calculations
Ratio Strength to Percentage Strength
% strength = 100 / ratio strength
what is the osmolarity of normal saline? MW 58.5 - round to whole
- convert 0.9% to g/L - use that 9g/L into formula - NaCL dissociates into 2 particles - answer is 308 dissociation of particles- mannitol/dextrose=1 Nacl=2 KCL=2 cacl=3 sodium citrate= 4 sodium acetate= 2
express 0.00022% as PPM
0.00022/100 = X/1,000,000 2.2 PPM
express 0.04% as a ratio strength
0.04/100 = 1 part / X parts x = 2,500 ratio strength is 1:2,500
how many grams are equal to 50,000,000 ng?
0.05 g (iPad or pg 8)
the e-value for ephedrine sulfate is 0.23. How many grams of sodium chloride are needed to compound the following prescription? Round to 3 decimal Ephedrine 0.4g Sodium chloride qs Purified water 30mL make isotonic soln Sig. For the nose
0.178g of nail needed for isotonic soln step 1. determine Nacl to make step 2. determine Nacl from ephedrine (0.4 * E-value) step 3. subtract #1 from #2 to get total Nacl needed
how many moles are equivalent to 45 grams of potassium carbonate (MW 138) round to thousandth
0.326
calculate E value for potassium iodide, dissociates to 2 particles, (MW 166) round 2 decimal places
0.35
a 165 lb patient is to receive 250mL of a dopamine drip at a rate of 17mcg/kg/min. The pharmacy has dopamine premixed in concentration of 3.2mg/mL in d5w. Calculate the infusion rate in mL/minute. Round to the nearest tenth.
0.4ml/min
digoxin injection is supplied in ampules of 500 mcg per 2 mL. how many mL must a nurse administer to provide a dose of 0.2mg?
0.8mL
a pharmacist received this bactrim rx and dispensed 3 oz to MB. How many days of therapy will she be short? bactrim 40-200 mg/5mL Sig: 1 tsp PO BID x 10d until all taken
1 day short
express 1:4000 as percentage strength
1 part/4000 part = x percent/ 100 or 100/4000= 0.025%
what is the percentage strength of imiquimod in following rx? round to nearest hundredth. imiquimod 5% cream-- 15g xylocaine--- 20g hydrophilic pint--- 25g
1.25%
the pharmacy has insulin vials containing 100 units of insulin/mL. A physician orders 15 units of regular insulin to be added to a liter of D5W to be given over 10 hours. How many units of insulin will the patient receive each hour if the IV set delivers 15 drops/mL. do not round
1.5 units/hr
if phenobarbital contains 18.2 mg of phenobarbital per 5mL, how many grams of phenobarbitals would be used in preparing a pint of the elixir? round to nearest tenth
1.7g
a patient is taking 3 calcium citrate tablets daily (one tablet, TID). Each weighs 1500mg total (non-elemental) weight. She wishes to trade her calcium tablets for the carbonate form. IF she is going to use 1250mg carbonate tablets (by weight) how many tablets will she need to take to provide the same total daily dose?
1.89 ~2 tablets
the pharmacist has calculated that a patient requires 30 mmol of phosphate and 80 meq of potassium. The pharmacy has stock solutions of potassium phosphate (3mmol of phosphate with 4.4 meq potassium/mL) and potassium chloride (2 meq K/mL). How much potassium phosphate and how much potassium chloride will be required?
10 mL KPO4 18 mL KCL
how many millimolses of calcium chloride (MW 147) are represented in 147 mL of a 10% w/v calcium chloride solution
100mmol
patient is receiving 660 mL of 10% intralipid on saturdays along with his normal daily PN therapy of 1420 mL of d20W, 450mL aminiosyn 15%, and 30mL of electrolytes. What is the daily art of calories provided by the lipids? round to nearest whole number.
104 kcal/day --> getting 660mL of intralipid on SAT (per week) so divide by 7 to get days
a patient has been receiving 200mL of an enteral mixture that contains 432 mOsm/L. the pharmacist will reduce the contents to 278 mOsm/L. How many mL of bacteriostatic water should be added to the bag? round to nearest mL.
111ml of bacteriostatic water p31
How many mL of 23.4% sodium chloride should be added to PN. Item/ qty Sodium chloride MW 58.5--> 44meq
11mL
how many grams of dextrose are in 250mL of D5W? round to nearest tenth
12.5g
a 45 mL nasal spray delivers 20 sprays per ml of solution. Each spray contains 1.5mg of active drug. How many mg of drug contained in the 45mL package?
1350mg
a prescription reads as follows: "prepare a 3% w/w coal tar preparation qs with petrolatum too 150g." How many grams of petrolatum are required to compound the prescription? round to nearest tenth.
145.5g
A patient will receive 400 mg of a drug that has been put in a 250mL IV bag. The rate of drug administration is 375mcg per minute. Calculate the flow rate in mL per hour. Round to nearest whole number.
14ml/hr
1 tbsp = ___ mL
15 mL
if 1 gallon of a 20% (w/v) solution is evaporated to a solution with 50% (w/v) strength, what will be the new volume (in mL)? round to nearest 100mL
1500 mL 1 gallon= 4 qt 4 qt= 2pint/1qt --> 8 pt 8pt= 16oz/ 1 pt --> 128 oz 128 oz= 30 mL/ 1 fl oz ---> 3840mL dilution/concentration
how many calories will wilma receive from the fat component of the 1 (8 fl.oz) shake. Round to the nearest whole number. Nutrition label- serving size 8 fl oz (237 mL) calories: 356 total fat: 17.8g protein: 19.6 g carbohydrate: 31/5 g
160 kcal
1 pint = ___ oz = ___ mL
16oz 1 oz= 30 mL
TE is a 35 year old female who is receiving 325 grams of dextrose, 85 grams of amino acids, and 300mL of 10% lipids via her PN therapy. What percentage of total calories is provided by the protein content? Round whole number
19%
there are 50mg of drug in 50mL of solution. Express the concentration as a ratio strength (%w/v)
1:1000
what is the concentration, in ratio strength of a trituration made by combining 150mg of albuterol sulfate and 4.05 grams of lactose?
1:28
a patient is to receive keeper at a rate of 5mg/min. The pharmacy has a 5 mL vial (100mg/mL) which will be diluted in 100mL of NS. What is the Keppra infusion rate, in mL/min?
1ml/min
1 quart = ____ pints
2 pints
1kg = ? lb
2.2 lb
how many grams NaCL are in 500mL of 1/2 NS? round nearest hundredth
2.25g
a 10mL mixture contains 0.25mL of active drug. Express the concentration as % strength (% v/v) and ratio strength.
2.5% 1:40
1 inch = ___ cm
2.54 cm
a cough syrup contains 4 g of brompheniramine maleate per liter. How many mg are contained in a teaspoonful dose of the elixir?
20 mg
pharmacist is making PN that needs to contain 80 meq of sodium and 45 meq of acetate. Available pharmacy stock solutions contain 4 meq/mL sodium as sodium chloride and 2meq/ml sodium as sodium acetate. The final volume of PN will be 2.5L to be given at 100ml/hr. what qty, in mL of each stock should be added to meet requirements?
22.5mL of acetate 8.75 ml of chloride
if 12 g of lanolin are combined with 2 grams white wax and 36g petrolatum to make an pint, what is % strength (w/w) of lanolin in the pint?
24% w/w
a pharmacist must prepare 100 grams of 50% HCT powder using 25% and 75% powders that she has in stock. How much of each is required?
25-50 = 25 parts 75-50 = 25 parts 50 total parts 25/50 *100g = 50 g for each
a 76 yo, 154 lbs (IBW) is NPO and needs hydration. She is AF and doesn't have HF, renal disease or ascites. What volume of fluid should the patient recieve per day?
2500 ml/day
a patient is to recieve flagyl at a rate of 12.5mg/min. the pharmacy has a 5mL (100mg/mL) flagly injection vial to be diluted in 100mL of NS. how much drug in mg will the patient receive over 20 minutes?
250mg
1 oz = ? grams
28.4
how many ml of mylanta contained in each dose of the prescription below? round to nearest whole number. belladonna tincture = 10mL phenobarb= 60mL mylanta susp qs ad= 120ml sig. 5mL BID
2mL mylanta per dose
an IV infusion contains 2mL of a 1:1,000 (w/v) solution of epinephrine and 250 mL of D5W. At what flow rate in mL/min, should the infusion be administered to provide 0.3 mcg/kg/min of epinephrine to an 80kg patient? round whole number.
2ml/min
a buffer solution is prepared using 0.3 mole of a weakly basic drug an an unknown quantity of its salt (aka of the drug=10.1). the final solution has a pH of 8.99. How much of the salt was used? Round to the nearest hundredth.
3.86
1 fl oz
30 mL
express 30 PPM as a percentage
30/1,000,000 = X/100 0.003%
a female patient is to receive a 5 mg/kg/day of theophylline. The patient is 5'7" and weighs 243 lb. Calculate daily theophylline dose the patient should receive.
308 mg Think- 1. calculate TBW 2. calculate IBW 3. what drug is it 4. pick right kg to calculate dosing
a physician writes order for aminophylline 500 mg IV, dosed at 0.5mg/kg/hr for pt 165 lb. Only theophylline in stock. How many mg of theophylline will pt recieve per hour?
30mg/hr theophylline take 37.5mg aminophylline *0.8
a patient is to receive 600,000 units pen G potassium in 100mL D5W. a vial of pen G potassium 1,000,000 units is available. The manufacturer states that when 4.6mL of diluent is added, 200,000 units/mL will result. How many mL of reconstituted solution should be withdrawn and added to the bag of D5W?
3mL
1 gallon= ___ quarts
4 quarts
RS is a 45 year old male, 5'5", 168 pounds, hospitalized with a diabetic food infection. the pharmacist prepared a 500mL bag of D5W containing 1 gram of Vancomycin to be infused over 4 hours using a 20 gtts/mL iV tubing set. How many mg of Vancomycin will the patient recieve each minute? (round nearest tenth)
4.2mg/min
how many milliosmoles of CaCl2 (MW 111) are represented in 150mL of 10%v (w/v) calcium chloride solution? round whole number
405 mOsm
1lb = ?g
454g
a pharmacist receives a prescription for a 1.5% (w/w) hydrocortisone cream using cold cream as the base. She will use hydrocortisone injection (100mg/mL, SG 1.5) to prepare the prescription because she has no hydrocortisone powder in stock. How many grams of cold cream are required to compound 60 grams of the preparation?
46.5 g cold cream
how many grams of petrolatum (diluent) should be added to 250 grams of a 20% ichthammol ointment to make 7% ichthammol ointment? round to nearest tenth
464.3 g petrolatum required Be careful as the question asks additional diluent so extra step needed (p. 30) q54
1 pint = ___ mL
473
1 tsp = ___ mL
5 mL
how many nanogram are equal to 5 kg?
5*10^12 pg 8 (iPad)
how many mL of a 1:2500 (w/v) solution of aluminum acetate can be made from 100mL of 0.2% solution?
500 mL q1xc1=q2xc2
a patient's blood contains 0.085 PPM of selenium. How many micrograms of selenium does the patient's blood contain if blood volume is 6 liters?
510 mcg
a pharmacist adds 5.3 grams of hydrocortisone to 150g of 2.5% hydrocortisone pint. what is the percentage (w/w) of hydrocortisone in the finished product? Round to nearest whole number.
6%
if 1250g of a mixture contains 80g of drug. what is percentage strength (w/w) of the mixture? round to nearest tenth
6.4%
the PN contains 6 mL of potassium phosphate (3mmol phosphate and 4.4 meq of potassium/mL) the daily potassium requirement from the PN order is 40 meq. How much potassium chloride (2meq/mL) in mL, should be added to the PN? round to nearest tenth
6.8 mL
how many g bacitracin and nystatin are required to prepare 150g of a 2:3 topical bacitracin: nystatin ointment?
60g bacitracin 90g nystatin (iPad or pg 9)
1 grain = ? mg
65 mg
a pharmacist has an order for parenteral nutrition that includes 550mL of D70%. The pharmacist checks the supplies and finds the closest strength he has available is D50%. How many mL of D50% will provide an equivalent energy requirement?
770mL 550ml x 70%= Q2 x 50%
1 quart = _____ milliliters
946mL
a patient is recieving 30 mol of phosphate and 8 meq of calcium. The volume of the PN is 2000mL. there are 2 meq PO4/mmol. Confirm that the sum of calcium and phosphorus does not exceed 45 meq/L.
= 34meq/L doesn't exceed
aminophylline to theophylline vice versa
A--> T (multiply by 0.8) T--> A (divide by 0.8)
equation for isotonicity
E = (58.5 * i)/ (MW * 1.8) # of dissociated ions & dissociation factor(i) 1--> 1 2--> 1.8 3--> 2.6 4-->3.4 5--> 4.2
pharmacist receives an order for 10mL of tobramycin 1% ophthalmic solution. He has tobramycin 40mg/mL solution. Tobramycin does not dissociate and has a MW of 468. Find E value for tobramycin and determine how many mg of Nacl needed to make this solution isotonic. Round to 2 decimal places
E value= 0.07 83 mg of nail needed
liquid conversion (gallons, qt, pint, oz)
Gallons>qt> pt> oz>mL
common IV fluid % NS (NaCL) 1/2 NS 1/4 NS D5W D20W
NS= 0.9g/100mL (0.9% w/v) 1/2 NS= 0.45 1/4 NS= 0.225 D5W= 5% (w/v) D20W= 20%
Percentage Strength to Ratio Strength
Ratio strength = 100 / % strength
a pharmacist will prepare an amoxil suspension to provide a 1600mg daily dose for a child with otitis media. The dose will be divided BID. To prepare an Amoxil suspension containing 200mg/5mL the pharmacist should add 76 mL of water to powder for final volume of 100mL. The pharmacist should add approximately 1/3 of water first, shake and then add remaining water. Pharmacist mistakenly adds too much and finds final volume to be 110. The pharmacy has no other bottles of amoxil and will dispense the bottle with extra water added. How many mL should the patient take BID to recieve the correct dose? round to whole number.
answer: 22mL 1. find daily dose in mL (200mg/5mL *1600mg)= 40mL daily dose (20ml/dose) 2. 20ml/100 final *(xmL/110final)= 22mL
osmolarity of each compound and dissociation of particles dextrose mannitol potassium chloride (KCL) sodium chloride (NaCL) sodium acetate (NaC2H3O2) sodium citrate (NaC6H5O7) calcium chloride (CaCl2)
dextrose --> 1 mannitol --> 1 potassium chloride (KCL) -->2 sodium chloride (NaCL) --> 2 sodium acetate (NaC2H3O2) -->2 sodium citrate (NaC4H5O7)-->4 calcium chloride (CaCl2) --> 3
mOsm equation
mOsm/L= (wt of substance/ MW g/mol) * (# of particles) * 1,000
a hospice pharmacist receives a prescription for 1% morphine sulfate oral solution. She has a 120mL bottle of morphine sulfate labeled 20mg/5mL and a 240mL bottle of morphine sulfate labeled 100mg/5mL. How much of the 100mg/5mL product must be mixed with the contents of the 20mg/5mL morphine sulfate bottle to prepare the desired percentage strength for the patient?
p. 34 72 mL of 2% morphine sulfate 120mL used for the 20mg/5mL
79 yo F, dry mouth w/ sjogre. Picking up rx below. What is max mg pilocarpine she will have per day? pilocarpine 1% (w/v) sodium chloride qs ad 15mL sig: 2gtts (0.05mL/gtt) po TID pro up to 5 days for dry mouth
pg 23 3mg pilocarpine
dilution and concentration equation for manipulating strength or qty of product to inc/dec
q1xc1=q2xc2 q1= old qty q2= new qty c1=old conc c2= new conc
what % ionization of amitriptyline, a weak base with a pka= 9.4, at a physiologic pH of 7.4?
weak base % ionization= 100/ 1+10 ^(ph-pka)
the pharmacist has an oder for heparin 25,000 units in 250mL D5W to infuse at 1,000 units/hour. How many hours will it take to infuse the entire bag?
x= 25 hours
