{"id":24614,"date":"2025-11-03T14:42:34","date_gmt":"2025-11-03T07:42:34","guid":{"rendered":"https:\/\/nhathuocngocanh.com\/bp\/?p=24614"},"modified":"2025-11-03T14:42:34","modified_gmt":"2025-11-03T07:42:34","slug":"selamectin","status":"publish","type":"post","link":"https:\/\/nhathuocngocanh.com\/bp\/selamectin\/","title":{"rendered":"Selamectin"},"content":{"rendered":"

(Selamectin for Veterinary Use, Ph. Eur. monograph 2268)<\/p>\n

C43<\/sub>H63<\/sub>NO11\u00a0<\/sub> \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0770\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0220119-17-5<\/p>\n

DEFINITION<\/h2>\n

(13a<\/sup>S,14<\/sup>R,17<\/sup>E,17a<\/sup>R,2\u2032R,4 R,42<\/sup>S,5\u2032S,6E,6\u2032S,8S,9S,10E,12E)-6\u2032-Cyclohexyl-8-[(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino- hexopyranosyl)oxy]-13a<\/sup>-hydroxy-17<\/sup>-(hydroxyimino)-16<\/sup> ,5\u2032,7,9-tetramethyl-13a<\/sup>,14<\/sup>,17<\/sup>,17a<\/sup> -tetrahydro-12<\/sup> H-3-oxa-1(4,3)-[1]benzofurana-4(4,2)-oxanaspiro[cyclododecaphane-6,10,12(1 )-trien-4 ,2\u2032-oxan]-2-one ((5Z,21R,25S)-25-cyclohexyl-25- de(butan-2-yl)-4\u2032-O-de(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino-hexopyranosyl)-5-demethoxy-5-(hydroxyimino)-22,23-
\ndihydroavermectin A1a<\/sub>).<\/p>\n

Semi-synthetic product derived from a fermentation product.<\/p>\n

Content<\/h3>\n

96.0 per cent to 102.0 per cent (anhydrous substance).<\/p>\n

CHARACTERS<\/h2>\n

Appearance<\/h3>\n

White or almost white, hygroscopic powder.<\/p>\n

Solubility<\/h3>\n

Practically insoluble in water, freely soluble in isopropyl alcohol, soluble in acetone and in methylene chloride, sparingly soluble in methanol.<\/p>\n

IDENTIFICATION<\/h2>\n

Infrared absorption spectrophotometry (2.2.24).<\/p>\n

Comparison: selamectin CRS.<\/p>\n

TESTS<\/h2>\n

Related substances<\/h3>\n

Liquid chromatography (2.2.29).<\/p>\n

Solvent mixture: water R, acetonitrile R (40:60 V\/V).<\/p>\n

Test solution: Dissolve 25 mg of the substance to be examined in the solvent mixture and dilute to 50 mL with the solvent mixture.<\/p>\n

Reference solution (a): Dilute 1.0 mL of the test solution to 100.0 mL with the solvent mixture.<\/p>\n

Reference solution (b): Dissolve 2.5 mg of selamectin for peak identification CRS (containing impurities A, C and D) in the solvent mixture and dilute to 5 mL with the solvent mixture.<\/p>\n

Reference solution (c): Dissolve the contents of a vial of selamectin impurity B CRS in 1 mL of reference solution (b).<\/p>\n

Column:<\/p>\n

\u2014 size: l = 0.15 m, \u00d8 = 3.9 mm;<\/p>\n

\u2014 stationary phase: end-capped octadecylsilyl silica gel for chromatography R (4 \u03bcm);<\/p>\n

\u2014 temperature: 30 \u00b0C.\\<\/p>\n

Mobile phase:<\/p>\n

\u2014 mobile phase A: water for chromatography R;<\/p>\n

\u2014 mobile phase B: acetonitrile for chromatography R;<\/p>\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 – 28<\/td>\n40<\/td>\n60<\/td>\n<\/tr>\n
28 – 45<\/td>\n40 \u2192 20<\/td>\n60 \u2192 80<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Flow rate: 2.0 mL\/min.<\/p>\n

Detection: Spectrophotometer at 243 nm.<\/p>\n

Injection: 20 \u03bcL.<\/p>\n

Identification of impurities: Use the chromatogram supplied with selamectin for peak identification CRS and the chromatogram obtained with reference solution (c) to identify the peaks due to impurities A, B, C and D.<\/p>\n

Relative retention: With reference to selamectin (retention time = about 22 min): impurity A = about 0.2; impurity B = about 0.4; impurity C = about 0.5; impurity D = about 1.7.<\/p>\n

System suitability: Reference solution (c):<\/p>\n

\u2014 resolution: minimum 2.5 between the peaks due to impurities B and C.<\/p>\n

Limits:<\/p>\n

\u2014 correction factor: for the calculation of content, multiply the peak area of impurity D by 1.5;<\/p>\n

\u2014 impurities A, B: for each impurity, not more than twice the area of the principal peak in the chromatogram obtained with reference solution (a) (2.0 per cent);<\/p>\n

\u2014 impurities C, D: for each impurity, not more than 1.5 times the area of the principal peak in the chromatogram obtained with reference solution (a) (1.5 per cent);<\/p>\n

\u2014 any other impurity: for each impurity, not more than the area of the principal peak in the chromatogram obtained with reference solution (a) (1.0 per cent);<\/p>\n

\u2014 total: not more than 4 times the area of the principal peak in the chromatogram obtained with reference solution (a) (4.0 per cent);<\/p>\n

\u2014 disregard limit: 0.2 times the area of the principal peak in the chromatogram obtained with reference solution (a) (0.2 per cent).<\/p>\n

Water (2.5.12, Method A)<\/h4>\n

Maximum 7.0 per cent, determined on 0.200 g.<\/p>\n

Sulfated ash (2.4.14)<\/h4>\n

Maximum 0.1 per cent, determined on 1.0 g.<\/p>\n

ASSAY<\/h2>\n

Liquid chromatography (2.2.29).<\/p>\n

Test solution: Dissolve 50.0 mg of the substance to be examined in the mobile phase and dilute to 250.0 mL with the mobile phase.<\/p>\n

Reference solution: Dissolve 50.0 mg of selamectin CRS in the mobile phase and dilute to 250.0 mL with the mobile phase.<\/p>\n

Column:<\/p>\n

\u2014 size: l = 0.15 m, \u00d8 = 3.9 mm;<\/p>\n

\u2014 stationary phase: end-capped octadecylsilyl silica gel for chromatography R (4 \u03bcm);<\/p>\n

\u2014 temperature: 30 \u00b0C.<\/p>\n

Mobile phase: water for chromatography R, acetonitrile for chromatography R (20:80 V\/V).<\/p>\n

Flow rate: 1.0 mL\/min.<\/p>\n

Detection: Spectrophotometer at 243 nm.<\/p>\n

Injection: 20 \u03bcL.<\/p>\n

Run time: Twice the retention time of selamectin.<\/p>\n

Retention time: Selamectin = about 9 min.<\/p>\n

Calculate the percentage content of C43<\/sub>H63<\/sub>NO11<\/sub> taking into account the assigned content of selamectin CRS.<\/p>\n

STORAGE<\/h2>\n

In an airtight container.<\/p>\n

IMPURITIES<\/h2>\n

Specified impurities A, B, C, D.<\/p>\n

\"Selamectin\"<\/p>\n

A. (5Z,21R,23S,25R)-25-cyclohexyl-25-de(butan-2-yl)-4\u2032-O-de(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino-hexopyranosyl)-5- demethoxy-23-hydroxy-5-(hydroxyimino)-22,23-dihydroavermectin A1a<\/sub>,<\/p>\n

\"Selamectin\"<\/p>\n

B. (5Z,25R)-25-cyclohexyl-25-de(butan-2-yl)-4\u2032-O-de(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino-hexopyranosyl)-5-demethoxy-5-(hydroxyimino)avermectin A1a<\/sub>,<\/p>\n

\"Selamectin\"<\/p>\n

C. (5Z,21R,25S)-25-cyclohexyl-25-de(butan-2-yl)-13-O-de[2,6-dideoxy-4-O-(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino- hexopyranosyl)-3-O-methyl-\u03b1-L-arabino-hexopyranosyl]-5-demethoxy-5-(hydroxyimino)-22,23-dihydroavermectin A1a<\/sub>,<\/p>\n

\"Selamectin\"<\/p>\n

D. (5Z,21R,25S)-25-cyclohexyl-25-de(butan-2-yl)-5-demethoxy-5-(hydroxyimino)-22,23-dihydroavermectin A1a<\/sub>.<\/p>\n","protected":false},"excerpt":{"rendered":"

(Selamectin for Veterinary Use, Ph. Eur. monograph 2268) C43H63NO11\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0770\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0220119-17-5 DEFINITION (13aS,14R,17E,17aR,2\u2032R,4 R,42S,5\u2032S,6E,6\u2032S,8S,9S,10E,12E)-6\u2032-Cyclohexyl-8-[(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino- hexopyranosyl)oxy]-13a-hydroxy-17-(hydroxyimino)-16 ,5\u2032,7,9-tetramethyl-13a,14,17,17a -tetrahydro-12 H-3-oxa-1(4,3)-[1]benzofurana-4(4,2)-oxanaspiro[cyclododecaphane-6,10,12(1 )-trien-4 ,2\u2032-oxan]-2-one ((5Z,21R,25S)-25-cyclohexyl-25- de(butan-2-yl)-4\u2032-O-de(2,6-dideoxy-3-O-methyl-\u03b1-L-arabino-hexopyranosyl)-5-demethoxy-5-(hydroxyimino)-22,23- dihydroavermectin A1a). Semi-synthetic product derived from a fermentation product. Content 96.0 per cent to 102.0 per cent (anhydrous substance). CHARACTERS Appearance White…<\/p>\n","protected":false},"author":2,"featured_media":24628,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[176],"tags":[],"class_list":["post-24614","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\/24614","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=24614"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/24614\/revisions"}],"predecessor-version":[{"id":24645,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/24614\/revisions\/24645"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/24628"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=24614"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=24614"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=24614"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}