[Medical | Nursing | Dosage] This formula uses the desired dosage amount and amount of the drug on hand to calculate the amount of dosage that should be administered to a patient. It reports in number of those units which is typically number of tablets or capsules.

Variables:

• `X` = Amount to be administered 
• `D` = Desired dose
• `H` = Amount of drug on hand
• `Q` = Quantity of drug on hand

Equation:

`X = D/H * Q`

Author: JustinLiller

Notes

Example:

We have 100 mg of a drug to administer to a patient.  So, the desired dose (D) is 100 mg

There are 25 mg of the drug in each tablet so Amount/ Quantity (H/Q is 25 mg / tablet.  This is the same a the amount on hand (H) being 25 mg while the quantity (Q) is 1 tablet.

So, in this example X = Q * D / H

                                   `X = 1 "tablet" * (50 mg) / (25 mg)`

                                   `X = 1 "tablet" * (50 mg) / (25 mg)`

                                   `X = 1 "tablet" * 50/ 25`

                                   `X = 1 "tablet" * 2`

                                   `X = 2 "tablet"`