1. Chapter 10 Oral Dosage of Drugs
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2. Oral Medications Oral medications come in a variety of forms Tablets
Capsules
Liquids
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3. Tablets and Capsules
Supplied in strengths or dosages in which they are commonly prescribed
Only scored tablets are intended to be divided
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4. Three-Step Approach to Dosage Calculations
Step 1: Convert
Ensure that all measurements are in the same system and same size unit; if not, convert before proceeding
Step 2: Think
Estimate what is a reasonable amount of the drug to administer
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5. Three-Step Approach to Dosage Calculations (Continued)
Step 3: Calculate
Apply the formula
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6. Three-Step Approach to Dosage Calculations (Continued)
D represents desired dosage
H represents dosage on hand per a quantity
Both H and Q represent the supply dosage found on the label of the drug available
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7. Three-Step Approach to Dosage Calculations (Continued)
Example
Order: Lopressor 100 mg
Supply: Lopressor 50 mg/tablet
Convert
No conversion necessary
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8. Three-Step Approach to Dosage Calculations (Continued)
Think
You want to give twice the equivalent of each tablet, or 2 tablets per dose
Calculate
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9. Example Example Convert Think Order: Flagyl 0.75 g po tid
Supply: Flagyl 500 mg/tablet
Convert
Conversion is needed
1 g = 1,000 mg, so g = 750 mg
Think
How many tablets per dose should be administered?
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10. Example (Continued) Calculate
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11. Caution
The maximum number of tablets or capsules for a single dose is usually three
Stop, think, and recheck your calculation if a single dose requires more
Question all orders that exceed that amount
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12. Converting to Same System
Preferable to convert to smaller unit
Usually eliminates decimal or fraction, keeping calculation in whole numbers
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13. Apothecary and Household Measurements
Convert to metric equivalents
Metric system is predominant system of measurement for drugs
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14. Converting to Different System
Order:
Codeine sulfate gr ¾ p.o. q.4h p.r.n., pain
Supply:
Codeine sulfate 30 mg per tablet
What do you notice?
Different system
Needs to be converted
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15. Converting to Different System (Continued)
Step 1: Convert
Convert to equivalent units: convert gr to mg
Approximate equivalent: gr i = 60 mg
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16. Converting to Different System (Continued)
Conversion factor is 60
Larger to Smaller (×)
Order: Codeine gr ¾ = 45 mg
Supply: Codeine 30 mg tablets
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17. Converting to Different System (Continued)
Step 2: Think
You estimate that you want to give more than one tablet but less than two tablets
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18. Converting to Different System (Continued)
Step 3: Calculate
Give every 4 hours as needed for pain
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19. Math Tip
When solving dosage problems for drugs supplied in tablets or capsules
Q = one tablet or capsule
Q (quantity) is always one, because the supply dosage is per one tablet or capsule
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20. Remember Do not always rely on a formula
Always estimate what is a reasonable amount of the drug to be administered
This helps to identify if the dosages calculated are reasonable and sound
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21. Remember
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