W22 Pharmaceutical calculations

Question 1

A patient requires 1400mg of a medicine. You have a 400mg/5mL solution in stock. How many millilitres of medicine should
be given?

Answer 1

17.5mL

What you want (mass)/ What you have (mass) X Volume it is in

Question 2

100 nanograms to kilograms

Answer 2

1x10^-10
nanograms/1000 (micrograms)/1000 (milligrams)/1000 (grams)/1000 (kilograms)

Question 3

What is Calpol 120mg/5ml expressed as %w/v?

Answer 3

w/v= g/100ml
2400mg/100ml
2.4g/100ml
= 2.4%

Ratio: 2.4 in 100 so 24:1000
(can’t express ratios in decimals)

Question 4

What is Calpol 250mg/5ml expressed as %w/v?

Answer 4

5000mg/100ml
5g/100ml
=5%

Ratio: 5 in 100ml so 50:1000

Question 5

How many millilitres of a 2% w/v stock solution is needed to make 200 mL of a 1% w/v solution?

Answer 5

C1V1=C2V2
2x?=200x1
=100ml

Question 6

How many millilitres of diluent would you need to make 200ml of a 2% w/v solution from a 5% w/v stock solution?

Answer 6

C1V1=C2V2
200x2=?x5
80mL stock and 120mL diluent

Question 7

You need to make 10 ml of a 1% w/v solution for administration to a patient. How many millilitres of a 2.5% w/v stock solution would be required?

Answer 7

2.5% xV1 = 1% x10mL
V1=4mL