PEBC Part I (MCQ) · Competency 1B Distribution (about 20%)

Pharmaceutical Calculations

Calculation items appear throughout Part I: weight-based and BSA dosing, creatinine clearance, IV rates, concentrations and dilutions, electrolytes, days' supply, compounding and opioid conversions. PEBC supplies an on-screen calculator and a formula sheet.

1B Distribution2 min read6 sections

Checked against the PEBC Examination Design and Style (SI units; formula sheet and on-screen calculator, checked 12 Oct 2026); Ansel's Pharmaceutical Calculations, 16th ed. (2021); Cockcroft-Gault (1976); Mosteller (1987); McMaster Opioid Manager (2017, updated 2022). Not affiliated with or endorsed by The Pharmacy Examining Board of Canada (PEBC).

Must-know for the exam

Cockcroft-Gault (SI): CrCl = (140 - age) x weight (kg) x 1.23 / SCr (umol/L); multiply by 0.85 for females.
Mosteller BSA (m2) = square root of [height (cm) x weight (kg) / 3,600].
IBW (Devine): 50 kg (male) or 45.5 kg (female) + 2.3 kg per inch over 5 feet; adjusted weight = IBW + 0.4 x (TBW - IBW).
Rate (mL/h) = dose per hour / concentration; drops/min = mL/min x drop factor.
C1V1 = C2V2 for dilutions; 1:1,000 = 1 mg/mL = 0.1%.
0.9% NaCl contains 154 mmol/L of sodium; calcium is divalent (1 mmol = 2 mEq).
Days' supply must include priming doses for insulin pens.
Morphine equivalents: oxycodone x 1.5, hydromorphone x 5, codeine x 0.15.
Fentanyl 50 mcg/h corresponds to 180-224 mg/day oral morphine in the Canadian table.
Always convert pounds to kilograms (divide by 2.2) before weight-based dosing.

On this page · 6 sections

Traps that cost marks

Forgetting to divide the total daily dose by the number of doses.
Leaving out the SI unit constant when serum creatinine is in umol/L.
Being reassured by a 'normal' serum creatinine in a small older patient.
Skipping the square root in the Mosteller formula.
Mixing up the concentrations of infant drops and children's suspension.
Giving the adult 0.5 mg dose to a child, or misplacing the decimal.
Miscalculating the bag concentration before converting units to mL.
Reporting mL/h when the question asks for drops per minute.

How this is tested on Part I

Most calculation items give the numbers needed and four answers built from common mistakes: forgetting a conversion, inverting a ratio, using a daily instead of a per-dose amount, or a decimal shift.

Worked approach

Write the units at every step and cancel them.

Estimate the answer first to catch tenfold errors.

Check whether the question asks per dose, per day or per course.

Recheck that pediatric doses stay below the adult maximum.

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Educational practice material for exam preparation only. Not medical advice and not a substitute for current product monographs, clinical guidelines or professional judgement. Questions have not yet been reviewed by a licensed pharmacist.