Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Penicillin antibacterial.
DEFINITION
Flucloxacillin Capsules contain Flucloxacillin Sodium Monohydrate.
The capsules comply with the requirements stated under Capsules and with the following requirements.
Content of flucloxacillin, C19H17ClFN3O5S
95.0 to 105.0% of the stated amount.
IDENTIFICATION
The infrared absorption spectrum of the contents of the capsules, Appendix II A, is concordant with the reference spectrum of flucloxacillin sodium (RS 145).
TESTS
Dissolution
Comply with the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
(a) Use Apparatus 2, rotating the paddle at 50 revolutions per minute.
(b) Use 900 mL of water, at a temperature of 37°, as the medium.
PROCEDURE
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in 50% v/v of acetonitrile.
(1) After 15 minutes withdraw a sample of the medium and filter. Use the filtered medium, diluted with 50% v/v of acetonitrile if necessary, to produce a solution expected to contain the equivalent of 0.01% w/v of flucloxacillin.
(2) 0.011% w/v of flucloxacillin sodium BPCRS.
(3) 0.0001% w/v of flucloxacillin impurity D EPCRS and 0.01% w/v of flucloxacillin sodium BPCRS.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 μm) (Zorbax SB-C18 is suitable).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 1.8 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 225 nm.
(f) Inject 10 μL of each solution.
MOBILE PHASE
Mobile phase A 0.118% w/v sodium hexanesulfonate monohydrate for ion-pair chromatography in a mixture of 0.8 volumes of concentrated ammonia and 1000 volumes of water. Adjust the pH of the resulting solution to pH 3.1 ± 0.1 with orthophosphoric acid.
Mobile phase B acetonitrile R1.
| Time (Minutes) | Mobile phase A (% v/v) | Mobile phase B (% v/v) | Comment |
| 0-8 | 65→41 | 35→59 | linear gradient |
| 8-12 | 41→65 | 59→35 | linear gradient |
| 12-18 | 65 | 35 | re-equilibration |
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between impurity D and flucloxacillin is at least 1.5.
DETERMINATION OF CONTENT
Calculate the total content of C19H17ClFN3O5S in the medium using the declared content of C19H16ClFN3NaO5S in flucloxacillin sodium BPCRS. Each mg of C19H16ClFN3NaO5S is equivalent to 0.9538 mg of C19H17ClFN3O5S.
LIMITS
The amount of flucloxacillin released is not less than 85% (Q) of the stated amount.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in 50% v/v of acetonitrile, protected from light.
(1) Disperse a quantity of the capsule contents containing the equivalent of 0.1 g of flucloxacillin with 50% v/v of acetonitrile and dilute to 100 mL.
(2) Dilute 1 volume of solution (1) to 100 volumes.
(3) 0.001% w/v of flucloxacillin impurity D EPCRS and 0.1% w/v of flucloxacillin sodium BPCRS.
(4) 0.1% w/v of flucloxacillin for peak identification EPCRS.
(5) Dilute 1 volume of solution (2) to 10 volumes.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 μm) (Zorbax SB-C18 is suitable).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 1.5 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 225 nm.
(f) Inject 10 μL of each solution.
MOBILE PHASE
Mobile phase A 0.118% w/v sodium hexanesulfonate monohydrate for ion-pair chromatography in a mixture of 0.8 volumes of concentrated ammonia and 1000 volumes of water for chromatography. Adjust the pH of the resulting solution to pH 2.9 ± 0.1 with orthophosphoric acid.
Mobile phase B acetonitrile R1.
| Time (Minutes) | Mobile phase A (% v/v) | Mobile phase B (% v/v) | Comment |
| 0-30 | 80→45 | 20→55 | linear gradient |
| 30-35 | 45→35 | 55→65 | linear gradient |
| 35-40 | 35→80 | 65→20 | linear gradient |
| 40-45 | 80 | 20 | re-equilibration |
When the chromatograms are recorded under the prescribed conditions, the relative retentions with reference to flucloxacillin (retention time about 18 minutes) are: impurity C, about 0.1; impurity A (isomer 1), about 0.48; impurity A (isomer 2), about 0.50; impurity F, about 0.55; impurity G, about 0.65; impurity B (isomer 1), about 0.75; impurity B (isomer 2), about 0.8; impurity D, about 0.9; impurity H, about 1.2; impurity E, about 1.25; impurity I, about 1.35; impurity J, about 1.55 and impurity K, about 1.6.
SYSTEM SUITABILITY
The test is not valid unless:
in the chromatogram obtained with solution (3), the resolution between impurity D and flucloxacillin is at least 1.5.
in the chromatogram obtained with solution (5), the signal-to-noise ratio of the principal peak is at least 40.
LIMITS
Identify any peak corresponding to impurities B and C in the chromatogram obtained with solution (1), using the chromatogram obtained with solution (4), and multiply the area of these peaks by a correction factor of 1.3 and 4.2 respectively.
In the chromatogram obtained with solution (1):
the sum of the areas of any peaks corresponding to impurity A is not greater than twice the area of the principal peak in the chromatogram obtained with solution (2) (2%);
the sum of the areas of any peaks corresponding to impurity B is not greater than 1.5 times the area of the principal peak in the chromatogram obtained with solution (2) (1.5%);
the area of any peaks corresponding to impurity C or E is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);
the area of any peak corresponding to impurity H is not greater than 0.5 times the area of the principal peak in the chromatogram obtained with solution (2) (0.5%);
the area of any peaks corresponding to impurity F, I, J or K is not greater than 0.4 times the area of the principal peak in the chromatogram obtained with solution (2) (0.4%);
the area of any peaks corresponding to impurity D or G is not greater than 0.3 times the area of the principal peak in the chromatogram obtained with solution (2) (0.3%);
the area of any other secondary peak is not greater than 0.2 times the area of the principal peak in the chromatogram obtained with solution (2) (0.2%);
the sum of the areas of all secondary peaks is not greater than 5 times the area of the principal peak in the chromatogram obtained with solution (2) (5%).
Disregard any peak with an area less than the area of the principal peak in the chromatogram obtained with solution (5) (0.1%).
ASSAY
Weigh the contents of 20 capsules. Mix and powder if necessary. Carry out the method for liquid chromatography,
Appendix III D, using the following solutions in 50% v/v acetonitrile.
(1) Disperse a quantity of the mixed capsule contents containing the equivalent of 0.5 g of flucloxacillin in 50% v/v of acetonitrile and dilute 200 mL. Dilute 1 volume of the resulting solution to 25 volumes.
(2) 0.011% w/v of flucloxacillin sodium BPCRS.
(3) 0.0001% w/v of flucloxacillin impurity D EPCRS and 0.01% w/v of flucloxacillin sodium BPCRS.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Dissolution may be used.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between impurity D and flucloxacillin is at least 1.5.
DETERMINATION OF CONTENT
Calculate the content of C19H17ClFN3O5S in the capsules using the declared content of C19H16ClFN3NaO5S in flucloxacillin sodium BPCRS. Each mg of C19H16ClFN3NaO5S is equivalent to 0.9538 mg of C19H17ClFN3O5S.
LABELLING
The quantity of active ingredient is stated in terms of the equivalent amount of flucloxacillin.
IMPURITIES
The impurities limited by the requirements of this monograph include those listed under Flucloxacillin Sodium Monohydrate.
