2 Oral Medication Dosage Calculations Free Online FlashCards

What is the basic formula for an oral medication dose?

Use $\text{amount to give}=(\text{ordered dose}\div\text{dose on hand})\times\text{quantity on hand}$. Match dose units before calculating.

Why must dose units match before calculating?

Convert the ordered dose and product strength to the same unit before dividing; for example, convert grams to milligrams when needed.

An order is $375\text{ mg}$; tablets contain $250\text{ mg}$ each. What does the calculation yield?

The calculation is $375\text{ mg}\div250\text{ mg/tablet}=1.5$ tablets. Give a fractional tablet only if that product can appropriately be split and policy permits it.

Can a capsule be divided to give a fractional capsule dose?

Do not split capsules to obtain a fractional capsule dose. Seek an appropriate strength or formulation, or clarify the order if the calculated dose cannot be given with the available form.

How do you calculate the volume of an oral liquid dose?

Divide the ordered dose by the amount of medicine per milliliter to find the volume. The result is a volume in $\text{mL}$, not a mass.

An order is $0.75\text{ g}$; capsules contain $250\text{ mg}$ each. How many capsules?

Convert $0.75\text{ g}$ to $750\text{ mg}$, then calculate $750\text{ mg}\div250\text{ mg/capsule}=3$ capsules.

When should a calculated dose be rounded?

Keep the full calculated value during the work and round only the final answer, following the stated instructions or local policy.

What common classroom rounding convention applies to oral liquid volumes?

As a common classroom convention, volumes over $1\text{ mL}$ may be rounded to the nearest tenth and volumes under $1\text{ mL}$ to the nearest hundredth. Follow more specific instructions or policy when given.

What decimal notation practices help reduce medication errors?

Use a leading zero for values below one, such as $0.5\text{ mL}$, and omit unnecessary trailing zeros, such as writing $5\text{ mg}$, not $5.0\text{ mg}$.

What should be used to measure an oral liquid dose?

Measure oral liquids with a suitable marked oral dosing device, preferably one marked only in metric units. Do not use kitchen spoons.

What should happen if the calculated dose cannot be given with the available form?

Do not round an impractical result into a different dose. Seek an appropriate strength or formulation, or clarify the order with a pharmacist or prescriber.

An order is $125\text{ mg}$; liquid contains $250\text{ mg}/5\text{ mL}$. What volume is calculated?

$(125\text{ mg}\div250\text{ mg})\times5\text{ mL}=2.5\text{ mL}$.