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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
(3S,6S,7R,8R)-8-benzyl-3-(3-hydroxy-4-methoxypyridine-2-amido)-6-methyl-4,9-dioxo-1,5-dioxonan-7-yl 2-methylpropanoate
Cas Number:
167173-85-5
Molecular formula:
C26H30N2O9
IUPAC Name:
(3S,6S,7R,8R)-8-benzyl-3-(3-hydroxy-4-methoxypyridine-2-amido)-6-methyl-4,9-dioxo-1,5-dioxonan-7-yl 2-methylpropanoate
Specific details on test material used for the study:
Substance name: X642188
Lot #: XS9-129333-47
Purity: 100%
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Duration of testopen allclose all
pH:
4
Initial conc. measured:
0.4 other: μg/mL
Remarks:
Duration of test: Until 90% had degraded, or for up to 30 days after dosing, whichever was the shorter
Temperature: 10, 25 & 35 ± 0.5°C
pH:
7
Initial conc. measured:
0.4 other: μg/mL
Remarks:
Duration of test: Until 90% had degraded, or for up to 30 days after dosing, whichever was the shorter
Temperature: 10, 25 & 35 ± 0.5°C
pH:
9
Initial conc. measured:
0.4 other: μg/mL
Remarks:
Duration of test: Until 90% had degraded, or for up to 30 days after dosing, whichever was the shorter
Temperature: 10, 25 & 35 ± 0.5°C
Number of replicates:
2
Positive controls:
yes
Negative controls:
yes

Results and discussion

Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
10 °C
Hydrolysis rate constant:
0.046 d-1
DT50:
14.9 d
Type:
other: Simple First Order
Key result
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.152 d-1
DT50:
4.5 d
Type:
other: Simple First Order
Key result
pH:
4
Temp.:
35 °C
Hydrolysis rate constant:
0.29 d-1
DT50:
2.4 d
Type:
other: Simple First Order
Key result
pH:
7
Temp.:
10 °C
Hydrolysis rate constant:
0.55 d-1
DT50:
1.3 d
Type:
other: Simple First Order
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
3.175 d-1
DT50:
0.22 d
Type:
other: Simple First Order
Key result
pH:
7
Temp.:
35 °C
Hydrolysis rate constant:
9.204 d-1
DT50:
0.075 d
Type:
other: Simple First Order
Key result
pH:
9
Temp.:
10 °C
Hydrolysis rate constant:
17.924 d-1
DT50:
0.039 d
Type:
other: Simple First Order
Key result
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
71.018 d-1
DT50:
0.01 d
Type:
other: Simple First Order
Key result
pH:
9
Temp.:
35 °C
Hydrolysis rate constant:
192.991 d-1
DT50:
0.004 d
Type:
other: Simple First Order

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Degradation rates were faster at higher temperatures. In pH 7 buffer samples, DT50 of the test substance was 1.3 days at 10°C, 0.22 days at 25°C and 0.075 days at 35°C. Degradation rates were fastest in pH 9 buffer and slowest in pH 4 buffer. In pH 4 buffer samples, DT50 of the test substance was 14.9 days at 10°C, 4.5 days at 25°C and 2.4 days at 35°C. In pH 9 buffer samples, DT50 of the test substance was 0.039 days at 10°C, 0.0098 days at 25°C and 0.0036 days at 35°C.
Executive summary:

The hydrolysis of the test substance was studied in the dark at 10, 25, and 35°C in sterile aqueous buffered solutions at pH 4 (potassium biphthalate), pH 7 (potassium dihydrogenorthophosphate), and pH 9 (sodium borate) until 90% had degraded, or for up to 30 days after dosing, whichever was the shorter. Separate applications of test substance were prepared in buffer so that the initial sample concentration was 0.4 μg a.i./mL.


The experiment was conducted in accordance with EC Regulation No. 1107/2009, the OECD Guideline for the Testing of Chemicals – Hydrolysis as a Function of pH- 111 and US EPA OPPTS 835.2120 Hydrolysis. This study was designed to meet the OECD Good Laboratory Practice Standards, ENV/MC/CHEM(98)17, Paris January 26, 1998.


Duplicate samples were analyzed after 0, 1, 3, 7, 14, 21, 28 and 30 days of incubation for samples at 10°C in buffered solutions at pH 4. Duplicate samples were analyzed after 0, 1, 2, 3, 6, 8, 10 and 16 days of incubation for samples at 25°C in buffered solutions at pH 4. Duplicate samples were analyzed after 0, 0.25, 1, 2, 3, 4, 5 and 9 days of incubation for samples at 35°C in buffered solutions at pH 4.


Duplicate samples were analyzed after 0, 6, 21, 30, 45, 54, 72, 98 and 144 hours of incubation for samples at 10°C in buffered solutions at pH 7. Duplicate samples were analyzed after 0, 1, 2, 3, 5, 7, 9, 16 and 24 hours of incubation for samples at 25°C in buffered solutions at pH 7. Duplicate samples were analyzed after 0, 0.5, 1, 1.5, 2, 3, 4, 6 and 9 hours of incubation for samples at 35°C in buffered solutions at pH 7.


Duplicate samples were analyzed after 0, 10, 20, 30, 40, 60, 90, 150 and 240 minutes of incubation for samples at 10°C in buffered solutions at pH 9. Duplicate samples were analyzed after 0, 5, 10, 15, 20, 25, 30, 45 and 75 minutes of incubation for samples at 25°C in buffered solutions at pH 9. Duplicate samples were analyzed after 0, 1, 2, 4, 7, 10, 15, 20 and 40 minutes of incubation for samples at 35°C in buffered solutions at pH 9.


The sterility of selected study samples (one sample at each pH and temperature at time zero and after the last sampling point) was determined by aseptically pipetting an aliquot onto a nutrient agar plate.


The hydrolysis reactions were stopped by adding formic acid. Formic acid was added to the samples to obtain a final formic acid concentration of 1% in the pH 4 and pH 7 samples and 2% in the pH 9 samples. Each sample (7 mL) was transferred to a 20 mL volumetric flask. The sample vessel was rinsed with acetonitrile containing 1% formic acid (7 mL) which was added to the volumetric flask. The sample vessel was rinsed again with water/acetonitrile/formic acid (50:50:1) (5 mL) which was added to the volumetric flask. The solution was made up to volume with water/acetonitrile/formic acid (50:50:1) and diluted to within the calibration range with water/acetonitrile/formic acid (50:50:1). Aliquots were analyzed by LC-MS/MS.


The pH of selected study samples (two samples were combined for each pH and temperature at time zero and after the last sampling point) was measured.


The test substance decreased to the lowest concentration at study termination.


Simple First Order degradation rates were calculated for the test substance at all three pH conditions. Degradation rates were faster at higher temperatures. In pH 7 buffer samples, DT50 of the test substance was 1.3 days at 10°C, 0.22 days at 25°C and 0.075 days at 35°C. Degradation rates were fastest in pH 9 buffer and slowest in pH 4 buffer. In pH 4 buffer samples, DT50 of the test substance was 14.9 days at 10°C, 4.5 days at 25°C and 2.4 days at 35°C. In pH 9 buffer samples, DT50 of the test substance was 0.039 days at 10°C, 0.0098 days at 25°C and 0.0036 days at 35°C.