A question about medication dosages

[Littlepeanurse]

The doctor prescribes acetaminophen and you have to calculate the dosages based on weight. And you find that there's a difference between the prescribed dosage and the dosage that you get when you from the dosage based on body weight calculations. If it was a 3 mg difference, would it be still okay? How high, in terms of dosage difference, can you go before you need to contact the doctor?

[klone, MSN, RN]

Is this a peds patient? How old/what size? Is the ordered dosage higher or lower than the dosage based on weight?

[Littlepeanurse]

It is a peds patient. The child weights 33.5 lbs. The ordered dosage is lower than the dosage based on weight. The practitioner orders 100 mg PO TID but the weight based dosage calculation yields 101.3 mg/dose.

[meanmaryjean, DNP, RN]

You would be hard pressed to measure out 101.3 mg. In the real world, you get it as close as you can relative to the measuring instrument you have at hand. So, if 0.752 mL of a med is ordered, you can only realistically measure to the nearest 100th with a 1 mL syringe.

[edmia, BSN, RN]

You would be hard pressed to measure out 101.3 mg. In the real world you get it as close as you can relative to the measuring instrument you have at hand. So, if 0.752 mL of a med is ordered, you can only realistically measure to the nearest 100th with a 1 mL syringe.[/quote']

Yes. And you have to think that if a drug dosage had to be so exact, then we would have tools that allowed us to measure exactly. And, if a dosage was so exact, would it be safe to not provide it in pre-filled amounts? In real life, you round up or down and to the tool you have. The MD probably did the math and thought, "who's gonna be able measure 101.3? I'll order 100."

Also, it is a 1.3mg difference, not 3.

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[klone, MSN, RN]

Yes, I'm sure the physician ordered 100 because s/he calculated out weight, discovered that the dosage would be 101.3, and knew nobody would be able to measure out that specific amount. Go with 100mg and call it good. That 1.3 mg is not going to make a difference in the efficacy of the med.

[KelRN215, BSN, RN]

It is a peds patient. The child weights 33.5 lbs. The ordered dosage is lower than the dosage based on weight. The practitioner orders 100 mg PO TID but the weight based dosage calculation yields 101.3 mg/dose.

And how do you expect to measure out 101.3 mg? With the way tylenol is supplied (325 mg/5 mL), you're going to have to round with either ordered dose.

Dosing for tylenol is not exact. Think of it- as an adult, you can take as little as one regular strength tablet (325 mg) to as much as 2 extra strength tablets (1000 mg) per dose. A child can receive 10-15 mg/kg/dose up to a max of 75 mg/kg/day. So I'm not sure what formula you're using to calculate this dose but if a child who weighs 15.22 kg is getting 100 mg of tylenol, he's only getting 6.5 mg/kg. It's probably not going to hurt him to give a lower dose but it's also probably not going to do what it's intended to do at that dose. Why is the child on standing tylenol TID rather than q 4-6 hrs PRN as is typical?

How, exactly, was this question worded?