Plasma concentration multiple doses Equations in js

Question

Currently my app needs to calculate the plasma concentration (multiple doses). I'm expecting it to be cyclical like depicted in this case:

However, when I try to calculate and plot it out, it comes out like

The equation that I was told that it should be is and my function looks like the one below

function calculatePlasmaConcentration(x, bioavailability, vd, ka, ke, dosing, dose) {
    var firstPart, secondPart, c;

    firstPart = ((bioavailability * dose * ka) / (vd * ka - vd * ke));
    secondPart = (Math.exp(-ke * x) / (1 - Math.exp(-ke * dosing))) - (Math.exp(-ka * x) / (1 - Math.exp(-ka * dosing)));
c = firstPart * secondPart;

    return c;
}

I can't seem to see that I wrote the equation wrong, what am I doing wrong? the parameter x should be time in hours.

adding the default values here:

defaultDrugInfo = {
    dose: 500,
    dosing: 24,
    bioavailability: .89,
    ka: .883,
    ke: .0578,
    vd: 6,
    optimalTopRange: 10,
    optimalBottomRange: 5
}

Thanks in advance!

Answer 1

You need to call the function calculatePlasmaConcentration(...) this way:

Fiddle

// four cycles
for (cycle = 0; cycle < 4; cycle++) {
    // 24 hr dosing
    for (t = 0; t < 24; t++) {
        nums.push(Math.round(calculatePlasmaConcentration(t, 0.89, 6, 0.883, 0.0578, 24, 500) * 1000) / 1000);
    }
}

The graph created by the numbers generated by this function is:

[Edit]

When the time hits 24 hour intervals, the plasma concentration values for the next day are supposed to add up with the last plasma concentration value from the previous day, since the dose doesn't just disappear from the body.

Next, when we append the tau(τ), (i in our case) along with the plasma concentration value(temp.push([i + delta, pcStack + pc]);) we need to add up 24 to i, everytime the time hits 24 hour intervals.

Fiddle

This is the updated function.

function generateData(drugInfo) {
    var pcStack = 0;
    var temp = [],
        mainArray = [],
        tempObject = {};
    var start = 0;
    var end = 24;
    var delta = 0;
    for (cycle = 0; cycle < 4; cycle++) {
        for (i = 0; i < 24; i += 0.05) {
            var pc = calculatePlasmaConcentration(i, drugInfo.bioavailability, drugInfo.vd, drugInfo.ka, drugInfo.ke, drugInfo.dosing, drugInfo.dosage);
            temp.push([i + delta, pcStack + pc]);
        }
        pcStack += pc;
        delta += 24;
    }
    tempObject = {
        data: temp
    };
    mainArray.push(tempObject);
    return mainArray;
}