{"id":85,"date":"2019-04-24T12:15:33","date_gmt":"2019-04-24T12:15:33","guid":{"rendered":"https:\/\/sepia2.unil.ch\/pharmacology\/?page_id=85"},"modified":"2019-04-26T13:53:20","modified_gmt":"2019-04-26T13:53:20","slug":"distribution","status":"publish","type":"page","link":"https:\/\/sepia2.unil.ch\/pharmacology\/mechanisms\/distribution\/","title":{"rendered":"Distribution"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\"> &#8220;Reversible transfer of drug between the systemic circulation and various sites within the body&#8221; <\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Description<\/h3>\n\n\n\n<div class=\"wp-block-columns has-2-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<p>  Upon ingestion, drug molecules are first absorbed and then disseminated  throughout the body. Distribution of a drug to body sites occurs at  various rates and to various extents. The factors determining the  pattern of distribution are the tissular delivery of drug by blood, the  ability of the drug to cross membranes, the binding of drug with blood  and tissues components, its partitioning between water and fat, and its  ability to undergo active transport through cell-membrane carriers (e.g.  P-gylcoprotein). <\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-video\"><video height=\"346\" style=\"aspect-ratio: 346 \/ 346;\" width=\"346\" controls src=\"https:\/\/sepia2.unil.ch\/pharmacology\/wp-content\/uploads\/2019\/04\/distribution_Trim.mp4\"><\/video><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>The <a href=\"\/pharmacology\/volumeofdistribution\">volume of distribution<\/a> quantifies the extent of distribution.\n<\/p>\n\n\n\n<p>The rate of distribution can be limited either by \nthe permeability or the perfusion of the tissue. Both the tissue \ninvasion and the release of drug from a tissue take longer the poorer \nthe perfusion and the greater the partitioning coefficient. Initially \nthe blood in liver, kidney, brain and other well-perfused tissues \ncontains most of the drug. During the terminal phase of disposition, \ndrug has equilibrated between various tissues and is progressively \nreleased into the circulation and eliminated.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Clinical implications<\/h3>\n\n\n\n<p>Distribution is a necessary step for the active \nmolecules to reach their pharmacological target. The extent of \ndistribution determines the amount of drug to be administered in order \nto acheive suitable concentration levels. Distribution also affects the \ndrug&#8217;s half-life.\n<\/p>\n\n\n\n<p>For some drugs, the distribution is the process that\n puts an end to an acute effect, as it quickly brings the circulating \nconcentrations below active levels (e.g. <a href=\"\/pharmacology\/thiopental\">thiopental<\/a>)\n<\/p>\n\n\n\n<p>In certain conditions such as in intoxication, \nhaemodialysis can be useful if the volume of distribution is small \nbecause most of the drug is concentrated in the extracellular water. If \nthe volume of distribution is large, most of the drug is concentrated in\n the tissues and is not accessible to dialysis. <\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Related terms<\/h3>\n\n\n\n<p><a href=\"\/pharmacology\/volumeofdistribution\">Volume of distribution<\/a>\n<\/p>\n\n\n\n<p>Distribution rate constant (kT): This rate constant \nmay be regarded as a measure of how rapidly drug would leave tissue if \nthe arterial concentration were to drop to zero. It is the fractional \nrate of drug distribution from an organ to blood. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>&#8220;Reversible transfer of drug between the systemic circulation and various sites within the body&#8221; Description Upon ingestion, drug molecules are first absorbed and then disseminated throughout the body. Distribution of a drug to body sites occurs at various rates and to various extents. The factors determining the pattern of distribution are the tissular delivery of &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/sepia2.unil.ch\/pharmacology\/mechanisms\/distribution\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Distribution&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":11,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-85","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/85","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/comments?post=85"}],"version-history":[{"count":4,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/85\/revisions"}],"predecessor-version":[{"id":293,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/85\/revisions\/293"}],"up":[{"embeddable":true,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/11"}],"wp:attachment":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/media?parent=85"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}