Registration Dossier

Administrative data

basic toxicokinetics in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
other information
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
no guideline followed
Principles of method if other than guideline:
The objective of this study was to investigate the hydrolytic stability of octocrilene in liver and gastrointestinal tract.
GLP compliance:
In accordance with the OECD Principles of GLP with limitations: The protocol, the conduct of study and the "Summary of Results" of this study were not inspected by the QAU. This study does not have a GLP status.

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
2-ethylhexyl 2-cyano-3,3-diphenylprop-2-enoate

Administration / exposure

Positive control reference chemical:
Testosterone (200 μM) for rat liver S9 fraction
Benzyl benzoate (250 μM) for intestinal-fluid and gastric juice simulant.
Details on study design:
Test substance was incubated in replicates at nominal concentrations of 100 and 250 μM for 2 h at 37°C with S9 fraction from rat liver, intestinal-fluid simulant including porcine pancreas lipase and gastric juice simulant. After incubation, the amount of remaining substrate was analysed in the appropriate incubate by HPLC/UV.

Negative Controls:
- Heat deactivated controls (HDC)
- Controls, directly stopped after addition of test substance (t=0 control) s
- Buffer control (BC, test substance in the incubation buffer) was used for calculation of recoveries in the HDC and t=0 controls.

Results and discussion

Metabolite characterisation studies

Metabolites identified:
Details on metabolites:
In S9 fraction from rat liver: One metabolite (not further specified) could be detected that was more polar than octocrilene and was present in the active incubate but not in the performed control incubations.
This metabolite was not detected in the intestinal fluid and gastric juice in vitro system.

Any other information on results incl. tables

S9 fraction rat liver:

In the active incubate, it could be clearly demonstrated that octocrilene was metabolized under the applied incubation conditions. The mean metabolic turnover values were 70% (100μM) and 42% (250μM).

Recoveries of octocrilene (peak areas in HDC and t=0 control versus BC) were between 53-100% (100μM) and 82-98% (250μM).


Intestinal-fluid simulant:

Octocrilene was not metabolized in any of the active incubates as compared to controls. The mean metabolic turnover values were 1% (100μM) and 0% (250μM).

Recoveries were 52-65% (100μM) and 49- 54% (250μM). The relatively low recoveries are assumed to be based on the lipophilicity of the test substance that may bind to the surface of the reaction vessels.


Gastric juice simulant:

Lower peak areas (as compared to t=0 controls) were observed in the active incubates for octocrilene. The mean metabolic turnover values were 0% (100μM) and 19.5% (250μM). Although this finding may imply that octocrilene was partly hydrolyzed by gastric juice simulant this interpretation is questionable since the polar metabolite observed in incubates of liver S9 fraction, being attributed to the degradation product of the substrate was not detected in this in vitro system.


Positive controls

Testosterone was metabolized extensively in liver S9 fraction (100% metabolic turnover).

Benzyl benzoate was hydrolyzed completely in intestine fluid simulant (100% metabolic turnover). In gastric juice simulant lower peak areas as compared to t=0 controls were observed in the active incubates (i.e. 57% metabolic turnover) and demonstrated that the positive control Benzyl benzoate partly degraded in this in vitro system.

In vitro


Concentration [µM]



 (HDC/BC*100)  [%]







Liver S9


100 1 97.1 100.4 77.6
2 60.1 52.8 63.1
250 1 82.4 98.4 22.6
2 83.6 90.6 62.3


fluid simulant

100 1 55.9 65.0 0.0
2 52.0 54.1 2.0
250 1 52.0 54.1 0.0
2 49.3 49.9 0.0




100 1 - - 0.0
2 - - 0.0
250 1 - - 34.3
2 - - 4.8

Applicant's summary and conclusion