Essential Nursing Drug Dosage Guide – Quick & Easy
1. Basic Drug Calculation Formulas
Formula 1: Dose = (Desired Dose / Available Dose) × Volume
Example: A patient needs 500 mg of a drug, but you have 250 mg tablets.
Calculation: (500 mg ÷ 250 mg) × 1 tablet = 2 tablets
Formula 2: IV Flow Rate (mL/hour) = Total Volume (mL) ÷ Time (hours)
Example: A 1,000 mL IV fluid must run over 8 hours.
Calculation: 1,000 mL ÷ 8 hr = 125 mL/hr
2. Common Medication Errors & How to Avoid Them
❌ Giving the wrong dose → Always double-check calculations.
❌ Misreading abbreviations → Avoid using "U" for units (can be confused
with 0).
❌ Mixing incompatible drugs → Use hospital reference guides.
3. IV Fluid Calculations (With Examples)
Example 1: A doctor prescribes 2 L of saline over 24 hours. How many drops
per minute (gtt/min) if the set delivers 20 gtt/mL?
Calculation: (2,000 mL ÷ 24 hr ÷ 60 min) × 20 gtt/mL = 28 gtt/min
Example 2: A patient requires 40 mg of a drug diluted in 100 mL saline over
30 minutes. What is the pump rate in mL/hr?
Calculation: 100 mL ÷ 0.5 hr = 200 mL/hr
1. Basic Drug Calculation Formulas
Formula 1: Dose = (Desired Dose / Available Dose) × Volume
Example: A patient needs 500 mg of a drug, but you have 250 mg tablets.
Calculation: (500 mg ÷ 250 mg) × 1 tablet = 2 tablets
Formula 2: IV Flow Rate (mL/hour) = Total Volume (mL) ÷ Time (hours)
Example: A 1,000 mL IV fluid must run over 8 hours.
Calculation: 1,000 mL ÷ 8 hr = 125 mL/hr
2. Common Medication Errors & How to Avoid Them
❌ Giving the wrong dose → Always double-check calculations.
❌ Misreading abbreviations → Avoid using "U" for units (can be confused
with 0).
❌ Mixing incompatible drugs → Use hospital reference guides.
3. IV Fluid Calculations (With Examples)
Example 1: A doctor prescribes 2 L of saline over 24 hours. How many drops
per minute (gtt/min) if the set delivers 20 gtt/mL?
Calculation: (2,000 mL ÷ 24 hr ÷ 60 min) × 20 gtt/mL = 28 gtt/min
Example 2: A patient requires 40 mg of a drug diluted in 100 mL saline over
30 minutes. What is the pump rate in mL/hr?
Calculation: 100 mL ÷ 0.5 hr = 200 mL/hr
