Chlorocresol

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 Dec 2008 - 21 Jan 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

adopted in 1984

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

adopted in 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss Federal Office of Public Health, Bern, Switzerland

Test material

Test material information

Constituent 1

Reference substance name:

Chlorocresol

EC Number:

200-431-6

EC Name:

Chlorocresol

Cas Number:

59-50-7

Molecular formula:

C7H7ClO

IUPAC Name:

4-chloro-3-methylphenol

Details on test material:

Batch No.: CHA0152

Radiolabelling:

yes

Remarks:

U-14C-phenol

Test animals

Species:

rat

Strain:

other: HanRcc:WIST

Details on species / strain selection:

Laboratory rats were selected as the recommended animal species recognized by international guidelines representing the acceptable model in case of human exposure.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories Ltd., Laboratory Animal Services, Füllinsdorf, Switzerland
- Weight at study initiation: 167 - 181 g (males), 168 - 180 g (females)
- Housing: groups of 2-3 rats in Makrolon cages with standard soft wooden bedding (acclimatization period), individually in metabolism cages (treatment period)
- Diet: Kliba 3433 certified standard diet (Provimi Kliba AG, Kaiseraugst, Switzerland), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 70
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Remarks:

PEG 400

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
A volume of the stock solution containing 15 mg radiolabelled test material was added to 885.6 mg unlabelled test material. The solvent was removed by a gentle stream of nitrogen and 15 mL vehicle was added. The new specific radioactivity was determined by liquid scintillation counting (LSC). This procedure yields to the test material with a final specific radioactivity of about 62.01 kBq/mg.

Duration and frequency of treatment / exposure:

single dose

Doses / concentrations

Dose / conc.:

300 mg/kg bw/day (nominal)

Remarks:

Actual dose: 299 ± 3 and 301 ± 2 mg/kg bw/day in males and females, respectively

No. of animals per sex per dose / concentration:

4

Control animals:

no

Details on dosing and sampling:

TOXICOKINETIC / PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, faeces, blood, plasma, selected organs/ tissues (adrenals, brain, carcass, epididymis (males), fat, femur, heart, intestine (small/large), intestinal contents, kidneys, liver, lung, muscle, ovaries (females), pancreas, prostate (males), spleen, stomach, testis (males), thymus, thyroids, uterus (females)), expired air, cage washes
- Time and frequency of sampling: 0-24, 24-48, 48-72, 72-96, 96-120, 120-144, and 144-168 h after administration (urine and faeces); 0-24, 24-48, 48-72, and 72-96 h (expired air in all animals); 96-120, and 120-144 h (expired air in selected animals); 168 h (blood, plasma selected organs and tissues)

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled: urine, faeces
- Time and frequency of sampling: 0-24, 24-48 h
- From how many animals: samples pooled from 3 males or 4 females
- Method type(s) for identification: HPLC-UV
- Limits of detection and quantification: The limits of quantification (LOQ) for tissue residues were calculated according to Currie (Anal. Chem., 40, 586, 1968) for the different tissues taking the following parameters into account: counts of background specimens, counting time for background specimens, excretion, weight of an aliquot, specific activity.

Statistics:

Mean values and standard deviation were calculated.

Results and discussion

Main ADME results

Main ADME results 1

Type:

absorption

Results:

91.54% (males) and 92.96% (females) of dose was excreted via urine while 6.69 and 4.35% (males and females, respectively) was found in faeces; thus, the absorption rate is estimated to be 91.54 and 92.96% in males and females, respectively

Main ADME results 2

Type:

distribution

Results:

< 1% of the administered dose was recovered in the carcass and GI tract

Main ADME results 3

Type:

metabolism

Results:

urine: at least 5 metabolite fractions (two major fractions 37-39% and 41-47% of the dose, respectively), 6 - 11% of dose unchanged parent compound; faeces: almost completely unchanged (3 - 5% of the dose)

Main ADME results 4

Type:

excretion

Results:

99.03% (males) and 98.94% (females) excreted via urine and faeces within 7 days after administration

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Absorption rates or details on absorption are not provided. However, since 91.54% (males) and 92.96% (females) of the administered dose was excreted via urine while 6.69 and 4.35% (males and females, respectively) was found in faeces the absorption rate is estimated to be approximately 91.54 and 92.96% in males and females, respectively.

Details on distribution in tissues:

Due to the fast excretion the determination of tissue residues 168 h after administration resulted in generally very low residues measurable in the tissues. Residues above LOQ were only found in selected tissues and organs. Please refer to Table 3 under "Any other informations on results incl. tables" for details.

Details on excretion:

The majority of the administered test material was rapidly excreted with urine, i.e. 85.21% and 84.30% of the administered dose within 24 h after administration in male and female rats, respectively. Minor amounts were excreted with faeces (3.70% and 1.44% of the administered dose) within 24 h after administration in males and females, respectively. In 1/4 male approximately 50% of the administered test material was found in urine, whereas approximately 50% was found in faeces within 24 h after administration suggesting a soaking of the feces sample with urine. Therefore, this animal was excluded from mean calculations. The amount of radioactivity found in absorption traps of the expired air was fairly low, not exceeding 1% of the administered dose. Within 7 days after oral administration 99.03% and 98.94% of the dose was totally excreted in males and females, respectively. In consequence, the remaining amount of radioactivity, which was still present in the animals after 7 days was very low, not exceeding 1% of the dose. Please refer to Table 4 under "Any other informations on results incl. tables" for details.

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

In urine HPLC analysis revealed 4 metabolite fractions in males and 5 metabolite fractions in females in addition to the parent compound. Unchanged parent compound accounted for 4.97% and 11.35% of the administered dose in urine of males and females, respectively. In both groups 2 major metabolites and 2 respectively 3 minor metabolites were detected. Four minor metabolites (< 1%) were detected in faeces of both sexes. Unchanged parent compound accounted for 4.93% and 2.67% of the administered dose in faeces of males and females, respectively. Please refer to Tables 5 and 6 under "Any other informations on results incl. tables" for details. The identified metabolites were not further characterised.

Any other information on results incl. tables

Table 3: Tissue residues

Tissues	Males*: Mean µg equivalents/g	Females: Mean µg equivalents/g	LOQ µg equivalents/g
Adrenals	<LOQ	0.073	0.058
Blood	0.071	0.144	0.028
Brain	<LOQ	0.057	0.051
Epididymis	<LOQ	n.d.	0.056
Fat (renal, white)	<LOQ	0.107	0.090
Femur	0.041	0.067	0.018
Heart	<LOQ	<LOQ	0.056
Kidneys	0.226	0.359	0.056
Large intestine	0.044	0.059	0.019
Liver	0.207	0.321	0.064
Lung	0.039	0.091	0.029
Muscle	<LOQ	<LOQ	0.059
Ovaries	n.d.	0.150	0.110
Pancreas	<LOQ	0.151	0.057
Plasma	<LOQ	<LOQ	0.058
Prostate	<LOQ	n.d.	0.072
Small intestine	0.089	0.085	0.051
Spleen	<LOQ	0.098	0.057
Stomach	<LOQ	0.098	0.055
Thymus	<LOQ	<LOQ	0.051
Thyroid	<LOQ	<LOQ	0.052
Uterus	n.d.	0.069	0.052

* Animal 1 of male group was excluded from mean calculations.

 

Table 4: Excretion

Percent of Administered Dose
	Males*		Females
	measured	normalized**	measured	normalized**
Urine               0 – 24 h	103.51	85.21	100.70	84.30
24 – 48 h	6.1	5.02	8.36	7.00
48 – 72 h	1.16	0.95	1.10	0.92
72 – 96 h	0.44	0.36	0.89	0.75
96 – 120 h	0.28	0.23	0.47	0.39
120 – 144 h	0.11	0.09	0.24	0.20
144 – 168 h	0.06	0.05	0.18	0.15
Subtotal	111.20	91.54	111.05	92.96
Feces               0 – 24 h	4.5	3.70	1.72	1.44
24 – 48 h	2.42	1.99	1.98	1.66
48 – 72 h	0.86	0.71	0.76	0.64
72 – 96 h	0.35	0.29	0.74	0.62
96 – 120 h	0.12	0.10	0.17	0.14
120 – 144 h	0.08	0.07	0.22	0.18
144 – 168 h	0.06	0.05	0.25	0.21
Subtotal	8.13	6.69	5.20	4.35
ExpiredAir       0 – 24 h	0.10	0.08	0.27	0.23
24 – 48 h	0.26	0.21	0.30	0.25
48 – 72 h	0.16	0.13	0.15	0.13
72 – 96 h	0.09	0.07	0.10	0.08
96 – 168 h	0.18	0.15	0.18	0.15
Subtotal	0.62	0.51	0.82	0.69
Cage Wash	0.98	0.81	1.94	1.62
Total Excretion	120.3	99.03	118.19	98.94
Tissues	<0.01	<0.01	<0.01	<0.01
Carcass	0.55	0.45	0.46	0.39
Total Recovery	121.48	100.00	119.46	100.00

* Animal 1 of male group was excluded from mean calculations.

** Since a mean total recovery of 121.48% and 119.46% was reached in male and female rats, respectively, the mean values were normalized to a recovery of 100%.

 

Table 5: Metabolite pattern in urine

Metabolite Pattern Urine (% of Administered Dose)
	Males*			Females
Pool	U1	U2	Sum	U1	U2	Sum
Sampling Time	0 - 24 h	24 - 48 h	0 - 48 h	0 - 24 h	24 - 48 h	0 - 48 h
Metabolite Fraction
U1	-	-	-	-	0.12	0.12
U2	0.90	0.08	0.98	1.79	0.18	1.97
U3	3.61	1.35	4.97	9.38	1.96	11.35
U4	36.13	2.38	38.51	33.59	3.32	36.91
U5	44.56	1.12	45.68	39.54	1.32	40.86
U6	-	0.10	0.10	-	0.10	0.10
Total	85.21	5.02	90.23	84.30	7.00	91.30

*Animal 1 of group 1 was excluded from urine pooling and HPLCanalysis.

Table 6: Metabolite pattern in faeces

Metabolite Pattern Faeces (% of Administered Dose)
	Males*			Females2
Pool	F1	F2	Sum	F1	F2	Sum
Sampling Time	0 - 24 h	24 - 48 h	0 – 48 h	0 - 24 h	24 - 48 h	0 – 48 h
Metabolite Fraction
F1	-	0.11	0.11	-	0.10	0.10
F2	0.06	0.10	0.16	-	-	-
F3	3.45	1.48	4.93	1.25	1.41	2.67
F4	0.09	-	0.09	-	-	-
F5	0.10	0.29	0.39	0.19	0.15	0.34
Total	3.70	1.99	5.69	1.44	1.66	3.10

*Animal 1 of group 1 was excluded from faeces pooling and HPLC analysis.

Applicant's summary and conclusion

Executive summary:

The toxicokinetic behavior (absorption, distribution, excretion) and metabolism of the test substance was investigated in the Wistar HanRcc:WIST rat according to OECD Guideline 417 (1984) and in compliance with GLP. The test compound was radiolabelled with 14C in the phenol moiety of the molecule. A group of 4 male and 4 female rats received the test substance at a single dose of 300 mg/kg bw orally via gavage suspended in polyethylene glycol (PEG 400) as vehicle. The excretion of radioactivity in urine, faeces and expired air was measured in daily intervals up to 7 days after administration. The animals were sacrificed 7 days after dosing and residues of the test material were determined in selected organs and tissues. The metabolite pattern was investigated in urine and faeces extracts.

Between 121.48% and 119.46% of the administered dose were recovered from measurement of the total radioactivity in males and females, respectively. All mean values were normalized to a recovery of 100%. Rapid excretion mainly via urine was observed after oral administration. Within 24 h 85.21% and 84.30% of the administered dose was excreted in urine of male and female rats, respectively. During the same period of time 3.70% and 1.44% was excreted via faeces of male and female rats, respectively. The radioactivity excreted in the expired air was low (< 1% of the administered dose). Almost the complete administered dose was excreted after 7 days (99.03 and 98.94% in males and females, respectively). Less than 1% of the test material was detected in the remaining carcass and GI-tract. Extensive metabolism of the test material was identified in urine and faeces and excretion of respective metabolites was mainly via urine. The urinary metabolite pattern consisted of at least 5 metabolite fractions dominated by 2 major fractions (37-39% and 41-47% of the dose, respectively). Unchanged parent compound accounted for 4.97% and 11.35% of the administered dose in urine of males and females, respectively. In the fecal metabolite pattern the major fraction was found as unchanged parent compound (3-5% of the dose) while 4 metabolites in negligible amounts (< 1%) were detected in both sexes. The metabolite pattern was very similar for both sexes with some quantitative differences. Thus, under the conditions of this study, after oral administration of the radiolabeled test material to male and female Wistar rats, the recovery of radioactivity in urine, faeces, expired air and cage wash was almost complete. The radioactivity was mainly recovered in urine and to a lower extent in faeces but to a negligible extent in the expired air.