Drugs Calculations

Question 1

1% solution contains…

if w/v or weight in volume

Answer 1

1g in 100ml

or 10mg in 1ml) (divided by 100

Question 2

1% contains…

if w/w or weight in weight

Answer 2

1g in 100g

Question 3

1% solution contains…

Answer 3

1g in 100ml

Question 4

1:1000 means…

Answer 4

1g in 1000ml

Question 5

what is 1% of 1:1000

Answer 5

1% x 0.1% = 0.01%

Question 6

how many mg in a g?

Answer 6

1g = 1000mg

Question 7

how many mcg in a mg?

Answer 7

1mg = 1000mcg
(1g = 1000000mcg)

Question 8

what volume of an 80 mg/2 mL solution is required to give a 40 mg dose?

Answer 8

write out the information in this format (making sure the units are the same for both numerators and both denominators):
2mL/80mg = X mL/40mg
rearrange so X is alone
2ml x 40mg/80mg = X
1ml = X

4. If you were asked to calculate the dose rather than the volume, use the same equation, but flip the numbers over on both sides so that X is still the numerator (on top). This will make rearranging the equation to solve X much easier.