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Basic toxicokinetics

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Administrative data

basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Well performed academic study, not adhering to OECD test guideline and GLP and with limted reporting of details.

Data source

Reference Type:
Absorption, distribution and excretion of [14C]CTAB, a quaternary ammonium surfactant, in the rat
Isomaa, B
Bibliographic source:
Fd. Cosmet. Toxicol. 13, 231-237

Materials and methods

Objective of study:
Principles of method if other than guideline:
Absorption, distribution and excretion of radiolabelled test substance in orally administered rats.
GLP compliance:

Test material

Details on test material:
- Name of test material (as cited in study report): cetyl-[1-14C]trimethyl ammonium bromide
- Lot/batch No.: not stated
- Radiochemical purity (if radiolabelling): 99%
- Specific activity (if radiolabelling): 17.6 µCi/mg
- Locations of the label (if radiolabelling): 1-14C-cetyl
[1-14C]cetyl trimethyl ammonium bromide

Test animals


Administration / exposure

Route of administration:
oral: gavage
Duration and frequency of treatment / exposure:
single gavage dose
Doses / concentrations
Doses / Concentrations:
0.8 mg/kg
No. of animals per sex per dose:
3-5 rats per experiment
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, bile, blood plasma, liver, kidney, spleen, heart, lungs, hind leg muscle
- Time and frequency of sampling: 2, 4, 8, 24, 48, 72 and 96 h
- Method type(s): Liquid scintillation counting

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
After 8 h, a about 80% of the administered radioactivity was found in the gastrointestinal tract, of which 87% was in the gastrointestinal content.
Details on distribution in tissues:
After 8 h, about 90% of the administered dose had left the stomach. Only small amounts of radioactivity were found in other organs. Peak levels were found at 4 or 8 h and were about 500 (liver), 200 (kidney), 40 (spleen), 20 (plasma) dpm/100 mg tissue. Kinetics in muscle was slower with a peak at about 24 h at 20 dpm/100 mg tissue. Levels in heart and lungs were similar to muscle (values not shown)
Details on excretion:
About 2% of the administered radioactivity was excreted into the bile during the first 12 h; excretion rate was linear over time after a lag phase of about 2 h. The authors concluded that there was no appreciable enterohepatic circulation. The total dose excreted in the urine was 1.22% after 72 hours; 1.06% were excreted within the first 24 h. No radioactivity was expired as carbon dioxide during day 1 after administration. After 3 d, 92% of the administered radioactivity had been excreted in the feces.

Metabolite characterisation studies

Details on metabolites:
Thin layer chromatography indicated that about 85% of the radioactive substance excreted in feces after 3 d was the parent compound. Analyses of bile and urine indicated that most of the absorbed substance was probably metabolised. Fecal homogenates and urine incubated with the parent compound did not cause changes in the thin layer chromatogram. Due to limited amounts, identification of metabolites was not possible.

Applicant's summary and conclusion

In a toxicokinetic study, female rats received a single oral gavage administration of 0.8 mg/kg [1-14C]cetyl trimethyl ammonium bromide in water. After 3 days 92% of the dose was excreted in feces and about 1% in urine. About 85% of the radioactive substance excreted in feces after 3 d was the parent compound. About 2% of the administrated radioactivity was excreted in the bile during the first 12 hours after treatment. Taken together, these data indicate that about 10% of the administered dose was absorbed. Only small amounts of radioactivity were found in the blood and organs. Highest peak concentratons (at 4-8 h) were found in liver (about 0.8% of administered radioactivity) and lower levels in kidneys, spleen, heart, lung and skeletal muscle.