Sterile and Nonsterile Compounding
The antiviral ophthalmic drug fomivirsen sodium (Vitravene) has been ordered by the physician 330 mcg. The vial is labeled 6.6 mg/mL. How many milliliters contain the prescribed dose?
answer = 0.05 mL the problem can be solved by using two proportions. first, convert 330 mcg to milligrams (1000 mcg/1 mg = 330 mcg/X mg, where X = 0.330 mg). next, calculate the number of millimeters by using the following formula: 6.6 mg/mL = 0.330 mg/X mL
You are asked to prepare 52 mL of a 28% Flagyl solution, and you have in stock 42 g/mL solution. How many milliliters of the 42 g/mL will you use?
answer = 0.35 mL IS = 42 g/mL, IV = unknown, FS = 0.28 g/mL, and FV = 52 mL: (42 g/mL)(IV) = (0.28 g/mL)(52 mL), where IV = 0.35 mL
How many milligrams are in one tablet of Nitrostat 1/150 gr?
answer = 0.4 mg 1 grain is equal 65 mg. solve by using the following proportion: 65 mg/1 gr = X mg/1/150 gr
The drug vial contains 1,000,000 units of penicillin G. The label directions state: Add 2.3 mL of sterile water to the vial, 1.2 mL = 500,000 units. How many milliliters equal 200,000 units?
answer = 0.48 mL this can be solved as a proportion using international units: 500,000 units/1.2 mL = 200,000 units/X mL
What is the percent of a 1:200 (w/w) ointment?
answer = 0.5 % convert the ratio to a proportion (1:200 is equal to 1/200). next, multiply 1/200 by 100 to obtain the answer of 0.5%
The physician ordered 0.725 mg of droperidol (Inapsine) IV stat. The vial reads 2.5 mg in 2 mL. Calculate the amount of drug you will administer to this patient in milliliters.
answer = 0.58 mL this can be solved using a proportion: 2.5 mg/2 mL = 0.725 mg/X mL
How many milliliters of aminophylline injection containing 250 mg in each 10 mL should be used in filling a medication order calling for 15 mg of aminophylline?
answer = 0.6 mL this can be solved using a proportion: 250 mg/10 mL = 15 mg/X mL. cross-multiplying and dividing will provide you with he answer
How many milliliters of a 1:50 (w/v) stock solution of a chemical should be used to prepare 2 L of a 1:4000 (w/v) solution?
answer = 25 mL 2 L = 2000 mL (2 L x 1000 mL/L). IS = 1:50, IV = unknown, FS = 1:4000, and FV = 2000 mL, where IV = 25 mL
The prescriber ordered atropine sulfate 0.2 mg SC q6h prn. What is the equivalent dose in micrograms?
answer = 200 mcg convert mg to micrograms by multiplying 0.2 mg by 1000 mcg/mg
If a child weighs 60 lb and the adult dose is 500 mg, how many milligrams should the child receive?
answer = 200 mg solve using clark's rule: (60/150) x 500 mg = 200 mg
A pharmacist has received an order to prepare 1 lb of 5% (w/w) salicylic acid ointment. How much salicylic acid is needed to prepare this ointment?
answer = 22.7 g 1 lb = 454 g. convert the % (5%) to a decimal (0.05). solve using the following equation FW x % (decimal) = amount of AI (g) or 454 g x 0.05 = 22.7 g. the AI is expressed in grams because it is a w/w problem
How much water should be added to 1 quart of 70% isopropyl alcohol to prepare a 20% solution for soaking sponges?
answer = 2400 mL 1 quart = 960 mL. this is a dilution problem asking for the amount of diluent (water) to be added in preparing this compound. IS = 70%, IV = 960 mL, FS = 20%, and FV = unknown: (70%)(960 mL) = (20%)(FV), where FV = 3360 mL. FV-IV= amount of diluent to be added or 3360 mL - 960 mL = 2400 mL
A 20% KCl solution has a strength of 40 mEq/tbsp. How many milliliters need to be dispensed for the patient to receive 20 mEq?
answer = 7.5 mL solve this problem by using the following proportion: 40 mEq/tbsp = 20 mEq/X mL, where X = 7.5 mL
If 125 mL of liquid weighs 95 g, what is its specific gravity?
answer = 0.76 specific gravity (sg) = weight of a substance/weight of an equal volume of water, where 1 mL of water weighs 1 g. you have been given the weight (95 g) and volume of the substance (125 mL = 125 g). SG = 95/125 or 0.76
What is the specific gravity of a substance that weighs 60 g and occupies a volume of 75 mL?
answer = 0.8 weight of substance is 60 g, and it occupies a volume of 75 mL. substituting into the equation for specific gravity: SG = 60/75, where SG = 0.8
How many milliliters of a 5% stock solution are needed to prepare 1 pint of a solution containing 100 mg of the chemical per liter?
answer = 0.96 mL convert 100 mg/1000 mL to a percent, which is 0.01%. 100 mg/1 L = 0.1 g/1000 mL. convert 0.1 g/1000 mL to X g/100 mL, where X = 0.01 g. solve the dilution problem by using the following formula: (IS)(IV) = (FS)(FV), where IS = 5%, FS = 0.01%, and FV = 480 mL (1 pint)
1500 mL TPN solution is given IV at 75 mL/hr using an administration set with a drop factor of 20 gtt/mL. If the infusion starts at 0900 hours, when will it end?
answer = 0500 hr on the next day calculate the amount of time the IV will last (time = volume/time) or 1500 mL/75 mL/hr = 20 hr. the first bag was hung at 0900 hours and will last 20 hours: 0900 hr + 2000 hr - 2400 hr/day = 0500 hr on the next day
How many milliliters of a 1/2% solution of gentian violet should be used in preparing 500 mL of a 1:100,000 solution?
answer = 1 mL convert 1:100,000 to a percent (0.001%); IS = 0.5%, IV = unknown, FS = 0.001% and FV = 500 mL: (0.5%)(IV) = (0.001%)(500 mL), where IV = 1 mL
How much metoclopramide 5 mg/mL is used to make 10 mL of 0.5 mg/ mL solution?
answer = 1 mL this is a dilution problem using concentration expressed as milligrams per milliliter but can be solved the same way. IS = 5 mg/mL, IV = unknown, FS = 0.5 mg/mL, and FV = 10 mL: (5 mg/mL)(IV) = (0.5 mg/mL)(10 mL), where IV = 1 mL
A patient is to receive 25 units of the hormonal drug vasopressin (Pitressin) IM. If the label reads 50 units per 2 mL, how many milliliters will you administer to the patient?
answer = 1.0 mL this is a proportion problem. 50 units/2 mL = 25 units/X mL, where X = 1.0 mL
How many grams of NaCl are in 250 mL of 1/2 NS (0.45%)?
answer = 1.125 g convert % (0.45%) to a decimal (0.0045). solve using the following equation: FV x % (decimal) = amount of AI (g) or 250 mL x 0.0045 = 1.125 g.
A patient is to receive a 100-mg dose of gentamicin. The medication is available in an 80-mg/mL vial. How many milliliters should the patient receive?
answer = 1.2 mL this can be solved using a proportion: 80 mg/mL = 100 mg/X mL
You have a 2-mL ampule of caffeine Na benzonatate containing gr viiss. If the physican orders gr v, how many milliliters will you dispense?
answer = 1.33 mL this is a proportion problem that uses both arabic and roman numerals (V = 5 and VIISS = 7.5) set the proportion up as 7.5 gr/2 mL = 5 gr/X mL
Carafate 400 mg/5 mL Cherry syrup 40 mL Sorbitol solution 40 mL Flavor qs Purified water ad 125 mL Sig: 5 mL tid How many 1-g Carafate tablets should be used in preparing the prescription?
answer = 10 1-g Carafate tablets calculate the amount of carafate needed for the compound; this can be done through the use of a proportion: 400 mg/5 mL = X mg/125 mL, where 10,000 mg of Carafate is the entire quantity. one can calculate the number of grams needed by using a proportion: 1 g/1000 mg = X g/10,000 mg, where X = 10 1-g tablets of Carafate
A drug has a concentration of 20 mg/mL. How many grams of the drug are in 1/2 L of the solution?
answer = 10 g convert 20 mg to grams by using the following proportion: 1000 mg/1 g = 20 mg/X g, where X = 0.02. next determine the number of mL in 0.5 L by using a proportion: 1 L/1000 mL = 0.5 L/X mL, where X = 500 mL. next, use a proportion to solve for the number of grams: 0.02 g/1 mL = X g/500 mL, where X = 10 g
You are asked to prepare 50 mL of a 1:100 rifampin suspension, and you have in stock a 1:20 rifampin suspension. How many milliliters of the 1:20 suspension will you need?
answer = 10 mL this is a diluent problem where the concentrations are expressed as ratios, but it can be solved in the same way. IS = 1:20, IV = unknown, FS = 1:100, and FV = 50 mL: (1:20)(IV) = (1:100)(50 mL), where IV = 10 mL
How many micrograms are in 1.0 mL of a 1:100 solution?
answer = 10,000 mcg convert ratio (1:199) to a fraction (1/100) to a decimal (0.01). in this problem, the FV (1.0 mL) x % as a decimal (0.01) = 0.01 g. one is asked to answer the problem in micrograms, which can be converted by (0.01 g)(1000 mg/1 g)(1000 mcg/1 mg) = 10,000 mcg
Convert 40° Celsius to Fahrenheit.
answer = 104° F solve by using the formula 9C = 5F - 160, where you replace C with 40: 9(40) = 5F - 160, and perform the necessary operations
If a 3-year-old child weighing 33 lb accidentally ingested 20 81-mg aspirin tablets, how much aspirin did the child ingest on a milligram per kilogram basis?
answer = 108 mg/kg convert the weight of the child in pounds to kilograms by dividing 33 lb by 2.2 lb/kg, which equals 15 kg. calculate the amount of aspirin the child consumed by multiplying 20 tablets by 81 mg/tablet, which equals 1620 mg. solve using proportion: 1620 mg/15 kg = X mg/1 kg, which equals 108 mg/kg
An IV piggyback of enalapril maleate containing 10 mg of drug in 50 ml of 0.9% sodium chloride injection is to be infused over 1 hour. The IV set is calibrated to deliver 15 gtt/mL. How many drops per minute should be administered?
answer = 12 gtt/min
The dose of a drug is 500 mcg/kg of body weight. How many milligrams should be given to a child weighing 55 lb?
answer = 12.5 convert weight in pounds to kilograms (55 lb x 1 kg/2.2 lb). multiply weight in kilograms by 500 mcg/kg to obtain the correct dose in micrograms. convert micrograms to milligrams by multiplying micrograms by 1 mg/1000 mcg
An IV piggyback of pentamidine isethionate containing 300 mg of drug in 150 ml of D5W is to be infused over 2 hr. The IV set is calibrated to deliver 20 gtt/mL. How many drops per minute should be administered?
answer = 25 gtt/min calculate the rate (150 mL/2 hr = 75 mL/hr). calculate drops per minute by multiplying the rate by the drop factor by the conversion factor: (75 mL/hr) x (20 gtt/mL) x (1 hr/60 min) = 25 gtt/min
How many grams of a 2.5% hydrocortisone cream should be mixed with 240 g of a 0.25% hydrocortisone cream to make a 1% cream?
answer = 120 g draw a tic tac toe table placing the highest concentration (2.5%) in the upper left corner, the desired concentration ( 1%) in the middle and the lowest concentration (0.25%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. calculate the proportions of each needed. set up a proportion to calculate the total weight of the preparation by using the 240 g of 0.25% ointment: 1.5 parts/2.25 parts = 240 g/X, where X = 360 g. to calculate the amount of 2.5% needed, subtract the amount of the 0.25% fro m the total weight of the compound: 360 g (total weight) - 240 g (weight of 0.25%) = 120 g (weight of 2.5%)
How many grams are in 100 mL of a liquid if its specific gravity is 1.25?
answer = 125 g specific gravity is 1.25 and equal volume of liquid if 100 mL. substituting into the equation for specific gravity: 1.25 = X/100, where X = 125 g
Calculate the flow rate to be used to infuse 1000 mL of NS over 8 hours if the set delivers 10 gtt/mL.
answer = 125 mL/hr rate = volume/time (hr), or 1000 mL/8 hr = 125 mL/hr
If a child weighs 45 lb and the adult dose is 50 mg, how much medication should the child receive?
answer = 15 mg solve using clark's rule: clark's rule = (weight [lb]/150) x adult dose = amount of dose (45/150) x 50 mg = 15 mg
An IV piggyback of lincomycin containing 1 g of drug in 100 mL is to be infused over 1 1/2 hours. The IV set is calibrated to deliver 15 gtt/mL. How many drops per minute will the patient receive?
answer = 16 gtt/min calculate the rate: (100 mL/1.5 hr) = 66 mL/hr. calculate drops per minute by multiplying the rate by the drop factor by the conversion factor: (66 mL/hr) x (15 gtt/mL) x (1 hr/60 min) = 16 gtt/min
If a child weighs 15 kg and the adult dose is 75 mg, how many milligrams should the child receive?
answer = 16.5 mg solve using clark's rule. first convert kilograms to pounds: 1 kg/2.2 lb = 15 kg/X lb, where X equals 33 lb. substitute into the equation: (33/150) x 75 mg = 16.5 mg
The usual pediatric dose of cefazolin sodium is 25 mg/kg/day divided equally into three doses. What would be the single dose in milligrams for a child weighing 44 lb?
answer = 166.67 mg/kg calculate the weight in kilograms by dividing 44 lb by 2.2 lb/kg, which equals 20 kg. calculate the number of milligrams per day by multiplying 25 mg/kg/day by 20 kg, which equals 500 mg. the patient is to receive three equal doses. divide the total amount of medication by three doses (500 mg/3 doses = 166.67 mg/dose)
If a child is 2 1/2 years old and the adult dose is 100 mg, how much medication should the child receive?
answer = 17 mg solve using young's rule: [2.5/(2.5+12)] x 100 mg = 17 mg
Convert 65° Fahrenheit to Celsius
answer = 18.33°C solve by using the formula 9C = 5F - 160, where you replace F with 65: 9(C) = 5(65) - 160, and perform the necessary operations
The usual dose range of dimercaprol is 2.5 mg to 5 mg/kg of body weight. What would be the dose range for a person weighing 165 lb?
answer = 187.5 to 375 mg convert pounds to kilograms (165 lb x 1 kg/2.2 lb). multiply the weight in kilograms by 2.5 mg to obtain the lower dose and multiply the weight in kilograms to obtain the upper dose
How many grams of silver nitrate are needed to make 1 L of a 0.25% solution?
answer = 2.5 g 1 L = 1000 mL. convert percent to a decimal (%/100 or 0.25%/100 = 0.0025). solve using the following equation: final volume (fv) x % (expressed as a decimal) = amount of active ingredient (AI). 1000 mL x 0.0025 = 2.5 g of silver nitrate. in this situation, because it is a solution (w/v), the AI will be expressed in grams
If 100 mL of 25% (w/v) solution is diluted to 1 L, what will be the percentage strength (w/v)?
answer = 2.5 mL 1 L = 1000 mL. this is a dilution problem, where IS = 25%, IV = 100 mL, FS = unknown, and FV = 1000 mL: (25%)(100 mL) = (FS)(1000 mL), where FV = 2.5%
How many milliliters of a 2.5% (w/v) chlorpromazine hydrochloride injection and how many milliliters of a 0.9% (w/v) sodium chloride injection should be used to prepare 500 mL of a 1.25% (w/v) chlorpromazine hydrochloride injection?
answer = 2.5%-109 mL; 0.9%-391 mL draw a tic tac toe table placing the highest concentration (2.5%) in the upper left corner, the desired concentration ( 1.25%) in the middle and the lowest concentration (0.9%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. calculate the proportions of each needed and multiply by the quantity to be prepared. 2.5%: (0.4 parts/1.65 parts) x 500 mL = 109 mL; 0.9%: (1.25 parts/1.65 parts) x 500 mL = 391 mL
Prepare 500 mL of D12.5W. You have on hand D5W, D10W, and D20W. How much of which two solutions will you use?
answer = 20% and 5%-250 mL; 20%-125 mL. 10%-375 mL
Prepare 300 mL of 7.5% dextrose using SWFI and D20W. How much of each is needed?
answer = 20%-112.5 mL; SWFI- 187.5 mL draw a tic tac toe table placing the highest concentration (20%) in the upper left corner, the desired concentration ( 7.5%) in the middle and the lowest concentration (0%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. SWFI is sterile water for injection and has a concentration of 0%, and D20W means 20% dextrose in water. calculate the proportions for each needed and multiply by the quantity to be prepared. 20%: (7.5 parts/20 parts) x 300 mL = 112.5 mL; SWFI: (12.5 parts/20 parts) x 300 mL = 187.5 mL
How much 10% dextrose solution and 20% dextrose solution should be mixed to prepare 1 L of 12.5 % dextrose solution?
answer = 20%-250 mL; 10%-750 mL draw a tic tac toe table placing the highest concentration (20%) in the upper left corner, the desired concentration ( 12.5%) in the middle and the lowest concentration (10%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. calculate the proportions of each needed and multiply by the quantity to be prepared (1 L = 1000 mL). 20%: (2.5 parts/10 parts) x 1000 mL = 250 mL; 10%: (7.5 parts/10 parts) x 1000 mL = 750 mL
If a physician prescribed cephalexin 250 mg qid for 10 days, how many milliliters of cephalexin oral dispension containing 250 mg/tsp should be dispensed?
answer = 200 mL the patient is to take 250 mg four times per day for 10 days. 250 mg is contained in a 1-tsp (5 mL) dose: (5 mL/dose)(4 doses/day)(10 days) = 200 mL
The physician has ordered Coumadin 5 mg to be taken on Monday, Wednesday, and Friday. On Tuesday, Thursday, Saturday, and Sunday, the patient is to receive 2 1/2 mg. How many milligrams will the patient take in 1 week?
answer = 25 mg multiply 5 mg by 3 days. multiply 2 1/2 mg by 4 days. add the sum of these two products
If a child is 4 years old and the adult dose of medication is 100 mg, how much medication should the child receive?
answer = 25 mg solve using young's rule. young's rule = {age (in years)/[age (in years) + 12]} x adult dose. in this problem, the child is 4 years old, and the adult dose is 100 mg. substituting into the equation will result in the following: [4/(4+12)] x 100 mg = 25 mg
Make 30 mL of a vitamin B12 dilution with a concentration of 100 mcg/ mL from a stock solution of 1 mg/mL. How much vitamin B 12 and diluent are needed?
answer = 3 mL of vitamin B12 and 27 mL of diluent IS = 1 mg/mL (1000 mcg/mL), IV = unknown, FS = 100 mcg/mL, and FV = 30 mL: (1000 mcg/mL)(IV) = (100 mcg/mL)(30 mL), where IV = 3 mL. the amount of diluent = FV - IV: 30 mL - 3 mL = 27 mL
The order is for K-Lor 60 mEq PO stat. Each packet contains 20 mEq. How many packets of K-Lor will you need?
answer = 3 packets this is a proportion problem using mEq: 20 mEq/ 1 packet = 60 mEq/X mL, where X = 3 packets
How many grams of antipyrine should be used in preparing the following prescription? Rx: Antipyrine 5% Glycerin ad: 60
answer = 3.0 g of antipyrine use the following formula: final weight x % (expressed as a decimal) = amount of active ingredient, where 60 g is the final weight and 5% is equal to 0.05
The prescriber ordered 175,000 units of urokinase IVPB. The vial directions read: "Add 4.2 mK to vial and each mL will contain 50,000 units." How many milliliters will you prepare?
answer = 3.5 mL this is a proportion problem. 50,000 units/1 mL = 175,000 units/X mL, where X = 3.5 mL
Prepare 15 ml of cefazolin dilution 50 mg / mL from a stock of 1 g/5 mL. How many milliliters of the diluent and cefazolin will be needed?
answer = 3.75 mL of cefazolin; 11.25 mL of diluent IS = 1 g/5 mL (1000 mg/5 mL), IV = unknown, FS = 50 mg/mL, and FV = 15 mL: (1000 mg/5 mL)(IV) = (50 mg/mL)(15 mL), where the IV = 3.75 mL of cefazolin. the problem asks for the amount of diluent that is needed and can be solved using (FV) - (IV) = amount of diluent: (15 mL) - (3.75 mL) = 11.25 mL of diluent
An initial heparin dose of not less than 150 units/ kg of body weight has been recommended for open heart surgery. How many milliliters of an injection containing 5000 heparin units per milliliter should be administered to a 280 lb-patient?
answer = 3.82 mL convert the patient's weight from pounds to kilograms (280 lb x 1 kg/2.2 lb = 128.27 kg). calculate the dose needed: (172.27 kg) x (150 units/kg) = 19,095 units/X mL, where X = 3.82 mL
How many milliliters of a 3% (w/v) solution will be necessary to make 6 oz of a 1:200 solution?
answer = 30 mL this is a dilution problem and can be solved using (IS)(IV) = (FS)(FV), where IS (3%), IV (unknown), FS (1:200), and FV (6 oz). one needs to make sure that both the strengths and volumes are in common terms. convert the ratio (1:200) to a fraction (1/200) to a decimal (0.005) to a percent (0.005 x 100 = 0.5%). next, convert ounces (6 oz) to millimeters: (6 oz)(30 mL/oz) = 180 mL. substitute into the following equation: (IS)(IV) = (FS)(FV) or (IV)(3%) = (0.5%)(180 mL), where IV is 30 mL
You are asked to prepare 36 mL of a 1:4 Bactrim solution, and you have in stock 30% solution. How many milliliters of the 30% solution will you use?
answer = 30 mL this is a dilution problem where concentrations are expressed as a concentration and a percentage. the concentrations need to be expressed in the same terms. convert the ratio (1:4) to a percent (25%). this is a dilution problem that can be solved using the following formula (IS)(IV) = (FS)(FV), where IS = 30%, IV = unknown, FS = 25%, and FV = 36 mL: (30%)(IV) = (25%)(36 mL), where IV = 30 mL
What will be the rate in gtt/min if a patient receives 1 L of an IV fluid over an 8-hr period if the drop factor = 15 gtt/mL?
answer = 31 gtt/min rate x drop factor x conversion factor = gtt/min: (1000 mL/8 hr) x (15 gtt/mL) x (1 hr/60 min) = 80 mL/hr
A dose of antacid is 1 tbsp. How many doses can be prepared from a pint bottle?
answer = 32 doses one tablespoon is equal to 15 mL, and 1 pint is equal to 480 mL. solve using a proportion: 15 mL/1 dose = 480 mL/X doses, where X = 32 doses
You are asked to prepare 50 mL of a 1:3 folic acid solution, and you have in stock a 1:2 solution. How many milliliters of the 1:2 solution will you use?
answer = 33 mL IS = 1:2, IV = unknown, FS = 1:3, and FV = 50 mL: (1:2)(IV) = (1:3)(50 mL), where IV =33 mL
How many milliliters of a 95% (v/v) alcohol should be used in preparing 1 pint of a 75% (v/v) solution?
answer = 379 mL IS = 95%, IV = unknown, FS = 75%, and FV = 1 pint (480 mL): (95%)(IV) = (75%)(480 mL), where IV = 379 mL
What is the percent of a 1:25 (w/v) solution?
answer = 4% convert the ratio to a proportion (1:25 is equal to 1/25). next, multiply 1/25 by 100 to obtain the answer of 4%
If a pharmacist adds 3 g of hydrocortisone to 120 g of a 5% hydrocortisone cream, what is the final percentage strength of hydrocortisone in the product?
answer = 4.88% this is a dilution problem and can be solved using the following equation: Initial strength (IS) x Initial weight (IW) = Final strength (FS) x Final weight (FW). IS = 5%, IW = 120 g, FS (unknown), FW = 123 g. (5%)(120 g) = (X%)(123 g), where X = 4.88%
How many milliliters of IV fluid will a patient receive if infused at the rate of 120 mL/hr over 3 1/2 hr?
answer = 420 mL volume = rate x time or 120 mL/hr x 3 1/2 hr = 420 mL
The formula for a buffer solution contains 1.24% (w/v) of boric acid. How many milliliters of a 10% (w/v) boric acid solution should be used to obtain the boric acid needed in preparing 1 gal of buffer solution?
answer = 476 mL 1 gallon = 3840 mL. IS = 10%, IV = unknown, FS = 1.24% and FV = 3840 mL: (10%)(IV) = (1.24%)(3840 mL), where IV = 476 mL
How many chloramphenicol capsules each containing 250 mg of chloramphenicol are needed to provide 25 mg/kg of body weight per day for 1 week for a person weighing 154 lb?
answer = 49 capsules convert pounds to kilograms ( 154 lb x 1 kg/2.2 lb). multiply the weight in kilograms by 25 mg/kg to obtain the dose per day. multiply the daily dose by 7 days. divide the total dose by 250 mg per capsule to obtain the number of capsules needed
How many grams are in 1 L of a 1:200 solution?
answer = 5 g 1:200 is a ratio. 1 L = 1000 mL. convert ratio (1:200) to a fraction (1/200) and express the answer as a decimal (0.05). this is a w/v problem and can be solved using the following: FV (1000 mL) x Percent as a decimal (0.05) = Amount of AI (5 g)
If a child weighs 50 lb and the adult dose is 1 tbsp, how many milliliters should the child receive?
answer = 5 mL solve using clark's rule: (50/150) x 15 mL = 5 mL
If 500 mL of an IV solution contains 0.1 g of a drug, at what flow rate in milliliters per minute should the solution be administered to provide 1 mg/min of the drug?
answer = 5 mL/min calculate the amount of time 0.1 g (100 mg) would be infused into the body if the patient is receiving 1 mg/min by using a proportion: 1 mg/min = 100 mg/X min, which is 100 min. 100 mg is contained in 500 mL, which will take 100 min to infuse. the flow rate = volume (500 mL)/ time (100 minutes) = 5 mL/min
In what proportion should 5% and 1% hydrocortisone ointments be mixed to prepare a 2.5% ointment?
answer = 5%-1.5 parts; 1%-2.5 parts draw a tic tac toe table placing the highest concentration (5%) in the upper left corner, the desired concentration ( 2.5%) in the middle and the lowest concentration (1%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. calculate the proportions of each needed. 5%: 1.5:4 and 1%: 2.5:4
The prescriber ordered 0.05 mg of Sandostatin PO, a hormone. How many micrograms are in this dose?
answer = 50 mcg convert 0.05 mg to micrograms. multiply 0.05 mg by 1000 mcg
If a child is 36 months old and the adult dose is 250 mg, how much medication should the child receive?
answer = 50 mg solve by using young's rule. 36 months/12 months/year = 3 years. [(3)/(3+12)] x 250 mg = 50 mg
How many colchicine tablets each containing 600 mcg may be prepared from 30 g of colchincine?
answer = 50,000 tablets convert 30 g to micrograms by multiplying by 1,000,000. divide 30,000,000 mcg by 600 mcg/tablet
A pediatric patient is to be given a 70-mg dose of Dilantin by administration of an oral suspension containing 50 mg of Dilantin per 5 mL. How many milliliters of the suspension must be administered?
answer = 5000 mcg this problem can be solved by using the following proportion: 20 mg/2 mL = X mg/0.5 mL, where X = 5 mg. convert 5 mg to micrograms by multiplying by 1000 mcg/mg
How many grams of Eucerin should be added to 4 oz of a 10% ointment to make a 7% ointment?
answer = 51 g one ounce (wt) is approximately 30 g. IS = 1:20, IW = 120 g (4 oz x 30 g/oz), FS = 7%, and FW = unknown: (10%)(120 g) = (75%)(FW) where FW = 171 g. the problem is asking for the amount of diluent to be added. FW - IW = amount of diluents, or 171 g - 120 g = 51 g of diluent
You are to prepare a dose of 300 mg and the tablets are available in 75-mg strength. How many tablets will the pharmacist need to dispense if the patient is to take 300 mg bid for 1 week?
answer = 56 tablets solve using the following proportion: 75 mg dose/1 tablet = 300 mg dose/X tablets, which is 4 tablets. the abbreviation "bid" means twice per day. solve for the number of tablets: 4 tablets/dose x 2 doses/day x 7 days = 56 tablets
How many grams of reserpine would be required to make 25,000 tablets, each contains 250 mcg of reserpine?
answer = 6.25 g multiply 250 mcg/tablet by 25,000 tablets. divide the product 1,000,000 mcg/g
You receive an order for 125 mL of 4% acetic acid solution and you have in stock a 75% acetic acid solution. How many milliliters of the 75% solution will you need?
answer = 6.67 mL this is a dilution problem and can be solved using (IS)(IV) = (FS)(FV), where IS = 75%, IV = unknown, FS = 4%, and FV = 125 mL: (75%)(IV) = (4%)(125 mL), where IV = 6.67 mL
How many 600-mg ibuprofen tablets will be needed to make 8 oz of a 15% ointment?
answer = 60 tablets 8 oz of ointment is approximately 240 g. the problem can be solved using the following equation: FW x % (decimal) = amount of AI (g) or 240 g x 0.15 = 26 g or 3600 mg (36 g x 1000 mg/g) of active ingredient. to calculate the number of tablets needed, divide the total amount of AI by the weight of one tablet, which is 36,000 mg/600 mg/tablet = 60 tablets
What is the total volume that will be delivered if a patient receives normal saline solution at 25 mL/hr for 24 hr?
answer = 600 mL this problem can be solved by multiplying the rate (25 mL/hr) by the amount of time (24 hr): (25 mL/hr) x (24 hr) = 600 mL
A physician orders 3 L D5W to be administered over 24 hr. How many drops per minute will be delivered using an administration set calibrated to deliver 30 drops per milliliter?
answer = 62 gtt/min rate = 125 mL/hr; drop factor (DF) = 30 gtt/mL and 1 hr/60 min (CF). solve using the following formula: rate x DF x CF = gtt/min: (125 mL/hr) x (30 gtt/mL) x (1 hr/60 min) = 62 gtt/min. remember drops per minute are always rounded downward when one has a fraction of a drop
Medication: Solu-Cortef 250 mg a. Fluid volume: 250 mL b. Time of infusion: 4 hr c. How many ml/hr? How many mg/hr?
answer = 62.5 mL/hr rate = volume/time or 250 mL/4 hr = 62.5 mL/hr. amount of drug/time. 250 mg/4 hr = 62.5 mg/hr
A stock bottle of Lugol solution contains 2 oz from the original pint bottle. The pharmacy technician is able to prepare four 8-oz bottles of a more dilute 4% solution. What was the original percentage strength of the Lugol solution?
answer = 64% this is a dilution problem and can be solved using the following: (IS)(IV) = (FS)(FV), where IS = unknown, IV = 2 oz, FS = 4%, and FV = 32 oz (4 bottles x 8 oz/bottle). (IS)(2 oz) = (4%)(32 oz), where IS = 64%
A prefilled syringe of furosemide contains 20 mg of drug in 2 mL of solution. How many micrograms of drug would be administered by an injection of 0.5 mL of the solution?
answer = 7 mL this problem can be solved using the following proportion: 50 mg/5 mL = 70 mg/ X mL
A 25-lb child is to receive 4 mg of phenytoin per kg of body weight as an anticonvulsant. How many milliliters of pediatric phenytoin suspension containing 30 mg/ 5 mL should the child receive?
answer = 7.5 mL convert 25 lb to kilograms using the following proportion: 2.2 lb/1 kg = 25 lb/X kg, where X = 11.36 kg. multiply the patients weight (kg) by the dose (4 mg/kg) or (4 mg/kg)(11.36 kg) = 45.45 mg. calculate the number of millimeters needed: 30 mg/5 m: = 45.45 mg/X mL, where X = 7.5 mL
How many milliliters of a 1:2000 iodine solution and a 7.5% iodine solution are needed to make 120 mL of a 3.5% solution?
answer = 7.5%-55.6 mL; 1:2000-64.4 mL this is an alligation problem. convert 1:2000 to a percent (0.5%). draw a tic tac toe table, placing the highest concentration (7.5%) in the upper left corner, the desired concentration (3.5%) in the middle and the lowest concentration (0.5%) in the bottom left corner. subtract the concentration in a diagonal manner and place the number opposite the remaining concentration. calculate the proportions of each needed and multiply by the quantity to be prepared. 7.5%: (3 parts/7 parts) x 120 mL = 55.6 mL; 0.5%: (4 parts/7 parts) x 120 mL = 64.4 mL
How many milliliters of water should be added to 500 mL of a 1:2000 (w/v) solution to make a 1:5000 (w/v) solution?
answer = 750 mL IS = 1:2000, IV = 500 mL, FS = 1:5000, and FV = unknown: (1:2000)(500 mL) = (1:5000)(FS), where FS = 1250 mL. the problem is asking for the amount of diluent to be added and can be calculated by substituting the initial volume from the final volume. 1250 mL - 500 mL = 750 mL of diluent
A volume of fluid weighs 80 g and has a specific gravity of 1.05. What is its volume?
answer = 76 mL specific gravity = 1.05 and weight is 80 g. substituting into the equation for specific gravity: 1.05 = 80/X, where X = 76 mL
You are asked to prepare 80 mL of a 72% lidocaine solution, and you have in stock a 75% solution. How many milliliters of the 75% solution will you use?
answer = 76.8 mL IS = 75%, IV = unknown, FS = 72%, and FV = 80 mL: (75%)(IV) = (72%)(80 mL), where IV = 76.8 mL
Convert 25° Celsius to Fahrenheit
answer = 77° F solve by using the formula 9C = 5F - 160, where you replace the C with 25: 9(25) = (5)(F) - 160, and perform the necessary operations
Convert 45° Fahrenheit to Celsius
answer = 7° C solve by using the formula 9C = 5F - 160, where you replace F with 45: 9(C) = 5(45) - 160 and perform the necessary operations
If 1000 mL at 20 drops/min is administered using a 15-drop set, what is the flow rate in milliliters per hour?
answer = 80 mL/hr (20 gtt/min)/(15 gtt/mL) x (1 hr/60 min) = 80 mL/hr
If the dose of a drug is 150 mcg, how many doses can be prepared form 0.120 g?
answer = 800 doses convert 0.120 g to micrograms (1,000,000 mcg/1 g = X mcg/0.120 g, where X = 120,000 mcg). calculate the number of doses using a proportion: 150 mcg/1 dose = 120,000 mcg/X doses, where X = 800 doses
Cyclosporine is an immunosuppressive agent administered before and after organ transplantation at a single dose of 15 mg/kg. How many milliliters of a 50 mL bottle containing 100 mg of cyclosporine per milliliter would be administered to a 140-lb kidney transplant patient?
answer = 9.54 mL convert pounds to kilograms (140 lb x 1 kg/2.2 lb). multiple the weight in kilograms by 15 mg/kg to obtain the daily dosage required. to calculate volume desired, solve using a proportion: 100 mg/mL = daily dosage/ X mL
You are asked to prepare 125 m L of 1:8 nystatin suspension, and you have in stock a 1:6 solution. How many milliliters of the 1:6 nystatin solution will you need?
answer = 91.94 mL this is a dilution problem using ratios as concentrations. IS = 1:6, IV = unknown, FS = 1:8, and FV = 125 mL: (1:6)(IV) = (1:8)(125 mL)m where IV = 91.94 mL
In what proportions should alcohols of 95% and 50% strengths be mixed to prepare 250 mL of a 75% alcohol solution?
answer = 95%-5:9; 50%-4:9 this is an alligation problem. draw a tic tac toe table, placing the highest concentration (95%) in the upper left corner, the desired concentration (75%) in the middle, and the lowest concentration (50%) in the bottom left corner. subtract the concentrations in a diagonal manner and place the number opposite the remaining concentration. 95%-75%= 20 parts of 50%. 75%-50%= 25 parts of 95%. total all of the parts (45); 95% will require 25/45 (5:9), and 50% will require 20/45 (4:9)
1 L NS is to be administered over 24 hr. The administration set to be used has a DF of 15 gtt/mL. What is the rate of infusion in a. mL/hr? b. gtt/min?
answer = a. 41 mL/hr rate = volume/time, or 1000 mL/24 hr = 41 hr. a number less than a whole is rounded down in flow rates. b. 10 gtt/min. the problem can be solved by the following formula: rate x drop factor x conversion factor = gtt/min: (41 mL/hr) x (15 gtt/mL) x (1 hr/60 min) = 10 gtt/min
Hydrocodone Bitartrate 0.2 g Phenacetin 3.6 g Aspirin 6.0 g Caffeine 0.6 g M ft caps no 24 Sig i cap tid prn pain a. How many milligrams of hydrocodone bitartrate would be contained in each capsule? b. What is the total weight, in milligrams, of the ingredients in each capsule? c. How many milligrams of caffeine would be taken daily?
answer = a. 8.33 mg/capsule b. 430 mg per capsule c. 75 mg you have been given a formula that will yield 24 capsules. divide the amount of hydrocodone bitartrate (0.2 g) by the number of capsules one is to prepare: 0.2 g/24 capsules = 0.00833 g/capsule. convert 0.00833 g x 1000 mg/g = 8.33 mg/capsule. b. 430 mg per capsule. add up the total weight of all of the ingredients (10.4 g) and divide by 24 capsules. each capsule will weigh 0.43 g. convert grams to milligrams: 0.43 g x 1000 mg/g = 430 mg. c. 75 mg. 0.6 g of caffeine/24 capsules = 0.025 g of caffeine/capsule. convert grams to milligrams. 0.025 g x 1000 mg/1 g = 25 mg. the directions state that the patient is to take one capsule three times per day. 25 mg of caffeine/capsule x 3 capsules = 75 mg
