4 Pharmacy Calculations Free Online FlashCards

Why write units throughout a pharmacy calculation?

Write units throughout the calculation so they cancel visibly; this helps reveal conversion and setup errors.

How many milligrams are in $1\text{ g}$?

$1\text{ g}=1{,}000\text{ mg}$.

What is the approximate pound equivalent of $1\text{ kg}$?

$1\text{ kg}$ is approximately $2.2\text{ lb}$.

What is the general setup for calculating an amount to give?

$\text{Amount to give} = \frac{\text{prescribed dose}}{\text{product strength}} \times \text{product quantity}$. Match units before calculating.

What is the concentration of a liquid labeled $125\text{ mg}$ per $5\text{ mL}$?

$125\text{ mg} \div 5\text{ mL}=25\text{ mg/mL}$.

At $15\text{ mg/kg/day}$, what is the daily dose for an $18\text{ kg}$ patient?

$18\text{ kg} \times 15\text{ mg/kg/day}=270\text{ mg/day}$.

How much is each dose if $270\text{ mg/day}$ is divided into three equal doses?

$270\text{ mg/day} \div 3=90\text{ mg/dose}$.

What volume provides $90\text{ mg}$ from a $25\text{ mg/mL}$ liquid?

$90\text{ mg} \div 25\text{ mg/mL}=3.6\text{ mL per dose}$.

What is the key difference between $\text{mg/kg/day}$ and $\text{mg/kg/dose}$?

$\text{mg/kg/day}$ specifies a total daily dose per kilogram; $\text{mg/kg/dose}$ specifies the amount per dose per kilogram.

How many $250\text{ mg}$ tablets provide a $500\text{ mg}$ dose?

$500\text{ mg} \div 250\text{ mg/tablet}=2\text{ tablets}$.

How do you calculate days’ supply for a fixed schedule?

$\text{Days’ supply}=\frac{\text{quantity dispensed}}{\text{quantity used per day}}$.

How long does a quantity of $60$ tablets last at one tablet twice daily?

One tablet twice daily uses $2$ tablets per day; $60\div2=30$ days’ supply.