Table of Contents
Understanding pharmacy math formulas is essential for accurate medication dosing and calculations. This cheat sheet provides quick reference formulas to help pharmacy professionals and students perform common calculations efficiently and accurately.
Basic Pharmacy Math Formulas
- Dose (mg) = Desired Dose / Stock Strength
- Amount to Dispense = Desired Dose x Formulation
- Concentration (mg/mL) = Drug Amount (mg) / Volume (mL)
- Flow Rate (mL/hr) = Total Volume (mL) / Time (hr)
Common Conversions
- 1 gram (g) = 1000 milligrams (mg)
- 1 milliliter (mL) = 1 cubic centimeter (cc)
- 1 teaspoon (tsp) = 5 mL
- 1 tablespoon (Tbsp) = 15 mL
- 1 ounce (oz) = 28.35 grams (g)
Calculating Body Surface Area (BSA)
- BSA (m²) = Square Root of [(Height (cm) x Weight (kg)) / 3600]
- Example: BSA = √[(170 x 70) / 3600] ≈ 1.84 m²
Drug Dosage Calculations
- Dose (mg) = Desired Dose / Concentration
- Infusion Rate (mL/hr) = Volume (mL) / Time (hr)
- Drop Rate (gtts/min) = (Volume (mL) x Drop Factor (gtts/mL)) / Time (min)
Important Tips
- Always double-check calculations for accuracy.
- Be familiar with common units and conversions.
- Use proper rounding rules as per pharmacy guidelines.
- Keep a calculator handy for complex calculations.
Having these formulas at your fingertips can improve efficiency and safety in pharmacy practice. Regular practice and familiarity with these calculations will enhance your confidence and competence in medication management.