Pharm Calculations Exam 1

Question 1

Percentage of Error formula

Answer 1

Error x 100% / qty desired

Question 2

Sensitivity Requirement (SR) is

Answer 2

The minimum weight which will move the index across one subdivision on the index plate.

Question 3

Minimum Weighable Qty (MWQ) formula

Answer 3

MWQ = 100 x sensitivity requirement / acceptable percentage error

Question 4

For percentage strength, what are the units of weight-in-volume (w/v)?

Answer 4

g/100mL

Question 5

For percentage strength, what are the units of volume-in-volume (v/v)?

Answer 5

mL/100mL

Question 6

For percentage strength, what are the units of weight-in-weight (w/w)?

Answer 6

g/100g

Question 7

How many grams of a drug are required to prepare 2 liters of a 4% (w/v) solution?

Answer 7

80 g

Question 8

What is the percentage strength of Normal Saline?

Answer 8

0.9% (w/v) means there are 0.9 g (900 mg) of NaCl in 100 mL of normal saline.

Question 9

What does 20% (v/v) alcohol solution mean?

Answer 9

There are 20 mL of alcohol in 100 mL of alcohol solution.

Question 10

What is percent in weight used for?

Answer 10

Used for solids in solids, such as ointment, but sometimes liquids, such as acids or heavy liquids

Question 11

What is USP?

Answer 11

tolerance permitted in the labeled quantities of ingredients

Range is expressed for many drugs: 95%- 105%
Example:
“Ibuprofen Tablets contain not less than 95% and not more than 105% of the labeled amount of ibuprofen.”

Question 12

A pharmacist needs to make 10% (w/w) zinc oxide ointment with 5 g of zinc oxide. How many grams of vaseline base (no active ingredient) are needed?

Answer 12

vaseline base = 50 g - 5 g = 45 g

Question 13

What is mg%?

Answer 13

Number of mg in 100 mL (mg/dL)

Question 14

A person’s blood test reveals that his blood glucose is 500 mg%. How many grams of glucose are in each 100 mL of his blood?

Answer 14

Question 15

Ration Strength: How would you interpret:

1/1000 as:
solid in liquid
liquid in liquid
solid in solid

Answer 15

1/1000 is interpreted as:
For solid in liquid: 1 gram in 1000 mL
For liquid in liquid: 1 mL in 1000 mL
For solid in solid: 1 gram in 1000 grams

Question 16

How is potency of products usually expressed?

Answer 16

Potency of many products is expressed in terms of units – biologic activity.

Question 17

How many mL of a heparin sodium injection containing 200,000 units in 10 mL should be used to obtain 5,000 heparin sodium units that are to be added to an intravenous (IV) dextrose solution?

Answer 17

0.25 mL

Question 18

Corticotropin injection is available in a concentration of 40 units/mL. How many mL of the injection should be administered to provide 0.4 unit/kg for a child weighing 66 lb?

Answer 18

0.3 mL

Question 19

If 10 mcg of ergocalciferol represent 400 units of vitamin D, how many 1.25 mg ergocalciferol capsules will provide a dose of 200,000 units of vitamin D?

Answer 19

4

Question 20

What is a stock solution?

Answer 20

a relatively concentrated solution of a medicinal or non-medicinal substance used as the source of that substance to prepare a solution of lesser concentration. They are prepared on a weight-in-volume basis, and their concentration is expressed as a ratio strength or, as percentage strength.

Question 21

What is Alligation?

Answer 21

A method of solving problems that involves the mixing of solutions or mixtures of solids possessing different percentage strengths.

Question 22

What are the two types of alligation?

Answer 22

Alligation medial

Alligation alternate

Question 23

What is alligation medial?

Answer 23

A method by which the average percentage strength of a mixture of two or more substances whose quantities and concentrations are known may be calculated.

Question 24

What is alligation alternate?

Answer 24

A method to calculate the number of parts of two or more components of a given strength when they are to be mixed to prepare a mixture of desired strength. A final proportion allows the translation of relative parts to specific denominations.