medication dosage question

RN BSN 2009 · Oct 4, 2007

MD order:Aminophylline 15cc/hr continuous infusion. Solution is 275mg in 250cc solution. The recommended dose is 0.3-0.5mg/kg/hr. The pt weighs 45kg. how many mg will the pt receive in an hour (mg/hr) Is the MD infusion safe and therapeutic?
MD order is for Aminophylline 45mg/hr. the concentration is 500mg in 250mls. The patient weighs 64kg. The recommended dose is 0.7-0.8mg/kg/hr. Is the MD dose safe/therapeutic? At what IV rate would you set this IV medication?

15 ml / hr

275 mg / 250 ml : x mg / 15 ml

250x = 275 x 15

4125/250 =

x = 16.5 mg

0.3 mg x 45 kg = 13.5 (low dose)

0.5 mg x 45 kg = 22.5 (high dose)

Yes it is safe, and yes it is therapeutic (between low & high dose window.)

45 mg / hr

64 kg patient

500 mg / 200 ml : 45 mg / x ml

500x = 200 x 45

9000/500 =

x = 18 ml, so 18 ml/hr

0.7 mg x 64 kg = 44.8 (low dose)

0.8 mg x 64 kg = 51.2 (high dose)

Yes it is safe, yes it is therapeutic.

tequilaseay13 · Oct 4, 2007

QUESTION: how do you justify the answer with the second problem I don't understand how you get the anwer.

RN BSN 2009 · Oct 4, 2007

QUESTION: how do you justify the answer with the second problem I don't understand how you get the anwer.

I multiplied the dose ranges by the patient's weight to get minimum and the maximum dosages.

The patient's dose is 45 mg/hr, so, since the minimum dose is 44.8 mg and the maximum dose is 51.2 mg, the dose *is* therapeutic because it is between the min. and max.

If your patient was recieving, let's say, 41 mg/hr, then the dose would be safe, but not neccesarily therapeutic (per manufacturers instructions).

On the other hand, if the patient was ordered 200 mg, that is much higher than the maximum dose. Unsafe? More than likely. Therapeutic? No.

nservice · Oct 4, 2007

I got a different infusion rate for the second question. 22.5 cc/hr. The concentration if 500 mg in 250 ml (not 200 ml). This is still safe and therapeutic.

RN BSN 2009 · Oct 4, 2007

I got a different infusion rate for the second question. 22.5 cc/hr. The concentration if 500 mg in 250 ml (not 200 ml). This is still safe and therapeutic.

Oops, Sorry, I should have double checked that! I think it's time to go to bed lol

Daytonite, BSN, RN · Oct 4, 2007

Here is how these problems are worked by dimensional analysis:

Aminophylline 15cc/hr continuous infusion. Solution is 275mg in 250cc solution. The recommended dose is 0.3-0.5mg/kg/hr. The pt weighs 45kg. how many mg will the pt receive in an hour (mg/hr) Is the MD infusion safe and therapeutic?

How many mg will the patient receive in an hour?

15 cc/1 hour

(dose patient is receiving)

x 275 mg/250 cc

(dose on hand)

=

16.5 mg/1 hour

(amount patient is receiving per hour)

Is the infusion rate safe and therapeutic?

To determine this you need to determine what the recommended therapeutic dose would be for a patient who weighs 45kg (this patients weight) using the parameters 0.3-0.5mg/kg/hr. So, you need to calculate the dose for 0.3mg/45kg/hr and the dose for 0.5mg/45kg/hr.

For 0.3mg/kg/hr for a 45 kg patient

:

0.3 mg/1 kg (low acceptable dose desired) x 45 kg/1 hour (patient's weight) = 13.5 mg/hour

For 0.5mg/kg/hr for a 45 kg patient

:

0.5 mg/1 kg (high acceptable dose desired) x 45 kg/1 hour (patient's weight) = 22.5 mg/hour

What these answers mean is that for a patient that weighs 45 kg, the acceptable and therapeutic dose range would be between 13.5 and 22.5 mg/hour. To determine if the infusion rate is safe and therapeutic you need to compare the dose that the doctor has ordered (you calculated this in the first part of the question: 16.5 mg/hour) with this therapeutic dose range for a 45 kg patient you just determined: 13.5 and 22.5 mg/hour. Is 16.5 mg/hour within the range of 13.5 and 22.5 mg/hour? Yes. So, the answer is

yes, the infusion rate is safe and therapeutic

.

MD order is for Aminophylline 45mg/hr. the concentration is 500mg in 250mls. The patient weighs 64kg. The recommended dose is 0.7-0.8mg/kg/hr. Is the MD dose safe/therapeutic? At what IV rate would you set this IV medication?

Is the MD dose safe/therapeutic?

This problem is already giving you the dose ordered of 45 mg/hour. You are going to do the same thing to determine the parameters of the recommended safe therapeutic dose based upon the patients weight of 64 kg.

For 0.7 mg/kg/hour for a 64 kg patient:

0.7 mg/1 kg x 64 kg/1 hour = 44.8 mg/hour

For 0.8 mg/kg/hour for a 64 kg patient:

0.8 mg/1 kg x 64 kg/1 hour = 51.2 mg/hour

What these answers mean is that for a patient that weighs 64 kg, the acceptable and therapeutic dose range would be between 44.8 and 51.2 mg/hour. To determine if the infusion rate is safe and therapeutic you need to compare the dose that the doctor has ordered: 45 mg/hour, with this therapeutic dose range for a 64 kg patient you just determined: 44.8 and 51.2 mg/hour. Is 45 mg/hour within the range of 44.8 and 51.2 mg/hour? Yes. So, the answer is

yes, the infusion rate is safe and therapeutic

.

At what IV rate would you set this IV medication?

45 mg/1 hour

(dose desired)

x 250 mL/500 mg

(dose on hand)

= 22.5 mL/hour =

23 mL/hour

(rounded off - most IV pumps cannot be programmed to decimal places and a whole number must be programmed into them.)

godsgrl444 · Sep 23, 2008

15 ml / hr
275 mg / 250 ml : x mg / 15 ml
250x = 275 x 15
4125/250 =
x = 16.5 mg
0.3 mg x 45 kg = 13.5 (low dose)
0.5 mg x 45 kg = 22.5 (high dose)
Yes it is safe, and yes it is therapeutic (between low & high dose window.)
45 mg / hr
64 kg patient
500 mg / 200 ml : 45 mg / x ml
500x = 200 x 45
9000/500 =
x = 18 ml, so 18 ml/hr
0.7 mg x 64 kg = 44.8 (low dose)
0.8 mg x 64 kg = 51.2 (high dose)
Yes it is safe, yes it is therapeutic.

I am kind of confused by this problem because isn`t (22.5 ml) less than the min-44.8 and the max-51.2 ? Isn`t that sub theraputic? but safe? Thank you for the help on advance

Daytonite, BSN, RN · Sep 23, 2008

i am kind of confused by this problem because isn`t (22.5 ml) less than the min-44.8 and the max-51.2 ? isn`t that sub theraputic? but safe? thank you for the help on advance

the questions asked were "is the md dose safe/therapeutic?" yes, it is. at what iv rate would you set this iv medication?" 45 mg/hour

look at the calculations again. are you confusing mls with mgs?

godsgrl444 · Sep 23, 2008

the questions asked were "is the md dose safe/therapeutic?" yes, it is. at what iv rate would you set this iv medication?" 45 mg/hour
look at the calculations again. are you confusing mls with mgs?

your right !! that must be what i am dooing on my medication dosage exams also.

godsgrl444 · Sep 23, 2008

Hello everyone

I have a question for you about the math calculation exam. ( I guess your probually saying ok whats new,lol). Is there a way to check your answers for both IV problems and oral medications problems? Also I have been trying to use all the ways available but is getting myself more confused. Can anyone tell me what is the best method for doing medication dosage problems? Especially for people like me who freaks out everytime they attemp to do the 40 minute timed exam? Thank you in advance for helping someone who is not having an easy time teaching their self how to master the medication dosage problems.