Calculations

[Da Alchemist]

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I have 2 questions...

1. How many milliliters of active ingredient are contained in a pint of 15% v/v solution?
my answer is 75ml. but my pharmtech exam book says 12ml. can anyone explain to me how it became 12ml?

2. I have this infant tylenol at home.... Infant tylenol 80mg per 0.8 mL. recommended dose is 1.6mL for 24lbs-35 lbs
and for under 24lbs it doesnt say. it says ask a doctor. for a 21 lbs baby....my calculation is around 1.5 dose for 5x day...is this wrong or right? what would be the right dose for 21lbs infant?

 

[Moxxie]

I have 2 questions...

1. How many milliliters of active ingredient are contained in a pint of 15% v/v solution?
my answer is 75ml. but my pharmtech exam book says 12ml. can anyone explain to me how it became 12ml?

2. I have this infant tylenol at home.... Infant tylenol 80mg per 0.8 mL. recommended dose is 1.6mL for 24lbs-35 lbs
and for under 24lbs it doesnt say. it says ask a doctor. for a 21 lbs baby....my calculation is around 1.5 dose for 5x day...is this wrong or right? what would be the right dose for 21lbs infant?

For question 1, I'm pretty sure that you're right, but you're assuming that a pint is 500ml. Some textbooks teach a pint = 473 ml, other that a pint is 480 ml. If you want to be precise with the household system, a pint = 480 ml (one teaspoon = 5ml; 3 tsp in one tablespoon; 16 tablespoons in one cup; 2 cups in a pint).

For question 2, it really depends - infants metabolize things differently (their CYTp450 system is not fully matured), so I think that "ask the doctor" is the right answer. But sdn1977 or someone else probably knows better than me.

 

[Da Alchemist]

ok good because ive been going crazy trying to figure out what im doing wrong. it was from NPTA exam review book by Johnson how can a book be wrong lol. should i get a refund? lol

 

[Farmercyst]

I have 2 questions...

1. How many milliliters of active ingredient are contained in a pint of 15% v/v solution?
my answer is 75ml. but my pharmtech exam book says 12ml. can anyone explain to me how it became 12ml?

2. I have this infant tylenol at home.... Infant tylenol 80mg per 0.8 mL. recommended dose is 1.6mL for 24lbs-35 lbs
and for under 24lbs it doesnt say. it says ask a doctor. for a 21 lbs baby....my calculation is around 1.5 dose for 5x day...is this wrong or right? what would be the right dose for 21lbs infant?

15% = 15 mg/100 mL. 1 pt = 16 oz , 1oz = 30 mL
480 mL/pt. x mg/480mL = 15 /100

100x= 7200

x=72 mL are you sure the 1 is not a 7 (72 instead of 12.)

In terms of the second question, I dare not answer. It's beyond what I'd be willing to give advice on just because pediatric dosages can't be extrapolated from adult dosages and I don't think even from other pediatric doses. (I may be wrong here, which is another reason why I wouldn't say.)

 

[sdn1977]

Yeah....agree with others....check the errata on your book - was it a typo??

As for the acetaminophen question - is this for yourself? Because you know we can't provide medical/pharmaceutical/professional advice - right?

But...lets just say....you're a pharmacist & a pt asked you this question. Why could you not extrapolate the dose by just using mathematical calculations?

The reason is because dosing for infants is dependent not just on body wt, but also body surface area & organ maturation. You could use a nomogram to calculate body surface area based on wt, but if you have an infant who, for any number of reasons, is delayed in organ development....you need to have more information for infant dosing. A premie may catch up by 1yr, 18mo, 2yr...but we don't have enough information - just based on the baby's wt to know they can handle a particular dose.

That's why we ask...what did the pediatrician recommend? If the baby's doctor recommended a particular dose....we go with that. The physician knows the various medical/physiologic reasons why or why not that infant may be able to handle a particular dose. So....the recommendation is to call the pediatrician, altho, most pediatricians have given a recommendation before this time since by the first set of immunizations, they normally recommend a dose of acetaminophen if the baby gets feverish. I always recommend the parent go back to the last recommendation the pediatrician gave then call in the AM for more clarification (pediatricians are very, very good about writing down instructions since most parents don't remember).

I can guarantee that question would never come up on a tech or pharmacist examination - to extrapolate a dose. However...dosing is a very big & difficult issue to learn in neonates & children who have had medical issues - at least for me & I have no end of respect for neonatal pharmacists. I'm not sure we have one on this forum.

However...if this is not theoretical - call your baby's doctor in the AM.

 

[Jeddevil]

I have 2 questions...

1. How many milliliters of active ingredient are contained in a pint of 15% v/v solution?
my answer is 75ml. but my pharmtech exam book says 12ml. can anyone explain to me how it became 12ml?

2. I have this infant tylenol at home.... Infant tylenol 80mg per 0.8 mL. recommended dose is 1.6mL for 24lbs-35 lbs
and for under 24lbs it doesnt say. it says ask a doctor. for a 21 lbs baby....my calculation is around 1.5 dose for 5x day...is this wrong or right? what would be the right dose for 21lbs infant?

1. 72 mL

2. I know it says ask your dr., but you get this question ten times a night at your local Walgreens. People don't want to hear, 'call your dr in the morning'. Many times the dr has already told them to go to your pharmacy and get APAP or benadryl or whatever without giving them dosing. So, IMHO, you need to have the doses available for kids for everything possible.

Ask if the child has any health problems, was a premie, etc. If the answer is no, give the pt a dose. 21 lbs - you can go age based or wgt based, both are similar.

wgt based, kids under 12: 10-15 mg/kg/dose q 4-6 h prn. no more than 5 doses a day. For the 21 lb child with no health conditions, that works out to 95 to 140 mg/dose.

age based: 0-3 mo - 40 mg, 4-11 mo - 80 mg, 1-2 yr - 120 mg, 2-3 yr 160 mg.

ASSUMING the kid is 1 -2 yrs old, and based on both regimens, I would give my kid 1.2 mL.


The big one I get all the time is Benadryl. The pediatrician sends the parent in to get benadryl for their kid and tells them to ask the pharmacist for dosing. It is available out there, so you better have it or you have a pissed off customer saying "the Dr. told me you would give me dosing, do you not know how to do that?"

I got tired of always having to look up dosing for kids so I made up a chart with ped dosing for all the OTC stuff we sell. I have it with me each night at work. All you clinical pharmacists can go ahead and say 'call you dr. in the morning'. People don't want to hear that when their kid needs help now and they were already on the phone calling the ped to find out what to get. Always ask them about their childs health conditions. If they have anything you are worried about, don't give the recommendation. Tell them why you don't want to and parents are usually fine with that answer. But telling them to call their dr when the child is healthy is not the answer for me.

 

[sdn1977]

We just gotta agree to disagree. I don't know of one pediatrician who does not give dosing, even over the phone, including my kids own pediatricians.

Also, having worked with them & had the benefit of having one as a friend (altho not my own kids dr).....the doses can be far, far different than what I might have recommended.

But, parents don't always "hear" - that's why they write stuff down - even on the well-child check.

I may be in an unusual area since I'm between 2 tertiary pedi hospitals, but I've never seen a child leave a physician's office without paperwork which states tylenol, benadryl, etc doses......

But - if you feel comfortable dosing on a nomogram - great. I just wouldn't - I've had to work once in a pediatric hospital & I would never do it again.

 

[Da Alchemist]

SDN, No the infant tylenol was not for me lol. I bought it for my niece but before i bought it I did ask the pharmacist what would be the formula to calculate the dosage for 21 lbs 15 months old. He said it is againts the law to give out advice. then he said he was sorry and and I said Its ok doc. The bottle says "ask a doctor" it is true that pharmacist are doctors also. it didnt say ask a pediatrician. and yea JEDDEVIL 1.2mL is about right, my sister called the pediatrician and they said to give 1.2 mL, I think they say that to every infant under 24lbs. ages 1-2.

 

[Jeddevil]

But - if you feel comfortable dosing on a nomogram - great.

I had three preceptors tell me that things to know for sure or have real close are all peds doses for child without health conditions (because they won't give out doses for kids that parents state have certain conditions) and what can and can't be used for pregnant women. They don't have any problems dosing for peds or telling pregnant women what to use and not to use, and with the same info, I don't either.

It cracks me up that pharmacists all over the profession (not directed at you) want to do all kinds of other crap like give immunizations (normal nurse task - like my time can't be spend doing something better for $50/hr) or do blood pressure screenings, etc. but when it comes down to something that pharmacists should know how to do, and paid thousands of dollars to learn how to do, will so easily say, "sorry, call your dr." Pharmacists all over the place want to get more respect from patients and other health care professionals, but on something that we should be very qualified to do, like give out a safe dose for a healthy child on an OTC product, we want to pass that off to the doc. Sorry, end of rant.

 

[kkelloww]

So, do we open ourselves up to any liability by recommending these doses? The pharmacists at my work refuse to do it also.

 

[Jeddevil]

So, do we open ourselves up to any liability by recommending these doses? The pharmacists at my work refuse to do it also.

You are going to have to do what you feel comfortable with. If I don't feel comfortable giving one out after asking questions about the kid, I don't. We open ourselves up to liability every time we open our mouths to anyone when we represent the pharmacy.

You are in the same part of the country as I am. Some pharmacists here won't do it, some will. Most of the ones I have seen say no are just busy and don't want to be bothered, or to lazy to ask questions about the child.

Personally, I know where to get dosing info from. I have been taught about products on the shelf and am expected to respond to people when they ask me questions about things out on the shelf in the pharmacy. I am paid to do so. If I can provide an answer to something I feel comfortable about, I try to give it to them. If I don't feel comfortable, I can refer them elsewhere, but at least I tried and asked about the problem, instead of just saying '"No, the box says ask a Doctor. I know I like to let everyone know I am a doctor through my PharmD degree, but you really need to go call your real doc. I am afraid to be sued!"