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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report date:
1995

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
(1R,3aS,3bR,9S,9aS,9bS,11aS)-1-acetyl-5-chloro-9-(chloromethyl)-9a,11a-dimethyl-7-oxo-1H,2H,3H,3aH,3bH,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-1-yl acetate
EC Number:
605-617-4
Cas Number:
17183-98-1
Molecular formula:
C24 H30 Cl2 O4
IUPAC Name:
(1R,3aS,3bR,9S,9aS,9bS,11aS)-1-acetyl-5-chloro-9-(chloromethyl)-9a,11a-dimethyl-7-oxo-1H,2H,3H,3aH,3bH,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-1-yl acetate
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Buffers:
- pH: 4
- Type and final molarity of buffer: 0.05 M
- Composition of buffer: 0.74 g = 0.009 mole sodium acetate p.a. Merck Art. 6268 (M = 82.03 g/mol) and 2.5 mlL= 0.0041 mole acetic acid 100 % Merck Art. 63 E (M = 60.05 g/mol) were dissolved to 1000 mL with double-distilled water. The pH value was adjusted to 4 by adding acetic acid 100 % p.a. (Merck Art. 63 E).

- pH: 7
- Type and final molarity of buffer: 0.0067
- Composition of buffer: solution A: 9.511 9 = 0.067 mole disodium hydrogen phosphate (Merck Art. 6589) (M = 141.96 g/mol)
solution B: 9.118 9 = 0.067 mole potassium dihydrogen phosphate (Merck Art. 4881)
(M = 136.09 g/mol) were dissolved to 1000 mL (each) with double distilled water. 61 mL of solution A and 39 mL of solution B were mixed and diluted 10-fold with double distilled water.

- pH: 9
- Type and final molarity of buffer: 0.05 M
- Composition of buffer: 4.78 g = 0.012 M disodium tetraborate Merck Art. 6315 (M = 381.37 g/mol)
46 mL = 0.0046 M 0.1 M hydrochloric acid Titrisol Merck Art. 9944 (M = 36.46 g/mol) were dissolved to 1000 mL with double distilled water.
Details on test conditions:
Three sets of sampies, buffered to pH values of 4, 7 and 9, each with a ZK 10882 concentration of approx. 0.15 mg/L containing 1 % acetonitrile, were prepared by adding a ZK 10 882 stock solution in acetonitrile to the corresponding buffer solution in HPLC autosampler vials. Before that, the buffer solutions had been purged with nitrogen to remove dissolved oxygen. All experiments were condueted using sterilized equipment, buffer solutions and double-distilled water.
Positive controls:
no
Negative controls:
no

Results and discussion

Transformation products:
not measured
Remarks:
As could be expected, hydrolytic cleavage of the acetic acid ester function occurs in neutral and alkaline solution leading to acetic acid and the corresponding alcohol. At pH 9, further hydrolysis of the alcohol was observed after complete hydrolysis.
Total recovery of test substance (in %)open allclose all
% Recovery:
> 90
pH:
4
Duration:
5 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
24.7
pH:
7
Temp.:
60 °C
Duration:
48 h
% Recovery:
27.4
pH:
7
Temp.:
60 °C
Duration:
48 h
% Recovery:
11.3
pH:
9
Temp.:
80 °C
Duration:
8 h
Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
88.2 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: extrapolated using Arrhenius equation
Key result
pH:
9
Temp.:
25 °C
DT50:
< 24 h
Details on results:
The data for the test solutions at pH 4 indicate less than 10 % degradation after 5 days at 50 ± 0.1 °C. According to the guideline, less than 10 % degradation within 5 days at 50°C correspond to a half-life of more than one year at 25°C and no further testing is necessary at the corresponding pH value. The half-life of ZK 10 882 at pH 9 and 50°C was determined with a kinetic data analyis software to be 1.02 h. The half-life at this pH value is thus smaJler than 2.4 hours at 50 oe: According to the guideline, this corresponds to a half-life of < 24 h at 25 °C and no further testing is necessary. At pH 7, more than 10 % decay of the test were observed within 5 days at 50 ± 0.1 °C. Therefore further hydrolysis experiments were necessary. The testing guideline offers two options: measurements at one temperature below 40 °C or at two elevated temperatures with replication at the lower of those two temperatures. The latter option was chosen as ZK 10 882 is hydrolysed quite slowly.

Applicant's summary and conclusion

Conclusions:
DT50: 88.2 d at pH 7.
Executive summary:

The rate of hydrolysis of ZK 10 882 was determined according to EC guideline C.7 at pH 4, 7 and 9. At pH 4, less than 10 % degradation within 5 days at 50 ± 0.1 °C were observed. This corresponds to a half-life > 1 year at 25°C. At pH 9, the experimentally determined half-life was smaller than 2.4 hours at 50 °C corresponding to a half-Iife of less than 24 hours at 25 °C. Therefore no further testing was necessary at these pH values. At pH 7, more than 10 % decay of the test substance was measured within 5 days at 50 ± 0.1°C. Therefore hydrolysis experiments at two elevated temperatures with replication at the lower of those two temperatures were conducted at pH 7 in order to extrapolate from the experimentally determined hydrolysis rate constants at higher temperatures to the rate constant at 25 °C by using the Arrhenius equation and the experimental data. The extrapolated rate constant and half-Iife at 25 °C are:


pH 7, 3.276x 10-4  t1/2 88.2 days