Calculations II: Compounding Flashcards
What are percents and how is it expressed?
A percent is the number of parts in 100. Percents are often often written as decimals or fractions.
What is percent weight-in-volume (%w/v)?
Percent weight-in-volume (%w/v) is expressed as g/100 mL (a solid mixed into a liquid) and applies to common IV fluids
What is percent volume-in-volume (%v/v)?
Percent volume-in-volume (%v/v) is expressed as mL/100 mL (a liquid mixed into a liquid)
What is percent weight-in-weight (% w/w)?
Percent weight-in-weight (% w/w) is expressed as g/100 g (a solid mixed into a solid)
What is the percentage strength of normal saline?
0.9% (w/v) NaCl in water
What is the percentage strength of 1/2NS?
0.45% (w/v) NaCl in water
What is the percentage strength of 1/4NS?
0.225% (w/v) NaCl in water
What is the percentage strength of D5W?
5% (w/v) dextrose in water
What is the percentage strength of D20W?
20% (w/v) dextrose in water
What is the percentage strength of D5NS?
5% dextrose and 0.9% NaCl in water
What is the percentage strength of D51/2NS?
5% dextrose and 0.45% NaCl in water
What is ratio strength and how is it expressed?
Ratio strength is another way of presenting a percentage strength. It is denoted as one unit of solute contained in the total amount of the solution or mixture
How do you convert from ratio strength to percentage strength?
% strength = 100/ratio strength
How do you convert from percentage strength to ratio strength?
Ratio strength = 100/% strength
What are parts per million (PPM) and parts per billion (PPB) used to express?
Parts per million (PPM) and parts per billion (PPB) are used to express the strength of very dilute solutions
What is the definitions of parts per million and parts per billion?
They are defined as the number of parts of the drug per 1 million (or 1 billion) parts of the whole
*The same designations are used as for percentage strength (%w/w, %w/v and %v/v)
What is the shortcut for converting PPM to percentage strength?
Move the decimal left 4 places
What is the shortcut for converting percentage strength to PPM?
Move the decimal right 4 places
What is specific gravity?
Specific gravity (SG) is the ratio of density of a substance to the density of water
What is the specific gravity of water?
Water has a specific gravity of 1 so 1 g of water = 1 mL of water
What does it mean when SG < 1?
Substances with a SG < 1 are lighter than water
What does it mean when SG > 1?
Substances with SG > 1 are heavier than water
What is the formula to calculate specific gravity?
SG = weight of substance (g)/weight of equal volume of water (g)
SG = g/mL
When would you use the Q1C1 formula?
This formula can be used to change the strength or quantity. Q1C1 is used when the problem deals with two concentrations
*The units on each side must match
What is the Q1C1 formula?
Q1 x C1 = Q2 x C2
- Q1 = old quantity
- C1 = old concentration
- Q2 = new quantity
- C2 = new concentration
When would concentration be 100%?
When a prescription calls for an ingredient that is pure
Why is the concentration of a diluent 0%?
A diluent does not contain any drug so the concentration of the diluent is 0%