Action and use<\/strong><\/p>\n Immunostimulant; antihelminthic.<\/p>\n (6S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole.<\/p>\n 98.5 per cent to 101.5 per cent (anhydrous substance).<\/p>\n White or almost white powder.<\/p>\n Slightly soluble in water, freely soluble in ethanol (96 per cent) and in methanol.<\/p>\n It shows polymorphism (5.9).<\/p>\n A. Specific optical rotation (see Tests).<\/p>\n B. Infrared absorption spectrophotometry (2.2.24).<\/p>\n Comparison: Ph. Eur. reference spectrum of levamisole.<\/p>\n If the spectra show differences, dissolve the substance to be examined in methylene chloride R, evaporate to dryness and record a new spectrum using the residue.<\/p>\n Dissolve 2.50 g in ethanol R and dilute to 50.0 mL with the same solvent.<\/p>\n Solution S is clear (2.2.1) and not more intensely coloured than reference solution BY6<\/sub> (2.2.2, Method II).<\/p>\n -89 to -85 (anhydrous substance), determined on solution S.<\/p>\n Liquid chromatography (2.2.29). Prepare the solutions immediately before use, protect from light and keep below 25 \u00b0C.<\/p>\n Test solution: Dissolve 0.100 g of the substance to be examined in methanol R and dilute to 10.0 mL with the same solvent.<\/p>\n Reference solution (a): Dissolve 10 mg of levamisole hydrochloride for system suitability CRS (containing impurities A, B, C, D and E) in methanol R, add 0.1 mL of concentrated ammonia R and dilute to 1.0 mL with methanol R.<\/p>\n Reference solution (b): Dilute 1.0 mL of the test solution to 100.0 mL with methanol R. Dilute 5.0 mL of the solution to 25.0 mL with methanol R.<\/p>\n Column:<\/p>\n \u2014 size: l = 0.10 m, \u00d8 = 4.6 mm,<\/p>\n \u2014 stationary phase: base-deactivated octadecylsilyl silica gel for chromatography R (3 \u03bcm).<\/p>\n Mobile phase:<\/p>\n \u2014 mobile phase A: dissolve 0.5 g of ammonium dihydrogen phosphate R in 90 mL of water R; adjust to pH 6.5 with a 40 g\/L solution of sodium hydroxide R and dilute to 100 mL with water R;<\/p>\n \u2014 mobile phase B: acetonitrile R;<\/p>\n Flow rate: 1.5 mL\/min.<\/p>\n Detection: Spectrophotometer at 215 nm.<\/p>\n Injection: 10 \u03bcL.<\/p>\n Identification of impurities: Use the chromatogram supplied with levamisole hydrochloride for system suitability CRS and the chromatogram obtained with reference solution (a) to identify the peaks due to impurities A, B, C, D and E.<\/p>\n Relative retention: With reference to levamisole (retention time = about 3 min): impurity A = about 0.9; impurity B = about 1.4; impurity C = about 1.5; impurity D = about 1.6; impurity E = about 2.0.<\/p>\n System suitability: Reference solution (a):<\/p>\n \u2014 the chromatogram obtained is similar to the chromatogram supplied with levamisole hydrochloride for system suitability CRS.<\/p>\n Limits:<\/p>\n \u2014 correction factors: for the calculation of content, multiply the peak areas of the following impurities by the corresponding correction factor: impurity A = 2.0; impurity B = 1.7; impurity C = 2.9; impurity D = 1.3; impurity E = 2.7;<\/p>\n \u2014 impurities A, B, C, D, E: for each impurity, not more than the area of the principal peak in the chromatogram obtained with reference solution (b) (0.2 per cent);<\/p>\n \u2014 any other impurity: not more than half the area of the principal peak in the chromatogram obtained with reference solution (b) (0.1 per cent);<\/p>\n \u2014 total: not more than 1.5 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.3 per cent);<\/p>\n \u2014 disregard limit: 0.25 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.05 per cent).<\/p>\n Maximum 0.5 per cent, determined on 1.00 g.<\/p>\n Maximum 0.1 per cent, determined on 1.0 g.<\/p>\n Dissolve 0.150 g in 50 mL of a mixture of 1 volume of anhydrous acetic acid R and 7 volumes of methyl ethyl ketone R. Titrate with 0.1 M perchloric acid, using 0.2 mL of naphtholbenzein solution R as indicator.<\/p>\n 1 mL of 0.1 M perchloric acid is equivalent to 20.43 mg of C11<\/sub>H12<\/sub>N2<\/sub>S.<\/p>\n In an airtight container, protected from light.<\/p>\n Specified impurities A, B, C, D, E.<\/p>\n A. 3-[(2RS)-2-amino-2-phenylethyl]thiazolidin-2-one,<\/p>\n B. 3-[(E)-2-phenylethenyl]thiazolidin-2-imine,<\/p>\n C. (4RS)-4-phenyl-1-(2-sulfanylethyl)imidazolidin-2-one,<\/p>\n D. 6-phenyl-2,3-dihydroimidazo[2,1-b]thiazole,<\/p>\n E. 1,1\u2032-[(disulfane-1,2-diyl)bis(ethylene)]bis[(4RS)-4-phenylimidazolidin-2-one].<\/p>\n","protected":false},"excerpt":{"rendered":" (Levamisole for Veterinary Use, Ph. Eur. monograph 1728) C11H12N2S\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0204.3\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a014769-73-4 Action and use Immunostimulant; antihelminthic. DEFINITION (6S)-6-Phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole. Content 98.5 per cent to 101.5 per cent (anhydrous substance). CHARACTERS Appearance White or almost white powder. Solubility Slightly soluble in water, freely soluble in ethanol (96…<\/p>\n","protected":false},"author":2,"featured_media":23693,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[176],"tags":[],"class_list":["post-23686","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\/23686","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=23686"}],"version-history":[{"count":3,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23686\/revisions"}],"predecessor-version":[{"id":32185,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/23686\/revisions\/32185"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/23693"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=23686"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=23686"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=23686"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}DEFINITION<\/h2>\n
Content<\/h3>\n
CHARACTERS<\/h2>\n
Appearance<\/h3>\n
Solubility<\/h3>\n
IDENTIFICATION<\/h2>\n
TESTS<\/h2>\n
Solution S<\/h3>\n
Appearance of solution<\/h3>\n
Specific optical rotation (2.2.7)<\/h4>\n
Related substances<\/h3>\n
\n\n
\n Time<\/strong>
\n(min)<\/strong><\/td>\nMobile phase A<\/strong>
\n(per cent V\/V)<\/strong><\/td>\nMobile phase B<\/strong>
\n(per cent V\/V)<\/strong><\/td>\n<\/tr>\n\n 0 – 8<\/td>\n 90 \u2192 30<\/td>\n 10 \u2192 70<\/td>\n<\/tr>\n \n 8 – 10<\/td>\n 30<\/td>\n 70<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Water (2.5.12)<\/h4>\n
Sulfated ash (2.4.14)<\/h4>\n
ASSAY<\/h2>\n
STORAGE<\/h2>\n
IMPURITIES<\/h2>\n
![\"Levamisole\"](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Levamisole-2-300x163.jpg\")
<\/p>\n![\"Levamisole\"](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Levamisole-3-300x163.jpg\")
<\/p>\n![\"Levamisole\"](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Levamisole-4-300x163.jpg\")
<\/p>\n![\"Levamisole\"](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Levamisole-5-300x163.jpg\")
<\/p>\n![\"Levamisole\"](\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/11\/Levamisole-6-300x163.jpg\")
<\/p>\n