Pharmaceutical Measurements and Calculations. 1. Presentation Topics. Systems of Pharmaceutical Measurement Basic Calculations Used in Pharmacy Practice Advanced Calculations Used in Pharmacy Practice. 2. Learning Objectives.
Pharmaceutical Measurements and Calculations
Systems of Pharmaceutical Measurement
Basic Calculations Used in Pharmacy Practice
Advanced Calculations Used in Pharmacy Practice
Describe four systems of measurement commonly used in pharmacy and convert units from one system to another.
Explain the meanings of the prefixes most commonly used in metric measurement.
Convert from one metric unit to another (e.g., grams to milligrams).
Convert Roman numerals to Arabic numerals.
Convert time to 24 hour military time.
Convert temperatures to and from the Fahrenheit and Celsius scales.
Round decimals up and down.
Perform basic operations with proportions, including identifying equivalent ratios and finding an unknown quantity in a proportion.
Convert percentages to and from fractions, ratios, and decimals.
Perform fundamental dosage calculations and conversions.
Solve problems involving powder solutions and dilutions.
Use the alligation method to prepare solutions.
Calculate the specific gravity of a liquid.
The metric system
Pharmacists and pharmacy techs must make precise measurements daily
Most important measurements are
a measurement system based on subdivisions and multiples of 10; made up of three basic units: meter, gram, and liter
the metric system’s base unit for measuring length
the metric system’s base unit for measuring weight
the metric system’s base unit for measuring volume
Legal standard of measure for pharmaceutical measurements
Developed in France in the 1700s
Has several advantages
Based on decimal notation
Clear correlations among units of measurement
Uses standardized units of Systeme International (SI)
Three basic units
Meter (distance, little use in pharmacy)
Gram (weight, used for solid form meds)
Liter (volume, used for liquid meds)
Numbers expressed as decimals rather than fractions
An error of a single decimal place is an error of a factor of 10.
Common measures are approximate.
Three types of common measures are used in the pharmacy:
Common measures are often converted to metric equivalents.
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For safety reasons, the use of the apothecary system is discouraged. Use the metric system.
Always carefully check and double-check all calculations.