OK Everyone! Pharm!

Born2BAnurse · Nov 17, 2003

Oh I forgot I have a test as soon as I come back from Thanksgiving of Im trying to figure out what I need to study to pass They told me it will be questions like:

MD ordered Dilatin 100mg

on hand Dilantin 125mg/5cc

or

IV of 1000 cc D5 1/2 NSS to be infused over 8hrs

Drip Factor is 15 gtts/1cc

How many cc/hr

how many gtts/min?

tnstudentnurse · Nov 17, 2003

MD ordered Dilatin 100mg

on hand Dilantin 125mg/5cc

Ok here is the answer i hope

on hand- 125mg/5cc ( cc =mL)

5mL 100mg 500

----- X -------- -----

125mg 125

Your mg will cancel out , then divide 500 by 125. Your answer will be in mL which is the same as cc for your doctor.

Hope this helps.

PJMommy · Nov 17, 2003

These are really more math problems vs. pharm. Pharm (IMHO) tends to be more about drugs, their methods of action, side effects, etc.

You should get an answer of 4 mL for Dilantin.

IV bag with 1000 cc to go over 8 hours. First thing they want is cc/hr. So, just take the 1000 cc and divide it by 8 hours to know what you need the rate per hour to be. (You should come up with 125 cc/hr).

Okay, now you know the rate is 125cc/hr. How many cc's per minute is this? 125cc/hr divided by 60 minutes = 2.083 cc/min... Now...how many drops per minute is this. You know it takes 15 gtts to get 1 cc so just take 15 * 2.083 = 31.25 gtts/min.

jenrninmi, MSN, RN · Nov 18, 2003

I'm confused. Are you just taking a drug calculation class or are you taking a Pharmacology class? If it's a pharmacology class, you don't need to worry about the math. You will be learning different drugs, their mechanisms, side effects etc... At least that's what we are learning in my Pharmacology class.

medicrnohio, RN · Nov 18, 2003

There are two books that I have used to learn drug calculations. They are Math for Meds and Clinical Calculations. I also have seen some books such as Drug Math Made Incredibly Easy or something to that effect. I love drug calculations and don't mind helping others learn them. If you still need help, feel free to PM me and maybe I can help you via email. Good luck.

Michelle

PMHNP10 · Nov 18, 2003

dimensional analysis is the way to go for drug calculations. You don't have to remember what to multiply and divide. Just set up units so that they cancel eachother out and remember that what was ordered is always the first:

MD ordered Dilatin 100mg

on hand Dilantin 125mg/5cc

set it up like this:

100 mg | 5cc

----------------------

...........| 125 mg

see how the mg cancel out? now all you have to do is 100 * 5= 500/125=4; now you look at units left, and since you have cancelled out mg, only cc's are left, so it's 4 cc

or

IV of 1000 cc D5 1/2 NSS to be infused over 8hrs

Drip Factor is 15 gtts/1cc

How many cc/hr

how many gtts/min?

again, what the dr orders is the first thing you write...1000cc per 8 hrs

1000 cc

---------- ...this is a fraction at this point, so reduce it to...

8 hrs

125 cc

---------

1 hr

which is of course your answer 125 cc/hr

now to make this into gtts/ min, start with what you figured out for cc/hr and set up the units so that they cancel out to give you gtts/hr:

125cc | 15 gtts

---------------------, cc's cancel out, giving you

1 hr .. | 1 cc

gtts

-----

hr

of course the question asks for gtts/ min, so simply use the conversion factor to go from hrs to min (1 hr = 60 min)

125cc | 15 gtts | 1hr

-------------------------------, cancel units and you have

1 hr .. | 1 cc .. | 60 min

gtts

-----

min

now you can either do some reducing to work with smaller numbers on the top and bottom of this fraction, or just multiply 125 * 15 = 1875/60 = 31.25 gtts/min

Here is the tricky thing about some of these questions--rounding. You can't measure out a partial drop, so putting 31.25 will be wrong (unless your instructors are lax about these things) and there most likely won't be partial credit, so all your work is for naught because of a rounding error; so 31 gtts/min is the answer.

Any other problems, I'd be glad to help.

*note: the .. you see are only there so I could get the vertical | to align

nightingale, RN · Nov 18, 2003

Originally posted by psychrn03
dimensional analysis is the way to go for drug calculations. You don't have to remember what to multiply and divide. Just set up units so that they cancel eachother out and remember that what was ordered is always the first:

MD ordered Dilatin 100mg
on hand Dilantin 125mg/5cc

EXCELLENT suggestion! That is exactly what you need to do. This is what I do for dosage calc though....

Pharm is a speed course in remember drug classifications.... YOu also must memorize mechanisim (sp?) of action.

Tale lots of notes, use cards you write up, figure out what you do not know and study that.

Good luck to you!

LilRedRN1973 · Nov 18, 2003

We don't do ANY math in Pharmacology! None. Zip. Nada.

We did have to take a stupid 10 question test at the beginning of the semester to make sure we knew how to do drug calculations. We were allowed to retake it if we failed the first time. Missing more than one was failing. But it was easy.

Pharmacology, on the other hand, is much more than doing calculations. In fact, we have a killer exam tomorrow that I'm DREADING. Thank God I have a 92 and 86 on the two previous exams. This one will be over adrenergic, adrenergic-blocking, cholinergic, anticholinergic, respiratory drugs, positive inotropic agents, antidysrhythmic agents, antianginal agents, antihypertensive agents, diuretics, and fluids and electolytes. ACK!!!!!!!! I'm saying my prayer tonight before I head off to bed...........:chair:

Born2BAnurse · Nov 18, 2003

ok I dont know why my school is mixing Pharm with Drug Calculations but they are.. IM just confused I need help...

I will be PMing you Michelle

Erin RN · Nov 19, 2003

I always used "Math for nurses" I think it was Lipincott. It was helpful. I don't remember having to do calculations for pharmacology. We had a 10 question math test at the begining of each sem we had to get 100% on. We had two chnaces if we didn't get it the second time we were out of the nursing program..I used to stress about that esp when they threw in things like "grains". We lost 20% of our class over the 2 year period...eeek. Erin

Nurse2bSandy · Nov 19, 2003

I got an "incredibly easy" book that had to do with drug calcs. It helped some... but actually our text book was pretty straight forward.

I'd just like to say that I am usually math challenged but as of today I PASSED MY MATH FOR MEDS CLASS!!!!

I still have to take the final, but we needed a 90% in the class to even be able to take it. I was sweating it today, but ended up the class with 25 extra points.

My biggest bit of advice: Don't panic... just practice! They will teach you a method, or you'll find one that works for you, then PRACTICE, PRACTICE, PRACTICE!

Good luck! Off to bed and then to study math!