Pharmacy Calculations and Rx Shorthand

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Questions and Answers

What is the concentration of single-strength chloroform water?

1.0%

0.5%

5.0%

0.25% (correct)

Which of the following terms indicates 'twice a day' in prescription shorthand?

bd (correct)

tid

qds

q6h

What is the symbol for the prefix that indicates a magnitude of $10^6$?

M (correct)

Which of the following routes of administration is represented by 'PO'?

Orally Signup and view all the answers

What is the SI equivalent of 1 ounce (oz) in grams?

28.35 g Signup and view all the answers

Which term in pharmacy shorthand indicates a duration for 5 days?

x 5/7 Signup and view all the answers

What is the significance of always writing a 0 before the decimal place in pharmaceutical calculations?

To prevent misinterpretation of the number Signup and view all the answers

Which of the following is the correct dosage representation for 'when required'?

prn Signup and view all the answers

What is the meaning of the abbreviation 'IM' in pharmacy prescriptions?

Intramuscularly Signup and view all the answers

What volume does one tablespoon (tbsp) equate to in milliliters (mL)?

15 mL Signup and view all the answers

What formatting rule should be applied when noting whole numbers in pharmaceutical calculations?

Always omit decimal points. Signup and view all the answers

When rounding a number, if the figure one place beyond the required number is '4', what should you do?

Leave the last digit unchanged. Signup and view all the answers

In a medication composed of 2 parts Drug X and 8 parts excipient, what is the percentage of Drug X in the total medication?

25% Signup and view all the answers

If a prescription states 'Ramipril 5 mg OD x 1/12 Repeat x 2', for how many months is the patient entitled to Ramipril?

2 months Signup and view all the answers

Given an Amoxicillin prescription of '250 mg 2 caps TID x 5/7', how many capsules will you dispense?

14 capsules Signup and view all the answers

Which is the correct unit format for a pharmaceutical calculation involving 100000 units?

100,000 units Signup and view all the answers

Which strategy should be followed if you are unsure about a calculation?

Ask a colleague to perform it and compare answers. Signup and view all the answers

When presenting a calculated quantity, which of the following must always be included?

Units Signup and view all the answers

What should you do first when performing calculations before using a calculator?

Perform calculations manually. Signup and view all the answers

If you prescribe 1 mg instead of 1 g, what is a potential consequence?

The medication has no therapeutic effect. Signup and view all the answers

Study Notes

Course Objectives

Students will learn to confidently convert units and measurement systems
Students will understand and perform basic dosage calculations
Students will be able to perform calculations for basic compounding

Peppermint Water Case

Peppermint water contains 3.75 ml peppermint emulsion, 75 ml chloroform water (double-strength), and purified water up to 150 ml.
There are three different concentrations of chloroform water: single-strength (0.25%), double-strength (0.5%), and concentrated (10%).

Rx Shorthand

Rx shorthand was more prevalent in the past and used to aid in speedier prescription writing.
Based on English and Latin words, common ones will be used in these sessions.

Rx Shorthand - General Terms

℞/Rx/Rx: The prescription, derived from the Latin word "recipe" meaning "to receive."
Sig.Label: To write on a label, derived from the Latin word "Signa."
Mitte: Total Quantity, derived from the Latin word "Mitte" meaning "send/give."

Rx Shorthand - Frequency

bd/BD: Twice a day, from the Latin phrase "bis dei" (twice per day).
bid/BID: Twice a day, from the Latin phrase "bis in die" (twice a day).
mane: In the morning, derived from the Latin word "mane".
nocte: At night, derived from the Latin word "nocte."
od/OD: Once a day, from the Latin phrase "omni die" (every day).
prn/PRN: When required, from the Latin phrase "pro re nata" (as the need arises).
q6h: Every 6 hours, from the Latin phrase "quaque 6 hora" (every 6 hours).
qds/QDS: Four times a day, from the Latin phrase "quarter die sumendus" (to be taken four times a day).
qid/QID: Four times a day, from the Latin phrase "quarter in die" (four times a day).
tds/TDS: Three times a day, from the Latin phrase "ter die sumendus" (to be taken three times a day).
tid/TID: Three times a day, from the Latin phrase "ter in die" (three times a day).
tarde: In the evening, derived from the Latin word "tarde."

Rx Shorthand - Duration/Route

x 5/7: For 5 days.
x 4/52: For 4 weeks.
Repeat x 2/12: Repeat for 2 more months.
Rx2: Repeat twice.
PO: Orally.
SC s/c: Subcutaneously.
IV: Intravenously.
IM: Intramuscularly.

Pharmaceutical Calculation Basics - Prefixes

Prefixes and symbols used for SI unit subdivisions and multiples.
Tera (T): 10¹² - 1 000 000 000 000
Giga (G): 10⁹ - 1 000 000 000
Mega (M): 10⁶ - 1 000 000
kilo (k): 10³ - 1000
hecto (h): 10² - 100
deka (da): 10¹ - 10
deci (d): 10^-1 - 0.1
centi (c): 10^-2 - 0.01
milli (m): 10^-3 - 0.001
micro (µ/mc): 10^-6 - 0.000 001
nano (n): 10^-9 - 0.000 000 001

Pharmaceutical Calculation Basics - Imperial Units

Mass:
- 1 ounce (oz) = 28.35 g
- 1 pound (lb) = 453.59 g
- 1 stone (st) = 6.35 kg
Volume:
- 1 teaspoon (tsp) = 5 mL
- 1 tablespoon (tbsp) = 15 mL
- 1 pint = 568 mL
Length:
- 1 inch (in) = 2.54 cm
- 1 foot (ft) = 30.5 cm

Pharmaceutical Calculation Basics - Performing Calculations

Writing:
- Always write a zero before the decimal point (e.g., 0.5 mg, not .5 mg).
- Always omit decimal points from whole numbers (e.g., 1 mg, not 1.0 mg).
- Always group zeros in 3s using a comma (e.g., 100,000 units, not 100000 units).
- Always include units in every line of your calculations.
Rounding:
- If the figure one place beyond the required number of figures is 5 or more, add 1.
- If the figure one place beyond the required number of figures is less than 5, add zero.
Calculators:
- Calculate without a calculator first.
- Then, calculate with a calculator.
Approximation:
- Check if the answer makes sense.
- Ask yourself: Does the quantity have no therapeutic effect or kill the patient? (e.g., paracetamol 1mg qds instead of 1g qds)
- Is the quantity impractical? (e.g., 100L injection)
Colleagues:
- If unfamiliar with a calculation, ask a colleague to perform it and compare answers.

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Description

Test your knowledge on unit conversions, dosage calculations, and compounding methods in pharmacy. This quiz also covers Rx shorthand terms derived from Latin, enhancing your understanding of prescription writing. Perfect for pharmacy students or those looking to refresh their skills!