Hyoscine

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-08-26 to 2016-04-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

29.82 g/L

Conc. based on:

test mat.

Temp.:

20 °C

pH:

8.8

Table 1: Preliminary Test Procedure

01 g soluble in ´x´ mL of water	0.1	0.5	1	2	10	100	>100
Approx. solubility (g/L)	>1000	1000 to 200	200 to 100	100 to 50	50 to 10	10 to 1	<1

Table 2: Preliminary test result in deionised water (1000 g/L to 5 g/L)

Test item [mg]	Total volume of water [mL]	Time of shaking [min]	remarks	Approx. solubility [g/L]
103	0.10	10	not dissolved completely	< 1000
	0.50	10	not dissolved completely	< 200
	1.0	10	not dissolved completely	< 100
	2.0	10	not dissolved completely	< 50
	10	10	not dissolved completely	< 10
	20	10	dissolved completely	5 - 10

 

Therefore, the approximate solubility of the test item was estimated to be between 5 – 10 g/L at 20°C.

Table 3: Results of the water solubility of Scopolamine in deionised water being in equilibrium with atmospheric carbon dioxide

Samping Time [h]	Calculated Concentration Flask 1 [mg/l]	Calculated Concentration Flask 2 [mg/l]	pH value
91	27.84	27.85	8.91
116	29.29	28.13	8.85
140	29.53	29.17	8.82
162	30.34	30.51	8.82
239	31.44	31.39	8.70
259	31.46	30.83	8.69
Overall Mean	29.82		8.80
Standard Deviation	1.38		0.09
RSD* [%]	4.6		1.0

*RSD – relative standard deviation

 

The two independent flasks do not differ by more than 15% from each other.

The Abiotic Degradation study (Study No. S15-04511) showed degradation of Scopolamine at pH 7 (DT50 = 3904 h) and pH 9 (DT50 = 339 h) at 20°C.

As the solubility of Scopolamine in water was determined over a period of 259 hours and the pH value of the test item solution was determined to be 8.80, it has to be considered that a certain amount of Scopolamine underwent degradation.

It can be assumed that about 41% of the dissolved test item underwent degradation within 259 hours at pH 9 and 20°C. The determined solubility of 29.82 mg/l represents 59% of the dissolved test item.

Conclusions:

It can be assumed that about 41% of the dissolved test item underwent degradation within 259 hours at pH 9 and 20°C. The determined solubility of 29.82 g/L represents 59% of the dissolved test item as determined by flask method according to Regulation EC No. 440/2008 Method A.6., OECD Test Guideline 105 (1995).

Description of key information

The Abiotic Degradation study (study report S15 -04511; CSR section 4.1.1.1. Hydrolysis) showed degradation at pH 7 (DT50 = 3918 h / 163 d) and pH 9 (DT50 = 339 h / 14 d) at 20°C. As the solubility in water was determined over a period of 259 hours and the pH value of the test item solution was determined to be 8.80, it has to be considered that a certain amount of Scopolamine underwent degradation. It can be assumed that about 41% of the dissolved test item underwent degradation within 259 hours at pH 9 and 20°C. The determined solubility of 29.82 g/L represents 59% of the dissolved test item as determined by flask method according to Regulation EC No. 440/2008 Method A.6., OECD Test Guideline 105 (1995).

Key value for chemical safety assessment

Water solubility:

29.82 g/L

at the temperature of:

20 °C