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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2019-12-11 to 2019-12-07
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
April 13, 2004
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Lot No.: C170806
Purity: 100%
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: 5 days
- Sampling method: At initiation, 1 mL was taken out from two test solutions in each pH using transfer pipette. After 5 days, two test solutions in each pH were taken out from the dry thermos unit and were cooled to room temperature.
- Sampling intervals/times for pH measurements: at initiation and after 5 days
Buffers:
- pH: 4, 7 and 9
- Preparation of buffer solution:
pH 4.0: The solution was prepared by mixing 4.5 mL of 1 mol/L sodium hydroxide solution and 50 mL of 0.5 mol/L potassium dihydrogen citrate solution, and then filling up to 500 mL with purified water (Takasugi Pharmaceutical, The Japanese Pharmacopoeia), and then adjusting to pH 4.0 with 1 mol/L hydrochloric acid.
pH 7.0: The solution was prepared by mixing 14.8 mL of 1 mol/L sodium hydroxide solution and 50 mL of 0.5 mol/L potassium dihydrogen phosphate solution, and then filling up to 500 mL with purified water. This solution was pH7.0.
pH 9.0: The solution was prepared by mixing 10.7 mL of 1 mol/L sodium hydroxide solution and 50 mL of 0.5 mol/L potassium chloride and 0.5 mol/L boric acid solution, and then filling up to 500 mL with purified water, and then adjusting to pH 9.0 with 1 mol/L hydrochloric acid.
Details on test conditions:
TEST SYSTEM
- Test vessel: 10-mL test tube with glass stopper
- Sterilisation method: sterilized with ethanol in advance
- Test temperature: 49.8-50.0 ℃
- Lighting: Protection from light (Test vessels were covered with aluminum foil)
- Measures to exclude oxygen: aerated for about 5 minutes with helium gas
- If no traps were used, is the test system closed

TEST MEDIUM
- Volume used/treatment: about 10 mL
- Preparation of test item solution:
The test sample (250.03 mg) was precisely weighed with an electronic analytical balance and then filled up to 10 mL with purified water to obtain 25000 mg/L test item solution.
- Test procedures:
The test procedures in a) and b) were performed in a clean bench. The glasswares for preparation of test solution in a) and b) were sterilized with ethanol in advance.
a) A portion (1 mL, 25.0 mg as test item) of the test item solution was put into a 100-mL volumetric flask and then filled up with each buffer solution. The each test solution was filtrated with a sterile filter (0.22 μm) and aerated for about 5 minutes with helium gas to obtain a test solution.
b) The test solution (about 10 mL) was poured into three test vessels and the test vessels were sealed.
c) At initiation, the remaining two test solutions in each pH after taken for HPLC analysis were covered with aluminum foil and put into the dry thermos unit and warmed at the test temperature.
d) After 5 days, samples were taken for HPLC analysis and pH measurement.

OTHER TEST CONDITIONS
- Adjustment of pH: no
Duration:
5 d
pH:
4
Temp.:
50 °C
Initial conc. measured:
>= 258 - <= 260 mg/L
Duration:
5 d
pH:
7
Temp.:
50 °C
Initial conc. measured:
>= 255 - <= 261 mg/L
Duration:
5 d
pH:
9
Temp.:
50 °C
Initial conc. measured:
>= 252 - <= 278 mg/L
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Preliminary study:
The residual percentage of test item at each pH was larger than 90% after 5-day incubation at 50±0.5°C. The test item is hydrolytically stable at pH4.0, pH7.0 and pH9.0.
Transformation products:
not measured
Remarks on result:
hydrolytically stable based on preliminary test
Details on results:
- pH of test solutions:
For pH 4.0: at test initiation: 4.02; after 5 days: 3.99-4.00;
For pH 7.0: at test initiation: 7.00; after 5 days: 6.98;
For pH 4.0: at test initiation: 9.03-9.04; after 5 days: 8.96;

- Residual percentage of test item:
The residual percentage of test item were 96.7%, 98.7% and 96.0 for pH 4.0, 7.0 and 9.0 respectively after 5-day incubation at 50±0.5°C.
Validity criteria fulfilled:
yes
Conclusions:
The test item is hydrolytically stable at pH4.0, pH7.0 and pH9.0.
Executive summary:

In this study, the preliminary test (Tier 1) in OECD guideline for Testing of chemicals No. 111 was performed to evaluate the hydrolysis of test item.

The residual percentage of test item were 96.7%, 98.7% and 96.0 for pH 4.0, 7.0 and 9.0 respectively after 5-day incubation at 50±0.5°C. The test item is hydrolytically stable at pH4.0, pH7.0 and pH9.0.

Description of key information

The hydrolysis of test item was evaluated in accordance with OECD 111. The test item is hydrolytically stable at pH4.0, pH7.0 and pH9.0.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

The residual percentage of test item at each pH was larger than 90% after 5-day incubation at 50±0.5°C.