Ptcb & Pharmacy Calculations Exam – Questions And Answers | Verified And Well Detailed Answers |

PTCB & PHARMACY CALCULATIONS EXAM – QUESTIONS AND ANSWERS | VERIFIED AND
WELL DETAILED ANSWERS | PLUS RATIONALES | GUARANTEED PASS | LATEST EXAM UPDATE




express 1:100 as a percent - CORRECT ANSWER -% = (1/100) X 100====>>1%

How many milligrams of active drug are in 100 ml

of a 1% solution? - CORRECT ANSWER -0.01 = (x gm/100ml)

x = 1 gm (1000 mg)

H ow many milliliters of a 5% solution would be

needed to deliver500 mg of active drug? - CORRECT ANSWER -0.05 = (0.5 gm / x ml)



x = 10 ml

Calculating Drug Doses & Percentages

To calculate drug dosages, remember one basic

statement:



One gram or ml of drug in 99 ml of diluent will yield a 1%

solution. Therefore, 1 ml of a 1% solution contains .01 gm

(10 mg) of the drug. - CORRECT ANSWER -• The formula that proves this statement is:



% (in decimals) = amount of solute (gm)/total amount of solution (ml)

Mixing Solutions



• When mixing two solutions to obtain a desired

drug percentage, the following formula is used: - CORRECT ANSWER -(amount of solute
needed)/(amount of solution desired )=

(concentration of desired solution)/

(concentration of on - hand solution)

Mixing Solutions

,• Example



- prepare 5 ml of a 5% solution of acetylcysteine,

using 20% acetylcysteine and normal saline - CORRECT ANSWER -(x/5) = (5/20)

therefore X = (25/20)



x = 1.25



To prepare 5 ml of 5% acetylcysteine, mix 1.25 ml of the 20% acetylcysteine with 3.75 ml
normal saline.

1. A .3 ml dose of 5% Metaprel contains how many mg metaproterenol? - CORRECT ANSWER
-% (in decimals) =



(amount of solute (gm))/(total amount of solution (ml)

2. A .5 ml dose of 1:200 Isuprel contains how many mg isproterenol?

First, convert 1:200 to a percentage (in decimal form) - CORRECT ANSWER -% (in decimals) =

(amount of solute (gm)/total amount of solution (ml))

3. How many ml of 1:200 Proventil would be needed to deliver 5 mg

albuterol? - CORRECT ANSWER -% (in decimals) =

( amount of solute (gm)/total amount of solution (ml))

4. What is the percentage strength of a solution of Ventolin that

contains 5 mg albuterol per ml? - CORRECT ANSWER -% (in decimals) =

( amount of solute (gm)/total amount of solution (ml))

5. What is the ratio strength of an epinephrine solution that contains 1 mg epinephrine per
ml? - CORRECT ANSWER -% (in decimals) =

( amount of solute (gm)/total amount of solution (ml))

1. Prepare 250 ml of 1% NaCl using H2O and 10% NaCl solution. - CORRECT ANSWER -
(amount of solute needed)/(amount of solution desired )=

, (concentration of desired solution)/

(concentration of on - hand solution)

2. Prepare 50 ml of 5% acetylcysteine solution using NS and 20% acetylcysteine - CORRECT
ANSWER -(amount of solute needed)/(amount of solution desired )=

(concentration of desired solution)/

(concentration of on - hand solution)

3. Prepare 2 L of 20% NaHCO3 solution using H2O and NaHCO3 crystals. - CORRECT ANSWER
-(amount of solute needed)/(amount of solution desired )=

(concentration of desired solution)/

(concentration of on - hand solution)

4. Prepare 1 L of NS using H2O and NaCl crystals. - CORRECT ANSWER -(amount of solute
needed)/(amount of solution desired )=

(concentration of desired solution)/

(concentration of on - hand solution)

5. Prepare 1 L of 2% acetic acid using water and vinegar (5%). - CORRECT ANSWER -(amount
of solute needed)/(amount of solution desired )=

(concentration of desired solution)/

(concentration of on - hand solution)

How many grams of drug should be used to prepare 120 grams of a 2% w/w solution in
water? - CORRECT ANSWER -

What is the percentage strength (w/v) of a solution of drug if 40 mL contain 5 grams? -
CORRECT ANSWER -

PPM AND PPB (PARTS PER MILLION AND PARTS PER BILLION)

When ppm or ppb is used as a designation for concentration, some systems are w/w, some
are v/v and some are w/v. Concentration is always a ratio or fraction in w/w and v/v
situations. Weight by volume (w/v) concentrations are always defined in terms of grams and
milliliters. The same default rules are followed as for percentage systems.




Express 2 ppm of ferrous gluconate in water in percentage strength and ratio strength. -
CORRECT ANSWER -(1/500,000) * 100 = %