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Reference Guide For Pharmaceutical CalculationsKrismanREFERENCE GUIDE FORPHARMACEUTICALCALCULATIONS2014-2015 EDITIONMANAN SHROFFwww.pharmacyexam.com1

Reference Guide For Pharmaceutical CalculationsKrismanThis reference guide is not intended as a substitute for the advice of a physician. Students orreaders must consult their physician about any existing problem. Do not use any information of thisreference guide for any kind of self treatment. Do not administer any dose of mentioned drugs inthis reference guide without consulting your physician. This is only a review guide for preparationof pharmaceutical calculations.The author of this reference guide is not responsible for any kind of misinterpreted, incorrect ormisleading information or any typographical errors in this guide. Any doubtful or questionableanswers should be checked in other available reference sources.All rights reserved.No part of this guide may be reproduced or transmitted in any form or by any means, electronicallyphotocopying, recording or otherwise, without prior written permission of the publisher.RXEXAM is a registered trademark of Pharmacy Exam of Krishna Publication inc. Anyunauthorized use of this trade mark will be considered a violation of law.NAPLEX , PARE and FPGEE exams are federally registered trademark owned by NationalAssociation Board of Pharmacy (NABP ). PTCB is registered trade mark owned by PharmacyTechnician Certification Board and this review guide is in no way authorized or sponsored byNABP or PTCB .www.pharmacyexam.com2

Reference Guide For Pharmaceutical CalculationsKrismanPREFACEI am very pleased to announce to release of the 2014-2015 Edition for The ReferenceGuide For Pharmaceutical Calculations. It is a resourceful practice guide for preparation of theNAPLEX , FPGEE , PTCB and California Pharmacy Board exams.This edition contains 650 calculation problems to prepare students for an actual exam. Inthis Third Edition, I have also included some calculations on creatinine clearance and opioidconversions.The NAPLEX , FPGEE , PTCB and California Pharmacy Board exams are currentlyputting more emphasis on calculation problems. A significant percentage of these exams, at least25% to 30%, consist of calculations.Calculations related to I.V., I.V. infusion, TPN and dosages are very important in retail andinstitutional pharmacy settings. This guide will provide complete practice on related calculationproblems and help in the achievement of an exceptional score on the examinations.Best of luck,Manan Shroffwww.pharmacyexam.com3

Reference Guide For Pharmaceutical CalculationsKrismanTABLE OF CONTENTSSECTION - I1.CALCULATIONS92.ANSWERS45SECTION - II1.PRACTICE CALCULATIONS872.ANSWERS129www.pharmacyexam.com4

Reference Guide For Pharmaceutical CalculationsKrismanCOMMONLY USED UNITS FOR PHARMACEUTICAL CALCULATIONS*********************************1 kilogram1 gram1 milligram1 microgram1 microgram1 nanogram1 grain1 liter1 ounce (oz)16 ounce (oz)1 pint1 quart1 gallon1 kg1 lb1 teaspoonful1 tablespoonful1 teacupfulDensityProof gallon% strengthProof galPVPVEquivalent wtmEqmOsmol/LpHYoung (child)Clark’sChild’s doseFried’s ruleFP of blood*********Each gm of hydrous dextrose providesEach gm of anhydrous dextrose providesEach gm of fat providesEach gm of protein/aminoacid providesEach gm of medium chain triglyceride (mct)Each gm of glycerol providesEach cc of alcohol provides1 cc of 10% fat emulsion provides1 cc of 20% fat emulsion provideswww.pharmacyexam.com 1000 grams1000 milligrams1000 micrograms0.001 milligrams10-6 grams10-9 grams65 milligrams1000 cc30 cc480 cc 1 pint480 cc960 cc 2 pints3840 cc 8 pints 4 quarts2.2 lbs454 grams5 cc15 cc120 ccweight/volume(gal x % v/v strength) / 50% v/vproof spirit / 2(gal x proof spirit) / 100nRTW/M x R x Tmolecular weight / number of valenceequivalent weight in mg / 1000(weight of substance [g/L] x no of species x 1000) / mol wtpKa log (salt/acid)(age in years / age 12) x adult dose(weight in lbs / 150) x adult dose(body surface area of child / 173 mm2 ) x adult dose(age in months / 150) x adult dose-0.52oC 3.4 calories / kcal4 calories / kcal9 calories / kcal4 calories / kcal8.3 calories / kcal4.3 calories / kcal5.6 calories / kcal1.1 calories / kcal2.0 calories / kcal5

Reference Guide For Pharmaceutical CalculationsKrisman**pHpH pKa log (salt/acid) or (ionized/unionized) (for weak acid)pKw - pKb log (base/salt)(for weak base)*B 2.3 x C Ka x H3O (Ka H3O )2(Van slyke’s buffer capacity equation)where, C total buffer concentration, H3O hydrogen ion concentration*Bmax 0.576 x C(maximum buffer capacity)where C total buffer concentration980 cm/sec20.082 lit atm / mole deg4.184 x 107 erg6.0221 x 1023 mole-****Acceleration gravity (g)Gas constant (R)1 calorieAvogrado’s number *K 2.303 log CotCwhere Co initial concentration of drugwhere C concentration of drug at time ‘t’*t 1/2 0.693/Kwhere t1/2 half life of drugwhere K rate constant*Vd M/Cpwhere Vd volume of distributionwhere M amount of drug in bodywhere Cp plasma concentration of drug*Ri Css x Vd x Kwhere Ri rate of infusionwhere Css steady state plasma concentrationwhere Vd volume of distributionwhere K drug elimination constant*Ld Css x Vdwhere Ld loading dose of drugwhere Css steady state plasma concentrationwhere Vd volume of distribution*Normality (N):It is defined as the presence of number of gram equivalentweight of solute in 1000 ml or (1L) solution.*Molarity (M):It is defined as the presence of number of moles of solute in1000 ml or (1L) of solution.*Molality (m):It is defined as the presence of number of moles of solute in1000 gm of solvent.www.pharmacyexam.com6

Reference Guide For Pharmaceutical Calculations9 (oC) 5 (oF) - 160*Temperature conversion:*CrCl*CrCl (female) 0.85 x male (CrCl)*The number of vials of Digibind required Krismanweight (kg) x (140-age)72 x serum creatinine (mg/dL)www.pharmacyexam.comTotal digitalis body load in mg x 0.80.5mg of digitalis bound7

Reference Guide For Pharmaceutical CalculationsKrismanQUESTIONSwww.pharmacyexam.com8

Reference Guide For Pharmaceutical Calculations1.Sulfur3%Salicylic acid3%White Petrolatum.q.s. 80 gmFind out the amount of Sulfur required to fill theabove prescription?a.b.c.d.1.2 gm2.4 gm3.0 gm4.8 gm2.How many grams of Dextrose are required to prepare 5% of 500 cc solution?a.b.c.d.2.5 gm25 gm55 gm5 gm3.How much Lidocaine is required to prepare 1 : 1000, 30 cc of solution of Lidocaine?a.b.c.d.10 mg0.03 mg30 mg300 mgKrisman6.How many cc of 75% alcohol should bemixed with 10% of 1000 cc alcohol to prepare30% of 500 cc alcohol solution ?a.b.c.d.346.16 cc234.43 cc153.84 cc121.12 cc7.How many grams of Heparin are requiredto prepare 1 quart of 0.45% solution?a.b.c.d.2.16 gm4.32 gm0.45 gm4.5 gm8.If a prescription reads “Augmentin 875mg po bid x 10 days,” how many cc of Augmentin 250 mg/5 cc are required to fill aten-day supply?a.b.c.d.350 cc35 cc17.5 cc5 cc9.How many milligrams are equal to1/150 gr of Nitroglycerine?If 250 mg of Cefazolin powder are diluted with water up to the 250 cc mark, what isthe % of drug in the final solution ?a.b.c.d.a.b.c.d.4.150 mg65 mg55 mg0.43 mg5.How much Atropine is required to dispense 1 quart of 1 in 100 solution?a.b.c.d.9.6 mg1.48 gm2.3 mg9600 mgwww.pharmacyexam.com10%0.1%11%0.01%10.If 1 teaspoonful of Thioridazine concentrated solution (30 mg/cc) is diluted up to the 480cc mark with plain water, what is the strength ofdrug in mg/ml in the finalsolution ?a.b.1mg/cc0.52 mg/cc9

Reference Guide For Pharmaceutical Calculationsc.d.0.31 mg/cc0.75 mg/cc11.If a prescription reads “Diphenhydramine50 mg po hs x 30 days ”, what would be thedispensed quantity of drug in ml (12.5 mg / 5 cc)for thirty-day supply?a.b.c.d.20 cc5 cc300 cc600 ccKrismana.b.c.d.431216.If 1000 tablets of Risperdal 1 mg cost 2250 and the mark-up on prescription is 20%,what would be the retail price for 30 tablets?a.b.c.d. 150 17 500 8112.Erythromycin 2% 60 cc topical solutioncontains:a.b.c.d.2 gm erythromycin2.4 gm erythromycin0.6 gm erythromycin1.2 gm erythromycin17.How much Clobetasole is present in 60gm of 0.5% ointment?a.b.c.d.1.2 gm3.0 gm2.1 gm0.3 gm13.If 60 mg of elementary iron are present in325 mg of ferrous sulfate, what is the % ofelementary iron?a.b.c.d.20.00%10.25%18.46%9.25%18.If the ratio of ionized to unionized species of drugs is 103 and PKa 2.2, what is thepH of the solution?a.b.c.d.2.20.85.23.014.If 60 gm of 1% hydrocortisone are mixedwith 80 gm of 2.5% hydrocortisone, what is the% of hydrocortisone in the final mixture?a.b.c.d.2.2% w/w1.85% w/w0.25% w/w1.75% w/w15.If a prescription reads “100 mcg cyanocobalamin i.m. every week”, how many ampulsof 1000 mcg / cc are required to fill a monthsupply?www.pharmacyexam.com19.If a prescription reads “Augmentin 875mg by mouth twice a day”, how many cc ofAugmentin 400 mg/5 cc are required to dispensea 10 day supply?a.b.c.d.10.93 cc218.75 cc75.00 cc100.00 cc20.Find out the weight in gm of 500 cc glycerine. [Specific gravity 1.25 gm/ml]10

Reference Guide For Pharmaceutical Calculationsa.b.c.d.625 gm50 gm400 gm0.25 gmKrisman26.How many 500 mg tablets of erythromycin are required to prepare 240 cc of 2% solution of erythromycin?Find out the volume of 5 lb of glycerine.[density 1.25 gm/ml]a.b.c.d.35610a.b.c.d.27.How many milligrams are equal to 1/15021.1816 cc6.25 cc637 cc40 ccgrains?Calculate the weight of 500 cc of acid.[density of acid 2.5 gm/ml]a.b.c.d.a.b.c.d.28.22.1000 gm1250 gm500 gm200 gmHow many 975 mg tablets of aspirin arerequired to prepare 100 tablets of 1 grain?Find out the ratio of ionized to unionizedspecies of drugs at pH 7. [pKa 5]a.b.c.d.a.b.c.d.29.23.10110010000.65 mg1.21 mg0.43 mg1.56 mg6 tablets10 tablets5 tablets3 tabletsIf 3 capsules of 150 mg of Clindamycinare added to 150 cc of 1% Cleocin topical solution, what is the % of Clindamycin in the finalmixture ?24.If the pH of the solution is 3, what is theconcentration of H3O in gm ion /L?a.b.c.d.0.01 gm-ion/L1 x 103 gm-ion/L0.05 gm-ion/L10-3 gm-ion/L25.What is the pH of a solution having a ratioof ionized to unionized species of drugs of1 x 10-6 ?[PKa 1.1%0.9%30.The adult dose of a drug is 500 mg. Whatis the dose for a 2 year old child? [use youngrule]a.b.c.d.71.42 mg101.53 mg25.46 mg31.18 mg11

Reference Guide For Pharmaceutical Calculations280. How many mls of Infed (50mg/2 ml) arerequired for a patient with blood loss of 350mls?[Patient’s hematocrit 25%]a.b.c.d.1.752.523.464.15281. If 1 teaspoonful of Diazepam concentrated solution (5mg/cc) is diluted up to the 1 pintmark with plain water, what is the strength of drugin mcg/ml in the final solution?Krismana.b.c.d.1.211.852.143.47285. How many mEqs of K are present in750mg of a KCl capsule? [ K 39, Cl- 35.5]a.b.c.d.10196354286. How many grams of CaCl2 are requireda.b.c.d.12522235282. If a normal dose of a drug is 0.02mg/kg/day, how many 250mcg/50cc ready-infusion bagsare required to fill the above order ? [Patient’sweight 155 lbs.]to prepare a 1 gallon solution that contains 20meq of calcium ions? [mw CaCl2 111gm/mole]a.b.c.d.2.521.113.254.54287. What is the half-life of a drug that has arate of constant of 0.025 minutes-?a.b.c.d.3654a.b.c.d.0.22 hrs0.56 hrs0.65 hrs0.46 hrs283. If 10cc of Lidocaine 0.05mg/cc arediluted with water up to the 50cc mark, whatwould be the strength of drug in mcg/ml?a.b.c.d.10609040284. Four grams of Levofloxacin (mixed with500cc 0.9% NaCl) is administered via slow I.V.infusion over 24 hours. If the I.V. set delivers 10drops/ml, what would be the rate of flow in drops/min?www.pharmacyexam.com287. If the I.V. dose of a drug is 10mg/I.V./kg,what would be the plasma concentration of thedrug in micrograms per ml for a patient weighing95 lbs.? [An apparent volume of distribution ofdrug is 0.025 L/kg]a.b.c.d.40025433365241