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Toxicological information

Basic toxicokinetics

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Administrative data

Endpoint:
basic toxicokinetics in vitro / ex vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication which meets basic scientific principles.

Data source

Reference
Reference Type:
publication
Title:
Biological N-oxidation of piperidine in vitro
Author:
Wang DY, Gorrod JW, Beckett AH
Year:
1989
Bibliographic source:
Acta Pharmacol. Sin. 10, 252-256 (1989)

Materials and methods

Objective of study:
metabolism
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
In the study the biological N-oxidation of piperidine was investigated in vitro. After incubation of piperidine-HCl in a fortified rat liver microsomal preparation (9000 x g supernatant) at 37°C for 30 min, metabolites were analysed by Thin-layer chromatography (TLC), Gas-liquid chromatography (GLC) HPLC, Gas chromatography (GC)-MS and MS.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Pip-HCL
Radiolabelling:
no

Administration / exposure

Details on exposure:
VEHICLE
- Concentration in vehicle: 10 µmol Pip-HCl/mL water
Duration and frequency of treatment / exposure:
30 min
Doses / concentrations
Remarks:
Doses / Concentrations:
0.121 mg/mL
Details on study design:
INCUBATION
- Incubation of a microsomal preparation of the liver of male albino Wistar rats (9000 x g supernatant fractions) together with the test substance (0.5 mL of the substrate solution) was carried out in a volume of 3.5 mL at 37°C for 30 min using a shaking water bath.
Details on dosing and sampling:
METABOLITE CHARACTERISATION STUDIES
- Extraction of metabolites: After incubation, a two step extraction of metabolites was performed using NaCl and chloroform. The chloroform extract was evaporated at 42 °C under nitrogen. The residue was dissolved in methanol. Controls and blanks were treated in the same manner.
- Time of sampling: After 30 minutes incubation
- Method type(s) for identification:
• Thin-layer chromatography (TLC) was carried out on precoated silica gel; As solvents, methanol and a chloroform, methanol and acetic acid mixture were used. Primary and secondary amines were also detected by converting to dinitrophenyl (DNP) derivatives. DNP derivatives were extracted with cyclohexane.
• Gas-liquid chromatography (GLC)
• High performance liquid chromatography (HPLC) ,
• Gas chromatography (GC)-MS
• Mass spectrometry (MS).

Results and discussion

Metabolite characterisation studies

Metabolites identified:
yes
Details on metabolites:
Piperidine hydrochloride was oxidized in a fortified rat liver microsomal preparation to N-hydroxy piperidine (N-OH-Pip) and 2,3,4,5-tetrahydropyridine-1-oxide (THPO):
After chloroform extraction, TLC and subsequent exposure to Iodide (I₂) vapour two new metabolites were detected. The products have Rf (retardation factor) values close to those of authentic N-OH-Pip and THPO. After GLC, GC-MS, HPLC and TLC both metabolites were identified.
Other known metabolites are 3-hydroxy piperidine, 4-hydroxy piperidine and Piperidone-2.

Piperidine is N-oxidized to the corresponding N-Hydroxylamine.

Applicant's summary and conclusion