hey everyone it's sarah with registerednessrn.com and in this video i'm going to review the desired over have method for solving dosage calculations and as always whenever you get done watching this youtube video you can access the free quiz that will test you on this content so let's get started the desired over have method is a formula you can use to help you solve dosage calculations now there's a few other methods you can use to also help you solve dosage calculations and that includes like ratio proportion or dimensional analysis now if you like dimensional analysis i have a whole playlist that you can access where i cover different types of dosage calculations and use a dimensional analysis method to help you do that now the method you use to help you solve these calculations really you know depends on your personal preference and what your program is requiring you to use in order to solve these dosage calculations so in this video i'm going to concentrate on the desired over have method now with this method you set up a formula so you want to make sure that you commit this formula to your memory bank and let the name of this method guide you with the setup of that formula so we're talking about the desired over have method so that's what we start out with we start out with d d is the desired dose that that prescribing provider has ordered for your patient so it's going to be the ordered dose that you're going to plug in here this is going to be over h which stands for have this is what you have on hand what you've been dispensed with from pharmacy so you get that information from the medication label you look and you find the dosage strength and that is what's going to be plugged in here and that's going to be multiplied by the quantity the quantity is the volume or the amount of that dosage strength that you have on hand so that's also found on that medication label so let me give you an example you have a bottle of capsules and it says that the dosage strength of those capsules is a thousand milligrams so that goes on the half part because that's what we have on hand and it says that each capsule so each one capsule has a thousand milligrams so you have a quantity of one now this can be tablets it can be capsules it can be milliliters your quantity then you're going to solve that and that's going to equal x which is the dose to be given this is your answer that is what you are solving for now some things you have to remember about this method whenever you're trying to solve for your dosage calculation is that you need to make sure that whenever you're ready to solve that the units match up for the desired and the half part because they have to cancel out if they don't match you're going to have to do some conversions and i'm going to walk you through how to do that a little bit later on but in order to help you do conversions you have to have the metric table memorized so if you don't have the metric table memorized just take some time to look at that table and commit it to memory so now let's solve some practice problems using this method so our problem says that the physician has ordered 500 milligrams by mouth daily and we are supplied with 250 milligram capsules so we need to solve for how many capsules are we going to give per dose so let's plug this information into this formula to solve so the first part we need to plug in is the desired part the d so it's desired for the patient to have 500 milligrams that is our dose that is ordered so 500 milligrams that is over what we have on hand and we are supplied with 250 milligram capsules so 250 milligrams is going to go here now that is multiplied by the quantity and our problem tells us that each capsule contains 250 milligrams so here one is going to go so it's one capsule equals or 250 milligrams and now we're going to solve but before we solve we have to make sure that these units match up because if they don't we would have to convert and they do they're both milligrams so they cancel out so 500 divided by 250 is 2 times one capsule and two times one is two so our answer is two capsules that is how much we are going to administer to our patient now let's look at our next problem this problem says that the physician orders 3.6 grams iv daily and we're supplied with a vial that says for every two milliliters that we draw up there's going to be 1200 milligrams in it and we're trying to solve for how many milliliters per dose are we going to draw up in this syringe to inject in the patient so let's set up our problem using our formula so the desired dose for this patient is 3.6 grams that's how much they want the patient to have its order dose and on hand we have a dosage strength from our vial from our medication label it told us that there's 1200 milligrams and our quantity which is in milliliters it's a volume amount that there's two milliliters in it so equals x and that's what we're solving for okay so right here we t we can tell that we can't solve our formula because our units do not match we have grams here milligrams there so what we need to do is take an extra step and convert so then we can solve so what we're going to do is we need to get this to milligrams on hand we have milligrams so let's take our physician's order and convert that to milligrams so what we need to figure out is 3.6 grams equals how many milligrams so this is where we pull from the metric table and we know from our memory of the metric table that one gram equals a thousand milligrams so there's one of two ways you can do this it's really your preference on what you like to do so to figure that out what you can do is you can take 3.6 and multiply that by a thousand and that gives us thirty six hundred so three point six grams equals thirty six hundred milligrams or you can do the decimal method where you don't have to multiply because it's the same exact way of saying multiplied by a thousand but it's just a little bit more simpler it's like a little trick so we have 3.6 and because we are going from grams which is bigger than milligrams milligrams is smaller we're going to move the decimal to the right and we're going to move it three places because we're trying to multiply by a thousand so we go one two three and our decimal goes here went from there to there so that is the same way of r as writing thirty six hundred three thousand six hundred so now we're converted we are ready to solve so we have thirty six hundred milligrams that's our desired dose we just converted three point six into that to what we have on hand so that's over what we have on hand so 1200 milligrams times again the quantity 2 milliliters equals x so our units cancels out we're excited about that and we're ready to solve so 3 600 divided by 1200 gives us 3 times 2 milliliters you multiply that out you get 6 milliliters and that is our answer that's how many milliliters we're going to give produce this problem says the physician orders 750 micrograms by mouth daily and we're supplied with from pharmacy with 0.25 milligrams per tablet and we need to figure out how many tablets we're going to give per dose so let's plug it into our formula first we're going to start with the d the desired so it's desired for the patient the order dose is 750 micrograms and that is over h have what we have on hand so what we have on hand we look at the medication label it tells us that there's a strength of 0.25 milligrams and we're already looking at this formula and we're like hey we're going to have to take an extra step and convert because these units are not matching up we have micrograms here milligrams there but we'll finish filling out our formula we're going to multiply that by the quantity and we know that it's one tablet equals 0.25 milligrams so one tablet and then that equals x and that's what we're solving for that's ours to be given so we're going to take that extra step and convert since we're dealing with milligrams we're holding milligram tablets we're going to convert the doctor's order that's in micrograms into milligrams so what we need to figure out is 750 micrograms equals how many milligrams so this is where we access that metric table from our memory bank and we know from that that one milligram equals a thousand micrograms so there's one of two ways you can do this it depends on what you like to do we can take 750 and divide by a thousand now the reason we're dividing is because we are going from a smaller unit which is micrograms hence micro to a little bit of a larger one which is milligrams so this time we're going to divide by a thousand last time we were doing the opposite we were going from grams which was higher to milligrams which is lower so we multiply this time we're going from something lower to something higher so we're going to divide by a thousand so whenever you divide that out you get 0.75 so 750 micrograms equals 0.75 milligrams now an easy trick you can do instead of having to do all that you can just move a decimal so you have 750 whenever you have that your decimal is right there we don't normally write it like that but that's where the decimal hangs out and because we are dividing by a thousand we're going to go left with our decimal movement and we're going to go three places because we're dividing by a thousand so it would go one two three decimal would be there and your number would look like this 0.75 hence like that so we have converted now we're ready to go back to our formula and solve so 750 micrograms is 0.75 milligrams so that is our desired dose our have dose what we have on hand is .25 milligrams our milligrams cancels out and we're going to multiply by our quantity which is one tablet equals x that's what we're solving for so when you divide this out you get three times one tablet just bringing that down equals x and three times one is three so the patient needs three tablets to equal that dose that was ordered by the physician okay so that wraps up this video on how to use the desired over have method for dosage calculations and if you're interested in watching more videos about this topic you can access the link in the youtube description below