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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
From February 10, 2004 to March 13, 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Objective of study:
absorption
distribution
excretion
metabolism
Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Didecyldimethylammonium chloride
EC Number:
230-525-2
EC Name:
Didecyldimethylammonium chloride
Cas Number:
7173-51-5
Molecular formula:
C22H48N Cl
IUPAC Name:
N,N-Didecyl-N,N-dimethylammonium chloride
Test material form:
liquid
Radiolabelling:
yes

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 Laboratories France, L’Arbresle, France. Caesarean Obtained, Barrier Sustained-Virus Antibody Free (COBS-VAF®).
- Age at study initiation: 7 wk old; for the bile collection group, animals were around 10 wk (males) 12 wk females).
- Weight at study initiation: 229 g males and 159 g females
- Fasting period before study: Overnight
- Housing: 2 or 3 animals/cage in oral groups and singly in dermal and bile collection group
- Diet (e.g. ad libitum): A04 C pelleted diet ad libitum
- Water (e.g. ad libitum): Filtered tap water ad libitum
- Acclimation period: At least 7 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22± 2 °C
- Humidity (%): 50±20%
- Air changes (per hr): 12 cycles/h of filtered, non-recycled air
- Photoperiod: 12 h light/ 12 h dark

Administration / exposure

Route of administration:
other: Oral gavage and dermal
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg



TEST SITE
- Area of exposure: Interscapular/upper back region
- % coverage: 10 % (25 -30 cm2 for 250-300 g rat)


REMOVAL OF TEST SUBSTANCE
- Washing (if done): Washed to remove all traces of test material by wiping with at least 3 cotton swabs dampened with water and diluted normal hand soap solution.
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.5 mL of dosage form/kg ( Dose: 1.5 mg/kg)

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes
Duration and frequency of treatment / exposure:
6 h
Doses / concentrations
Remarks:
Doses / Concentrations:
Oral: 50 and 200 mg/kg/day;
Dermal: 1.5 and 15 mg/kgbw/day
No. of animals per sex per dose / concentration:
9/sex/dose - Plasma/blood pharmacokinetics (Group 1-5)
5/sex/dose - Excretion balance (Group 6-8)
5/sex/dose bile collection (Group 9)
Control animals:
other: Yes: For the purposes of pre-dose sample analysis, plasma, blood and tissues will be collected from at least one untreated supplementary animal/sex using the above mentioned procedures.
Positive control reference chemical:
Not applicable
Details on study design:
- Rationale for animal assignment (if not random): Random
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled : Blood, plasma, serum, urine, feces, cage washes, bile, skin-application site
- Time and frequency of sampling: Oral groups: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h post gavage on Day 1 (Groups 1, 2 and 5)
Dermal group: 3, 6, 7, 8, 10, 16, 24, 48 and 72 h post dermal application (Groups 3 and 4)
Excreta and tissue collection: 0-24, 24-48, 48-72, 96-120, 120-144 and 144-168 h after the radioactive gavage/dermal application (Group 6-8)
Bile collection: 0-3, 3-6, 6-12 and 12-24 h post injection/gavage (Group 9)

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : urine, faeces, tissues, cage washes, bile
- Method type(s) for identification : Radio- HPLC for urine samples and LSC for biological samples

Statistics:
None

Results and discussion

Preliminary studies:
None
Main ADME resultsopen allclose all
Type:
absorption
Results:
Low oral bioavailability (0.93 to 3.16 %); rapidly eliminated with a 48 h period
Type:
distribution
Results:
Radioactive levels generally decreased over time in all tissues
Type:
excretion
Results:
A mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Single dose: The minimal fraction(from urine data) of the oral dose absorbed systemically was below 3.16 and 1.75 % for males and females respectively.
Repeated dose: The minimal fraction (from urine data) of the oral dose absorbed systemically was below 0.93 and 1.18 % for males and females respectively.
Details on distribution in tissues:
Oral gavage:
50 mg/kg (single dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys and liver
200 mg/kg (single dose): The mean radioactivity levels were above quantifiable limits (Group 2) in half analysed tissues and organs at 24 h. Specifically high levels were present in adrenals, abdominal fat, eyes, heart, kidneys, liver, lungs, lymph nodes and pancreas.
50 mg/kg (repeated dose): The mean radioactivity levels were below quantifiable limits (Group 1) in all tissues except for intestines, kidneys, liver and mesenteric lymph nodes

Dermal application:
Single application (1.5 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site and intestine (15 mg/kg)
Single application (15 mg/kg): Radioactivity levels were below quantifiable limits in all tissues/organs at all time points except for the stripped skin from the application site, adrenals, heart, kidneys, liver and lungs
Details on excretion:
Following single oral gavage at a nominal dose level of 50 mg/kg to rats, a mean 2.57±2.39 (males) and 1.14±0.69 % (females) of the radioactive dose was recovered over the 24 h period in the bile.
Toxicokinetic parametersopen allclose all
Key result
Toxicokinetic parameters:
other: Oral: Mean plasma and blood radioactivity levels were all below quantifiable limits
Key result
Toxicokinetic parameters:
other: Dermal: Mean plasma and blood radioactivity levels were all below quantifiable limits

Metabolite characterisation studies

Metabolites identified:
no
Details on metabolites:
No metabolites nor parent drug were found in urine samples

Any other information on results incl. tables

Conclusion: Low dermal and oral absorption. The actual minimal fraction of the oral dose absorbed was 0.93 to
3.16%; this was eliminated rapidly, essentially within a 48-hour period.

Applicant's summary and conclusion

Conclusions:
Under the study conditions, the test substance was found to have low dermal and oral absorption. The total oral absorption value therefore was roughly in the range around 3-7%, based on urinary (0.93 - 3.16%) and bile (1.8-4.0%) excretion. Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.
Executive summary:

A study was conducted to determine the blood and plasma pharmacokinetics, tissue distribution and mass balance of the test substance, 14C-test substance, DDAC (non-radiolabellled: 40.5% active, radilabelled: 98% active) following oral and dermal administrations, according to OECD guideline 417, in compliance with GLP.

Single dermal administration (at 1.5 and 15 mg/kg, as 6 h exposure over 10% of the body surface) and single (at 50 and 200 mg/kg) and repeated (at 50 mg/kg/d) oral gavage administrations of test substance were performed to male and female Sprague-Dawley rats. In addition, the elimination of radioactivity in bile after single oral administration at 50 mg/kg was investigated. Investigations included blood and plasma pharmacokinetics, tissue distribution and mass balance of total radioactivity. The animals were divided into 9 groups; groups 1 to 5 (each of 9 animals/sex) for plasma/blood pharmacokinetics of radioactivity and tissue distribution, groups 6 to 8 (each of 5 animals/sex) principally for excretion balance and group 9 (4 animals/sex) for bile collection. Animals of groups 1 to 4 and 6 and 7 were treated once with the radiolabelled test item. Animals of groups 5 and 8 were treated once per day for 6 d with the unlabelled test item, followed by a single administration of the radiolabelled test material on Day 7. All oral dosages applied 2.2 MBq/kg for radioactive dose-levels, and 3.7 MBq/kg for dermal applications. Dermal dosages were applied on clipped skin approx. 10% of the total body surface area, over the interscapular/ upper back region. The animals wore an Elizabethan collar to prevent ingestion of the test item. At the end of the exposure period, the collar was removed and kept with the swabs for analysis. After 6 h, the treated areas were washed using dampened cotton swabs with diluted hand soap followed by two dry swabs to remove all traces of the test material.

Blood and plasma sampling were performed as follow: (a) Oral group: 0.5, 1, 2, 4, 8, 24, 48, 72 and 96 h (b) Dermal group: 3 and 6 (i.e. during the exposure period), 7, 8, 10, 16, 24, 48 and 72 h. Following the final blood sampling/animal (i.e. at 24, 48 and 72/96 h), each sampled animal was sacrificed by cervical dislocation, under isoflurane anesthesia. The carcass were weighed and the following tissues dissected out and weighed: Adrenals, Gastro intestinal tract (complete), Lymph nodes (mesenteric and mandibular), Brain, Heart, Muscle (right leg adductor), Eyes, Kidneys, Pancreas, Fat (abdominal), Liver, Skin (lower back), Femur (right with marrow), Lungs, Spleen. In addition, for the dermal treated animals, the application site will be dissected out and weighed. Thereafter, the application site and the skin from the lower back will be each stripped completely (using tape) 13 times. No macroscopic examination was performed on the prematurely sacrificed animals or those found dead. Urine and faeces were collected from the groups 6 to 8 animals for the radioactive treatments at the following times: (a) During a period of 24 h before radioactive dosing on Day 1 (Groups 6 and 7), or Day 7 (Group 8) (b) during the periods 0-24, 24-48, 48-72, 72-96, 96-120, 120 -144 and 144-168 h after the radioactive gavage/dermal application. After each collection of faeces, the cages and trays will be carefully rinsed with not more than 20 mL of water (cage wash) (except for last collection; approximately 100 mL will be used).

Following single and/or repeated oral gavage at 50 and 200 mg/kg bw/day, the plasma and blood radioactivity levels were non-quantifiable indicating a low oral bioavailability. The actual minimal fraction of the oral dose absorbed was 0.93 to 3.16%; this was eliminated rapidly, essentially within a 48 -h period. The vast majority of the oral dose was excreted rapidly in the faeces. At the high oral dose-level only, quantifiable levels of radioactivity were found in some central organs at 24 h post- dosing (intestines, liver. kidney) ; otherwise, the vast majority of the dose was confined to the intestines and levels decreased over time. Only 2.57/1.14% (males/females) of the oral dose was eliminated in the bile in a 24-h period. No metabolites or parent drug were found in urine.

Following single dermal application at 1.5 and 15 mg/kg bw, the plasma and blood radioactivity levels were non-quantifiable at all time-points. For the 1.5 mg/kg bw group, around 1% and 50% of the dose was eliminated in the urine and faeces, respectively, mostly within a 48 h period, suggesting that the dermal dose was highly absorbed via the skin. However, as the test site was not protected with an Elizabethan collar during the main part of the collection period (the collar was worn during the exposure period only), this may have been due to the animal licking the test site. This is also supported with the finding that after oral dosing only 1-2.5% was excreted via bile back to intestines, and 2-3 % excreted via urine. At 24 h post- dosing, most of the radioactivity was in the "stripped" skin (dermis and epidermis) application site (6.07 to 21.6% of the dose) and intestines for both dose- levels, though some radioactivity was in the skin adjacent to the application site (most likely from cross- contamination due to grooming) and minor traces were in the eyes and other organs. At 72/168 h, levels in the application site were 1.06 to 2.82% of the radioactive dose, suggesting the skin acted as a drug reservoir. In the stratum corneum of the application site, the levels of radioactivity were of similar magnitude in the different layers at each time point. For all tissues/organs, the radioactivity levels essentially decreased over time. All data showed generally a low inter-animal variability. In addition, there was no evidence of gender differences.

Under the study conditions, the test substance was found to have low dermal and oral absorption. The actual minimal fraction of the oral dose absorbed roughly ranged from 0.93 to 3.16 % (based on urinary excretion) and ((1.8-4.0%) biliary excretion), which was eliminated rapidly, essentially within a 48 h period (Appelqvist, 2006). Further, the study was flawed with respect to the dermal absorption part and did not allow a precise quantification of percutaneous absorption. Nevertheless, based on the results, it can be assumed that dermal absorption is very limited compared to absorption via the oral route.