{"id":145,"date":"2019-04-24T12:51:16","date_gmt":"2019-04-24T12:51:16","guid":{"rendered":"https:\/\/sepia2.unil.ch\/pharmacology\/?page_id=145"},"modified":"2020-09-04T03:36:24","modified_gmt":"2020-09-04T03:36:24","slug":"intravenous-infusion","status":"publish","type":"page","link":"https:\/\/sepia2.unil.ch\/pharmacology\/profiles\/intravenous-infusion\/","title":{"rendered":"Intravenous Infusion"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\"> &#8220;Drug administration through the intravenous route at a constant rate over a determined time interval&#8221; <\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Description<\/h3>\n\n\n\n<p>When a drug is infused intravenously at a \nconstant rate, a plateau concentration will be reached progressively (in\n the most frequent case of <a href=\"\/pharmacology\/intravenous-infusion\">first order kinetics<\/a>).\n<\/p>\n\n\n\n<p>On starting the infusion, there is no drug in the \nbody and therefore, no elimination. The amount of drug in the body then \nrises, but as the drug concentration increases, so does the rate of \nelimination. Thus, the rate of elimination will keep rising until it \nmatches the rate of infusion. The amount of drug in the body is then \nconstant and is said to have reached a steady state or plateau.\n<\/p>\n\n\n\n<p>The factors affecting the steady state plasma drug concentration are:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>Infusion\n rate (Ro): The steady state drug concentration is proportional to the \ninfusion rate. Thus, a higher infusion rate will result in a higher \nsteady state plasma drug concentration.<\/li><li><a href=\"\/pharmacology\/clearance\">Clearance<\/a>: Higher clearance of the drug will result in lower plasma drug concentration at plateau. <\/li><\/ol>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"336\" style=\"aspect-ratio: 334 \/ 336;\" width=\"334\" autoplay controls loop src=\"https:\/\/sepia2.unil.ch\/pharmacology\/wp-content\/uploads\/2019\/07\/intravenousinfusion_Trim.mp4\"><\/video><\/figure>\n\n\n\n<p>The\n time to reach the plateau is determined by the elimination half-life of\n the drug, which results from clearance and volume of distribution. \nThus, the Vd does not influence the steady state concentration but \nmerely the time required to approach the plateau. After 4 elimination \nhalf-lives the drug plasma concentration is 93,75% of the steady state \nplasma concentration. Likewise, when changing infusion rates, the time \nrequired to reach the new steady state also depends on the half-life of \nthe drug.\n<\/p>\n\n\n\n<p>When stopping an iv infusion, the decline in plasma drug concentration follows an exponential curve, as after an <a href=\"\/pharmacology\/intravenous-bolus\">iv bolus injection<\/a> of the drug.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Clinical implications<\/h3>\n\n\n\n<p>The constant rate infusion regimen is used to \nensure a constant exposure to the drug over a prolonged time. The drug \ninfusion rate must be adapted to the patient&#8217;s clearance in order to \nhave the concentration reach a therapeutic target.<\/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 = 160;\n        let baseVd = 50;\n\n        let cl = 50;\n        let baseCl = 50;\n\n        let f = 1;\n        let baseF = 0.7;\n        \n        let tInf = 24;        \n\n        let ro = 10;\n\n        let ka = 1.5;\n        let tH;\n\n        const maxTime = 80;\n\n        function getPlasmaConcentration(h) {\n            \n            \/*\n            let tInfFormula = tInf;\n            if(tInf >= h) tInfFormula = h;\n            let tl = h;\n            *\/\n            \n            let formulaPlasmaContration;\n\n            if(h < tInf) {\n                formulaPlasmaConcentration = (ro\/cl*(1-Math.exp(-cl\/vd*h)));\n            } else {\n                formulaPlasmaConcentration = (ro\/cl*(1-Math.exp(-cl\/vd*tInf)))*Math.exp(-cl\/vd*(h-tInf));\n            }\n\n            \/\/let formulaPlasmaConcentration = ((ro*tInfFormula)*f*ka\/(vd*(ka-cl\/vd))*(Math.exp(-cl\/vd*tl)-Math.exp(-ka*h)));\n            \n            \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-tinf\" ).slider( \"option\", \"value\", tInf);\n            $( \"#slider-ro\" ).slider( \"option\", \"value\", ro);\n            chart.update();\n        }\n\n        let sliderTinf = '<div id=\"slider-tinf\" class=\"sliderRange\">' +\n                            '<span id=\"custom-handle-tinf\" class=\"ui-slider-handle customHandle\"><\/span>' +\n                            '<span class=\"spanUnit\" id=\"\">Tinf<\/span>' +\n                        '<\/div>';\n\n        $('#divSliderContainer').append(sliderTinf);\n\n\n        let sliderRo = '<div id=\"slider-ro\" class=\"sliderRange\">' +\n                            '<span id=\"custom-handle-ro\" class=\"ui-slider-handle customHandle\"><\/span>' +\n                            '<span class=\"spanUnit\" id=\"\">Ro<\/span>' +\n                        '<\/div>';\n\n        $('#divSliderContainer').append(sliderRo);   \n\n        $(function() {\n\n            let handleTinf = $('#custom-handle-tinf');\n\n            $( \"#slider-tinf\" ).slider({\n                orientation: \"vertical\",\n                range: \"true\",\n                min: 2,\n                max: 50,\n                step: 1,\n                value: tInf,\n                create: function() {\n                    handleTinf.text( $( this ).slider( \"value\" ) );\n                },\n                slide: function( event, ui ) {\n                    tInf = ui.value;\n                    handleTinf.text( ui.value );\n                    updateSlider();\n                }\n            });\n\n            let handleRo = $('#custom-handle-ro');\n\n            $( \"#slider-ro\" ).slider({\n                orientation: \"vertical\",\n                range: \"true\",\n                min: 5,\n                max: 20,\n                step: 1,\n                value: ro,\n                create: function() {\n                    handleRo.text( $( this ).slider( \"value\" ) );\n                },\n                slide: function( event, ui ) {\n                    ro = ui.value;\n                    handleRo.text( ui.value );\n                    updateSlider();\n                }\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\">Related terms<\/h3>\n\n\n\n<p>Ro: rate of constant intravenous infusion, mg\/h. <\/p>\n\n\n\n<p>tinf: infusion duration, h.  <\/p>\n\n\n\n<p>IV bolus dose: In some situations, steady state \nplasma concentration must be reached more rapidly. An iv bolus dose is \nthen administered. The plasma drug concentration is then equal to the \nsum of the concentrations resulting from iv bolus and iv infusion.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Assessment<\/h3>\n\n\n\n<p>Css is the drug plasma concentration at steady state. Css can be determined by the equation:\n<\/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> <p class=\"formula\">$$C_{ss}={Ro \\over CL}$$<\/p><\/div>\n\n\n\n<p><strong>Ro<\/strong> = Rate of constant intravenous infusion (mg\/h) <\/p>\n\n\n\n<p><strong>CL<\/strong> = <a href=\"\/pharmacology\/clearance\">Clearance<\/a><\/p>\n\n\n\n<p>During the infusion, the equation of the plasma concentration-time curve is:\n<\/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> <p class=\"formula\">$$C=C_{ss}*(1-e^{-\\lambda*t})$$<\/p><\/div>\n\n\n\n<p> <strong>\u03bb<\/strong>  = <a href=\"\/pharmacology\/halflife\">elimination constant rate<\/a> = CL\/Vd <\/p>\n\n\n\n<p><strong>t<\/strong> = time <\/p>\n\n\n\n<p><strong>Vd<\/strong> = <a href=\"\/pharmacology\/volumeofdistribution\">Volume of distribution<\/a><\/p>\n\n\n\n<p>At the end of the infusion, the equation of the exponential decrease in plasma concetration is :\n<\/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> <p class=\"formula\">$$C=C_{ss}*e^{-\\lambda*t}$$<\/p><p class=\"formula\"><\/div>\n","protected":false},"excerpt":{"rendered":"<p>&#8220;Drug administration through the intravenous route at a constant rate over a determined time interval&#8221; Description When a drug is infused intravenously at a constant rate, a plateau concentration will be reached progressively (in the most frequent case of first order kinetics). On starting the infusion, there is no drug in the body and therefore, &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/sepia2.unil.ch\/pharmacology\/profiles\/intravenous-infusion\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Intravenous Infusion&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":8,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-145","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/145","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=145"}],"version-history":[{"count":30,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/145\/revisions"}],"predecessor-version":[{"id":1316,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/145\/revisions\/1316"}],"up":[{"embeddable":true,"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/pages\/8"}],"wp:attachment":[{"href":"https:\/\/sepia2.unil.ch\/pharmacology\/wp-json\/wp\/v2\/media?parent=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}