pharmacy math

1 kilogram is how many grams?

1,000

1 kilogram is how many pounds?

2.2

1 liter is how many mL?

1,000

1 gram is how many mg?

1,000

1 milligram is how many micrograms?

1,000

1 grain is how many miligrams

65

1 ounce is how many grams?

30

1 teaspoon is how many mL?

5

1 tablespoon is how many mililiters?

15

1 pound is how many grams?

454

how would you convert 1:5,000 to a percentage strength.

divide 1/5,000 and multiply by 100

how would you convert 0.75% to a ratio strength.

0.75% = 0.75/100 —> flip it and do 100/0.75 = 133.33 —> 1:133.33

what roman numeral is 5?

V

what roman numeral is 10?

X

what roman numeral is 50?

L

what roman numeral is 100?

C

what roman numeral is 500?

D

what roman numeral is 1000?

M

when one Roman numeral is used after another

the total of both is taken

When you place a smaller Roman numeral before a larger Roman numeral

we must subtract the smaller value from the higher value:

IX = 1 taken from 10 = 9

IV = 1 taken from 5 = 4

CD = 100 taken from 500 = 400

When you place a smaller Roman after a larger Roman numeral

you add the smaller numeral to the larger numeral:

when a smaller Roman numeral is sandwiched between two larger Roman numeral values

we first do the subtraction step, before finally doing the addition step:

XIX = X + (1 taken from 10) = X + 9 = 10 + 9 = 19

XXIV = XX + (1 taken from 5) = 10 + 10 + 4 = 24

To calculate BMI (body mass index), we use this formula:

kg/m²

BSA refers to

body surface area

The standard formula used to calculate BSA is:

(m²) = Height cm x Weight kg / 3600

how to do dosage calculation questions

1. Ensure that units are consistent – milligrams, grams etc.

2. Find the total dose prescribed to the patient.

3. Use the dose available in the pharmacy to determine how many tablets should be given to meet that total dose.

what factors must be considered for pediatric dosages?

Differences in body size and weight.

Variations in body metabolism.

Differences in organ function and development.

Pharmacokinetics and pharmacodynamics.

Potential for side effects and adverse effects.

Ethical and practical considerations in pediatrics.

Clark’s Rule is a formula used to determine pediatric dosages based on

a child’s weight in comparison to the average adult weight.

Clark’s Rule is expressed by the following formula:

pediatric dose = adult dose (child’s weight (lbs)/150)

Young’s Rule is used to calculate pediatric dosages based on the

child’s age relative to the average age of an adult

Young’s Rule is expressed by the following formula:

Pediatric dose = adult dose (child’s age/child’s age + 12).

why is aspirin avoided for children?

its association with Reye’s syndrome – a rare but severe condition that can cause damage to the liver and brain.

why is Codeine avoided for kids?

due to the risk of severe respiratory depression.

why is Promethazine avoided in kids?

due to the risk of severe respiratory depression and sedation

why are Certain antidepressants, such as paroxetine avoided for kids?

limited data on safety and efficacy in young children which raises concerns about potential side effects, including an increased risk of suicidal thoughts.

why are Certain antipsychotics, such as olanzapine avoided in kids?

due to limited safety data and the risk of significant side effects, including metabolic syndrome and weight gain

why is high-dose acetaminophen avoided for kids?

risk of liver toxicity

why is Topical benzocaine avoided for kids?

risk of methemoglobinemia, a serious condition where the blood cannot carry oxygen effectively. For this reason

why are Certain anti-seizure medications, such as phenytoin avoided for kids?

significant side effects and the need for precise blood level management

why are Chemotherapy agents like methotrexate avoided for in kids?

high risk of toxicity and adverse effects

why are Medicines with potential for abuse or dependence, such as opioids avoided for kids?

risk of addiction and overdose

why are Stimulants such as methylphenidate avoided for kids?

potential for misuse and abuse

why are Certain antifungals and antibiotics, like ketoconazole and chloramphenicol avoided for kids?

risk of significant drug interactions or severe side effects, including liver damage and bone marrow suppression.

why are Tetracycline antibacterial drugs avoided for kids?

they bind to teeth and bone during fetal development, infancy and early childhood and so must be avoided.

Alligation

a simple method used to calculate the proportion of two solutions needed to produce a final solution of required concentration. 

w/v

weight per 100mL – typically weight is measured in grams.

v/v

volume per 100mL

10% w/v means

10 grams of drug dissolved in 100mL of solution

Purified water has a conc. of

0% v/v

Acquisition cost:

the price the pharmacy pays to purchase the drug.

Additional costs

may include shipping, handling, and storage expenses.

Gross profit

the profit a company makes after deducting the cost of goods sold (COGS) from its revenue

costs of goods sold (COGS)

direct costs attributable to the production of the goods sold by the company, such as raw materials and labor.

gross profit formula

Revenue – Cost of Goods Sold (COGS)

net revenue

the profit remaining after all expenses have been deducted from total revenue. This includes not only COGS but also operating expenses, interest, taxes, and any other expenses.

net revenue formula

revenue - total expenses

Mark-Up

the percentage or amount added to the cost price of the medicine to cover overheads and profit for the pharmacy.

The formula to calculate the selling price using mark-up is:

Selling Price = Cost + (Cost × Mark-Up Percentage)

If we have the selling price and the cost price, we can calculate the mark-up percentage using the following formula:

The formula for gross margin percentage is:

High Gross Margin: indicates that

a large portion of the sales revenue is retained as profit. It means the product has a low-cost relative to its selling price, which suggests good profitability.

Low Gross Margin: suggests that

a smaller portion of the sales revenue is retained as profit, indicating higher costs relative to the selling price. This could mean lower profitability.

generic drugs with the lowest co-pay is what tier?

tier 1

preferred brand-name drugs with a moderate co-pay is what tier?

tier 2

non-preferred brand-name drugs with a higher co-pay is what tier?

tier 3

high-cost specialty drugs with the highest co-pay is what tier?

speciality tier

Average Wholesale Price (AWP)

refers to a pricing benchmark used primarily by pharmacies for purchasing prescription medicines from wholesalers or suppliers.