Fenbendazole Veterinary Paste
Action and use
Antihelminthic.
DEFINITION
Fenbendazole Veterinary Oral Paste contains Fenbendazole finely dispersed in a suitable basis.
The veterinary oral paste complies with the requirements stated under Veterinary Oral Pastes and with the following requirements.
Content of fenbendazole, C15H13N3O2S
95.0 to 105.0% of the stated amount.
IDENTIFICATION
In the Assay, the retention time of the principal peak in the chromatogram obtained with solution (1) is the same as that of the principal peak in the chromatogram obtained with solution (2).
TESTS
Related impurities A, B and 1
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Mix with the aid of ultrasound, a quantity of the oral paste containing 0.1 g of Fenbendazole with 50 mL of 0.1M methanolic hydrochloric acid for 30 minutes, cool, dilute to 100 mL with methanol (65%), mix, filter through a glass-fibre filter (Whatman GF/C is suitable).
(2) Dilute 1 volume of a 0.001% w/v solution of fenbendazole impurity A EPCRS (methyl (1H-benzimidazole-2-yl)carbamate) in 0.1M methanolic hydrochloric acid to 2 volumes with methanol (65%).
(3) Dilute 1 volume of a 0.001% w/v solution of fenbendazole impurity B EPCRS (methyl (5-chloro-1H-benzimidazole-2-yl)carbamate) in 0.1M methanolic hydrochloric acid to 2 volumes with methanol (65%).
(4) Dilute 1 volume of a 0.001% w/v solution of fenbendazole impurity 1 BPCRS((5-phenylthio)-2-aminobenzimidazole) in 0.1M methanolic hydrochloric acid to 2 volumes with methanol (65%).
(5) Dilute 1 volume of a solution containing 0.002% w/v each of fenbendazole impurity A EPCRS, fenbendazole impurity B EPCRS, fenbendazole impurity 1 BPCRS and 0.20% w/v of fenbendazole BPCRS in 0.1M methanolic hydrochloric acid to 2 volumes with methanol (65%).
CHROMATOGRAPHIC CONDITIONS
Fenbendazole Veterinary Oral Paste
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 μm) (Nucleosil C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 280 nm.
(f) Inject 20 μL of each solution.
MOBILE PHASE
350 volumes of a 0.5% w/v solution of sodium dihydrogen orthophosphate and 650 volumes of methanol containing 1.88 g of sodium hexanesulfonate, the pH of which has been adjusted to 3.5 with orthophosphoric acid
SYSTEM SUITABILITY
The test is not valid unless the chromatogram obtained with solution (5) closely resembles the reference chromatogram supplied with fenbendazole BPCRS.
LIMITS
In the chromatogram obtained with solution (1):
the area of any peaks corresponding to fenbendazole impurity A (methyl (1H-benzimidazol-2-yl)carbamate), fenbendazole impurity B (methyl (5-chloro-1H-benzimidazol-2-yl)carbamate) and fenbendazole impurity 1 ((5-phenylthio)-2-aminobenzimidazole) are not greater than the areas of the corresponding peaks in the chromatograms obtained with solutions (2), (3) and (4) respectively (0.5% each).
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Mix with the aid of ultrasound a quantity of the oral paste containing 0.1 g of Fenbendazole with 50 mL of 0.1M methanolic hydrochloric acid for 30 minutes, cool, dilute to 100 mL with methanol (65%), mix, filter through a glass-fibre filter (Whatman GF/C is suitable). Dilute 5 volumes of the resulting solution to 50 volumes with 0.1M hydrochloric acid in methanol (85%).
(2) 0.01% w/v of fenbendazole BPCRS in a mixture of 1 volume of 0.1M hydrochloric acid and 1 volume of methanol (85%).
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related impurities A, B and 1 may be used.
DETERMINATION OF CONTENT
Calculate the content of C15H13N3O2S in the veterinary oral paste from the chromatograms obtained and using the declared content of C15H13N3O2SS in fenbendazole BPCRS.
IMPURITIES
The impurities limited by the requirements of this monograph include impurities A and B listed under Fenbendazole and the following:
1. (5-phenylthio)-2-aminobenzimidazole.
