Chlorhexidine dihydrochloride

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Version / remarks:

Cited as Directive 92/69/EEC, C.7

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

ca. 300 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

ca. 300 mg/L

Transformation products:

no

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

As result from the preliminary tests at 50°C the main test at pH 4 and pH 7 was not required because the degree of hydrolysis was lower than 10% within 5 days (mean at pH 4: 1.9%; mean at pH 7: 0.4%). The performance of the test at pH 9 was not possible due to precipitation of chlorhexidine (base).

Validity criteria fulfilled:

yes

Conclusions:

No hydrolysis was observed in the preliminary tests at 50°C (mean at pH 4: 1.9%; mean at pH 7: 0.4%).The main test was not required because the degree of hydrolysis was lower than 10% within 5 days.

Description of key information

A GLP guideline study according to OECD Guideline 111 (hydrolysis as a function of pH) was conducted. As result from the preliminary tests at 50°C the main test at pH 4 and pH 7 was not required because the degree of hydrolysis was lower than 10% within 5 days (mean at pH 4: 1.9%; mean at pH 7: 0.4%). The performance of the test at pH 9 was not possible due to precipitation of chlorhexidine (base).

The half-life at pH 4 and pH 7 (25°C) was > 1 year.