Tablet Dosage Calculations

Most of the examples in this lesson refer to medication provided in tablet form; however, this also applies to other dry oral medications such as pills and capsules.

Examples

These two examples show the dosage ordered, the stock availability, a step-by-step look at the dimensional analysis, and the result. These example emphasize the three major steps in the dimensional analysis.

Ordered:  750 mg of xyz
On Hand:  250 mg tablets

Set up the ratios:
 750 mg x 1 tablet 1 250 mg
Cancel the labels:
 750 x 1 tablet 1 250
Complete the math:
 750 x 1 tablet = 3 tablets 1 250
Result: 3 tablets

Ordered:  150 mg of xyz
On Hand:  100 mg tablets

Set up the ratios:
 150 mg x 1 tablet 1 100 mg
Cancel the labels:
 150 x 1 tablet 1 100
Complete the math:
 150 x 1 tablet = 1.5 tablet 1 100
Result: 11/2 tablets

The preceding examples emphasize the step-by-step procedure for determining how to deliver the prescribed dosage. The form you will actually use is a bit simpler — you don't have to break down each step in a table. Here is an example of how you should actually perform these operations on a pad of paper.

Ordered: 10 mg of xyz.
On Hand: 20 mg tablets

 10 x 1 tablet = 0.5 tablet 1 20

Result: 0.5 or ½ tablet

Tablet Dosage Drill

 Work with this drill routine until you can consistently answer the questions correctly. Be sure to write out the DA sequence You should have no need for a calculator.Click the Answer button to see the correct answer to the question. Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

Real-World Examples

1. You are to administer Dilantin 300 mg PO to a patient. Dilantin is stocked in 100 mg capsules. You will administer _____ capsules.

 300 x 1 capsules = 3 capsules 1 100

Ans: 3 capsules

2. Aspirin tablets are labeled 0.3 gm. How many tablets are needed for a dose of 600 mg?_____

First notice that the units are not the same — one is in grams and the other in milligrams. So change 0.3 gm to 300 mg. (You make the units the same by changing 600 mg to 0.6 gm, but you should always try to work with decimals that are 1 or greater). Then set up the ratios.

 600 x 1 tablet = 2 tablets 1 300

Ans: 2 tablets

3. The doctor has ordered Diabinese tablets 0.25 gm for your patient. You have available Diabinese 100 mg tablets. You will administer _____ tablets to your patient.

Change the 0.25 gm to 250 mg in order to have both units the same.

 250 x 1 tablets = 25 tablets 1 100

Ans: 2½ tablets

4. You are to administer Digoxin 0.375 mg PO to a patient. On hand are 0.25 mg tablets. You will administer _____ tablets.

 0.375 x 1 tablets = 1.5 tablets 1 0.25

Ans: 1.5 or 1½ tablets

Tablet Dosage Word Problems

 Work with this drill routine until you can consistently answer the questions correctly. You should have no need for a calculator.Click the Answer button to see the correct answer to the question. Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.