{"id":102,"date":"2019-04-24T12:37:17","date_gmt":"2019-04-24T12:37:17","guid":{"rendered":"https:\/\/sepia2.unil.ch\/pharmacology\/?page_id=102"},"modified":"2020-08-10T07:23:38","modified_gmt":"2020-08-10T07:23:38","slug":"bioavailability","status":"publish","type":"page","link":"https:\/\/sepia2.unil.ch\/pharmacology\/parameters\/bioavailability\/","title":{"rendered":"Bioavailability"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\"> &#8220;Fraction of a dose of drug that is absorbed from its site of  administration and reaches, in an unchanged form, the systemic  circulation&#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>The drug, its route of administration and its <a href=\"\/pharmacology\/galenics\">galenic formulation<\/a> determine the amount of administered dose <a href=\"\/pharmacology\/absorption\">absorbed<\/a> into the circulation. Patient dependant factors also influence bioavailability.\n<\/p>\n\n\n\n<p>When the drug is administered orally the bioavailability depends on several factors:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>Physicochemical\n properties of the drug and its excipients that determine its \ndissolution in the intestinal lumen and its absorption across the \nintestinal wall.<\/li><li>Decomposition of the drug in the lumen.<\/li><li>pH and perfusion of the small intestine.<\/li><li>Surface and time available for absorption.<\/li><li>Competing reactions in the lumen (for example of the drug with food).<\/li><li><a href=\"\/pharmacology\/metabolism\">Hepatic first-pass effect<\/a>.<\/li><\/ol>\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\/bioavailability_Trim.mp4\"><\/video><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p>Bioavailability can also be determined for other <a href=\"\/pharmacology\/extravascular-administration\">extravascular<\/a>\n routes of administration such as intramuscular, subcutaneous, rectal, \nmucosal, sublingual, transdermal etc. Sublingual and rectal routes are \noften used to bypass hepatic first-pass effect. Bioavailability of most \nsmall molecular weight drugs administered i.m. or s.c. are perfusion \nrate-limited. Large molecules administered i.m or s.c. enter the blood \nin part via the lymphatic pathway. <\/p>\n\n\n\n<p><p class=\"hiddenTitle\">Chart Pharmacokinetics<\/p>\n<div>\n\n    <div id=\"chartContainer\">\n        <canvas id=\"chart\"><\/canvas>\n        <div class=\"\" id=\"divSliderContainer\"><\/div>\n    <\/div>\n\n    <script>\n\n        let chart;\n        let baseDataChartValues = [];\n        let dataChart = [];\n        let dataChartStoredValues = [];\n        let labelsChart = [];\n\n        let dose = 1000;\n        let baseDose = 1000;\n\n        let mDose = 1000;\n        let baseMDose = 1000;\n\n        let tau = 6;\n        let baseTau = 6;\n\n        let vd = 50;\n        let baseVd = 50;\n\n        let cl = 10;\n        let baseCl = 10;\n\n        let f = 0.7;\n        let baseF = 0.7;\n\n        let ka = 2;\n        let tH;\n\n        const maxTime = 100;\n\n        function getPlasmaConcentration(h) {\n            let formulaPlasmaConcentration = (dose*f*ka\/(vd*(ka-cl\/vd))*(Math.exp(-cl\/vd*h)-Math.exp(-ka*h))+(mDose*f*ka\/(vd*(ka-cl\/vd))*((1-Math.exp(-Math.floor((h)\/tau)*cl\/vd*tau))\/(1-Math.exp(-cl\/vd*tau))*Math.exp(-cl\/vd*(h-Math.floor(h\/tau)*tau))-(1-Math.exp(-Math.floor((h)\/tau)*ka*tau))\/(1-Math.exp(-ka*tau))*Math.exp(-ka*(h-Math.floor(h\/tau)*tau)))));\n\n            return formulaPlasmaConcentration;\n        }\n\n        \/*\n         *\n         * t1\/2 = ln(2) * (volume of distribution \/ clearance)\n         *\n         *\/\n        function getHalfLife() {\n            tH = Math.log(2)*(vd\/cl);\n            return (Math.round(tH * 100) \/ 100);\n        }\n\n        function updateSlider(updateStored = false) {\n            dataChart = [];\n            if(updateStored) dataChartStoredValues = [];\n\n            for(let i = 0; i <= maxTime; i++) {\n                let concentration = getPlasmaConcentration(i);\n                dataChart.push(concentration);\n                if(updateStored) dataChartStoredValues.push(concentration);\n            }\n\n            chart.data.datasets[0].data = dataChart;\n            chart.data.datasets[1].data = dataChartStoredValues;\n\n            $( \"#slider-f\" ).slider( \"option\", \"value\", f);\n            chart.update();\n        }\n\n        let sliderF = '<div id=\"slider-f\" class=\"sliderRange\">' +\n                            '<span id=\"custom-handle-f\" class=\"ui-slider-handle customHandle\"><\/span>' +\n                            '<span class=\"spanUnit\" id=\"\">F<\/span>' +\n                        '<\/div>';\n\n        $('#divSliderContainer').append(sliderF);\n\n\n   \n\n        $(function() {\n\n            let handle = $('#custom-handle-f');\n\n            $( \"#slider-f\" ).slider({\n                orientation: \"vertical\",\n                range: \"true\",\n                min: 0,\n                max: 1,\n                step: 0.01,\n                value: f,\n                create: function() {\n                    handle.text( $( this ).slider( \"value\" ) );\n                },\n                slide: function( event, ui ) {\n                    f = ui.value;\n                    handle.text( ui.value );\n                    updateSlider();\n                }\n            });\n        });\n\n        Chart.pluginService.register({\n            beforeInit: function(chart) {\n\n                for(let i = 0; i <= maxTime; i++) {\n                    labelsChart.push(i);\n                    dataChart.push(getPlasmaConcentration(i));\n\n                    dataChartStoredValues = dataChart;\n                    baseDataChartValues = dataChart;\n                }\n\n            }\n        });\n\n        chart = new Chart(document.getElementById(\"chart\"), {\n            type: 'line',\n            data: {\n                labels: labelsChart,\n                datasets: [{\n                    label: \"Plasma Concentration\",\n                    data: dataChart,\n                    borderColor: colorDatasetMain.borderColor,\n                    fillColor: colorDatasetMain.fillColor,\n                    strokeColor: colorDatasetMain.strokeColor,\n                    highlightFill: colorDatasetMain.highlightFill,\n                    highlightStroke: colorDatasetMain.highlightStroke,\n                    borderWidth: \"1\",\n                    pointRadius: 0,\n                    fill: false\n                }, {\n                    label: \"Plasma Concentration\",\n                    data: dataChartStoredValues,\n                    borderColor: colorDatasetStored.borderColor,\n                    fillColor: colorDatasetStored.fillColor,\n                    strokeColor: colorDatasetStored.strokeColor,\n                    highlightFill: colorDatasetStored.highlightFill,\n                    highlightStroke: colorDatasetStored.highlightStroke,\n                    borderWidth: \"1\",\n                    pointRadius: 0,\n                    fill: false\n                }]\n            },\n            options: {\n                scales: {\n                    xAxes: [{\n                        scaleLabel: {\n                            display: true,\n                            labelString: 'h [hour]'\n                        }\n                    }],\n                    yAxes: [{\n                        scaleLabel: {\n                            display: true,\n                            labelString: 'C [mg\/l]'\n                        }\n                    }]\n                },\n                responsive: true,\n                maintainAspectRatio: false\n            }\n        });\n\n    <\/script>\n\n<\/div><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Clinical implications<\/h3>\n\n\n\n<p>When changing the route of administration or the <a href=\"\/pharmacology\/galenics\">formulation<\/a> of a drug, the dose must be adapted with regard to the respective bioavailability of each route.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Related terms<\/h3>\n\n\n\n<p>Bioavailability of a drug administered <a href=\"\/pharmacology\/intravenous-bolus\">intravenously<\/a> is by definition 100%. Bioavailability is less or equal to 100% for any other route of administration.\n<\/p>\n\n\n\n<p>The term absolute bioavailability is used when the fraction of <a href=\"\/pharmacology\/absorption\">absorbed<\/a> drug is related to its i.v. bioavailability. The term relative bioavailability is used to compare two different <a href=\"\/pharmacology\/extravascular-administration\">extravascular<\/a> routes of drug administration.\n<\/p>\n\n\n\n<p>The term bioequivalence is used when two different <a href=\"\/pharmacology\/galenics\">galenic formulations<\/a> of a drug have a similar bioavailability.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Assessment<\/h3>\n\n\n\n<p>Bioavailability is proportional to the total <a href=\"\/pharmacology\/areaunderthecurve\">area under the plasma concentration-time curve<\/a> (AUC). The relative bioavailability of drug 1 compared to drug 2 can be calculated using the following equation: <\/p>\n\n\n\n<div class=\"wp-block-blocks-latex-block-latex\"><script type=\"text\/x-mathjax-config\">   MathJax.Hub.Config({tex2jax: {inlineMath: [['$','$'], ['\\\\(','\\\\)']]}}); <\/script> $$F = { AU C_2 \\over AU C_1}*{ D_1 \\over D_2}$$<\/div>\n","protected":false},"excerpt":{"rendered":"<p>&#8220;Fraction of a dose of drug that is absorbed from its site of administration and reaches, in an unchanged form, the systemic circulation&#8221; Description The drug, its route of administration and its galenic formulation determine the amount of administered dose absorbed into the circulation. Patient dependant factors also influence bioavailability. When the drug is administered &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/sepia2.unil.ch\/pharmacology\/parameters\/bioavailability\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Bioavailability&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":7,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-102","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/102","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=102"}],"version-history":[{"count":54,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/102\/revisions"}],"predecessor-version":[{"id":1278,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/102\/revisions\/1278"}],"up":[{"embeddable":true,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/7"}],"wp:attachment":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/media?parent=102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}