1. Drug Dose Calculations
{ What you need to know

2. Drug dose calculations
can be tackled using
the following formula:
The Formula

3. WxI
G
The Formula

4. ‘Want’ is the amount of drug
the patient needs
‘In’ is the volume of your
syringe
‘Got’ is the total amount of
drug in your syringe
How it works

5.  Mr Blogs requires 2mg of drug X
Want = 2
 You have a 500ml syringe
In = 500
 There is 10mg of drug X in the
syringe
Got = 10
How it works

6. Want = 2
In = 500 (2 x 500) / 10
Got = 10 = 1000 / 10
= 100
(WxI) / G
Mr Blogs needs
100 ml!
How it works

7. WxI
G

8. Always convert the
units to mg and ml
Managing the Units

9. Sometimes questions give the
concentration of a drug, rather
than an amount and a volume
E.g. you have a syringe with
drug Y at 1.5mg/ml
Managing Concentrations

10. Concentration = 1.5mg/ml
Got = 1.5mg
In = 1ml
Easy as that!
Managing Concentrations

11. Now try it yourself!
Practice!