{"id":23364,"date":"2025-10-31T17:03:55","date_gmt":"2025-10-31T10:03:55","guid":{"rendered":"https:\/\/nhathuocngocanh.com\/bp\/?p=23364"},"modified":"2025-10-31T17:03:55","modified_gmt":"2025-10-31T10:03:55","slug":"fenbendazole","status":"publish","type":"post","link":"https:\/\/nhathuocngocanh.com\/bp\/fenbendazole\/","title":{"rendered":"Fenbendazole"},"content":{"rendered":"

(Fenbendazole for Veterinary Use, Ph. Eur. monograph 1208)<\/p>\n

C_{15<\/sub>H_{13<\/sub>N_{3<\/sub>O_{2<\/sub>S\u00a0 \u00a0 \u00a0 299.3\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 43210-67-9<\/p>\n}}}}

Action and use<\/strong><\/p>\n

Antihelminthic.<\/p>\n

Preparations<\/strong><\/p>\n

Fenbendazole Granules<\/p>\n

Fenbendazole Veterinary Oral Paste<\/p>\n

Fenbendazole Veterinary Oral Suspension<\/p>\n

DEFINITION<\/h2>\n
Methyl [5-(phenylsulfanyl)-1H-benzimidazol-2-yl]carbamate.<\/p>\n
Content<\/h3>\n
98.0 per cent to 101.0 per cent (dried substance).<\/p>\n
CHARACTERS<\/h2>\n
Appearance<\/h3>\n
White or almost white powder.<\/p>\n
Solubility<\/h3>\n
Practically insoluble in water, sparingly soluble in dimethylformamide, very slightly soluble in methanol, practically insolublein heptane.<\/p>\n
IDENTIFICATION<\/h2>\n
Infrared absorption spectrophotometry (2.2.24).<\/p>\n
Comparison: fenbendazole CRS.<\/p>\n
TESTS<\/h2>\n
Related substances<\/h3>\n
Liquid chromatography (2.2.29). Prepare the solutions immediately before use.<\/p>\n
Test solution: Dissolve 50.0 mg of the substance to be examined in hydrochloric methanol R and dilute to 10.0 mL with the same solvent.<\/p>\n
Reference solution (a): Dilute 1.0 mL of the test solution to 50.0 mL with hydrochloric methanol R. Dilute 1.0 mL of this solution to 10.0 mL with hydrochloric methanol R.<\/p>\n
Reference solution (b): Dissolve 5 mg of fenbendazole impurity A CRS, 5 mg of fenbendazole impurity B CRS and 5 mg of mebendazole CRS in hydrochloric methanol R and dilute to 50 mL with hydrochloric methanol R. Dilute 1 mL of the solution to 10 mL with hydrochloric methanol R.<\/p>\n
Column:<\/p>\n
\u2014 size: l = 0.10 m, \u00d8 = 2.1 mm;<\/p>\n
\u2014 stationary phase: end-capped ethylene-bridged octylsilyl silica gel for chromatography (hybrid material) R (1.7 \u03bcm);<\/p>\n
\u2014 temperature: 30 \u00b0C.<\/p>\n
Mobile phase:<\/p>\n
\u2014 mobile phase A: glacial acetic acid R, methanol R, water for chromatography R (1:30:70 V\/V\/V);<\/p>\n
\u2014 mobile phase B: glacial acetic acid R, water for chromatography R, acetonitrile R (1:30:70 V\/V\/V);<\/p>\n\n\n\n\n\n\n
Time<\/strong>
\n(min)<\/strong><\/td>\n Mobile phase A<\/strong>
\n(per cent V\/V)<\/strong><\/td>\n Mobile phase B<\/strong>
\n(per cent V\/V)<\/strong><\/td>\n<\/tr>\n
0 – 2<\/td>\n 100<\/td>\n 0<\/td>\n<\/tr>\n
2 – 5<\/td>\n 100 \u2192 50<\/td>\n 0 \u2192 50<\/td>\n<\/tr>\n
5 – 26<\/td>\n 50<\/td>\n 50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Flow rate: 0.3 mL\/min.<\/p>\n
Detection: Spectrophotometer at 280 nm.<\/p>\n
Injection: 1 \u03bcL.<\/p>\n
Identification of impurities: Use the chromatogram obtained with reference solution (b) to identify the peaks due to impurities A and B and mebendazole.<\/p>\n
Relative retention: With reference to fenbendazole (retention time = about 8 min): impurity A = about 0.2; impurity B = about 0.6; mebendazole = about 0.8.
\nSystem suitability Reference solution (b):<\/p>\n
\u2014 resolution: minimum 13.0 between the peaks due to impurity B and mebendazole.<\/p>\n
Calculation of percentage contents:<\/p>\n
\u2014 correction factor: for the calculation of content, multiply the peak area of impurity A by 0.4;<\/p>\n
\u2014 for each impurity, use the concentration of fenbendazole in reference solution (a).<\/p>\n
Limits:<\/p>\n
\u2014 impurity B: maximum 0.5 per cent;<\/p>\n
\u2014 impurity A: maximum 0.2 per cent;<\/p>\n
\u2014 unspecified impurities: for each impurity, maximum 0.20 per cent;<\/p>\n
\u2014 total: maximum 1.0 per cent;<\/p>\n
\u2014 reporting threshold: 0.10 per cent.<\/p>\n
Loss on drying (2.2.32)<\/h4>\n
Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105 \u00b0C for 3 h.<\/p>\n
Sulfated ash (2.4.14)<\/h4>\n
Maximum 0.3 per cent, determined on 1.0 g.<\/p>\n
ASSAY<\/h2>\n
Dissolve 0.200 g in 30 mL of anhydrous acetic acid R, warming gently if necessary. Cool and titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20).<\/p>\n
1 mL of 0.1 M perchloric acid is equivalent to 29.93 mg of C_{15<\/sub>H_{13<\/sub>N_{3<\/sub>O_{2<\/sub>S.<\/p>\n}}}}
STORAGE<\/h2>\n
Protected from light.<\/p>\n
IMPURITIES<\/h2>\n
Specified impurities A, B.<\/p>\n
Other detectable impurities (the following substances would, if present at a sufficient level, be detected by one or other of the tests in the monograph. They are limited by the general acceptance criterion for other\/unspecified impurities and\/or by the general monograph Substances for pharmaceutical use (2034). It is therefore not necessary to identify these impurities for demonstration of compliance. See also 5.10. Control of impurities in substances for pharmaceutical use) C.<\/p>\n
<\/p>\n
A. methyl (1H-benzimidazol-2-yl)carbamate,<\/p>\n
<\/p>\n
B. methyl (5-chloro-1H-benzimidazol-2-yl)carbamate,<\/p>\n
<\/p>\n
C. methyl [5^{2<\/sup> -amino-3^{1<\/sup> H-2,6-dithia-4-aza-3(5,6)-[1,3]benzimidazola-1,7(1),5(1,4)-tribenzenaheptaphan-3^{2<\/sup> -yl]carbamate.<\/p>\n","protected":false},"excerpt":{"rendered":"}}}
(Fenbendazole for Veterinary Use, Ph. Eur. monograph 1208) C15H13N3O2S\u00a0 \u00a0 \u00a0 299.3\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 43210-67-9 Action and use Antihelminthic. Preparations Fenbendazole Granules Fenbendazole Veterinary Oral Paste Fenbendazole Veterinary Oral Suspension DEFINITION Methyl [5-(phenylsulfanyl)-1H-benzimidazol-2-yl]carbamate. Content 98.0 per cent to 101.0 per cent (dried substance). CHARACTERS Appearance White or almost white powder. Solubility Practically insoluble…<\/p>\n","protected":false},"author":2,"featured_media":23388,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[176],"tags":[],"class_list":["post-23364","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-british-pharmacopoeia-veterinary-2020"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=23364"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364\/revisions"}],"predecessor-version":[{"id":23390,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364\/revisions\/23390"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/23388"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=23364"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=23364"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=23364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

Time<\/strong> \n(min)<\/strong><\/td>\n	Mobile phase A<\/strong> \n(per cent V\/V)<\/strong><\/td>\n	Mobile phase B<\/strong> \n(per cent V\/V)<\/strong><\/td>\n<\/tr>\n
0 – 2<\/td>\n	100<\/td>\n	0<\/td>\n<\/tr>\n
2 – 5<\/td>\n	100 \u2192 50<\/td>\n	0 \u2192 50<\/td>\n<\/tr>\n
5 – 26<\/td>\n	50<\/td>\n	50<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Flow rate: 0.3 mL\/min.<\/p>\n Detection: Spectrophotometer at 280 nm.<\/p>\n Injection: 1 \u03bcL.<\/p>\n Identification of impurities: Use the chromatogram obtained with reference solution (b) to identify the peaks due to impurities A and B and mebendazole.<\/p>\n Relative retention: With reference to fenbendazole (retention time = about 8 min): impurity A = about 0.2; impurity B = about 0.6; mebendazole = about 0.8. \nSystem suitability Reference solution (b):<\/p>\n \u2014 resolution: minimum 13.0 between the peaks due to impurity B and mebendazole.<\/p>\n Calculation of percentage contents:<\/p>\n \u2014 correction factor: for the calculation of content, multiply the peak area of impurity A by 0.4;<\/p>\n \u2014 for each impurity, use the concentration of fenbendazole in reference solution (a).<\/p>\n Limits:<\/p>\n \u2014 impurity B: maximum 0.5 per cent;<\/p>\n \u2014 impurity A: maximum 0.2 per cent;<\/p>\n \u2014 unspecified impurities: for each impurity, maximum 0.20 per cent;<\/p>\n \u2014 total: maximum 1.0 per cent;<\/p>\n \u2014 reporting threshold: 0.10 per cent.<\/p>\n Loss on drying (2.2.32)<\/h4>\n Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105 \u00b0C for 3 h.<\/p>\n Sulfated ash (2.4.14)<\/h4>\n Maximum 0.3 per cent, determined on 1.0 g.<\/p>\n ASSAY<\/h2>\n Dissolve 0.200 g in 30 mL of anhydrous acetic acid R, warming gently if necessary. Cool and titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20).<\/p>\n 1 mL of 0.1 M perchloric acid is equivalent to 29.93 mg of C_{15<\/sub>H_{13<\/sub>N_{3<\/sub>O_{2<\/sub>S.<\/p>\n}}}} STORAGE<\/h2>\n Protected from light.<\/p>\n IMPURITIES<\/h2>\n Specified impurities A, B.<\/p>\n Other detectable impurities (the following substances would, if present at a sufficient level, be detected by one or other of the tests in the monograph. They are limited by the general acceptance criterion for other\/unspecified impurities and\/or by the general monograph Substances for pharmaceutical use (2034). It is therefore not necessary to identify these impurities for demonstration of compliance. See also 5.10. Control of impurities in substances for pharmaceutical use) C.<\/p>\n <\/p>\n A. methyl (1H-benzimidazol-2-yl)carbamate,<\/p>\n <\/p>\n B. methyl (5-chloro-1H-benzimidazol-2-yl)carbamate,<\/p>\n <\/p>\n C. methyl [5^{2<\/sup> -amino-3^{1<\/sup> H-2,6-dithia-4-aza-3(5,6)-[1,3]benzimidazola-1,7(1),5(1,4)-tribenzenaheptaphan-3^{2<\/sup> -yl]carbamate.<\/p>\n","protected":false},"excerpt":{"rendered":"}}} (Fenbendazole for Veterinary Use, Ph. Eur. monograph 1208) C15H13N3O2S\u00a0 \u00a0 \u00a0 299.3\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 43210-67-9 Action and use Antihelminthic. Preparations Fenbendazole Granules Fenbendazole Veterinary Oral Paste Fenbendazole Veterinary Oral Suspension DEFINITION Methyl [5-(phenylsulfanyl)-1H-benzimidazol-2-yl]carbamate. Content 98.0 per cent to 101.0 per cent (dried substance). CHARACTERS Appearance White or almost white powder. Solubility Practically insoluble…<\/p>\n","protected":false},"author":2,"featured_media":23388,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[176],"tags":[],"class_list":["post-23364","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-british-pharmacopoeia-veterinary-2020"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=23364"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364\/revisions"}],"predecessor-version":[{"id":23390,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23364\/revisions\/23390"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/23388"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=23364"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=23364"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=23364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

Content<\/h3>\n98.0 per cent to 101.0 per cent (dried substance).<\/p>\n

CHARACTERS<\/h2>\n

Appearance<\/h3>\nWhite or almost white powder.<\/p>\n

Solubility<\/h3>\nPractically insoluble in water, sparingly soluble in dimethylformamide, very slightly soluble in methanol, practically insolublein heptane.<\/p>\n

IDENTIFICATION<\/h2>\nInfrared absorption spectrophotometry (2.2.24).<\/p>\nComparison: fenbendazole CRS.<\/p>\n

TESTS<\/h2>\n

Loss on drying (2.2.32)<\/h4>\nMaximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105 \u00b0C for 3 h.<\/p>\n

Sulfated ash (2.4.14)<\/h4>\nMaximum 0.3 per cent, determined on 1.0 g.<\/p>\n

STORAGE<\/h2>\nProtected from light.<\/p>\n

Content<\/h3>\n
98.0 per cent to 101.0 per cent (dried substance).<\/p>\n

Appearance<\/h3>\n
White or almost white powder.<\/p>\n

Solubility<\/h3>\n
Practically insoluble in water, sparingly soluble in dimethylformamide, very slightly soluble in methanol, practically insolublein heptane.<\/p>\n

IDENTIFICATION<\/h2>\n
Infrared absorption spectrophotometry (2.2.24).<\/p>\n
Comparison: fenbendazole CRS.<\/p>\n

Loss on drying (2.2.32)<\/h4>\n
Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105 \u00b0C for 3 h.<\/p>\n

Sulfated ash (2.4.14)<\/h4>\n
Maximum 0.3 per cent, determined on 1.0 g.<\/p>\n

STORAGE<\/h2>\n
Protected from light.<\/p>\n