Somebody please....help me solve this!!

Annebelle · Jan 18, 2011

i am going to try to do this step by step. i dont know that my math is an exact formula but it makes sense to me to reason it out. i hope i dont leave anything out and i hope i dont sound too simple either.

1. a child has seizures.

order: phenytoin 124 mg, po, q.d

child's height and weight: 36 in, 45 lb.

bsa is 0.74 m²

pediatric dose parameter: 350 mg/m²/d

drugs avalilabe: dilantin 30 mg/5 ml and 100 mg/5 ml

a. what is the child's body surface area (bsa) in meters squared? it appears this is already figured out for you (0.74m²)

b. what is the dose parameter according to the child's bsa? so it is asking you how many mg of this medicine can the child have since his bsa is 0.74m². take the 0.74m² and multiply it by 350 (the parameter). so you get 259mg/day. (think of the '/' saying per - 350mg 'per' m² 'per' day.

c. is the dose within safe parameters? the dose 'ordered' is 124mg 'per' day (qd means per day to me - not sure where you are from but hopefully it does to you too) is less than the maximum amount the patient is allowed (which means the same as parameter)

d. how many milliliters would you give the child per day? or would you give? since you have two options available, not sure if you can give both - in my hospital it would be available only in one of the dose forms. remember each dosage listed is a different strength (100mg/5ml being much stronger), i know that sounds very simple but when i was learning med math, i would get tripped up by this fact. funny how sometimes the little things are what trips you up.

so going by the first dosage listed (30mg/5ml). i try to simplify it (like a fraction). i have 30 mg in 5 ml, which means each ml has 6mg (6mg/ml or 6mg 'per' ml). i need 124mg, so i take 124 and see how many ml i need by dividing 124 (what i need) by 6 (what i have). another way to look at it is the amount i need is 124, what times 6 will make 124. i come up with 20.67ml. remember each ml contains 6mg. so 20.67ml would make 124mg.

now if i was doing the other dosage listed (100mg/5ml). i would simplify it down to 20mg/ml (20mg 'per' ml). i need 124 mg, so i take 124 and see how many ml i would need by dividing 124 by 20. i come up with 6.2ml. so i would need 6.2ml of this medicine to be able to administer 124mg to this child.

or if you want to mix the doses, 5ml of the stronger med (100mg/5ml) and 4ml (which would give you 24mg) of the weaker one (30mg/5ml). remember simplify it down and then divide the amount you want by the amount you have on hand.

2. a child has pain. order: codeine gr 1.4, po, q4-6h, prn

child's height and weight: 42 in., 50 lb or 0.84 m²

pediatric dose parameter: 100 mg/m²/d

drug available: codeine 15 mg tablets

a. what is the child's body surface area? again this one is given to 0.84m².

b. what is the dose parameter according to the child's bsa? (convert grains to milligrams) ugh - conversions. ok. you need 100mg 'per' each 0.84m² which would be 84mg 'per' day. so we need to turn it into grains. our conversion we were taught was 60mg in 1gr. so we have 84mg and need to see how many grains that would make. so, take 84 divided by 60 and that will tell us how many grains we would have. i came up with 1.4grains per day as the parameter.

c. is the dose within safe dose parameters? explain since the parameter is for 1.4gr 'per' day the order is not a safe dose.

d. how many tablet(s) would lyou give the child per dose? oh my! since this is not a safe dose i wouldnt administer the dose until it was confirmed with the pharmasist and physcian, but just for fun, we can figure it out anyway. now convert back. so 1.4gr is equal to 84mg (thats what we came up with before). we need to figure out how many tablets would equal up to 84 mg. take 84 and divide it by 15. i get 5.6, so i would administer 5 and a half pills (cause you cant really administer exactly 6 tenths of a pill).

i hope my explanations dont make you more confused. :eek:

good luck!

Annebelle · Jan 20, 2011

I received your message but for some reason I can not reply, so I am replying on this thread. The information you gave me doesnt say what the parameters are, so there is no way to know what you should do. I hope that isnt one that you are being tested on. Let me know if you find out more information on the problem.

californiadreaming · Jan 20, 2011

Thanks Annebelle....I got your personal message.