Dosage and Calculations

Dosage and CalculationsBy H Williams320 mls of 5% Dextrose in 0.45% Sodium Chloride remains and is being infused at 55 drops/minute.

The drop factor is 15. How long will the infusion take to complete at this rate. Your answer should be rounded off to the nearest whole number.

FORMULA FOR TIME REMAINING

Volume (ml) X drop factor (drops/mL) = time (min/hr) Rate (drops/min)

Place values in formula: = 320 x 15 = 87.272 or 55 = 87mins or 1hr 27mins

1L of 10% Dextrose in water is prescribed over 10 hours.

The drop factor is 10.

What is the drip rate required? Your answer should be rounded off to the nearest whole number

FORMULA FOR DRIP RATE

Volume (ml) X drop factor (drops/ml) Time (min) = drops/minute

First convert the volume to be infused into millilitres: - to convert 1litre to millilitres: move the decimal place.

Work out how many decimal places to be moved by subtracting the conversion factor numerators for example..

1 litre = 10^0

1 millilitre = 10^-3 litre = 0- -3 = 3 move the decimal 3 places to the right

1 litre = 1000 mls

Convert time to minutes: 10 hrs = (10x60) = 600 minutesPlace the values in the formula = 1000 x 10 600= 16.6666 = 17 drops/minutes

125 mgs of Pethidine IM 4 hourly prn is prescribed. On hand you have 100 mg in 2mls. How many millilitres will you administer?FORMULA FOR FLUID DOSAGES

Required dose (what you want) x stock volume Stock dose (what you have) 1= (dosage in mls)

Place the values in formula:

125 mgs x 2mls = 1.25 x 2mls = 2.5mls 100mgs 1

3 milligrams of Haloperidol is prescribed bd. On hand you have 1.5 milligram tablets. How many tablets will you give?

FORMULA FOR TABLETS

Required dose (what you want) x 1 Stock dose (what you have)= number of tablets

Place the values in the formula: 3mgs x 1 1.5mgs= 2tablets