Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Inhibitor of phosphodiesterase type III; calcium sensitizer.
DEFINITION
Pimobendan Capsules contain Pimobendan.
The capsules comply with the requirements stated under Capsules and with the following requirements.
Content of pimobendan, C19H18N4O2
95.0 to 105.0% of the stated amount.
IDENTIFICATION
A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Shake a quantity of capsule contents containing 10 mg of Pimobendan with 10 mL of methanol. Filter and dilute the filtrate with sufficient methanol to produce a solution containing 0.005% w/v of Pimobendan.
(2) 0.005% w/v of pimobendan BPCRS in methanol.
CHROMATOGRAPHIC CONDITIONS
(a) Use as the coating silica gel F254 (Merck silica gel 60 F254 plates are suitable).
(b) Use the mobile phase as described below.
(c) Apply 10 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry in air and examine immediately under ultraviolet light (254 nm).
MOBILE PHASE
1 volume of methanol and 9 volumes of dichloromethane.
CONFIRMATION
The principal spot in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).
B. In the Assay, the retention time of the principal peak in the chromatogram obtained with solution (1) is similar to that of the principal peak in the chromatogram obtained with solution (2).
TESTS
Dissolution
Comply with the requirements in the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
(a) Use Apparatus 2, rotating the paddle at 75 revolutions per minute.
For capsules containing 1.25 mg or less of Pimobendan
(b) Use 500 mL of 0.01M sodium acetate, adjusted to pH 5.0 with glacial acetic acid, at a temperature of 37°, as the medium.
For capsules containing more than 1.25 mg of Pimobendan
(b) Use 900 mL of 0.01M sodium acetate, adjusted to pH 5.0 with glacial acetic acid, at a temperature of 37°, as the medium.
PROCEDURE
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) After 45 minutes withdraw a sample of the medium and filter. Use the filtered medium, diluted with water if necessary, to produce a solution expected to contain 0.00025% w/v of Pimobendan.
(2) 0.0025% w/v of pimobendan BPCRS in methanol. Dilute 1 volume to 10 volumes with the dissolution medium.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (6 cm × 4.0 mm) packed with end-capped octadecylsilyl silica gel (5 µm) (Nucleosil RP C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 0.7 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 328 nm.
(f) Inject 20 µL of each solution.
MOBILE PHASE
35 volumes of acetonitrile and 65 volumes of 0.05M diammonium hydrogen orthophosphate, adjusted to pH 5.5 with orthophosphoric acid.
DETERMINATION OF CONTENT
Calculate the total content of C19H18N4O2, in the medium from the chromatograms obtained and using the declared content of C19H18N4O2, in pimobendan BPCRS.
LIMITS
The amount of pimobendan released is not less than 75% (Q) of the stated amount.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in methanol.
(1) Disperse a quantity of the capsule contents containing 12.5 mg of Pimobendan in 10 mL of water and dilute to 50 mL. Dilute 1 volume of the resulting solution to 5 volumes.
(2) Dilute 1 volume of solution (1) to 100 volumes.
(3) 0.05% w/v of pimobendan for system suitability EPCRS.
(4) Dilute 3 volumes of solution (2) to 10 volumes.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (12.5 cm × 4.0 mm) packed with end-capped octadecylsilyl silica gel (5 µm) (Nucleosil RP C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 0.7 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelengths of 328 nm and 312 nm.
(f) Inject 10 µL of each solution.
(g) Allow the chromatography to proceed for 1.5 times the retention time of pimobendan.
MOBILE PHASE
34 volumes of acetonitrile and 66 volumes of 0.05M diammonium hydrogen orthophosphate, previously adjusted to pH 5.5 with orthophosphoric acid.
When the chromatograms are recorded under the prescribed conditions the retention times relative to pimobendan (retention time about 5 minutes) are; impurity A, about 0.6 and impurity B, about 0.7.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3) at 328 nm, the resolution between impurity A and impurity B is at least 1.5.
LIMITS
At 312 nm In the chromatogram obtained with solution (1), the area of any peak corresponding to impurity B is not greater than half the area of the principal peak due to impurity B in the chromatogram obtained with solution (2) (0.5%).
At 328 nm In the chromatogram obtained with solution (1):
the area of any peak corresponding to impurity A is not greater than twice the area of the principal peak A in the chromatogram obtained with solution (2) (2.0%);
the area of any other secondary peak is not greater than half the area of the principal peak in the chromatogram obtained with solution (2) (0.5%);
the sum of the areas of any other secondary peaks is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1.0%).
Disregard any peak with an area less than the area of the principal peak in the chromatogram obtained with solution (4) (0.3%).
Uniformity of content
Capsules containing less than 2 mg and/or less than 2% w/w of Pimobendan comply with the requirements stated under Capsules using the following method of analysis. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Add one capsule to 5 mL of water and shake until the capsule has dispersed. Add 15 mL of methanol and mix with the aid of ultrasound. Allow to cool and dilute to 25 mL with methanol. Centrifuge and dilute a quantity of the supernatant liquid with methanol, if necessary, to produce a solution expected to contain 0.005% w/v of Pimobendan.
(2) 0.005% w/v of pimobendan BPCRS in methanol.
(3) 0.05% w/v of pimobendan for system suitability EPCRS in methanol.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used with a wavelength of 328 nm.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between impurity A and impurity B is at least 1.5.
DETERMINATION OF CONTENT
Calculate the total content of pimobendan, C19H18N4O2, in each capsule using the declared content of C19H18N4O2, in pimobendan BPCRS.
ASSAY
For capsules containing the equivalent of less than 2 mg and/or less than 2% w/w of Pimobendan
Use the average of the individual results determined in the test for Uniformity of content.
For capsules containing the equivalent of 2 mg or more and 2% w/w or more of Pimobendan
Weigh and powder the contents of 20 capsules. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in methanol.
(1) Disperse a quantity of the mixed capsule contents containing 25 mg of Pimobendan and dilute to 100 mL. Further dilute 1 volume to 5 volumes.
(2) 0.005% w/v of pimobendan BPCRS.
(3) 0.015% w/v of pimobendan for system suitability EPCRS.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used with a wavelength of 328 nm.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between impurity A and impurity B is at least 1.5.
DETERMINATION OF CONTENT
Calculate the total content of C19H18N4O2, in the capsules using the declared content of C19H18N4O2, in pimobendan BPCRS.
IMPURITIES
The impurities limited by the requirements of this monograph include impurity A and B listed under Pimobendan.
