:

half-life 1st: 6 h (initial half-life [4 - 24 h]; low dose, in blood and plasma, respectively)

Toxicokinetic parameters 2

Test no.:

#2

Toxicokinetic parameters:

half-life 2nd: 26 h (final half-life [24 - 96 h]; low dose; blood)

Toxicokinetic parameters 3

Test no.:

#2

Toxicokinetic parameters:

half-life 2nd: 36 h (final half-life [24 - 96 h]; low dose; plasma)

Toxicokinetic parameters 4

Test no.:

#2

Toxicokinetic parameters:

AUC: 26.8 µg*h/g [0 - 96 h] for blood; 53.4 µg*h/g [0 - 96 h] for plasma

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

DCPP was extensively metabolized and excreted via urine and feces. About 5-10% of the radioactivity was found as unchanged parent in urine and feces. The majority of radiolabeled metabolites were excreted with the urine. The urinary metabolite pattern consisted of at least 16 metabolite fractions. It was dominated by DCPP-glucuronide conjugate accounting for 18-22% of the low dose (2 mg/kg bw) and 31-61 % of the high dose administered (200 mg/kg bw), followed by glucuronide and sulfate conjugates of hydroxylated DCPP, accounting for about 10-12 % of the low dose and 3-6 % of the high dose. Thus, the major metabolite pathway was the forming of glucuronic acid conjugates of DCPP and/or hydroxylated DCPP. To a minor extend the sulfuric acid conjugates of DCPP and/or hydroxylated DCPP were found in the urine metabolite pattern.