Medications management

You can also get Nanograms which comes after Micrograms, so would be multiplied by 1000 to go from MCG, to go from Nanogram to MCG you would divide by 1000

e.g. 0.145mg to microgram (mcg) you could X by 1000, or move 3 decimal places down to get 145mcg.

NHS drug calculations for tablets:

What you Need divided by what you Have timed by Solution

The solution for tablets will always be 1.

Calculations for injections/solution:

You divide how many Mg  by how many mL

e.g. 40mg/20ml is 40 divided by 20 gives you 2mg/ml

You can also use the NHS version Need divided by what you Have timed by Solution 

e.g. a drug come is 20mmol in 5 ml, 10 ml has been prescribed- how many ml... so:

10 divided by 20 times 5 = 2.5 ml

When calculating an hourly infusion rate you need to:

Divide the fluid needed in mL by the amount of time needed to deliver

e.g. 1000 ml needed delivering over 10 hours so..

1000 divided by 10 = 100ml/ per hour.

Sometimes the amount neededs to be rounded to the nearest decimal place 

e.g. 1L needs delivering over 6 hours so...

1000ml divided by 6 = 166.6 would be 166.7ml/ per hour

If you need to work out the infusion rate per minute you times the time by 60 and divide this by the volume. Round this up to the nearest decimal place so...

1) Times the time by 60 ...............6 X 60 = 360

2) Divide the volume by 360 ............1000 divided by 360 = 2.77 round this to the nearest decimal place 2.8 ml/min

You need to times the quantity of drug by the weight of the patient e.g.

patient weight 68kg, your patient is prescribed 30mg/kg so..

68 X 30 = 2040mg

If you need to calculate how much to give in doses

e.g. if the patient needs it in 4 doses you divide the amount by 4 so..

2040 divided by 4= 510mg each dose

To calculate the drop rate you:

Drop factor (giving set) X the volume (mL) divided by the time X 60 = drop rate. 

This must be rounded up to the nearest whole number 

example: patient needs 1000ml infulsed over 12 hours. Drop factor (giving set) is 15 gtt/ml.   So..

1) Times the time by 60

12 X 60= 720

2) Divide the volume by the 720

1000/ 720 = 1.38

3) Times the drop factor by 1.38

15 X 1.38 = 20.7 

Round to the nearest whole number = 21 drops/ min