120 Calculations Review for NAPLEX

[rx2010]

Enjoy! or not, since we hate calculations, hahaha.

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[Sure2Pass]

Hey guys, on the exam, will they give us all the valences and MWs we need (unlike in the packet)?

Also, I saw someone saying that we will not be given any formulas at all. But what about BSA? Will that be given?

I was given the formula for BSA on my exam

 

[nextyearrx]

Hey guys! I was wondering if I can get some input....correct me if I'm wrong please =)... but the answer has it that the molecular weight of Lithium carbonate 74mg=2mmol of lithium.....however, isn't it by definition that 1mole = molecular weight of Li carbonate? In other words, shouldn't the answer be 12.2mmol/day? Any help would be awesome! Thanks!

Can you explain why the answer 24.3m Moles is INCORRECT and 12.2 is correct? I know it is confusing,,

 

[CUpharmD2013]

Good luck to everyone!

 

[inim]

Great link! Thank you thank you

 

[ches123]

Hi,
Can anybody solve and explain Question # 55 from SDN 120 calculations for me please.
Thanks. why cant be there just drops in 30 ml. why we have to calculate the amount of dose.
please explain.

 

[queenietess]

Please email to [email protected]. Thanks!

 

[lut555]

would you kindly send your study guides to [email protected]. I am currently studying for my naplex. Thanks so much. Greatly appreciate it from class of 2013 MCV.

 

[GatorPrePharm]

For question 100 I got a different answer. Please help clarify whether or not I am making a mistake or not. Thanks!

The answer given says to add 30mL of 14.9% KCl, but if you add 30mL of the 14.9% KCl you then have 510mL in your bag (480 of previous remainder plus 30mL from KCl), which contains your 80mEq of KCl. However, since they restricted your flow rate to 480ml over 12 hours your patient will not receive all 80 mEq.

I think you should set up and an alligation with 14.9% being added to your 0.298% (remaining 480mL in bag) and have your desired concentration be 1.24%. Using 480mL (parts) for your 0.298% you can determine that you need 0.9436 parts of the 14.9% KCl, which gives you 35.14mL that needs to be added to your existing bag.

I hope that made sense! :X Thanks for any help anyone can provide!

 

[GatorPrePharm]

I also got different answers for 101-104

101: 40mL
102: Still Water
103: 15ml/hr
104: 3.75 drops/min

 

[SeaSound]

Might be a bit late to change anything, but the answer to number 101 is incorrect! Anyone else find any errors?

I agree. Problem 101 concentration was not doubled.

 

[Aquarian85]

If there is anyone still on this blog, I really need help with this packet. I keep getting different answers for almost every one of these questions. If there is anyone still active could someone please respond? I need all the help i can get.

 

[molyhelp]

And someone said to know titrations well but I don't think I saw any titrations in the packet? ._.

titrations?
I heard TRITURATION as part of finding answer of compounding math.

 

[molyhelp]

it can be solved using c1v1=c2v2
xmL (70%) = (x + 1015mL) (10%)

Thanks for the tip.
I follow your advice with full details:

it can be solved using

C1 * V1 = C2 * V2
(70%) * (X ml) = (10%) * (X ml + 1015mL)

(70 / 100) * (X ml) = (10 / 100) * (X ml + 1015mL)

70 * X ml /100 = (10 * X ml + 10150) / 100

70 * X ml *100 = (10 * X ml + 10150) * 100

7000 * X ml = (1000 * X ml + 1015000)

7000 * X ml - 1000 * X ml = 1015000

6000 * X ml = 1015000 ml

X = 1015000 ml / 6000 ml

X = 169.166 = 169.2

 

[cloe_chill]

thanks for link.

 

[anomaly285]

Can someone please explain why Question #100 to me? I Have no idea how to even go about solving this whole problem...

 

[john888]

Hey guys! I was wondering if I can get some input....correct me if I'm wrong please =)... but the answer has it that the molecular weight of Lithium carbonate 74mg=2mmol of lithium.....however, isn't it by definition that 1mole = molecular weight of Li carbonate? In other words, shouldn't the answer be 12.2mmol/day? Any help would be awesome! Thanks!

It looks like they are just asking for mMol of Li, not mMol of the entire Li carbonate compound.

I know that post was years ago but I'm posting for others because I was also confused before realizing the above point - I noticed that in RxPrep they only ask for mMol of entire compounds, not single elements in a compound. Is this why the answer is 24.3 mMol/day instead of 12.2? I don't understand how that really works, because if 1 mMol is the molecular weight, then why wouldn't 1 mMol of Li be 7?

Anyways, it basically looks like they took the molecular weight of Li carbonate and divided it by 2 because there are 2 Li atoms in the compound. As I said I don't understand the reasoning behind that, but it's easy enough to memorize the process (the same thing is done in the 2nd part of the question where the molecule has 3 Li atoms and the MW is divided by 3 to get the mMol)

Anybody that can confirm or tell me the reasoning, please do

 

[Swoosh1703]

Are these still relevant?

 

[lopsky]

I cannot seem to be able to download the 2006 pdf file for the 120 calculation questions and the link isn't working. Can someone pls help me or send me a link that would work? Email is [email protected] please help me

 

[Pharmacygrad3741]

Hi there! I'm having a lot of difficulty with figuring out when to do allegation or use a ratio - such as the problems on the SDN 120 like #12 and, #30, #78. For example #12 I solved it setting up proportional ratios - I set up like:
1) I need 10% which is 10g/100mL = x/1000mL (total IV is 1L)
X= 100g needed
2) if I need 100g, how many mLs of the 70% dextrose will I need so:
70g/100mL = 100g/x
X = 142.9mL needed
--- this is way off from the answer key as they used allegation. However I'm SO confused as to when to set up direct ratios like I did above and when I need allegation. Please help if you can my exam is in 4 days and I'm borderline panic attack

   0.7x mL         1
-------------- = ------
1015 mL + x mL    10

1015 mL + x mL = 7x mL
1015 mL = 6x mL
169.17 mL = x

If the calculations on the NAPLEX are this level, should be a breeze. I went through all the questions and checked my answers after I was done in about 3 hours. I was an engineering major before pharmacy school, so I rather enjoy the number crunching.

Bi

 

[molyhelp]

I cannot seem to be able to download the 2006 pdf file for the 120 calculation questions and the link isn't working. Can someone pls help me or send me a link that would work? Email is [email protected] please help me

Emailed to you. Please check your email.
I also attached file here right below for anyone that needs the file.

Dear LopSky,
Please see attached file for 120 Math Questions with Answers.
Good luck with your exam. After you pass, please come back to help others. Thank you very much for your help in advance...
molyhelp
[email protected]

 

[molyhelp]

Can someone please explain why Question #100 to me? I Have no idea how to even go about solving this whole problem...

Here is the clue.....
In the guide, 120 Questions, then, 120 Answers.

Answer for #100 was:
100.

80 ml/hr (x) 6.5 hr = 520 ml administered (480 ml remain) 480 ml = 12 hours of fluid
40 ml/hr available
40 mEq KCl in 1000 ml = 4 mEq per 100 ml
X mEq = 4 mEq = 20.8 mEq of KCl 40 mEq (minus) 20.8 mEq = 19.2 mEq
520 ml 100 ml have been given that remain in the bag



Could also do for KCl X mEq = 4 mEq = 19.2 mEq of KCl remaining in the bag still in the bag 480 ml 100 ml
80 mEq (minus) 19.2 mEq = 60.8 mEq needed to add to the bag
K = 39 + Cl = 35.5 = 74.5 mg per mEq (x) 60.8 mEq = 4529.6 mg needed
14.9% = 149 mg per ml 4529.6 mg (div by) 149 mg per ml = 30.4 ml
(This is same as 2 mEq/ml)



Because of spacing problem, copy and paste did not look right.
Please see page 23 of 27 for Answer of Question 100.
File is attached right below this line:

 

[PharmDRG]

Has this changed for the 2014 Naplex? I did notice in this packet that you are expected to know the molecular formula in order to calculate the molecular weight yourself. For example #68 asks you to calculate mEq for magnesium sulfate and the MW is not given so you need to know that magnesium is MgSO4 to calculate it. It's been awhile since general chemistry and, embarrassingly, I may forget how many oxygens are in magnesium sulfate!

The exam will give you the MW when needed

 

[aroshia]

Hi I am new on this forum. Thank you so much for posting the link for calculations

 

[Pharmacygrad3741]

Are the answers to 101-104 wrong? They didnt double the concentration please help!!!

 

[molyhelp]

Are the answers to 101-104 wrong? They didnt double the concentration please help!!!

Agree with you.
Given in the question is non-double-strength, which is 400 mg in 250 ml.
QUOTE FROM THE QUESTION: "The usual Dopamine drip concentration is 400 mg in 250 ml."
Therefore, our educated guess suggests double strength should be 800 mg in 250 ml.
Meaning: 1600 mg in 500 ml.
++++++++++++++++++++++++++++++++++++++
SOURCE:
http://www.leememorial.org/FormsManagement/PDF/PhysicianOrders/Pediatrics/3355TitratableDripPICU.pdf

DOCUMENT: A premade form for doctor to pick and give prescription:
File title (included as reference): 3355TitratableDripPICU.pdf
QUOTE:
"

++++++++++++++++++++++++++++++++++++++
Another source for pharmacy:

https://apps.aahs.org/CriticalCare/dopamine.pdf

"Withdraw 43 ml from 250 ml* bag of D5W
and discard. Add 20 ml (40 mg/ml) of
dopamine to the 460 ml D5W. This will
replace the discarded volume and yield a
final concentration of 800 mg / 250 ml or
3200 mcg/ml. Label bag as DOUBLE
STRENGTH 3200 mcg/ml"

So, those supporting evidence shows us that DOUBLE STRENGTH means: 800 mg in 250 ml.
Therefore, if the bag will be 500 ml, we will need 1600 mg in 500 ml.

To get 1600 mg, we will have to use 40 mg in 1 ml.
To get 1600 mg, we will need:
(1600 mg MULTIPLY BY 1 ml) DIVIDE OVER (40 mg) = 40 ml.

To get 1600 mg, we will need 40 ml.

If I am wrong, please kindly correct. Thank you very much in advance.

 

[NorthStar white]

Update: I passed the NAPLEX and I thought the SDN 120 calculations were a great help on the NAPLEX. If you can do these problems, you will do well on the NAPLEX calculation. They count calculation problems more on the NAPLEX so make sure you know how to do them.

I also found these sources to be a great help:

Ebay pharmacy charts: http://www.ebay.com/itm/2014-Editio...3?pt=US_Texbook_Education&hash=item3ccde1ea77

Rxprep: http://www.rxprep.com

More calculation problems: http://faculty.ksu.edu.sa/hisham/Documents/eBooks/Pharmaceutical and Clinical Calculations ed 2.PDF

hi
congrats!
did u still keep ur reading materials fo

 

[Q&APharm]

Does anyone understand number #26? I have no idea why I can't figure it out

 

[zamir]

Does anyone understand number #26? I have no idea why I can't figure it out

#26 states that the patient has been taking 300 mg of Li2CO3 (lithium carbonate) tid (300 mg x 3 = 900 mg) and wants to know what is the amount of millimoles taken per day. The first thing you have to do is find out the MW of Li2CO3 which is (7x2) + 12 + (16x3) = 74, this is 74 grams per mol (74g/mol), at this point I like to convert the MW into mg/mmol which would be 74mg/mmol. Next you divide the dose (900 mg) by the MW (74mg/mmol) = 12.16. Now because you have 2 atoms of Li (Li2) per molecule of lithium carbonate you have to multiply the 12.16 by 2, resulting in 24.32 mmol.

 

[Q&APharm]

#26 states that the patient has been taking 300 mg of Li2CO3 (lithium carbonate) tid (300 mg x 3 = 900 mg) and wants to know what is the amount of millimoles taken per day. The first thing you have to do is find out the MW of Li2CO3 which is (7x2) + 12 + (16x3) = 74, this is 74 grams per mol (74g/mol), at this point I like to convert the MW into mg/mmol which would be 74mg/mmol. Next you divide the dose (900 mg) by the MW (74mg/mmol) = 12.16. Now because you have 2 atoms of Li (Li2) per molecule of lithium carbonate you have to multiply the 12.16 by 2, resulting in 24.32 mmol.

Thank you!!

 

[PharmDBro2017]

editted

 

[Kikbox]

Hi can someone provide a valid link to the 120 sdn questions. The previous link opens with a glitch or random characters. Thanks!

 

[RumDMC]

10 years later and I'm making my students do these questions on their rotation...