Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Vitamin B component.
DEFINITION
Calcium Folinate Tablets contain Calcium Folinate Hydrate.
The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of folinic acid, C20H23N7O7
90.0 to 110.0% of the stated amount.
IDENTIFICATION
A. To a quantity of the powdered tablets containing the equivalent of 180 mg of folinic acid add 10 mL of water, mix with the aid of ultrasound, and filter. Add 125 mg of ammonium oxalate to the filtrate, shake, and centrifuge until a clear supernatant liquid is obtained. To the supernatant add 1 mL of methanol and 3 drops of hydrochloric acid, and shake. If the preparation is cloudy, add methanol until a clear solution is obtained and filter, if necessary, to remove any undissolved material. Cool the preparation at 0° until a precipitate forms and centrifuge. The cooling and centrifuging steps may be repeated, if necessary, to increase the amount of precipitate collected. Decant the supernatant liquid and dissolve the precipitate in 2 mL of methanol. Evaporate to dryness under a current of air and dry the residue at 50° for 30 minutes. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of calcium folinate (RS 368).
B. The powdered tablets yield reaction B characteristic of calcium salts, Appendix VI.
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions protected from light.
(1) Add 20 mL of water to a quantity of the powdered tablets containing the equivalent of 25 mg of folinic acid, shake for
15 minutes and dilute to 25 mL with water. Filter through a glass fibre filter (Whatman GF/C is suitable).
(2) Dilute 1 volume of solution (1) to 100 volumes with water.
(2) Dilute 1 volume of solution (1) to 100 volumes with water.
(3) 0.1% w/v of calcium folinate BPCRS in water.
(4) Dilute 1 volume of solution (2) to 10 volumes with water.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with end-capped octadecylsilyl silica gel for chromatography (5 μm) (Hypersil ODS is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 280 nm.
(f) Inject 20 μL of each solution.
(g) For solution (1) allow the chromatography to proceed for 2.5 times the retention time of folinate.
MOBILE PHASE
220 mL of methanol and 780 mL of a solution containing 2.0 mL of tetrabutylammonium hydroxide solution and 2.2 g of disodium hydrogen orthophosphate, previously adjusted to pH 7.5 with 10% v/v orthophosphoric acid.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the peaks
corresponding to folinate and formylfolic acid is at least 2.2. If necessary, adjust the methanol content in the mobile phase.
LIMITS
In the chromatogram obtained with solution (1):
the area of any peak corresponding to formylfolic acid is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);
the area of any other secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);
the sum of the areas of any secondary peaks, excluding the peak corresponding to formylfolic acid, is not greater than 2.5 times the area of the principal peak in the chromatogram obtained with solution (2) (2.5%).
Disregard any peak with an area less than that of the principal peak in the chromatogram obtained with solution (4) (0.1%).
ASSAY
Protect the solutions from light. Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Add 200 mL of water to a quantity of the powdered tablets containing the equivalent of 25 mg of folinic acid, shake for 15 minutes and dilute to 250 mL with water. Filter through a glass fibre filter (Whatman GF/C is suitable).
(2) 0.011% w/v of calcium folinate BPCRS in water.
(3) 0.1% w/v of calcium folinate BPCRS in water.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the peaks corresponding to folinate and formylfolic acid is at least 2.2. If necessary, adjust the methanol content in the mobile phase.
DETERMINATION OF CONTENT
Calculate the content of C20H23N7O7 in the tablets using the declared content of C20H21CaN7O7 in calcium folinate BPCRS. Each mg of C20H21CaN7O7 is equivalent to 0.9255 mg of C20H23N7O7
STORAGE
Calcium Folinate Tablets should be stored at a temperature not exceeding 30°.
LABELLING
The quantity of active ingredient is stated in terms of the equivalent amount of folinic acid.
