Calculations II Flashcards by Emily Byford

What are the types of percentage concentrations that are used in Percentage Strength?

Weight-in-Volume [%W/V] = g/100 ml
Volume-in-Volume [%V/V] = ml/100 ml
Weight-in-Wieght [%W/W] = g/100 g

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Example Quesiton 1

How many grams of NaCl are in 1 Liter of Normal Saline [NS]?

NS = 0.9 g / 100 ml

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Example Question 2

How many grams of NaCl are in 500ml of 1/2 NS? Round to the nearest hundereth.

1/2 NS = 0.45 g / 100 ml

2.25 g

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Example Question 4

How many milligrams of triamcinolone should be used in preparing the following perscription? Round to the neartest whole number.

Triaminolone [w/v] = 5%
Glycerin qs = 60 mL
Sig: Two drop in right ear once daily

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Example Quesiton 3

How many grams of Dextrose are in 250 ml of D5W? Round to the nearest tenth?

D5W - 5% = 5 g / 100 ml

12.5 g

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Example Question 5

A prescription reads as follows: “Prepare a 3% w/w coal tar preparation; qs with petrolatum to 150 grams.” How many grams of Petrolatum are required to compound the prescription? Round to the nearest tenth.

145.5 g petrolatum

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Example Question 6

A pharmacist is compounding a vancomycin suspension. The master recod says to reconstitute a 5 g vial of vancomycin powder for injection with 50 ml of sterile water, then dilute with sterile water to 200 ml. What is the final precentage strength of the compounded product [w/v]?

2.5 g / 100 mL OR 2.5%

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Example Question 7

If 1,250 grams of a mixture contains 80 grams of a drug, what is the percentage strength [w/w] of the mixture? Round to the nearest tenths.

6.4 g / 100 g OR 6.4%

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Example Question 8

A mouth rinse contains 1/12 % w/v of Chlorhexidine Gluconate. How many grams of Cholrhexidine Gluconate should be used to perpare 18 Liters of mouth rinse? Round to the nearest whole number.

15 g

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Example Question 9

SS is a 79 year old female with dry mouth and dry eyes from Sjogren’s Syndrome/ She is picking up the prescription below. What is the maximum milligrams of pilocarpine she will recieve per day?

Pilocarpine = 1% w/v
Sodium Chloride qs ad = 15 ml
Sig: 2 gtts [0.05 ml/gtt] po TID prn up to 5 days for Dry Mouth

3 mg

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Exampke Question 10

A pharmacist dissolves 6 tablets. Each contains 250 mg of methronidazole. The pharmacist will put the drug into a puquid base to perpare 60 ml of a topical solution. What is the percentage strength [w/v] of the metronidazole in the prescription? Round to the nearest tenth.

2.5 g / 100 mL OR 2.5%

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Example Question 11

If 12 grams of Lanolin are combined with 2 grams of white wax and 36 grams of patrolatum to make an onitment, what is the percentage strength [w/w] of lanolin in the onitment.

24 g / 100 g OR 24%

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Example Question 12

A pharmacist adds 5.3 grams of hydrocortisone to 150 grams of a 2.5% hydrocortisone ointment. What is the percentage strength [w/w] of hydrocortisone in th e finished product? Round to the neast whole number.

6 g / 100 g OR 6%

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Example Question 13

How many milliliters of hydrocortisone liquid [40 mg/mL] will be needed to prepare 30 grams of a 0.25% cream [w/w]. Round to the nearest hundredth.

1.88 mL

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Example Question 14

What is the precentage strength of imiquimod in the following precription? Round to the nearest hundredth

Imiquimod 5% cream = 15 g
Xylocaine = 20 g
Hydrophilic Ointment = 25 g

1.25 g / 100 g OR 1.25%

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How is Ratio Strength denoted?

One unit of solute in the total amount

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What is the “shortcut” method for Ratio Strength?

Ratio –> %: % strength = 100 / Ratio
% –> Ratio” Ratio = 100 / %

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Example Question 15

Express 0.04% as a ratio strength?

1:2500

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Example Question 16

Express 1:4000 as a percentage strength

0.025 / 100 OR 0.025%

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Example Question 17

There are 50 mg of a drug in 50 ml of a solution. Express the concentration as a ratio strength.

1:1000

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Example Question 18

How many milligrams of iodine should be used in compounding the following precription?

Iodine = 1:400
Hydropholoc Ointment qs ad = 10 g
Sig: Apply as directed

25 g Iodine

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Example Queastion 19

A 10 ml mixture contains 0.25 ml of active drug. Express the concentration as percentage strength [v/v] and ration strength.

2.5 ml / 100 ml OR 2.5%
1:40

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Example Question 20

What is the Concentration, in ratio strength, of a trituration made by combining 150 mg of albuterol sulfate and 4.05 grams of lactose.

1:28

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What does it mean to express something in Parts Per Million [or billion]

PPM or PPB

Expresses VERY dilute solutions - parts of drug per 1 million [or 1 billion] parts of the whole

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What is the "Shortcut" methods ata finding **PPM**?

- PPM --> %: move decimal to **LEFT** 4 spaces - % --> PPM: move decimal to **RIGHT**4 spaces

# Example Questions 21 Express **0.00022% [w/v]** as **PPM**. Round to the nearest tenth.

- 2.2 PPM

# Example Question 22 Express **30 PPM** of copper in soultion as a percentage

- 0.003%

# Example Question 23 Express **5 PPM** of iron in water as a percentage

- 0.0005%

# Example Question 24 A patients blood contains **0.085 PPM** of selenium. How many **mircograms** of selenium does the patients blood contian if the blood volume is **6 Liters**?

- 510 mcg

# Example Question 25 A Sample of an intravenous solution is found to contain **0.4 PPM** of DEHP. How much of the solution, in **milliliters**, will contain **50 mircograms** of DEHP?

- 125 ml

What is **Specific Gravity** and what is the specific gravity of **water**?

- ratio of the density of a substance to the density of water - SG of water is **1 g**; 1 g of water = 1 ml water

# Example Question 26 What is the **specific gravity** of **150 ml** of glycerin weighting **165 grams**? Round to the nearest tenth.

- 1.1

# Example Question 27 What is the **weight** of **750 ml** of concentrated acetic acid [**SG = 1.2**]?

- 900 g

# Example Question 28 How many **milliliters** of polysorbate 80 [**SG = 1.08**] are needed to prepare a prescription that includes **48 grams** of the surfactant/emulsifier (polysorbate)? Round to the nearest hundredth.

- 44.44 ml

# Example Question 29 What is the **specific gravity** of **30 ml** of a liquid weighing **23,400 milligrams**? Round to the nearest hundredth.

- 0.78

What is the **weight** of **0.5 L** of polyethylene glycol 400 [**SG = 1.13**]

- 565 g

# Example Question 31 Nitroglycerin has a specific gravity of **1.59**. How much would **one quart** wieght in **grams**? Use 1 quart = 946 ml. Round to the nearest whole number.

- 1504 g

# Example Question 32 A pharmacist has an order for parenteral nutrition that includes **550 ml of D70%**. The Pharmacist check the supplies and finds the closest strength he has available is **D50%**. How many milliliters of D50% will provide an equivalent energy requirement.

- 770 mL

# Example Question 33 How many **grams** of petrolatum (diluent) should be added to **250 grams** of **20%** ichthammol onitment to make a **7%** ichthammol onitment? Round to the nearest tenth.

- 464.3 g

# Example Question 34 A patient has been receiving **200 ml** of an enteral mixture that contains **432 mOsm/L**. The Pharmacist will reduce the contents to **278 mOsm/L**. How many **Milliliters** of bacteriostatic water should be added to the bag? Round to the nearest mL

- 111 ml

# Example Question 35 If **1 gallon** of a **20% [w/v]** solution is evaporated to a solution with **50% [w/v]** strength, what will be the new **volumue [in milliliters]**? Round to the nearest 100 mL/.

- 1500 ml

# Example Questions 36 Using **20 grams** of a **9%** boric acid ointment base, the pharmacist will manufacture a **5%** onitment. How much diluent is required?

- 16 g

# Example Question 37 A pharmacist is asked to prepare **80 grams** of a **12.5%** icthammol ointment with **16% and 12%** icthammol ointments that she has in stock. How many **grams** of the 16% and 12% onitments are required?

- 10 g of the 16 % - 70 g of the 12 %

# Example Question 38 A pharmacist is asked to prepare **1 gallon** on tincture containing **5.5%** iodine. The phramacy has **3%** iodine tincture and **8.5%** iodine tincture in stock. How many **milliliters** of the 3% and 8.5% iodine tincture should be used? (Used 1 gallon - 3785ml)

- 1720 ml of 8.5% - 2065 ml of 3 %

# Example Question 39 A hospice pharmacist receives a prescription for **1%** morphine sulfate oral solution. She has a **120 ml** bottle of morphine sulfate labed **20mg / 5 ml** and a **240 mg** bottle of morphine sulfate labeled **100 mg / 5 ml**. How much of the 100 mg / 5 ml product must be mixed with the contents of the 20 mg / 5 ml morphine sulfate bottle to prepare the desired percentage strength for the patient?

- 72 ml

# Example Question 40 A pharmacist must prepare **100 grams** of a **50%** hydrocortisone powder using the **25% and 75%** powders that she has in stock. How much of each is required?

- 50 g of both 25% and 75%

What is **osmolarity**?

- total number of particles per liter of solution

What compounds are **dissociated** by **1 particles** for **Osmolarity**?

- Dextrose - Mannitol

What compounds are **dissociated** by **2 particles** for **Osmolarity**?

- Potassium Chloride - Sodium Chloride - Sodium Acetate - Magnesium Sulfate

What compounds are **dissociated** by **3 particles** for **Osmolarity**?

- Calcium Chloride - Sodium Citrate

What is the **equation** for **osmolarity**?

- (Weight [g/L] / MW [g/mole]) x (# of particles) x 1000 ## Footnote step 1: add up the number of particles step 2: calculate the number of grams of the compound in 1 L step 3: Use the molecular weight [MW]

# Example Question 41 What is the osmolarity, in mOsml/L, of normal saline [**0.9% NaCl**]? MW = 58.5 g/mol. Round to the nearest whole number

- 308 mOsmol/L

# Example Question 42 What is the **osmolarity**, is mOsmol/L, of **D5W**? MW = 198 g/mol. Round to the nearest tenth.

- 252.5 mOsmol/L

# Example Question 43 How many **milliosmoles** of CaCl2 [**MW = 111 g/mol**] are represented in **150 mL** of a **10% [w/v]** calcium chloride solution? Round to the nearest whole number

- 405 mOsmol/L

# Example Question 44 A solution contains **373 mg** of Na ions per liter. How many **milliosmoles** are represented int he solution? **MW = 23 g/mol**. Round to the nearest tenth.

- 16.2 mOsmol/L

# Example Question 45 How many **grams** of Potassium Chloride are need to make **200 ml** of a solution containing **250 mOsmol/L**? Round to the nearest hundredth. K [**Mw = 39 g/mol**], Cl [**MW = 35.5 g/mol**]

- 1.86 g

# Example Question 46 A solution contains **200 mg** of Ca ions per liter. How many **milliosmoles** are represented in the solution? **MW = 40 g/mol**

- 5 mOsmol/L

# Example Question 47 Calculate the osmolar concetration, in **milliosmoles**, represented by **1 liter** of a **10% [w/v]** solution of anhydrous dextrose [**MW = 180 g/mol**] in water. Round to the nearest one decimal place,

- 555.6 mOsmol/L

# Example Question 48 A patient was ordered **1 Liter** of D5NS with **20 mEq** of KCl of dehydration. How many **milliosmoles** are in **1 liter** of this fluid [**MW dextrose = 198 g/mol**], Na [**MW = 23 g/mol**], K [**MW = 39 g/mol**], Cl [**MW - 35.5 g/mol**]? round to the nearest whole number.

- 600 mOsmol/L

# Example Questions 49 Calculate the **E value** for Mannitol [**MW = 182 g/mol**]. round to the nearest hundredth.

- 0.18

What is the equation for finding the **E value**?

- E = (**(58.5)(i)**)/(**(MW)(1.8)**)

# Example Question 50 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 places. ## Footnote - Ephedrine Sulfate = 0.4 g - Sodium Chloride = qs - Purified Water qs = 30 mL - Make isotonic soln. - Sig: Use 2 drops in each nostril as directed

- 0.178 g of NaCl are needed

# Example Question 51 Calculate the **E value** for Potassium Iodide, which dissociates into **2 particles** [**MW = 166 g/mol**]. Round to two decimal places.

- 0.35

# Example Question 52 Physostigmine Salicyclate [**MW = 413 g/mol**] is a 2-ion electrolyte, dissociating **80%** in a given concentration [i.e., use a dissociation factor of 1.8]. Calculate its sodium chloride equivalent. Round to two decimal places.

- 0.14

# Example Question 53 The pharmacist receives an order for **10 ml** of tobramycin 1% ophthalmic solution. He has tobramycin **40 mg/mL** solution. Tobramycin does not dissociate and has a **MW = 468 g/mol**. Find the **E value** for tobramycin and determind how many **milligrams** of NaCl are needed to make the soultion isotonic?

- 83 mg

What are the equations used for finding **moles**?

- mols = g / MW

# Example Question 54 How many moles of anhydrous magnesium sulfate [**MW = 120.4 g/mol**] are present in **250 grams** of the substance? round to the nearest hundredth

- 2.08 mols

# Example Question 55 How many **moles** equivalent to **875 milligrams** of aluminum actate [**MW = 204 g/mol**]? Round to 3 decimal places.

- 0.004 mols

# Example Question 56 How many **millimoles** of sodium phophate [**MW = 138 g/mol**] are present in **90 g** of the substance? Round to the nearest whole number.

- 0.652 mols --> 652 mmols

# Example Question 57 How many **moles** are equivalent to **45 grams** of potassium carbonate [**MW = 138 g/mol**]? Round to the nearest thousandth/

- 0.326 mols

# Example Question 58 How many **millimoles** of calcium chloride [**MW = 147 g/mol**] are represented in **147 ml** of a **10% [w/v]** calcium chloride solution?

- 100 mmols

# Example Question 59 How many **milligrams** of sodium chloride [**MW= 58.5 g/mol**] represent **0.25 mmol**? Do not round the answer

- 14.625 mg

# Example Question 60 How many **grams** of sodium Chloride [**MW = 58.5 g/mol**] should be usd to prepar this solution? D not round the answer ## Footnote - Methylprednisolone = 0.5 g - NaCl solution = 60 mL - Each 5 ml should contain 0.6 mmols of NaCl

- 0.4212 g NaCl

Which common conpounds have **1 valence**?

- Ammonium Chloride - Potassium Chloride - Potassium Gluconate - Sodium Acetate - Sodium Bicarbonate - Sodium Chloride

Which common compounds have **2 Valence**?

- Calcium Carbonate - Calcium Chloride - Ferrous Sulfate - Lithium Carbonate - Magnesium Sulfate

What is the **Equation** for finding **milliequivalents**?

- mEq = (mg x valence) / MW

# Example Question 61 A **20 ml** vial is labeled **potassium chloride [2 mEq/ml]**. How many **grams** of potassium chloride [**MW = 74.5 g/mol**] are present? round to the nearest hundredths

- 2.98 g

# Example Question 62 How many **milliequivalents** of **potassium chloride** are present in a **12 ml** dose of a **10% [w/v]** potassium chloride [**MW = 74.5 g/mol**] elixir? Round to 1 deciaml place

- 16.1 mEq

# Example Question 63 Calculate the **milliequivalents** of a standard **ammonium chloride [MW = 53.5 g/mol] 21.4 mg/mL** strile solution in a **500 ml**container?

- 200 mEq

# Example Question 64 How many **milliequivalents** of **MgSO4 [MW = 120.4 g/mol]** are represented in **1 gram** of anhydrous magnesium sulfate? round to the nearest tenth

- 16.6 mEq

# Example Question 65 How many **milliequivalents** of sodium are in a **50 mL** of **8.4%** sodium Bicarbonate [**MW = 84 g/mol**]

- 50 mEq

# Example Question 66 A 74 year old male takes *Lithobid* (lithium carbonate, Li2CO3) **450 mg po BID**, but reports difficulty swallowing the capsules. How many **milliliters** of lithium citrate syrup provide an equiva;ent daily dose of lithium? Round to the nearest whole number. [**MW of Lithium Carbonate = 74 g/mol**]

- 15 ml of lithium citrate per day