LUNCH AND LEARN. December 11, 2015

Transcription

1 LUNCH AND LEARN A Refresher on Basic Pharmaceutical Calculations December 11, 2015 Featured Speaker: Ronald L. Koch, PhD Associate Professor, Emeritus University of Illinois at Chicago, College of Pharmacy Founder, Ronald L. Koch Consultants 1 CE Activity Information & Accreditation (Pharmacist and Tech CE) 1.0 contact hour Funding: This activity is self funded through PharMEDium. It is the policy of to ensure balance, independence, objectivity and scientific rigor in all of its continuing education activities. Faculty must disclose to participants the existence of any significant financial interest or any other relationship with the manufacturer of any commercial product(s) discussed in an educational presentation. Dr. Koch has no relevant commercial and/or financial relationships to disclose

2 Online Evaluation, Self-Assessment and CE Credit Submission of an online self assessmentand and evaluation isthe only way to obtain CE credit for this webinar Go to Print your CE Statement online Live CE Deadline: January 8, 2016 CPE Monitor CE information automatically uploaded to NABP/CPE Monitor within 1 to 2 weeks of the completion of the self assessment and evaluation Event Code Code will be provided at the end of today s activity Event Code not needed for On Demand 3 Ask a Question Submit your questions to your site manager. Questions will be answered at the end of the presentation. Your question...? 4 2

3 Resources Visit to access: Handouts Activity information Upcoming live webinar dates Links to receive CE credit 5 LUNCH AND LEARN A Refresher on Basic Pharmaceutical Calculations December 11, 2015 Featured Speaker: Ronald L. Koch, PhD Associate Professor, Emeritus University of Illinois at Chicago, College of Pharmacy Founder, Ronald L. Koch Consultants 6 3

4 Ansel Pharmaceutical Calculations 14 th Edition 7 Basic Conversions for Weights and Volumes Weights Volumes 1 kg = 1,000 grams 1kL = 1,000 liters 1 g = 1,000 mg 1 L = 1,000 ml 1 mg = 1,000 mcg 1mL = 1,000mcL 1 mcg = 1,000 ng 1mcL = 1,000 nl 8 4

5 Some Useful Equivalents Weights 1 kg = 22lb g = 1 lb (Avoirdupois) g = 1 oz. (Avoirdupois)(round to 30g) Volumes 1 gallon (US) = 3785 ml 1 pint (16 fl.oz.) = 473 ml 1 fl. oz. = 29.57mL (round to 30mL) 9 Chapter 6 Expressions of Percentage strength or % always indicates parts in a hundred or rate per hundred. ex. 5% = 5 parts per 100 parts. 0.9% = 0.9 parts per 100 parts. a. Percent weight in volume [%w/v] expresses the number of grams in 100 ml. b. Percent volume in volume [%v/v]expresses the number of milliliters in 100 ml of soln. c. Percent weight in weight [%w/w] expresses the number of grams per 100 g of preparation

6 Where would one see or use %w/v? Solids in liquids:,. Where would one see or use %v/v? Liquids in liquids:,. Where would one see or use %w/w? Solids in solids:,,,. 11 Example problems: A. Prepare 1 liter of 5% dextrose. 5% = 5g/100mL x 1000mL = 50 g OR 5g Xg = ; Solve for X 100mL 1,000mL 5g x 1,000mL = 100 ml x X g 5,000g ml /100 ml = X g 50 g = X

7 Example problems: B. Prepare 1 liter of 0.9% NaCl. 0.9% = 0.9g/100mL x 1000mL = 9g OR 0.9g X g = ; Solve for X 100mL 1,000mL 0.9g x 1,000mL = 100 ml x Xg 900 g ml /100 ml = X g 9g = X 13 C. How much D70W should be used to prepare 500mL of D20W? Use x Volume = x Volume [C1 x V1 = C2 x V2] 20% x 500mL = 70% x XmL 10,000 ml = 70 X mL = X [Use mL of 70% Dextrose and qs ad 500mL [sufficient amount to make 500mL ] with Sterile Water for Injection.]

8 Example problems: Norepinephrine i bitartratet t is available in 4 ml ampules at 1mg/mL [norepinephrine base]. What is the concentration when one ampule is added to 1,000 ml D5W? 1. 1mg/mL X 4 ml = 4mg [= 4,000mcg] 2. 4,000mcg / 1,000 ml = 4mcg/mL 15 The previous Norepinephrine concentration we dt determined dto be 4mcg/mL. What is the concentration in terms of percent [% = grams per 100 ml]? 4mcg/mL X 100/100 = 400mcg/100mL = 0.4mg/100ml = g/100mL 0004g/100mL = %. 0004% Remember, percent is a ratio of grams per 100mL. This leads us to Ratio strengths

9 Ratio Strength generally used to express the concentration of very weak or dilute solutions. For 1:1000 a. solids in liquids means 1 g in 1,000mL b. liquids in liquids means 1mL in 1,000mL c. solids in solids means 1 g in 1,000g of mixture. In all cases, this equals 0.1% 17 Common Ratio Strengths. 1:10, = 1 part per 10, parts = 0.1 part per 1,000 parts = 0.01 part per 100 parts = 0.01% 1:5,000 = 1 part per 5,000 parts = 01part 0.1 per 500 parts = [hint divide by 5] 0.02 parts per 100 parts = 0.02%

10 Ratio Strengths Examples of Common Ratio Strengths: a. Use of Benzalkonium Chloride as a preservative in ophthalmics. b. Use of other preservatives in vaccines. c. Use of preservatives in contact lens solutions. 19 Milligrams % or mg% is the number of milligrams per 100mL of liquid. id Used to denote natural substances in a body fluid, ex. 30 mg% Non protein Nitrogen means there is 30 mg of Non protein nitrogen wastes per 100mL of blood. This may also be expressed as 30mg/dL which is 30 mg per deciliter. A deciliter = 100mL

11 Other examples of Milligrams % or mg% we may encounter [milligrams/100ml of liquid]. This may be in plasma or serum and may also be expressed as mg/dl [deciliter means 100mL], examples are: Serum Glucose, Creatinine, Calcium, Cholesterol, Triglycerides, HDL Cholesterol, Bilirubin and perhaps others. 21 Parts per Million [ppm] and Parts per Billion [ppb] [seldom in Medicine but environment]. Treat as you do for ratio strengths: Ex. 5 ppm = 5 parts in 1,000,000 parts = 1 part in 200,000 parts = [hint divide by 2] 0.5 part in 100,000 parts = part in 100 parts = %

12 Where may we encounter ppm or ppb. a. Particulate counts for sterile environments. b. Particulates in parenterals. 23 Chapter 9 Calculations with units, μg/mg and other measures Potency of natural products and products derived dthrough h biotechnology vary from batch to batch. ex. Penicillin is produced from a mold and the strength varies for each batch. The active drug needs to be purified, concentrated and prepared for use

13 Chapter 9 Calculations with units, μg/mg and other measures The prepared drug is then measured for activity versus a given standard. Units [of activity], e.g. there are 1590 USP units of Penicillin G sodium per mg of antibiotic μg/mg micrograms of activity per milligram, e.g. 600 micrograms Neomycin per milligram. International Units [I.U. or IU] Lf Unit [flocculating or precipitating capacity for toxoids relative to 1 unit of standard antitoxin. 25 Chapter 9 Calculations with units, μg/mg and other measures These units have NO relationship to one another. Generally specific for a particular drug entity. Treat these notations as if they are no different than how you would work with grams, or mg, orotherother metric units

14 Chapter 9 Calculations with units, μg/mg and other measures Example 1: How many ml of Heparin are needed from a vial containing 10,000units per ml to provide: a. 5,000units for an initial intravenous injection? 10,000units = 5,000units ; X = 0.5 ml 1 ml X ml b. How much would be needed to draw up for a subcutaneous dose of 14,000 units? 10,000units = 14,000units ; X = 1.4 ml 1 ml X ml 27 Chapter 9 Calculations with units, μg/mg and other measures Example 2: How many ml of U 100 insulin zinc suspension [100 units/ml] should be used to obtain 20 units of insulin? 100 units = 20 units ml X = 0.2mL X ml

15 Additional examples D. How much each of D5W and D70W should be used to prepare 500mL of D20W? Use C1C V1 + C2 V2 = C3 V3, so we have: 5% x XmL + 70% x YmL = 20% x 500mL Here we have 2 unknowns but we DO know that X + Y = 500, so Y = 500 X, substitute this for Y. 5% x XmL + 70% x (500mL X) = 20% x 500mL 5X + 35,000mL 70X = 10,000 5X 70X = 10,000 35,000 65X = 25,000 X = mL of D5W needed 500mL mL D5W = mL of D70W is needed. 29 Additional examples Vancomycin is available in a 1 g vial and is reconstituted with 20 ml sterile water to yield a final concentration of 50mg/mL. How many mls should be withdrawn to prepare a central line catheter instillation of 3mL volume at 12mg/mL? 12mg/mL X 3 ml = 36mg 50mg = 36 mg ; X = 0.72 ml diluted to 1 ml X ml 3 ml

16 References for Pharmaceutical Calculations Pharmaceutical Calculations, 14 th Edition by Howard C. Ansel, pub. Lippincott, Williams & Wilkins. Remington s Pharmaceutical Sciences, The Science and Practice of Pharmacy, 22 nd Edition, Ed. Loyd V. Allen, Jr., [Calculations Chapter]. Pharmaceutical and Clinical Calculations, 2 nd Edition, Mansoor A. Kahn and Indra K. Reddy. 31 References for Pharmaceutical Calculations Website references: 1. Pharmaceutical Calculations, 13 th edition Xpharmac 2.pdf Adobe Reader [This has the 13 th edition of the Ansel textbook on line.] 2. Pharmaceuticalcalculations.org/downloads.phporg/downloads

17 References for Pharmaceutical Calculations For something more specific, try Google: 1. websites for pharmaceutical calculations for technicians PDF 2. websites for pharmaceutical calculations PDF