Pharmaceutical Calculations The International System of Units Danielle

Objectives • Demonstrate an understanding of the International System of Units • Convert measures

Introduction • International System of Units (SI) – Formerly called metric system – Base

Guidelines for Correct Use • Two symbols for microgram – mcg – μg •

Common Conversions • Length – 1 m = 100 cm – 100 cm =

Useful Equivalents Ansel, H. C. (2009) Phamaceutical Calculations (13 th Ed. ). Philadelphia: Lippincott

Practice Problem 1: Reducing SI Units • By decimal shift – Reduce 9876 milligrams

Practice Problem 2: Reducing SI Units • Reduce 85 micrometers to centimeters – By

Practice Problem 3: Addition • Reduce to common denomination then add or subtract •

Practice Problem 4: Subtraction • Reduce to common denomination then add or subtract •

Practice Problem 5: Multiplication • Multiply 820 m. L by 12. 5 and express

Practice Problem 6: Division • Divide 0. 465 g by 15 and express the

Reference • Ansel, H. C. (2009) Phamaceutical Calculations (13 th Ed. ). Philadelphia: Lippincott

Chapter 2 Problem 2 • Add 7. 25 L and 875 c. L. Reduce

Chapter 2 Problem 8 • A liquid contains 0. 25 mg of a substance

Chapter 2 Problem 13 • Aspirin tablets generally contain 325 mg of aspirin. How

Chapter 2 Problem 15 • Norgestrel and ethinyl estradiol tablets are available containing 0.

Chapter 2 Problem 20 • A patient is instructed to take three 50 mcg

Chapter 2 Problem 31 • A prefilled syringe contains 20 mg of a drug

Chapter 2 Problem 38 • If an albuterol inhaler contains 18 mg of albuterol,

Chapter 2 Problem 49 • The product of biotechnology, filgrastim (NEUPOGEN), is available in

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Pharmaceutical Calculations: The International System of Units Danielle Del. Villano, Pharm. D. 1

Objectives • Demonstrate an understanding of the International System of Units • Convert measures within the International System of Units • State equivalent measures and complete conversions between the International System of Units and other systems of measure used in pharmacy • Apply the International System of Units correctly in calculations 2

Introduction • International System of Units (SI) – Formerly called metric system – Base units • Meter • Kilogram • Liter http: //kaffee. 50 webs. com/Science/activities/Activity. SI. Unit. Conversions. 2. htm 3

Guidelines for Correct Use • Two symbols for microgram – mcg – μg • Decimals are used, not fractions – 5. 25 mg – NOT 5 ¼ mg • Leading zero should be used before all decimals – 0. 5 mg – NOT. 5 mg • Trailing zeros should not be placed after whole numbers – 5 mg – NOT 5. 0 mg 4

Common Conversions • Length – 1 m = 100 cm – 100 cm = 1000 mm • Volume • Weight – 1 g = 1000 mg – 1 g = 0. 001 kg – 1 mg = 1000 mcg – 1 L = 1000 m. L 5

Useful Equivalents Ansel, H. C. (2009) Phamaceutical Calculations (13 th Ed. ). Philadelphia: Lippincott Williams & 6 Wilkins, and Wolters Kluwer Publishers

Practice Problem 1: Reducing SI Units • By decimal shift – Reduce 9876 milligrams to grams • • To convert from smaller to larger number shift the decimal RIGHT 9876 mg = 9. 876 g – Reduce 2. 525 liters to microliters • • To convert from larger to smaller number shift the decimal LEFT 2. 525 L = 2525 m. L = 2, 525, 000 μL 7

Practice Problem 2: Reducing SI Units • Reduce 85 micrometers to centimeters – By ratio and proportion: (KNOW 1 cm = 10000 μm) 1 cm 10000 mcg = x cm 85 mcg (85 mcg)(1 cm) = x cm (10000 mcg) x = 0. 0085 cm 8

Practice Problem 2: Reducing SI Units • Reduce 85 micrometers to centimeters – By dimensional analysis: (KNOW 1 cm = 10000 μm) 85 μm X 1 cm__ = 0. 0085 cm 10000 μm 9

Practice Problem 3: Addition • Reduce to common denomination then add or subtract • Add 1 kg, 250 mg, and 7. 5 g – 1 kg = 1000 g – 250 mg = 0. 25 g 1000 g 0. 25 g + 7. 5 g 1007. 75 g 10

Practice Problem 4: Subtraction • Reduce to common denomination then add or subtract • Subtract 2. 5 mg from 4. 85 g – 2. 5 mg = 0. 0025 mg - 4. 85 g 0. 0025 g 4. 8475 g 11

Practice Problem 5: Multiplication • Multiply 820 m. L by 12. 5 and express the result in liters 820 m. L x 12. 5 _ 10250 m. L = 10. 25 L 12

Practice Problem 6: Division • Divide 0. 465 g by 15 and express the result in milligrams 0. 465 g ÷ 15__ 0. 031 g = 31 mg 13

Questions 14

Reference • Ansel, H. C. (2009) Phamaceutical Calculations (13 th Ed. ). Philadelphia: Lippincott Williams & Wilkins, and Wolters Kluwer Publishers 15

Additional Problems 16

Chapter 2 Problem 2 • Add 7. 25 L and 875 c. L. Reduce the result to m. L. 17

Chapter 2 Problem 8 • A liquid contains 0. 25 mg of a substance per milliliter. How many grams of the substance will 3. 5 L contain? 18

Chapter 2 Problem 13 • Aspirin tablets generally contain 325 mg of aspirin. How many such tablets may be prepared from the 5 kg of aspirin? 19

Chapter 2 Problem 15 • Norgestrel and ethinyl estradiol tablets are available containing 0. 5 mg of norgestrel and 50 mcg of ethinyl estradiol. How many grams of each ingredient would be used in making 10, 000 tablets? 20

Chapter 2 Problem 20 • A patient is instructed to take three 50 mcg tablets of pergolide mesylate (PERMAX) daily. How many mg of the drug would the patient receive weekly? 21

Chapter 2 Problem 31 • A prefilled syringe contains 20 mg of a drug in 2 m. L of solution. How many micrograms of drug would be administered by an injection of 0. 5 m. L of the solution? 22

Chapter 2 Problem 38 • If an albuterol inhaler contains 18 mg of albuterol, how many inhalation doses can be delivered if each inhalation dose contains 90 mcg? 23

Chapter 2 Problem 49 • The product of biotechnology, filgrastim (NEUPOGEN), is available in vials containing 0. 3 mg of drug in each milliliter. Which choice is equivalent in concentration? (a) 0. 03 mg/0. 1 d. L (b) 300 mcg/0. 01 d. L (c) 3 mcg/0. 01 c. L (d) 300 mcg/10 c. L 24