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Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1987
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1987
Report date:
1989

Materials and methods

Objective of study:
absorption
distribution
excretion
metabolism
Test guideline
Qualifier:
according to guideline
Guideline:
EPA OPP 85-1 (Metabolism and Pharmacokinetics)
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Quaternary ammonium compounds, benzyl-C12-16-alkyldimethyl, chlorides
EC Number:
270-325-2
EC Name:
Quaternary ammonium compounds, benzyl-C12-16-alkyldimethyl, chlorides
Cas Number:
68424-85-1
Molecular formula:
C12-14H25-29-(CH3)2-C6H5-N.CL
IUPAC Name:
Quaternary ammonium compounds, benzyl C12-C16 (even numbered)-alkyldimethyl chlorides
Constituent 2
Chemical structure
Reference substance name:
Water
EC Number:
231-791-2
EC Name:
Water
Cas Number:
7732-18-5
Molecular formula:
H2O
IUPAC Name:
water
Test material form:
liquid
Radiolabelling:
yes
Remarks:
14C-labelled test substance

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
Test animals:
- Source: Charles River
- Age at study initiation: 6 weeks
- Weight at study initiation: Average body weight: 268.6 g (male) and 167.0 g (female)

Administration / exposure

Details on exposure:
Preparation of dosing solutions:
Preliminary experiments: Oral gavage – single low dose
Experiment 1: Oral gavage – single low dose
Experiment 2: Dietary – repeated low dose
Experiment 3: Oral gavage – single high dose
Experiment 4: Intravenous


Vehicle:
Distilled water (Preliminary experiments and Experiments 1, 3 and 4)
Rodent diet/distilled water (Experiment 2)

Concentration in vehicle:
Preliminary experiments and Experiment 1: 1.0 mg/mL
Experiment 2: 100 ppm in diet for 14 d/1 mg/mL in water single oral dose
Experiment 3: 5.0 mg/mL
Experiment 4: 4 mg/mL


Homogeneicity and stability of the test material: Stable
Duration and frequency of treatment / exposure:
Preliminary experiments: Oral gavage – single low dose
Experiment 1: Oral gavage – single low dose
Experiment 2: Dietary – repeated low dose for 14 d
Experiment 3: Oral gavage – single high dose
Experiment 4: Intravenous
Doses / concentrationsopen allclose all
Dose / conc.:
10 mg/kg bw/day
Remarks:
Preliminary experiments and Experiment 1 and Experiment 4
Dose / conc.:
100 ppm
Remarks:
Experiment 2: 100 ppm non-radiolabelled substance for 14 d, followed by 10 mg/kg radiolabelled.
Dose / conc.:
50 mg/kg bw/day
Remarks:
Experiment 3
No. of animals per sex per dose / concentration:
Preliminary experiments: 2 per sex per group (Total 8 animals)
Main experiments:5 per sex per group (Total 40 animals)
Control animals:
no
Details on dosing and sampling:
Pharmacokinetic study (Absorption, distribution, excretion):
- Tissues and body fluids sampled: urine, faeces, blood, plasma, cage washes
- Time and frequency of sampling: Urine, faeces and urine/feces separator washing samples were collected at the following time intervals: 0-4, 4-8, 8-12, 12-24, 24-36, 36-48, 48-72, 72-96, 96-120, 120-144 and 144-168 h.

Metabolite characterisation studies:
- Tissues, urine and faeces were collected and analysed for radioactivity and faeces were analysed by TLC, HPLC and MS for metabolites and parent compound.



Results and discussion

Preliminary studies:
Results in preliminary studies indicated that negligible amounts of 14CO2 (0.020%) were found in expired air, demonstrating that radiolabel was localized in a stable portion of the molecule

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Following oral administration, 14C-ADBAC was rapidly absorbed, although in very limited amount as indicated by the low blood levels (<0.003% of the administered dose/ml) attained starting from 15 min after dosing and peaking between 3 and 8 h. Blood concentration declined to approximately 25% of the peak value within 24 h.

Based on data on urine excretion and tissue residues after oral administration, and indication from i.v. experiment, it can be expected that the test subsatnce absorption through the g.i. tract is about 20% (conclusion not included in the study report; as assessed by the Italian Rapporteur Member state in the biocide dossier).
Details on distribution in tissues:
Residual 14C in tissues was negligible (<1%) after administration of radiolabelled test substance by gavage both after single and repeated dosing, indicating low potential for bioaccumulation. After i.v. administration a higher amount of radioactivity (30−35%) was found as residue in the tissues.
Details on excretion:
Percent Recovery:

Experiment 1:
Males: 5.77% urine; 98.61% faeces
Female: 6.88% urine; 91.20% faeces
Total Recovery: 104.54 ± 5.29% - males; 98.11 ± 3.25% females

Experiment 2:
Males: 4.76% urine; 95.12% faeces
Female: 5.80% urine; 97.22% faeces
Total Recovery: 100.19 ± 4.94% - males; 103.1 ± 5.18% females

Experiment 3:
Males: 7.75 % urine; 90.03% faeces
Female: 6.95% urine; 87.48% faeces
Total Recovery: 98.36 ± 2.42% - males; 94.58 ± 7.57% females

Experiment 4:
Males: 30.63% urine; 44.44% faeces
Female: 20.58% urine; 55.09% faeces
Total Recovery: 108.43 ± 5.56% - males; 111.45 ± 3.96% females

Remarks:
- About 6−8% of orally administered test substance is excreted in the urine whereas, 87−98% was found in the faeces. Since no data on bile duct-cannulated rats are available, it is not possible to conclude if this radioactivity accounts exclusively for unabsorbed test substance or not. However, the i.v. experiment showed that 20−30% was excreted in the urine and 44-55% in the faeces, suggesting that both the kidney and liver are capable of excreting test substance once absorbed and that absorption is higher than the % found in the urine after oral administration.
- Little or no gender or dose-dependent differences were observed in the excretion patterns nor in rats receiving a single or repeated dose.
- Based on the 5-8% of the test substance administered dose eliminated via urine and tissue residues (less than 1% of the administered dose 7 days after single and repeated oral dosing), it can be expected that the test substance absorption through the g.i. tract is about 10% (ECHA biocides assessment report, 2015).
- Although it was not possible to discriminate between unabsorbed/absorbed material, based on the chemical nature of the test substance, it can be anticipated that about 90% is present in faeces as unabsorbed material (ECHA biocides assessment report, 2015)

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
Over 50% of the faecal radioactivity was unchanged parent compound. Four major metabolites were identified, as oxidation products of the two decyl side chains to hydroxy and hydroxyketo derivatives. The only metabolism which occurred involved oxidation of the two decyl side chains to hydroxy and hydroxyketo derivatives. All were more polar and presumed less toxic than the parent compound. It is predicted that there is no major metabolite greater than 10% of the dosed radioactivity.

Any other information on results incl. tables

All rats receiving the test substance i.v. experienced clear signs of toxicity, including death, and all but one showed red urine during the first 4 h after the treatment.

Applicant's summary and conclusion

Conclusions:
Under the conditions of the study, the test substance was found to have limited absorption (ca. 10%), negligible distribution (no bioaccumulation), and majorly excreted majorly via faeces (87-98%) following oral administration. However, following i.v. administration, it was found to be widely distributed (30-35%) in tissues and excreted both via faeces (40-55%) and urine (20-30%). Four major metabolites were identified, formed via oxidation of the alkyl chain  Repeated dosing did not alter the uptake, distribution or metabolism of test substance.
Executive summary:

A study was conducted to determine the basic toxicokinetics of the radiolabelled test substance, C12-16 ADBAC (30% active in water; 99.4% radiolabelled purity), according to EPA OPP 85-1, in compliance with GLP. Sprague-Dawley rats (10 animals per sex per group) were treated with radiolabelled test substance. The study was conducted in four phases: a single low dose (10 mg/kg); a single high dose (50 mg/kg); a 14 d repeated dietary exposure with non-radiolabelled test substance (100 ppm) and single low dose of radiolabelled (14C) test substance (10 mg/kg); and single intravenous dose (10 mg/kg). Following the single doses or the last dietary dose, urine and faeces were collected for 7 d. A preliminary study had indicated that insignificant 14CO2 was generated. Tissues, urine and faeces were collected and analysed for radioactivity and faeces were analysed by TLC, HPLC and MS for metabolites and parent compound. Following oral administration, radiolabelled test substance was rapidly absorbed, although in very limited amounts, consistent with its highly ionic nature. Residual 14C in tissues was negligible after administration by gavage both after single and repeated dosing, indicating low potential for bioaccumulation. After i.v. administration a higher amount of radioactivity (30−35%) was found as residue in the tissues. About 6−8% of orally administered test substance is excreted in the urine whereas, 87−98% was found in the faeces. Since no data on bile duct-cannulated rats are available, it was not possible to conclude if this radioactivity accounts exclusively for unabsorbed test substance or not. However, the i.v. experiment showed that 20−30% was excreted in the urine and 44-55% in the faeces, suggesting that both the kidney and liver are capable of excreting test substance once absorbed and that absorption is higher than the % found in the urine after oral administration. Based on the urinary mean value 3-4% (with a single peak value of 8.3%) and biliary excretion values (3.7-4.6%), as well as on the absence of residues in the carcass, as measured at 168 h, it can be expected that the test substance absorption through the g.i. tract is about 10% (conclusion not included in the study report; as assessed by the Italian Rapporteur Member state in the biocides dossier; ECHA biocides assessment report, 2015). Less than 50% of the orally administered test substance was found to be metabolised to side-chain oxidation products. In view of the limited absorption of the test substance, the four major metabolites identified were expected to be at least partially formed in the gut of rats, apparently by microflora. No significant difference in metabolism between male and female rats or among the dosing regimens was observed. Repeated dosing did not alter the uptake, distribution or metabolism of test substance. Under the conditions of the study, the test substance was found to have limited absorption (ca. 10%; due to its ionic nature), negligible distribution (no bioaccumulation), and majorly excreted majorly via faeces (87-98%) following oral administration. However, following i.v. administration, it was found to be widely distributed (30-35%) in tissues and excreted both via faeces (40-55%) and urine (20-30%). Four major metabolites were identified, formed via oxidation of the alkyl chain (Selim, 1987).