Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Expert judgement is combined with the prediction of metabolism provided by the OECD QSAR Application Toolbox.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Objective of study:
toxicokinetics
Principles of method if other than guideline:
No guideline exists for this type of appraisal.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
not applicable

Test animals

Species:
other: not applicable
Details on test animals and environmental conditions:
not applicable

Administration / exposure

Route of administration:
other: oral and dermal route are considered
Details on exposure:
not applicable

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
MPA is predicted to be moderately bioavailable (50%) via the oral route and readily absorbed via skin.
Details on distribution in tissues:
MPA and its metabolites are very polar and are predicted to have no accumulation potential. They are expected to be enter the urine shortly after systemic absorption.
Details on excretion:
MPA as well as the oxidised metabolites are very polar and will be excreted rapidly via urine. Faecal excretion is not expected.

Metabolite characterisation studies

Metabolites identified:
not measured
Details on metabolites:
MPA is expected to undergo stepwise oxidation of the thiol group yielding 3-sulfinopropanoic acid and 3-sulfopropanoic acid. Both substances are very polar and thus subject to renal elimination.
In addition, disulphide bridge formation with cysteine or with another MPA molecule may occur.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): no bioaccumulation potential based on study results
MPA is predicted to be moderately bioavailable (50%) via the oral route and readily absorbed via skin.
MPA is expected to undergo stepwise oxidation of the thiol group and also disulphide bridge formation with cysteine or with another MPA molecule.
MPA and its metabolites are very polar and thus subject to renal elimination. Tissue accumulation can be excluded.
Executive summary:
The toxicokinetic behaviour of MPA [3-mercaptopropionic acid] was assessed. The OECD QSAR Application Toolbox was used to make a qualitative prediction of metabolites formed in liver, skin and gastrointestinal tract.

The Danish QSAR Database was used to predict dermal and oral bioavailability of MPA.

The fate of these metabolites is predicted on the basis of their chemical structure based on expert judgement.

MPA is predicted to be moderately bioavailable (50%) via the oral route and readily absorbed via skin.

MPA is expected to undergo stepwise oxidation of the thiol group yielding 3-sulfinopropanoic acid and 3-sulfopropanoic acid. Both substances are very polar and thus subject to renal elimination.

In addition, disulphide bridge formation with cysteine or with another MPA molecule may occur.

Tissue accumulation can be excluded.