A prescription for a suspension calls for a dose of 250mg to be given twice a day. If the suspension contains 300mg/5ml, how many ml are needed for one dose?

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Apr 02, 2012
by: AZ

I already took my PTCB and Passed. I got 90 questions and time given was 120 min. All were multiple choice and in the answers to select they had either 4.16ml or 4.2ml. This is I realized a pharmacy math exam and not a rounding off test. Regarding the sketch pad, I saw the girl taking a picture of my sketch pad calculations. I do like their tight security this way the cheaters cannot pass this exam. GOOD LUCK TO ALL SINCERE STUDENTS.

Mar 23, 2012
solution is easy
by: Kateryna

we need 250 ml for 1 dose (ok)
we have susp. 300mg/5ml
300 ml - 5 ml
250mg - x ml
x =(250*5)/300=4.16ml
Answer: 4.16 or 4 ml rounded for 1 dose

Mar 23, 2012
look at sig
by: Anonymous

Sig: 250 mg TID which is THREE times a day not TWICE!!!!!!

Feb 22, 2012
by: Anonymous

I am going to take the pharm tech test tomorrow. I have read somewhere that in the test they give you a board to write and you can't erase what you calculate in that board. Is that true?

Feb 10, 2012
math eq
by: Anonymous

Rx; 250mg TID
On hand; 300mg/5ml
How many ml are needed for 1dose?

250mg TID = 500mg/ day 1day = 2 dose

500mg/2x :: 300mg/5ml
2x=(5x500)/300. =2500/300. =8.33
X=8.33/2. =4.16ml/dose

Feb 02, 2012
Problem solved?
by: Anonymous

So how do you solve the problem? Is there a way someone can actually write the problem? I'm really bad at pharmacy math and I need to see how it was solved to get the answer Please! Thanks

Jan 15, 2012
Unrealistic Volumes in Suspensions
by: Anonymous

4.16ml is a wonderful answer -- on a calculator. Take a 5ml syringe and place 4.16ml in it. That volume is not a realistic amount to draw up. Medical math problems must result in answers that can be realistically applied in real life.

Therefore, I agree that 4.16ml ends up rounding up to 4.2ml, a more realistic volume to be administered.

Dec 22, 2011
by: AZ

A prescription for a suspension calls for a dose of 250mg to be given twice a day. If the suspension contains 300mg/5ml, how many ml are needed for one dose?

Do not let "to be given twice a day" throw u off my friend. A dose of 250mg, thats it. The correct answer is 4.2ml it needs to be rounded off to one digit if there is any # before the zero. If in Multiple choice they have 4.16ml and 4.2ml then I will definitely choose 4.2ml because 4.16ml will be the wrong answer.

Dec 18, 2011
as simple as that
by: Anonymous

an ml contains 60 mg of drug and for 250 mg we need 4.16 ml.

Dec 07, 2011
per dose
by: G

250mg/ dose
so 350mg/5ml = 250mg/(x)ml
x =(5*250)/(300) = 4.16 per dose

Nov 07, 2011
by: Anonymous

Answer should be like this;5/300.250=4.16 we should do according to calculator which is more accurate and quick too.

Nov 06, 2011
suspension ans
by: Ebony

Its 250mg/xml times 300/5ml. Then u do ratio/proportion. 1250/300 which the answer will be 4.16

Nov 01, 2011
READ the question
by: ChRxis

I see so many people answering these questions wrong on here...thinking they are helping out the person that submitted the question.

I tell my students to READ the question before they do anything. Find out what the question is asking you to solve. Pay attention to detail!!!

This question asks how much for ONE DOSE!

***Sidebar*** (by Keith)
I agree with you here ChRxis. These little details are indeed big enough to make people choose the wrong answer and ultimately fail the PTCB. On the practice exams here on the site and the questions on Facebook, I try hard to make them tricky with the hope that people will get frustrated enough to learn to watch for them. By the time they sit for the exam, they should be looking for such things by second nature. No one like word problems, but that's what the PTCB and ExCPT exams are comprised of.

Sep 24, 2011
Metric Conversion?
by: Anonymous

Sorry to sound silly but has the last person who commented included the conversion from mg to ml?

Sep 23, 2011
Sorry that last answer is wrong
by: Tommy

A prescription for a suspension calls for a dose of 250mg to be given twice a day. If the suspension contains 300mg/5ml, how many ml are needed for one dose?

The answer to the question is 4.16ml (or rounded to 4.2ml). the suspension contains 60mg/ml. If you take 250/60 = 4.16ml. The question was how many ml's are needed for ONE DOSE...

Sep 17, 2011
by: Anonymous

rx order 250mg twice daily
so, total amount for a day is 500mg
suspension contains 300mg/5ml
so for one dose would be 500 divided by 300 multiply by 5ml =8.3ml for one dose

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