## Universal Formula

**(Toney-Butler, 2021)**

In the universal formula (or “desired over have method”), the ** desired amount (D)** is the dose prescribed and the

**or the amount you “have” is the available dose or concentration.**

__amount on hand (H)__**is the form and amount in which the drug is supplied (i.e. tablet, capsule, liquid). To calculate the dose, take the desired amount and divide it by the amount on hand, then multiply it by the quantity like this,**

__The quantity (Q)__**D/H×Q=Dose**. Here is the dose calculator based on this universal formula.

__For Example:__

Cephalexin 750 mg P.O. every 12 hours is ordered. The pharmacy stocks 250 mg tablets. How many tablets should be administered per dose?

D=750, H=250, Q=1

750/250×1 = 3Tablets

__General Tips:__

__General Tips:__

- Check that your answer makes sense clinically.
- Triple check your work.
- Have a colleague or pharmacist check your work.
- Know general therapeutic drug doses for commonly administered medications.

Jesus Marks