Transcript Drug Calculations

Drug Calculations
25 grams
100
ml
25 g/ 100 ml
75 grams
100
ml
75 g/ 100 ml
Dosage
Volume
Concentration
25 grams
100
ml
25 g/ 100 ml
75 grams
100
ml
75 g/ 100 ml
Dosage
25 grams
Volume
Concentration
100 ml
25 g/ 100 ml
75 grams
100 ml
75 g/ 100 ml
FORMULAS
• Dosage = Volume X Concentration
D=VxC
• Volume = Concentration / Dosage
V=D/C
GET THE CORRECT UNITS
And,
THE REST IS EASY
25 grams
100 ml
25 g/ 100 ml
Which represents the DOSAGE?
Which represents the VOLUME?
Which represents the CONCENTRATION?
DOSAGE
Dosage may be given in grams, or milligrams.
To work problem, dosage must be converted into milligrams,
1g
= 1000
mg = 1 g
2 g = 2000 mg
10 g = 10000 mg
Decimal point moves 3 places to the right when converting grams to milligrams
VOLUME
Volume needs to be converted to milliliters, ml.
Fortunately, it is normally presented in milliliters
25 mg
500 ml
DOSAGE
Convert to milligrams if necessary
25 grams = 25000 mg
VOLUME
Convert to milliliters if necessary,
.5 Liters = 500 ml
CONCENTRATION
Concentration can be presented in a variety of ways; often time as
a % solution.
x% means x grams per 100ml
25% means 25 grams per 100 ml
Or, 25 g/100 ml
5% means 5 grams per 100 ml
Or, 5 g/100 ml
12 g / 100 ml
Is a 12% solution
Dosage
25 grams
Volume
Concentration
100 ml
25 g/ 100 ml
A 25% solution
75 grams
100 ml
75 g/ 100 ml
A 75% solution
A 2% solution means 2 grams / 100 ml
CONCENTRATION
• Concentration must to be converted to
X mg per 1 ml
X mg/1 ml
CONCENTRATION
A 25% solution means 25 grams per 100 ml
Concentration must be in mg/1 ml, are we there?
25 grams = 25000 mg, 25000mg/100 ml, are we there?
25000mg/100ml = 250mg/1ml, are we there?
25 g
100 ml
250mg / 1ml
INDEX CARD
• Dosage is grams or milligrams; must be mg
• Volume is in milliliters
• Concentration must be in x mg/1ml
• D=VxC
• V=D/C
• % means g/100 ml
• CONCENTRATION CONVERSION
– g to mg, 3 places to right
– 100 ml to 1 ml, 2 places to left
• LETS PRACTICE CONCENTRATION CONVERSION….
Drug Calculation
• Albuterol is a 0.5 % solution
• You are giving a patient 2 ml of this
solution
• What dosage of the medication the
patient is receiving?
Drug Calculation
• Albuterol is a 0.5% solution
• CONCENTRATION
• You are giving a patient 2 ml of this
solution
• VOLUME
• What DOSAGE of the medication the
patient is receiving?
• We are solving for DOSAGE
• Dosage = Volume X Concentration
D=VxC
• V = 2 ml
• C = 0.5 % = 0.5 g/100 ml
–What units do we need?
•
•
•
•
•
0.5 g needs to be converted to mg
0.5 g = 500 mg (correct unit)
500mg / 100 ml
100 ml need to be converted to 1 ml
5mg/1 ml
GET THE CORRECT
UNITS
And,
THE REST IS EASY
Dosage = Volume X Concentration
D= ?
V = 2 ml
C = 5mg/1 ml
D=VxC
Dosage = 2 ml x 5 mg/ml = 10 mg