PTCE - Patient Safety and Quality Assurance (23.75% of the exam) - Section 3.5

Identify types of prescription errors including incorrect dose, quantity, patient, drug, and route of administration. (Calculation-based.)

Identify the standard medication error classification types - wrong dose, wrong drug, wrong patient, wrong quantity, and wrong route of administration - and the contributing factors associated with each. Apply this taxonomy to triage errors by severity and determine the appropriate corrective response.

Prescription errorWrong doseWrong patientMedication error classification

Practice question for this objective

Free samplePatient Safety and Quality Assurancemedium

A pharmacist asks a new technician to explain how a wrong dose error differs from a wrong quantity error, since both involve numbers on the label. Which statement correctly distinguishes the two error types?

AA wrong dose error involves an incorrect strength or amount per administration, while a wrong quantity error involves an incorrect total number of units supplied Correct
BA wrong dose error always relates to the total units dispensed, while a wrong quantity error relates to the strength taken at each time
CBoth terms describe the same event and may be used interchangeably when labelling a dispensing mistake
DA wrong dose error refers to the patient receiving the package, while a wrong quantity error refers to the active ingredient supplied

Differentiate a wrong dose error (amount per administration) from a wrong quantity error (total units supplied). Dose and quantity describe separate attributes: dose is the strength or amount taken at each administration, while quantity is the total number of units dispensed, so an error in one does not imply an error in the other.

Why A is correct: This captures the real distinction: dose describes how much is taken at each administration, whereas quantity describes the total units dispensed, so the two errors target different attributes of the order.

Why B is wrong: This is tempting because it sounds symmetrical, but it reverses the two definitions, which is exactly the confusion a careless candidate would make.

Why C is wrong: This is tempting as a shortcut, but the terms describe distinct attributes and error reports must separate them, so treating them as interchangeable is incorrect.

Why D is wrong: This is tempting because it borrows real error categories, but it actually describes wrong patient and wrong drug errors, not dose and quantity, so it confuses four separate types.

See more PTCE practice questions, answers explained.

Exam traps in Patient Safety and Quality Assurance

Answers that look right on this material and are not. Each one is a distractor from a different question in the PTCE bank for this domain.

A wrong-dose error; 40 units is an unsafe amount and must be reduced before the prescription is released
Why it is wrong: Adjusting the unit count is tempting because insulin dosing is high-risk, but the 40-unit amount matches the prescriber's intent; the discrepancy is the route entered, not the dose.
Wrong drug error, because the wrong medication was supplied for the patient who received it
Why it is wrong: This is tempting because the recipient got a medicine not meant for her, but the product itself was the correct amoxicillin order; the fault lies in recipient identification, not in the drug selected.
Wrong drug error, because the higher strength constitutes a different medication entirely
Why it is wrong: This is tempting because a higher strength feels like a different product, but the same active ingredient was supplied, so the medicine was not wrong; only the dosing instruction was.

Examworthy is not affiliated with or endorsed by PTCB. Original, blueprint-aligned practice material only.