Fusidic acid

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Principles of method if other than guideline:

The solubility was determined by shaking excess of the investigated compounds with the aqueous solutions for 24 hours in a temperature-controlled cabin at 25±2°C. The experiment was performed in duplicate. The solutions were then centrifuged. The upper liquid was transferred to a clean reaction tube and centrifuged again. The concentrations of the solutions were determined by reversed phase HPLC with UV detection against a standard curve.

GLP compliance:

not specified

Type of method:

flask method

Specific details on test material used for the study:

Fusidic acid, hemihydrate, micronized, Batch No. V 6391
Citrate-phosphate buffer pH 2.0, pH 4.0, pH 5.5, pH 7.4 and pH 8.0.

Key result

Water solubility:

0.6 other: µg/mL

Conc. based on:

other:

Remarks:

Hemihydrate micronized Batch no. V 6391

Incubation duration:

24 h

Temp.:

25 °C

pH:

2

Key result

Water solubility:

0.8 other: µg/mL

Conc. based on:

other:

Remarks:

Hemihydrate micronized Batch no. V 6391

Incubation duration:

24 h

Temp.:

25 °C

pH:

4

Key result

Water solubility:

8.1 other: µg/mL

Conc. based on:

other:

Remarks:

Hemihydrate micronized Batch no. V 6391

Incubation duration:

24 h

Temp.:

25 °C

pH:

5.5

Key result

Water solubility:

525 other: µg/mL

Conc. based on:

other: Hemihydrate micronized Batch no. V 6391

Incubation duration:

24 h

Temp.:

25 °C

pH:

7.4

Key result

Water solubility:

1 738 other: µg/mL

Conc. based on:

other: Hemihydrate micronized Batch no. V 6391

Incubation duration:

24 h

Temp.:

25 °C

pH:

8

Details on results:

The solubility is increasing with pH as expected, i.e., fusidic acid is a carboxylic acid with a pKa value of 4.91. At pH 2 and 4, the solubility is low and at the same level 0.6-0.8 µg/mL. At pH 5.5, the solubility is 8.1 µg/mL, 525 µg/mL at pH 7.4 and 1738 µg/mL at pH 8.0.

Solubility of Fusidic acid, hemihydrate in aqueous solution at 25±2°C

	pH 2.0 µg/mL	pH 4.0  µg/mL	pH 5.5 µg/mL	pH 7.4 µg/mL	pH 8.0 µg/mL
Hemihydrate, micronized Batch No. V 6391	0.6	0.8	8.1	525	1738

Conclusions:

The water solubility of fusidic acid is increasing with pH. Fusidic acid is a carboxylic acid with a pKa value of 4.91. At pH 2 and 4, the solubility is low and at the same level 0.6-0.8 µg/mL. At pH 5.5, the solubility is 8.1 µg/mL, 525 µg/mL at pH 7.4 and 1738 µg/mL at pH 8.0.

Executive summary:

The water solubility of fusidic acid was determined by shaking excess of the investigated compounds with the aqueous solutions for 24 hours in a temperature-controlled cabin at 25±2°C. The experiment was performed in duplicate.

The solubility is increasing with pH as expected, i.e., fusidic acid is a carboxylic acid with a pKa value of 4.91. At pH 2 and 4, the solubility is low and at the same level. .

Solubility of Fusidic acid, hemihydrate in aqueous solution at 25±2°C

	pH 2.0 µg/mL	pH 4.0  µg/mL	pH 5.5 µg/mL	pH 7.4 µg/mL	pH 8.0 µg/mL
Hemihydrate, micronized Batch No. V 6391	0.6	0.8	8.1	525	1738

Description of key information

The water solubility of fusidic acid was determined by use of a shaking flask method in aqueous solutions for 24 hours in a temperature-controlled cabin at 25±2°C.

The solubility is increasing with pH, i.e., fusidic acid is a carboxylic acid with a pKa value of 4.91. At pH 2 and 4, the solubility is low and at the same level 0.6-0.8 µg/mL. At pH 5.5, the solubility is 8.1 µg/mL, 525 µg/mL at pH 7.4 and 1738 µg/mL at pH 8.0.

Key value for chemical safety assessment

Water solubility:

525 mg/L

at the temperature of:

25 °C

Additional information

Water solubility given for pH 7.4. The solubility is increasing with increasing pH.