Drug Calculations

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Methods of Calculating Doses

1. Standard Formula for calculating the amount of medication to prepare is based on the DSQ formula:
   • $\frac{\text{Desired Dose}}{\text{Stock Amount}}\times \text{Quantity}=\text{Amount to deliver}$
2. Pediatric Formulas
   • Clark’s Rule: $\frac{\text{Weight (lbs)}}{150}\times \text{Adult Dose}$
   • Fried’s Rule: $\frac{\text{Age (mos.)}}{150}\times \text{Adult Dose}$
   • Young’s Rule: $\frac{\text{Age (yrs.)}}{\text{Age (yrs.)}+12}\times \text{Adult Dose}$
3. IV Rate Formula:
   • $\text{Drop Rate}=\frac{\text{Volume to Infuse}}{\text{Hours to Infuse}}\times \frac{\text{Drop Factor}}{60}$
   • If the value given is already in mL per hour, replace the first fraction with it: $\text{cc}/\text{hr}\times \frac{\text{Drop Factor}}{60}$
   • “Macro” tubing = 20 gtts/mL
   • “Micro” tubing = 60 µgtts/mL
   • “Soluset” tubing = 60 µgtts/mL
4. Variable Dosing is used for some orders that specify an amount of medication based on the patient’s weight, body surface area, or other parameter. Most of the time, the dose is obtained through multiplication, e.g., 12 mg/kg/hr for a 65 kilogram body weight patient will require 12 × 65 = 780 mg/hr. Calculate it as usual from there on.
5. Sliding Scale Dosing is a special tool for determining the appropriate amount of insulin to deliver based on the client’s blood sugar reading.

CBG Reading	Sample Dosage
180-220 mg/dL	4U
221-250 mg/dL	6U
251-300 mg/dL	8U
>300 mg/dL	10U