3 Injectable Medication Dosage Calculations Free Online FlashCards

How do you calculate an injectable medication volume?

Divide the ordered dose by the concentration per milliliter: $\text{volume (mL)} = \frac{\text{ordered dose}}{\text{concentration (dose per mL)}}$.

What must you do if the ordered dose and concentration use different units?

Convert the ordered dose so it uses the same units as the concentration before dividing.

A label says 150 mg in 3 mL. What is the concentration per mL?

$150\text{ mg} \div 3\text{ mL} = 50\text{ mg/mL}$. The concentration is $50\text{ mg/mL}$, not $150\text{ mg/mL}$.

What volume provides 30 mg from a 40 mg/mL solution?

$30\text{ mg} \div 40\text{ mg/mL} = 0.75\text{ mL}$.

What volume provides 75 mg from a label stating 150 mg in 3 mL?

First, $150\text{ mg} \div 3\text{ mL} = 50\text{ mg/mL}$. Then, $75\text{ mg} \div 50\text{ mg/mL} = 1.5\text{ mL}$.

What volume provides 0.2 g from a 100 mg/mL solution?

$0.2\text{ g} = 200\text{ mg}$. Then $200\text{ mg} \div 100\text{ mg/mL} = 2\text{ mL}$.

What volume provides 45 mg from a 30 mg/mL vial?

$45\text{ mg} \div 30\text{ mg/mL} = 1.5\text{ mL}$.

Which concentration should you use after reconstituting a powder?

A label gives the final concentration to use. Do not assume the added diluent volume is the same as the final solution volume.

How should injectable volumes below 1 mL be written?

Use a leading zero, such as $0.5\text{ mL}$, and avoid a trailing zero: write $1\text{ mL}$, not $1.0\text{ mL}$.

When should you round a calculated medication volume?

Round only as directed by applicable instructions and the measuring device.

How should leftover contents of a single-use ampule be handled?

Calculate the amount needed, but do not save leftover contents for later use or for another patient.

What equipment practice helps prevent unsafe injections?

Prepare injections aseptically with sterile equipment. Never reuse a syringe or needle.