t-Butyl (2S,2aS,5aR)-1-azabicyclo[3.3.0] oct-2-carboxylate monooxalate salt

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006-09-27 to 2009-06-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed according to OECD Guideline 111 (Hydrolysis as a Function of pH) without deviations.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Remarks:

The testing facility indicated that the protocol was followed without deviation.

GLP compliance:

yes

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): VRT-126028
- Molecular formula (if other than submission substance): Not applicable
- Molecular weight (if other than submission substance): Not applicable
- Smiles notation (if other than submission substance): Not applicable
- InChl (if other than submission substance): Not applicable
- Structural formula attached as image file (if other than submission substance): Not applicable
- Substance type: No data
- Physical state: White powder
- Analytical purity: 99.3% area by GC
- Impurities (identity and concentrations): 0.10% H2O; 0.6% unknown impurities
- Composition of test material, percentage of components: No data
- Isomers composition: Not applicable
- Purity test date: 2006-05-22
- Lot/batch No.: 25414
- Expiration date of the lot/batch: 2008-05-01
- Stability under test conditions: No data
- Storage condition of test material: Room temperature

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: Preliminary test - approximately 5 minutes after start of incubation, then after 2.4 and 120 hours; EEC Test 1 - initial sample taken immediately time zero and samples to cover the range 20 - 70% hydrolysis; EEC Test 3 - initial sample time zero, further samples taken to ensure that two were when the degree of hydrolysis was greater than 30%.
- Sampling method: No data
- Sampling methods for the volatile compounds, if any: Not applicable
- Sampling intervals/times for pH measurements: Start and end of the study
- Sampling intervals/times for sterility check: No data
- Sample storage conditions before analysis: Samples were not stored before analysis
- Other observation, if any (e.g.: precipitation, color change etc.): No data

Buffers:

- pH: 4.0, 7.0, 9.0
- Type and final molarity of buffer: Phosphate (pH 4.0 and 7.0) and borate (9.0) buffer; molarity not provided
- Composition of buffer: pH 4.0 - Potassium dihydrogen orthophosphate (6.0 g) and disodium hydrogen orthophosphate dodecahydrate (12.8 g) were dissolved in purified water (1900 mL), and the pH was adjusted to 4.0 +/- 0.05 with orthophosphoric acid. The volume was then adjusted to 2000 mL with purified water.
pH 7.0 - Potassium dihydrogen orthophosphate (27.2 g) was dissolved in purified water (3800 mL), 1 M sodium hydroxide (120 mL) was added and the pH was adjusted to 7.0 +/- 0.05 1M hydrochloric acid. The volume was then adjusted to 4000 mL with purified water.
pH 9.0 - Disodium tetraborate decahydrate (66.4 g) and potassium dihydrogen orthophosphate (7.2 g) were dissolved in purified water (3800 mL) and the pH was adjusted to 9.0 +/- 0.05 with 1M hydrochloric acid. The volume was then adjusted to 4000 mL with purified water.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 100 mL Wheaton vials
- Sterilisation method: No data
- Lighting: No
- Measures taken to avoid photolytic effects: Exclusion of light
- Measures to exclude oxygen: Vials with buffer soluation were purged with nitrogen.
- Details on test procedure for unstable compounds: Not applicable
- Details of traps for volatile, if any: Not applicable
- If no traps were used, is the test system closed/open: No data
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
TEST MEDIUM
- Volume used/treatment: 10 mL test solution in purified water (20 g/L), buffer solution of 90 mL.
- Kind and purity of water: Purified
- Preparation of test medium: 10 mL test solution was added to 90 mL buffer solution (pre-equilibrated at test temperature)
- Renewal of test solution: No
- Identity and concentration of co-solvent: No co-solvent used
OTHER TEST CONDITIONS
- Adjustment of pH: There was some decrease in the pH of test solution in the course of the preliminary test, and this being the case, stronger buffer solutions (containing twice the concentration of buffer salts) were employed in EEC Test 1 and 3. Additionally, it was necessary to slightly re-adjust test solutions back to nominal test pH, using 1 M sodium hydroxide, immediately on preparation.
- Dissolved oxygen: No data

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

-Concentration of test substance in the analysed solution (Ca): Ca (mg/L) = sample peak area x standard concentration (mg/L)/mean peak area of bracketing standards.
- Concentration of test substances in each test solution: Cb(mg/L) = Ca(mg/L) x dilution factor, where dilution factor was 10 for all samples tested.
- Observed rate constant, Kobs: Kobs = -slope x 2.303
- Hydrolytical half-life, t1/2: t1/2 = 0.693/Kobs.

Results and discussion

Preliminary study:

The preliminary study showed that after 2.4 hours at each pH 4, 7, and 9 and 50 +/- 0.5 deg C, less than 50% hydrolysis had occurred. However, greater than 10% hydrolysis had occurred after 120 hours (5 days) under these conditions (1 year>t1/2 >1 day), which necessitated proceeding to the next stage of testing (EEC Test 1) at each pH.

Test performance:

The hydrolysis reaction for the test substance at pH 4, 7, and 9 was shown to follow pseudo-first order behavior in EEC Test 1.
EEC test 3 was conducted at 25 deg C and the hydrolysis rate constant (Kobs) and hydrolytical half-lives (t1/2) were determined to be the following: pH4: Kobs(hour-1) 0.0037, t1/2 (days) 7.8; pH 7: Kobs(hour-1) 0.0037, t1/2 (days) 7.8; pH 9 : Kobs(hour-1) 0.0057, t1/2 (days) 5.1.

Transformation products:

not measured

Details on hydrolysis and appearance of transformation product(s):

- Formation and decline of each transformation product during test: No data
- Pathways for transformation: No data
- Other: No data

Any other information on results incl. tables

1. Test solutions were not confirmed to be sterilized. Although biotic degradation is not expected to be significant over the test period (see T003101.HLS.VEP0041/064309.CO2Evol.K1.QCE), the calculated half-lifes might overestimate the actual abiotic degradation rate.

2. The incubation vials (Wheaton) were not confirmed to be closed during the test period.

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

The test substance was determined to have hydrolytic half-lives of approximately 8, 8 and 5 days at pH 4, 7 and 9, respectively.

Executive summary:

Not applicable.