dosage questions

KelRN215, BSN, RN · Jan 15, 2014

#1
1 gram of cefoxin sodium in 50 ml of D5W is to infuse over 30 minutes.
At what ate will you set the IV infusion pump?
#2
An adult weighs 162 pounds (73.63 kg)
The doctor orders Rocephin 25 mg/kg
How many milligrams will you administer?
Thanks for the help fellow nurses....I'm a nursing student

#1. You have 50 mL to infuse in 30 min. So what is the rate in mL/hr? This is a very easy problem that can be done in your head.

#2. You know the patient's weight in kg and you know the dose for weight, so what do you do to figure out the appropriate dose? Right, multiply.

Guests · Jan 19, 2014

Seriously?..ok then what is it because I am damn sure it is. Unit of mass is grams and the unit of volume is ml and also 1 gram of water is equivalent to 1 ml..this is just a basic conversation in chemistry. Exceptions to basic conversion is when you are only given the conversion in the question yu want to solve..correct me if I am wrong, I am still a pre-nursing student but I am damn sure am right

As a graduate of engineering, chemistry, and nursing... and tutor of each... I am damn sure you are not right.

In fact, you are very confused and you should withhold comment on such questions because your confusion will simply confuse other people who are shaky on their fundamentals.

Guests · Jan 19, 2014

#1
1 gram of cefoxin sodium in 50 ml of D5W is to infuse over 30 minutes.
At what rate will you set the IV infusion pump?

First, do you understand what the word "rate" means?

It means something is changing as a function of something else... (this) per (that).

In this context, the rate is referring to the (change in volume) per (change in time). The mass (1 gram) doesn't matter in this question...

"per" simply denotes a division problem... (change in volume) per (change in time) == (change in volume) / (change in time)

The minute-rate is simply the change in volume (50 mL) divided by the change in time (30 min)...

[TABLE=width: 153]

[TR]

[TD=align: center]50 mL[/TD]

[TD][/TD]

[TD=align: center]mL[/TD]

[/TR]

[TR]

[TD=align: center]-------[/TD]

[TD][/TD]

[TD=align: center]=[/TD]

[TD][/TD]

[TD=align: center]1.7[/TD]

[TD][/TD]

[TD=align: center]---

[/TD]

[/TR]

[TR]

[TD=align: center]30 min[/TD]

[TD][/TD]

[TD=align: center]min

[/TD]

[/TR]

[/TABLE]

However, pumps aren't generally set in minute-rate, but rather hour-rate...

so, instead of per 30 min, you need to have per 1/2 hr...

[TABLE=width: 145]

[TR]

[TD=align: center]50 mL[/TD]

[TD][/TD]

[TD=align: center]mL[/TD]

[/TR]

[TR]

[TD=align: center]-------[/TD]

[TD][/TD]

[TD=align: center]=[/TD]

[TD][/TD]

[TD=align: center]100[/TD]

[TD][/TD]

[TD=align: center]----[/TD]

[/TR]

[TR]

[TD=align: center]1/2 hr[/TD]

[TD][/TD]

[TD=align: center]hr[/TD]

[/TR]

[/TABLE]

#2
An adult weighs 162 pounds (73.63 kg)
The doctor orders Rocephin 25 mg/kg
How many milligrams will you administer?

Start by thinking about it this way...

How many milligrams of Rocephin would be given to a 1 kg person? 25 mg per 1 kg... so 25 mg, right?

Well, what if it was a 2 kg person? Just double it, right? 50 mg???

What if it was a 10 kg patient? just multiply it by 10... 250 mg

You're just multiplying the patient's weight (mass) by the dosage (25 mg per 1kg)

[TABLE=width: 205]

[TR]

[TD][/TD]

[TD=align: center]25 mg[/TD]

[TD][/TD]

[/TR]

[TR]

[TD=align: center]73.6 kg[/TD]

[TD=align: center]x[/TD]

[TD=align: center]-------[/TD]

[TD][/TD]

[TD=align: center]=[/TD]

[TD][/TD]

[TD=align: right]1840[/TD]

[TD][/TD]

[TD=align: center]mg[/TD]

[/TR]

[TR]

[TD][/TD]

[TD=align: center]1 kg[/TD]

[TD][/TD]

[/TR]

[/TABLE]

You can also think about this in terms of a ratio...

In English: 25 mg of Rocephin is to 1 kg of patient weight AS (how many mg of Rocephin) is to 73.6 kg of patient weight

In maths:

[TABLE=width: 115]

[TR]

[TD=align: center]25 mg

[/TD]

[TD][/TD]

[TD=align: center]D

[/TD]

[/TR]

[TR]

[TD=align: center]-------

[/TD]

[TD=align: center]=[/TD]

[TD=align: center]-------

[/TD]

[/TR]

[TR]

[TD=align: center]1 kg

[/TD]

[TD][/TD]

[TD=align: center]73.6 kg

[/TD]

[/TR]

[/TABLE]

Now, solve for D algebraically... multiply both sides by 73.6 kg...

[TABLE=width: 253]

[TR]

[TD][/TD]

[TD=align: center]25 mg

[/TD]

[TD][/TD]

[TD=align: center]D

[/TD]

[TD][/TD]

[/TR]

[TR]

[TD=align: center]73.6 kg[/TD]

[TD=align: center]x[/TD]

[TD=align: center]-------[/TD]

[TD=align: center]=[/TD]

[TD=align: center]-------

[/TD]

[TD=align: center]x[/TD]

[TD=align: center]73.6 kg[/TD]

[/TR]

[TR]

[TD][/TD]

[TD=align: center]1 kg[/TD]

[TD][/TD]

[TD=align: center]73.6 kg

[/TD]

[TD][/TD]

[/TR]

[/TABLE]

Rearranging...

[TABLE=width: 253]

[TR]

[TD][/TD]

[TD=align: center]25 mg[/TD]

[TD][/TD]

[TD=align: center]73.6 kg[/TD]

[/TR]

[TR]

[TD=align: center]73.6 kg[/TD]

[TD=align: center]x[/TD]

[TD=align: center]-------[/TD]

[TD=align: center]=[/TD]

[TD=align: center]D

[/TD]

[TD=align: center]x[/TD]

[TD=align: center]-------[/TD]

[/TR]

[TR]

[TD][/TD]

[TD=align: center]1 kg[/TD]

[TD][/TD]

[TD=align: center]73.6 kg[/TD]

[/TR]

[/TABLE]

[TABLE=width: 218]

[TR]

[TD][/TD]

[TD=align: center]25 mg[/TD]

[TD][/TD]

[/TR]

[TR]

[TD=align: center]73.6 kg[/TD]

[TD=align: center]x[/TD]

[TD=align: center]-------[/TD]

[TD=align: center]=[/TD]

[TD=align: center]D[/TD]

[TD=align: center]x[/TD]

[TD=align: center]1[/TD]

[/TR]

[TR]

[TD][/TD]

[TD=align: center]1 kg[/TD]

[TD][/TD]

[/TR]

[/TABLE]

or just...

[TABLE=width: 177]

[TR]

[TD][/TD]

[TD=align: center]mg[/TD]

[TD][/TD]

[/TR]

[TR]

[TD=align: center]73.6 kg[/TD]

[TD=align: center]x[/TD]

[TD=align: center]25[/TD]

[TD=align: center]----[/TD]

[TD=align: center]=[/TD]

[TD=align: center]D[/TD]

[/TR]

[TR]

[TD][/TD]

[TD=align: center]kg[/TD]

[TD][/TD]

[/TR]

[/TABLE]

[TABLE=width: 128]

[TR]

[TD=class: xl24, width: 33, colspan: 2, align: center]or...[/TD]

[TD=class: xl24, width: 21, align: center]D[/TD]

[TD=class: xl24, width: 16, align: center]=[/TD]

[TD=class: xl24, width: 34, align: center]1840[/TD]

[TD=class: xl24, width: 24, align: center]mg[/TD]

[/TR]

[/TABLE]