Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study meets generally accepted scientific principles, acceptable for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1960
Report Date:
1960

Materials and methods

Objective of study:
metabolism
toxicokinetics
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
In vitro hydrolysis of the test substance by isolated mammalian liver enzymes.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: Solid, not further specified
Radiolabelling:
no

Test animals

Species:
rat
Strain:
not specified
Sex:
not specified

Administration / exposure

Route of administration:
other: not applicable, in vitro
Vehicle:
other: chloroform
Details on exposure:
Not applicable, in vitro.
Duration and frequency of treatment / exposure:
4 hours enzymatic hydrolysis at 37 °C
Doses / concentrations
Remarks:
Doses / Concentrations:
3.6 mg
No. of animals per sex per dose:
liver homogenate isolated from a single freshly sacrificed rat
Control animals:
no
Details on study design:
The fatty acid amidases (known as Fatty Acid Amide Hydrolases: FAAH) which occur in rat liver were chosen as typical representative of mammalian amidases, and used in hydrolysis investigation. A known quantity of test substance was dissolved in chloroform so that exactly 3.6 mg could be introduced into a Warburg vessel in 2 mL of solution. The solvent was evaporated with a stream of nitrogen, leaving a film of the amide an the inside surface of the flask.
Liver from a freshly killed exsanguinated rat was homogenised and a portion of the liver homogenate added to the pre-weighed Warburg flask. Two mL of Ringer-phosphate medium was then added and 0.2 mL of 2.5 N HCl pipetted into the side arm and well of the flask. Incubation at 37 °C and agitation was carried out for 4 hours.
Details on dosing and sampling:
At the end of the incubation time the HCl was tipped into the mixture which was then transferred to a test tube containing 1 mL of 15% trichloroacetic acid. After centrifugation, the supernatant liquid was drawn off and the precipitate washed 2 or 3 times with 3% trichloroacetic acid which was combined with the original solution. Total ammonia was determined using the aeration technique of Van Slyke and Cullen. As ammonia is formed naturally by liver homogenate, blank experiments were conducted on all constituents except the test substance.
Statistics:
The error cited along with the degree of hydrolysis was computed from a mathmatical treatment of the individual standard deviations of both sample and blank.

Results and discussion

Any other information on results incl. tables

Degree of Hydrolysis:

Volume of 0.01 consumed by sample minus blank (ml)

Ammonia liberated (micromoles)

Initial amount of sample

(micromoles)

Degree of Hydrolysis (%)

0.145

1.45

6.93

21±5

Because of the low range of the values obtained, a series of 7 separate blanks and three sample runs were made. Since ammonia is generated naturally by the liver, and since unequal amounts of liver homogenate were taken for each run, the average blank value was computed on the basis of micromoles of ammonia per unit weight of homogenate. This blank was then multiplied by the amount of liver used in each sample, to compute the appropriate correction.

Applicant's summary and conclusion