{"id":12922,"date":"2025-10-11T16:32:28","date_gmt":"2025-10-11T09:32:28","guid":{"rendered":"https:\/\/nhathuocngocanh.com\/bp\/?p=12922"},"modified":"2025-10-11T16:32:28","modified_gmt":"2025-10-11T09:32:28","slug":"dirithromycin","status":"publish","type":"post","link":"https:\/\/nhathuocngocanh.com\/bp\/dirithromycin\/","title":{"rendered":"Dirithromycin"},"content":{"rendered":"<p><em>(Ph. Eur. monograph 1313)<\/em><\/p>\n<p>C<sub>42<\/sub>H<sub>78<\/sub>N<sub>2<\/sub>O<sub>14<\/sub> 835 62013-04-1<\/p>\n<p><strong>Action and use<\/strong><\/p>\n<p>Macrolide antibacterial.<\/p>\n<h2>DEFINITION<\/h2>\n<p>(1R,2S,3R,6R,7S,8S,9R,10R,12R,13S,15R,17S)-9-[[3-(Dimethylamino)-3,4,6-trideoxy-\u03b2-D-xylo-hexopyranosyl]oxy]-3-ethyl-2,10-dihydroxy-15-[(2-methoxyethoxy)methyl]-2,6,8,10,12,17-hexamethyl-7-[(3-C-methyl-3-O-methyl-2,6dideoxy-\u03b1-L-ribo-hexopyranosyl)oxy]-4,16-dioxa-14azabicyclo[11.3.1]heptadecan-5-one (or (9S)-9,11-[imino[(1R)-2-(2-methoxyethoxy)ethylidene]oxy]-9-deoxo-11-deoxyerythromycin).<\/p>\n<p>Semi-synthetic product derived from a fermentation product.<\/p>\n<h3>Content<\/h3>\n<p>96.0 per cent to 102.0 per cent for the sum of the percentage contents of C42H78N2O14 and dirithromycin 15S-epimer (anhydrous substance).<\/p>\n<h2>CHARACTERS<\/h2>\n<h3>Appearance<\/h3>\n<p>White or almost white powder.<\/p>\n<h3>Solubility<\/h3>\n<p>Very slightly soluble in water, very soluble in methanol and in methylene chloride.<\/p>\n<p>It shows polymorphism (5.9).<\/p>\n<h2>IDENTIFICATION<\/h2>\n<p>A. Infrared absorption spectrophotometry (2.2.24).<\/p>\n<p>Comparison: dirithromycin CRS.<\/p>\n<p>B. Examine the chromatograms obtained in the assay.<\/p>\n<p>Results: The principal peak in the chromatogram obtained with test solution (a) is similar in retention time and size to the principal peak in the chromatogram obtained with reference solution (a).<\/p>\n<h2>TESTS<\/h2>\n<h3>Related substances<\/h3>\n<p>Liquid chromatography (2.2.29).<\/p>\n<p>Solvent mixture methanol R, acetonitrile R1 (30:70 V\/V).<\/p>\n<p>Test solution (a): Dissolve 20.0 mg of the substance to be examined in the solvent mixture and dilute to 10.0 mL with the solvent mixture.<\/p>\n<p>Test solution (b): Dissolve 0.10 g of the substance to be examined in the solvent mixture and dilute to 10.0 mL with the solvent mixture.<\/p>\n<p>Reference solution (a): Dissolve 20.0 mg of dirithromycin CRS in the solvent mixture and dilute to 10.0 mL with the solvent mixture.<\/p>\n<p>Reference solution (b): Dilute 5.0 mL of reference solution (a) to 50.0 mL with the solvent mixture.<\/p>\n<p>Reference solution (c): Dissolve 20 mg of dirithromycin CRS in the mobile phase and dilute to 10 mL with the mobile phase. Allow to stand for 24 h before use.<\/p>\n<p>Column:<\/p>\n<p>\u2014 size: l = 0.25 m, \u00d8 = 4.6 mm;<\/p>\n<p>\u2014 stationary phase: octadecylsilyl silica gel for chromatography R (5 \u03bcm);<\/p>\n<p>\u2014 temperature: 40 \u00b0C.<\/p>\n<p>Mobile phase: Mix 9 volumes of water R, 19 volumes of methanol R, 28 volumes of a solution containing 1.9 g\/L of potassium dihydrogen phosphate R and 9.1 g\/L of dipotassium hydrogen phosphate R adjusted to pH 7.5 if necessary with a 100 g\/L solution of potassium hydroxide R, and 44 volumes of acetonitrile R1.<\/p>\n<p>Flow rate: 2.0 mL\/min.<\/p>\n<p>Detection: Spectrophotometer at 205 nm.<\/p>\n<p>Injection: 10 \u03bcL of test solution (b) and reference solutions (b) and (c).<\/p>\n<p>Run time: 3 times the retention time of dirithromycin.<\/p>\n<p>Relative retention: With reference to dirithromycin: impurity A = about 0.7; 15S-epimer = about 1.1.<\/p>\n<p>System suitability: Reference solution (c):<\/p>\n<p>\u2014 resolution: minimum 2.0 between the peaks due to dirithromycin and its 15S-epimer; if necessary, adjust the concentration of the organic modifiers in the mobile phase.<\/p>\n<p>Limits:<\/p>\n<p>\u2014 impurity A: not more than 0.75 times the area of the principal peak in the chromatogram obtained with reference solution (b) (1.5 per cent);<\/p>\n<p>\u2014 any other impurity: for each impurity, not more than 0.5 times the area of the principal peak in the chromatogram obtained with reference solution (b) (1 per cent);<\/p>\n<p>\u2014 disregard limit: disregard the peak due to the 15S-epimer.<\/p>\n<h3>Dirithromycin 15S-epimer<\/h3>\n<p>Liquid chromatography (2.2.29) as described in the test for related substances with the following modifications.<\/p>\n<p>Injection: Test solution (b) and reference solution (b).<\/p>\n<p>System suitability: Reference solution (b):<\/p>\n<p>\u2014 repeatability: maximum relative standard deviation of 5.0 per cent after 6 injections.<\/p>\n<p>Limit:<\/p>\n<p>\u2014 15S-epimer: maximum 1.5 per cent.<\/p>\n<h3>Acetonitrile (2.4.24, System A)<\/h3>\n<p>Maximum 0.1 per cent.<\/p>\n<p>Prepare the solutions using dimethylformamide R instead of water R.<\/p>\n<p>Sample solution: Dissolve 0.200 g of the substance to be examined in dimethylformamide R and dilute to 20.0 mL with the same solvent.<\/p>\n<p>Static head-space injection conditions that may be used:<\/p>\n<p>\u2014 equilibration temperature: 120 \u00b0C;<\/p>\n<p>\u2014 equilibration time: 60 min;<\/p>\n<p>\u2014 transfer-line temperature: 125 \u00b0C.<\/p>\n<h3>Water (2.5.12)<\/h3>\n<p>Maximum 1.0 per cent, determined on 1.00 g.<\/p>\n<h3>Sulfated ash (2.4.14)<\/h3>\n<p>Maximum 0.1 per cent, determined on 1.0 g.<\/p>\n<h2>ASSAY<\/h2>\n<p>Liquid chromatography (2.2.29) as described in the test for related substances with the following modifications.<\/p>\n<p>Injection: Test solution (a) and reference solution (a).<\/p>\n<p>System suitability: Reference solution (a):<\/p>\n<p>\u2014 repeatability: maximum relative standard deviation of 1.0 per cent after 6 injections.<\/p>\n<h2>IMPURITIES<\/h2>\n<p>Specified impurities A.<\/p>\n<p>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) B, C, D, E.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-12917\" src=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/2-144-300x163.jpg\" alt=\"Dirithromycin\" width=\"300\" height=\"163\" srcset=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/2-144-300x163.jpg 300w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/2-144-1024x555.jpg 1024w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/2-144-768x416.jpg 768w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/2-144.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>A. (9S)-9-amino-9-deoxoerythromycin,<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-12918\" src=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/3-134-300x163.jpg\" alt=\"Dirithromycin\" width=\"300\" height=\"163\" srcset=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/3-134-300x163.jpg 300w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/3-134-1024x555.jpg 1024w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/3-134-768x416.jpg 768w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/3-134.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>B. (9S)-9-amino-3-de(2,6-dideoxy-3-C-methyl-3-O-methyl-\u03b1-L-ribo-hexopyranosyl)-9-deoxoerythromycin,<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-12920\" src=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/5-96-300x163.jpg\" alt=\"White or almost white powder.\" width=\"300\" height=\"163\" srcset=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/5-96-300x163.jpg 300w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/5-96-1024x555.jpg 1024w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/5-96-768x416.jpg 768w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/5-96.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>C. (9S)-9,11-[imino[(1RS)-2-(2-methoxyethoxy)ethylidene]oxy]-9-deoxo-11,12-dideoxyerythromycin (dirithromycin B)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-12919\" src=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/4-122-300x163.jpg\" alt=\"Dirithromycin\" width=\"300\" height=\"163\" srcset=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/4-122-300x163.jpg 300w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/4-122-1024x555.jpg 1024w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/4-122-768x416.jpg 768w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/4-122.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>D. (9S)-9,11-[imino[(1RS)-2-(2-methoxyethoxy)ethylidene]oxy]-3\u2032-O-demethyl-9-deoxo-11-deoxyerythromycin (dirithromycin C),<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-12921\" src=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/6-80-300x163.jpg\" alt=\"Dirithromycin\" width=\"300\" height=\"163\" srcset=\"https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/6-80-300x163.jpg 300w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/6-80-1024x555.jpg 1024w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/6-80-768x416.jpg 768w, https:\/\/nhathuocngocanh.com\/bp\/wp-content\/uploads\/2025\/10\/6-80.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/p>\n<p>E. 9,11-[imino(1-methylethylidene)oxy]-9-deoxo-11-deoxyerythromycin.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>(Ph. Eur. monograph 1313) C42H78N2O14 835 62013-04-1 Action and use Macrolide antibacterial. DEFINITION (1R,2S,3R,6R,7S,8S,9R,10R,12R,13S,15R,17S)-9-[[3-(Dimethylamino)-3,4,6-trideoxy-\u03b2-D-xylo-hexopyranosyl]oxy]-3-ethyl-2,10-dihydroxy-15-[(2-methoxyethoxy)methyl]-2,6,8,10,12,17-hexamethyl-7-[(3-C-methyl-3-O-methyl-2,6dideoxy-\u03b1-L-ribo-hexopyranosyl)oxy]-4,16-dioxa-14azabicyclo[11.3.1]heptadecan-5-one (or (9S)-9,11-[imino[(1R)-2-(2-methoxyethoxy)ethylidene]oxy]-9-deoxo-11-deoxyerythromycin). Semi-synthetic product derived from a fermentation product. Content 96.0 per cent to 102.0 per cent for the sum of the percentage contents of C42H78N2O14 and dirithromycin 15S-epimer (anhydrous substance). CHARACTERS Appearance White or almost white powder. Solubility Very slightly&#8230;<\/p>\n","protected":false},"author":4,"featured_media":12916,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[174],"tags":[],"class_list":["post-12922","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicinal-substances"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/12922","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\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=12922"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/12922\/revisions"}],"predecessor-version":[{"id":12926,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/12922\/revisions\/12926"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/12916"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=12922"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=12922"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=12922"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}