This formula is used to calculate the the amount of medication in solution for oral,
intramuscular, intravenous or subcutaneous injection to be administered when given a
dosage, stock dose and volume.
| Required Dose | x | Stock Volume | = Volume to be given |
| Stock Dose | 1 |
N.B. Units for required dose and stock dose must be the same.
Example
A person is ordered 15mg of stemetil. You have 2ml of solution on hand which contains 25 mg
stemetil. What volume of solution would you give?
| 15 mg | x | 2 ml | = | 30 | = 1.2 ml |
| 25 mg | 1 | 25 |
Example
A dose of 75 mg of pethidine has been ordered. It is available in ampoules containing 100 mg in 2 ml. What volume must be administered?
| 75 mg | x | 2 ml | = | 150 | = 1.5 ml |
| 100 mg | 1 | 100 |
| Other Calculations | |||||
| Metric Conversions | Body Mass Index | Tablet Dosages | Fluid Dosages | IV Flow Rates | Dosage by Weight |