Math problem

[fostersgirl6993]

Can someone please help me with these two nursing calculations?

1. 0.25g of liquid Dilantin has been prescribed po by the physician. How many ml should you administer if the Dilantin is available in a strength labeled 125 mg in 1 tsp.

2. You have available an ampule of Atropine Sulfate labeled 1 mg in 1 ml. 1/150 gr of Atropine Sulfate has been prescribed by the physician IM. What volume of drug will you prepare?

I'm not just looking for answers, but how to go about finding the answer.

Thanks so much

[elkpark]

Yes. 2 tsp (10 ml) is right.

Now, problem 2 -- 1 grain = 60 mg, so, if we want 1/150 of a grain, that means we want 1/150 of 60 mg. What is 60 (mg) divided by 150?

[morte, LPN, LVN]

i looked up grains to mg and it comes up 65 to 1 not 60 (actually 64. with many places, lol)

[elkpark]

i looked up grains to mg and it comes up 65 to 1 not 60 (actually 64. with many places, lol)

One of the interesting, frustrating things about learning dosage calculations is that different sources will tell you that i grain = 60, 64, or 65 mg. I remember, being v. frustrated with this myself as a nursing student, asking my father, a physician who had been practicing when the apothecary system was the standard system and survived the transition to metrics, so, is it 60, 64, or 65 milligrams (how can it possibly be all three?) and, if any one of the three is correct, how the heck do you know which one to use in a given dosage calculation???? His wise, insightful reply? "Whichever one makes the math come out easiest." (Words to live by! :))

To avoid driving their students completely mad, most nursing programs pick one factor and stick with it. I'm guessing that, since the OP identified i grain as equalling 60 mg, that's the preferred value at her school. (Also, it makes the math come out easiest in this particular problem. )