Pharmacy calculation

calculate the percent profit using this equation:

% profit =profit dollars/overhead

Young's Rule

(Age in years)/(Age in years+12)x Adult Dose

Clark's Rule

(weight in lbs/150) x adult dose

lowest place value

is the last digit on the right of a written numeral

Calculating Doses Based on Weight: A patient weighs 60 kg, and she is to receive a medication of 15 mg/kg. What will her dose be? If the medication is available in a 300 mg capsule, how many will be dispensed for 1 dose?

Determine the dose. x mg/60 kg = 15 mg/1 kg x mg= 900 Determine the number of capsules to be dispensed for 1 dose. 900 mg × 1 capsule/300 mg = 3 capsules

8 fluid ounces

1 cup

2 tablespoonfuls

1 fluid ounce

4 quarts

1 gallon

2.2 lb

1 kg

16.23 minims

1 mL

2 cups

1 pint

2 pints

1 quart

3 teaspoonfuls

1 tablespoonful

1 g active ingredient

10,000 g product for a solid

1 mL active ingredient

10,000 mL mixture for a liquid

1 g active ingredient:

10,000 mL solution for a solution

it is essential to know the smallest amount that can be accurately weighed on your balance. The following formula will determine this amount.

100 × balance sensitivity/permissible % margin of error = least weighable quantity

1 Kg

1000 g

1 l

1000 mL

1 mg

1000 mcg

1 gram

1000 milligrams

1 tbsp

15 mL

1 pound

16 ounces

1 cup

240 mL

1 oz

30 g

1 fl oz

30 mL

1 gal

3840 mL

1 lb

454 g

1 pt

480 mL

1 tsp

5 mL

converting ratios to percents.

5:1 = 5/1× 100 = 5 × 100 = 500%

1 grain

65 mg

1 qt

960 mL

Express the components of a 5% solution of dextrose in the form of a weight-in-volume solution.

A 5% dextrose solution contains 5 g of dextrose in each 100 mL of D5W.

The pharmacy receives a prescription for 100 mg of amoxicillin to be taken three times daily for 10 days. The pharmacy has a 150 mL bottle of 125 mg/5 mL amoxicillin. How many milliliters of the suspension will be dispensed, and what will the patient's dosing instructions on the label say?

Determine what quantity of suspension contains 100 mg amoxicillin. This can be determined by using the ratio-proportion method or the dimensional analysis method. We will use the latter. 100 mg × 5 mL/125 mg= 4 mL Using the amount determined for a single dose, determine the total amount of suspension to be dispensed for 10 days. 4 mL × 3 doses/day × 10 days = 120 mL

Significant figures are digits that have a practical meaning or value. Here are some steps to help you identify how many significant figures a written numeral has.

Begin counting at the first nonzero digit. Continue counting to the right until you reach the place value that is last. Zeros that are located between digits are significant and should be counted. Do not count zeros that are placed to the left of the first digit. They only mark the place of the decimal. One or more final zeros may or may not be significant depending on the accuracy to which the number is held.*

A patient is to purchase a 12 fl oz bottle of antacid. The patient is to take 15 mL before each meal and at bedtime. How many doses does the bottle contain? And if the patient eats 3 times a day, how many days will the antacid last?

Begin solving this problem by converting to a common unit of measure using the conversion values in the above table. 1 fl oz = 30 mL Now, let's multiply 12 fl oz by 30 mL.12 × 30 = 360 mL Next, to figure out the number of doses, we divide 360 mL by 15 mL. 360 mL ÷ 15 mL = 24 doses Finally, if the patient is taking the four doses a day, we need to divide 24 doses by 4 doses.24 doses ÷ 4 doses = 6

If a 12 fl oz bottle of mouthwash contains 0.75 g of the active ingredient, how many milligrams will be in a 1 tbsp dose?

Begin the problem by converting all of the household measure units to metric units. 12 fl oz = 360 mL 1 tbsp = 15 mL Also, convert 0.75 g to 750 mg. Using these converted values, this problem can be solved by the ratio-proportion method or the dimensional analysis method. We will use the first.x mg15 mL = 750 mg360 mL x mg = 31.25 mg

Dexamethasone is available as a 4 mg/mL preparation; an infant is to receive 0.35 mg. Prepare a dilution so that the final concentration is 1 mg/mL. How much diluent will you need if the original product is in a 1 mL vial and you dilute the entire vial?

Part I. Determine the volume (in milliliters) of the final product. Since the strength of the dexamethasone is 4 mg/mL, a 1 mL vial will contain 4 mg of the active ingredient. Then, for a final volume x of solution, you will have a concentration of 4 mg/x mL. Diluted solution = Desired concentrationx mL/4 mg = 1 mL/1 mg x mL = 4 mL final product Part II. Subtract the volume of the concentrate from the total volume to determine the volume of diluent needed. 4 mL total volume − 1 mL concentrate = 3 mL diluent needed

If 300 mL of a 5% solution is diluted to 500 mL, what will be the percent strength of the resulting solution?

Step 1. Calculate how many grams are contained in 300 mL of the 5% solution. x g/300 mL = 5 g/100 mL x g = 15 g Step 2. The 15 g is then diluted in 500 mL. To find the percentage strength, calculate how many grams are in 100 mL (remember % means per 100). x g/100 mL = 15 g/500 mL x g = 3%

Here are the steps for volume aliquot measuring:

Step 1. Determine the minimum volume that can be measured accurately. Unlike the previous aliquot calculations, there is no equation for this step. You will know the volume based on the size of syringe or graduated cylinder available in your pharmacy. Step 2. Determine the multiple of the active ingredient that will provide the smallest volume that can be accurately measured. Step 3. Determine the total volume of the mixture by multiplying the volume of active ingredient by the same multiple (factor) used in Step 2. Step 4. Determine the amount of diluent needed by subtracting the amount of active ingredient calculated from the mixture total. Step 5. Determine the amount of mixture needed to provide the originally ordered amount by using the ratio-proportion method.

amount of error formula

actual amount − quantity desired = amount of error

percentage of error by using the following formula:

amount of error quantity desired × 100 = percentage of error

The physical inventory value is then used to determine the average inventory as follows.

average inventory = beginning inventory + present inventory/2

The duration of therapy may be calculated using the following formula.

duration of therapy = volume of fluid or amount of drug to be infused/flow rate

The markup rate is expressed as a percentage and is computed as

markup/pharmacy's purchase price × 100 = markup rate

weight in weight (w/w)

number of grams in the drug in 100 g of the final product x g drug/100 g product

weight in volume (w/v)

number of grams in the drug in 100 ml of the final product x g drug/100 mL product

To convert back and forth between a substance's weight in milligrams and its dissolving weight in milliequivalents, use the following formula:

number of milliequivalents = weight of substance (in milligrams) /milliequivalent weight

volume in volume (v/v)

number of milliliters of the drug in 100 mL of the final product x mL drug/100 mL product

formula for overall cost and net profit

pharmacy's purchase price + cost to dispense = overall cost selling price − overall cost = profit overall cost × desired percent profit = amount of net profit

Solutions Using Powders formula

powder volume = final volume − diluent volume or pv = fv − dv

average wholesale price (AWP)

prescription reimbursement = AWP + percentage + dispensing fee

The markup is computed as

selling price − purchase price = markup or gross profit

How many 1 tsp doses are in 3 cups of liquid medication?

tsp = 3 cups ×8 fl oz/1 cup× 2 tbsp/1 fl oz× 3 tsp/1 tbsp= 144 tsp

Turnover rate formula

turnover rate = annual purchases of inventory/average inventory value

To determine the rate in drops per minute at which the IV fluid is to be infused, the volume of fluid, delivery time, and calibration of the administration set must be known. The following formula is used.

x gtt/min = (volume of fluid ÷ delivery time) × (drop rate of administration set used)/60 min/hour

You are requested to add 44 mEq of sodium chloride (NaCl) to an IV bag. Sodium chloride is available as a 4 mEq/mL solution. How many milliliters will you add to the bag?

x mL/44 mEq = 1 mL/4 mEq x mL = (44 mEq) × 1 mL/4 mEq = 11 mL

degrees Fahrenheit to degrees Celsius:

°C =°F − 32°/1.8

degrees Celsius to degrees Fahrenheit:

°F = (1.8° × °C) + 32