1. Medication Calculations
Introduction to clinical calculations using DA

2. Calculating dosages Three steps:
1. Determine whether drug dosage desired (written order) is in the same measurement system as the drug dosage available. If not, convert between two systems.
2. Simplify by reducing to lowest terms whenever possible.
3. Calculate dosage quantity to be administered.

3. Conversion between systems
1. Convert to the unit used on the container or bottle so your answer is in the system of the drug to be dispensed.
E.g. label is mg, order is grains, conversion from grains to mg.

4. Conversion between systems
Several methods may be used to convert from one system to another
fractions, ratios or proportions or desired over available methods.
Most conversions can be done using proportion or D/A

5. Calculate dosage quantity to be administered
Three general methods for calculating drug doses:
Basic fraction method
ratio and proportion.
D/A x Q
Select one method and use that consistently.
Focus on D/A x Q

6. DESIRED over AVAILABLE or HAVE
Method combines conversion and computation into one step.
Desired units X conversion factor X quantity available
Desired (caps, tabs)
Have available (caps, tabs) = Q (quantity given)

7. Desired over available method
Ordered: gr
Available: 300 mg tablets

8. Desired over available method
Step 1 Set up and Convert to same equivalance
10 gr x 60 mg x 1 tab = ?
1 gr mg
Step 2 solve
10 x 60 x = = 2 tablets
Give two 300 mg tablets

9. Steps to convert one unit to another with unit equivalence
Canceling unwanted units
Identify the desired unit dimension or units
Keep desired unit dimension in proper numerator/denominator orientation.
Identify link or unit equivalence
Identify unwanted dimension or units
Cancel unwanted units
Perform arithmetic

10. Choice of methods
Fraction or ratio/proportion or desired over available
All use same information and same format for solving problems.
All do same thing.
Always use method for drug calculations that makes most sense and is closest conversion to what you want to give.

11. Calculating oral doses
Capsules, tablets or liquids
Need to calculate proper drug dosage when using open stock or an individual dose
(not in unit dose system)
Use when drug available is
in a smaller dose than that ordered.
In a larger dose than that ordered.
In a different unit of measure than that ordered.

12. Calculations
Prepare a 0.6 g dose.
Available 500 mg / 5 ml

13. ASSIGNMENTS
DO WORKSHEETS- Administration of oral medications