Dosage Calculation Formulas Flashcards

Dosage Calculation Formulas

• Use Formula Method:
  Formula: ( \text{Dose Ordered} / \text{Dose On Hand} \times \text{Quantity} = \text{Amount to be Given} )
  Denoted as ( D/H \times Q = H )

• Use Ratio and Proportion Method:
  Formula: ( \text{Dosage on Hand} : \text{Quantity Available} = \text{Dosage Ordered} : X )
  Denoted as ( H : Q = D : X )

• Use Dimensional Analysis Method:
  Formula: ( Q \times C(H) \times D / H \times C(D) \times 1 = X )
  Translates units for accurate dose calculation

IV Flow Rate Calculation

• Calculate IV flow rate with:
  Amount of solution (mL) divided by Hours to infuse equals ( \text{mL/hr} )

IV Administration by Gravity

• Formula for drop rate:
  ( \text{Amount of solution to be given} \times \text{Drop factor} / \text{Total minutes} = gtt/min )

Therapeutic Dose Calculation

• Step one: ( \text{Drug dose} \times \text{Patient's weight (kg)} = \text{Patient's dose/day} )
• Step two: ( \text{Patient's dose/day} / \text{Number of doses ordered} )

Conversion from mcg/kg/min to mL/hr

• Step one: ( \text{Ordered mcg/min} \times \text{Patient's weight (kg)} \times 60 = \text{mcg/hr} )
• Step two: ( \text{mcg/hr} / \text{Dose on hand in mcg} \times \text{Quantity} = \text{mL/hr} )

Measurement Conversions

• 1 kg equals 2.2 lbs
• 1 gr equals approximately 60 mg/64 mg/65 mg
• 1 quart equals 1000 mL (1 liter)
• 1 oz equals 30 mL
• 1 teaspoon equals 5 mL
• 1 tablespoon equals 15 mL
• 1 teaspoon equals 3 tablespoons

Rounding Guidelines

• Round capsules and drops to whole numbers; parts of capsules and drops cannot be administered.
• Round injectable medications less than 1 mL to hundredths using tuberculin syringe.
• Round injectable medications more than 1 mL to tenths using a 3 cc or larger syringe.
• Always round at the end of calculations; maintain more decimal places for smaller numbers with a general guideline of hundredths place.