Registration Dossier

Administrative data

Endpoint:
additional toxicological information
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report date:
2000

Materials and methods

Principles of method if other than guideline:
Evaluation of D5 as a potential inhibitor of human and rat cytochrome P450 enzymes.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Decamethylcyclopentasiloxane
EC Number:
208-764-9
EC Name:
Decamethylcyclopentasiloxane
Cas Number:
541-02-6
Molecular formula:
C10H30O5Si5
IUPAC Name:
2,2,4,4,6,6,8,8,10,10-decamethyl-1,3,5,7,9,2,4,6,8,10-pentoxapentasilecane

Results and discussion

Any other information on results incl. tables

D5 appears to inhibit rat CYP2B1/2 in a manner that does not conform to prototypical  types of inhibition; this inhibition increases significantly with an increase in marker substrate concentration. D5 also appears to be a weak competitive inhibitor of human  CYP3A4/5 and a strong metabolism-dependent inhibitor of human CYP3A4/5.

Applicant's summary and conclusion

Conclusions:
In an in vitro study that investigated whether D5 is a potential inhibitor of human and rat cytochrome P450 enzymes it was found that D5 appears to inhibit rat CYP2B1/2 in a manner that does not conform to prototypical  types of inhibition; this inhibition increases significantly with an increase in marker substrate concentration. D5 also appears to be a weak competitive inhibitor of human  CYP3A4/5 and a strong metabolism-dependent inhibitor of human CYP3A4/5.