1) Prepare a 1% solution of Brevital (500
mg of powder in bottle). How many mL of sterile water will
you use?
Answer: First convert 1% solution to mg/cc. A 1% solution
is the same as 1000 milligrams in 100 cc or 10mg/cc.
Percent solutions all are 1000mg/100cc. For example a 2%
= 20mg/cc, 5% = 50mg/cc, 5.5% = 55mg/cc, etc...
Now you have all the information needed to use the IV
dosage calculator. This problem is the same
as the doctor ordering a 500 mg IV bag of Brevital: 500
mg = dose ordered, 10mg = dose available, and 1cc = mL available
(the last two values come from 10mg/cc obtained above).
The answer is 50cc.
2) 1.4cc of ½% tetracaine (Pontocaine)
was given in a subarachoid block. How many mg were given?
Answer: First convert ½% to mg/cc. A 0.5% solution
is the same as 500mg/100cc (5mg/cc).
Now you have all the information needed to use the mL/hr
to dose/hr calculator. 1.4 cc = mL given, 5mg = dose available,
and 1cc = mL available. So 7mg of tetracaine were given.
Epinephrine
Solutions
Epinephrine vials are also labeled by concentration of
a ratio of medication per mL. For example, a solution may
be labeled as 1:100,000. This concentration represents 1000mg/100,000mL
or 0.01mg/mL. Here are some others:
CONCENTRATION
DOSAGE
EQUIVALANCE
PERCENT
1:1,000
1mg/mL
0.1%
1:10,000
0.1mg/mL
0.01%
1:100,000
0.01mg/mL
0.001%
1:200,000
0.005mg/mL
0.0005%
Example
How many mg of epinephrine are in 5cc of a
1:10,000 solution?
Answer: First convert 1:10,000 into mg/cc.
1:10,000 = 1000mg/10,000cc = 0.1mg/cc
Next use the IV dose
given calculator. 5cc = mL given, 0.1mg = dosage
available, and 1cc = mL available. The answer is 0.5 mg
of epinephrine were given.
