Nursing Math & Dosage Foundations · 500-Question Practice Bank (worked answers)
Oral Dosages — practice set (Q41–100)
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60 dosage-calculation problems (questions 41–100) with a full worked answer for each: dimensional-analysis setup, raw calculation, rounding rule, final labeled answer, rationale and clinical pearl. Work each one on paper first, then open the answer.
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60 review questions from the chapter. Try each one, then open the answer.
Question 41. Scenario: A nurse is preparing a scheduled PRN dose for an adult on a general medical unit. Order: Acetaminophen 650 mg PO every 6 hours PRN for temperature ≥ 101°F. Available: Acetaminophen 325 mg tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole tablet.
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Correct answer: 2 tablets Setup (dimensional analysis): 650 mg × (1 tablet / 325 mg) Raw calculation: 650 ÷ 325 = 2.0 Rounding: The result is already a whole tablet; no rounding is needed. Final answer: 2 tablets Rationale: The ordered dose is double the available tablet strength, so two 325 mg tablets exactly supply 650 mg. Clinical pearl: When the ordered dose is a whole-number multiple of the available strength, give whole tablets — never estimate fractional pieces.
Question 42. Scenario: A child with acute otitis media is prescribed an antibiotic suspension. Order: Amoxicillin 250 mg PO every 8 hours. Available: Amoxicillin oral suspension 125 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 10 mL Setup (dimensional analysis): 250 mg × (5 mL / 125 mg) Raw calculation: 250 × 5 = 1250; 1250 ÷ 125 = 10.0 Rounding: Whole number; no rounding needed. Final answer: 10 mL Rationale: The suspension delivers 125 mg in every 5 mL, so 250 mg (double the reference dose) requires 10 mL. Clinical pearl: Always match the units in your label (mg per mL or mg per 5 mL) before setting up the ratio.
Question 43. Scenario: An adult patient with hypertension is due for a beta-blocker dose. Order: Metoprolol tartrate 25 mg PO twice daily. Available: Metoprolol tartrate 50 mg scored tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole or half tablet as appropriate.
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Correct answer: 0.5 tablet (half tablet) Setup (dimensional analysis): 25 mg × (1 tablet / 50 mg) Raw calculation: 25 ÷ 50 = 0.5 Rounding: Nearest half tablet = 0.5 tablet. Final answer: 0.5 tablet (one-half of a 50 mg scored tablet) Rationale: 25 mg is exactly half of the 50 mg strength. The tablet is scored, so splitting it in half is accurate and appropriate. Clinical pearl: Split a tablet only when it is scored (or otherwise approved by the manufacturer) and when a half tablet is clinically appropriate.
Question 44. Scenario: An older adult with heart failure takes a digitalis preparation by oral solution. Order: Digoxin 0.125 mg PO daily. Available: Digoxin oral solution 0.05 mg/mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 2.5 mL Setup (dimensional analysis): 0.125 mg × (1 mL / 0.05 mg) Raw calculation: 0.125 ÷ 0.05 = 2.5 Rounding: Whole tenth; no rounding needed. Final answer: 2.5 mL Rationale: Each mL contains 0.05 mg, so 0.125 mg requires 2.5 mL. This is measurable with a 3 mL oral syringe. Clinical pearl: Digoxin is a narrow-therapeutic-index drug — measure the solution with an oral syringe, not a household spoon.
Question 45. Scenario: A patient with constipation has a bedtime laxative ordered; the family will measure it at home. Order: Milk of magnesia 30 mL PO at bedtime. Available: Milk of magnesia liquid, dosing cup with tablespoon markings (1 tbsp = 15 mL). Question: How many tablespoons should be given? (Use the exact conversion 1 tbsp = 15 mL.)
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Correct answer: 2 tablespoons Setup (dimensional analysis): 30 mL × (1 tbsp / 15 mL) Raw calculation: 30 ÷ 15 = 2.0 Rounding: Exact conversion; no rounding needed. Final answer: 2 tablespoons Rationale: Because 1 tbsp = 15 mL (exact), a 30 mL dose equals exactly 2 tablespoons. Clinical pearl: Teach caregivers that kitchen tablespoons vary — use the dosing device provided with the medication for accuracy.
Question 46. Scenario: A home health nurse teaches a caregiver to measure a cough preparation using a kitchen teaspoon. Order: Guaifenesin 100 mg PO every 4 hours PRN. Available: Guaifenesin syrup 100 mg/5 mL. Question: How many teaspoons should be given per dose? (Use the exact conversion 1 tsp = 5 mL.)
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Correct answer: 1 teaspoon (5 mL) Setup (dimensional analysis): 100 mg × (5 mL / 100 mg) = 5 mL; 5 mL × (1 tsp / 5 mL) = 1 tsp Raw calculation: 100 ÷ 100 × 5 = 5 mL = 1 tsp Rounding: Exact conversion; no rounding needed. Final answer: 1 teaspoon (5 mL) Rationale: The syrup is 100 mg/5 mL, so the ordered 100 mg is exactly 5 mL, which equals 1 teaspoon. Clinical pearl: For home dosing, a calibrated oral syringe or dosing spoon is more accurate than a kitchen teaspoon.
Question 47. Scenario: A nurse must measure a small volume of a cardiac glycoside elixir precisely. Order: Digoxin 0.15 mg PO daily. Available: Digoxin elixir 0.05 mg/mL. Question: First calculate the volume to administer, then state which measuring device — an oral syringe or a medicine cup — the nurse should use to measure that volume accurately, and why.
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Correct answer: 3 mL; use an oral syringe Setup (dimensional analysis): 0.15 mg × (1 mL / 0.05 mg) Raw calculation: 0.15 ÷ 0.05 = 3.0 Rounding: Whole tenth; no rounding needed. Final answer: 3 mL, measured with an oral syringe Rationale: 3 mL is a small volume. Oral syringes are calibrated in fine (0.1–0.5 mL) increments and deliver small, precise volumes accurately. A medicine cup is calibrated in coarser increments and is unreliable for small or partial-milliliter doses. Clinical pearl: Use an oral syringe for volumes smaller than about 5 mL (and for any dose needing fine precision); reserve medicine cups for larger, whole-increment volumes.
Question 48. Scenario: A patient with a skin infection is started on a cephalosporin. Order: Cephalexin 500 mg PO every 6 hours. Available: Cephalexin 250 mg capsules. Question: How many capsules will the nurse administer per dose? Round to the nearest whole capsule.
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Correct answer: 2 capsules Setup (dimensional analysis): 500 mg × (1 capsule / 250 mg) Raw calculation: 500 ÷ 250 = 2.0 Rounding: Whole capsule; no rounding needed. Final answer: 2 capsules Rationale: Two 250 mg capsules provide exactly 500 mg. Clinical pearl: Capsules must not be split; if the strength doesn't allow a whole-capsule match, contact the prescriber or pharmacy.
Question 49. Scenario: A child with fever and mild pain receives an NSAID suspension. Order: Ibuprofen 200 mg PO every 6 hours PRN pain or fever. Available: Ibuprofen oral suspension 100 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 10 mL Setup (dimensional analysis): 200 mg × (5 mL / 100 mg) Raw calculation: 200 × 5 = 1000; 1000 ÷ 100 = 10.0 Rounding: Whole number; no rounding needed. Final answer: 10 mL Rationale: At 100 mg/5 mL (20 mg/mL), a 200 mg dose requires 10 mL. Clinical pearl: Check the concentration on the label each time — ibuprofen suspensions come in different strengths (e.g., 100 mg/5 mL vs 50 mg/1.25 mL).
Question 50. Scenario: A nurse draws up a liquid analgesic and wants to confirm the milligram dose it delivers. Order: Acetaminophen 240 mg PO every 4 hours PRN. Available: Acetaminophen liquid 160 mg/5 mL. Question: The nurse measures 7.5 mL. How many mg of acetaminophen will the patient receive? Round to the nearest whole mg.
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Correct answer: 240 mg Setup (dimensional analysis): 7.5 mL × (160 mg / 5 mL) Raw calculation: 160 ÷ 5 = 32 mg/mL; 32 × 7.5 = 240.0 Rounding: Whole mg; no rounding needed. Final answer: 240 mg Rationale: The liquid delivers 32 mg per mL, so 7.5 mL delivers exactly 240 mg — matching the order. Clinical pearl: Working "backward" (volume → mg) is a good double-check that the drawn volume delivers the ordered dose.
Question 51. Scenario: A patient with hypokalemia is prescribed a liquid potassium supplement. Order: Potassium chloride oral solution 20 mEq PO twice daily. Available: Potassium chloride oral solution 40 mEq/15 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 7.5 mL Setup (dimensional analysis): 20 mEq × (15 mL / 40 mEq) Raw calculation: 20 × 15 = 300; 300 ÷ 40 = 7.5 Rounding: Nearest tenth; 7.5 is already a tenth. Final answer: 7.5 mL Rationale: The solution contains 40 mEq per 15 mL, so 20 mEq (half the reference) requires 7.5 mL. Clinical pearl: Oral potassium is concentrated and irritating — dilute per facility practice and give with food or fluids as directed.
Question 52. Scenario: A patient with hypothyroidism takes a daily replacement hormone. Order: Levothyroxine 100 mcg PO daily. Available: Levothyroxine 50 mcg tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole tablet.
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Correct answer: 2 tablets Setup (dimensional analysis): 100 mcg × (1 tablet / 50 mcg) Raw calculation: 100 ÷ 50 = 2.0 Rounding: Whole tablet; no rounding needed. Final answer: 2 tablets Rationale: Two 50 mcg tablets supply exactly 100 mcg. Clinical pearl: Watch the prefix — levothyroxine doses are in micrograms (mcg), not milligrams (mg).
Question 53. Scenario: A child is prescribed a cephalosporin suspension for a respiratory infection. Order: Cefdinir 250 mg PO once daily. Available: Cefdinir oral suspension 125 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 10 mL Setup (dimensional analysis): 250 mg × (5 mL / 125 mg) Raw calculation: 250 × 5 = 1250; 1250 ÷ 125 = 10.0 Rounding: Whole number; no rounding needed. Final answer: 10 mL Rationale: The suspension is 125 mg/5 mL, so 250 mg (double the reference) equals 10 mL. Clinical pearl: Shake oral suspensions well before pouring so the drug is evenly distributed.
Question 54. Scenario: An adult with hypertension takes an ACE inhibitor; the pharmacy only has a higher-strength scored tablet in stock. Order: Lisinopril 10 mg PO daily. Available: Lisinopril 20 mg scored tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole or half tablet as appropriate.
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Correct answer: 0.5 tablet (half tablet) Setup (dimensional analysis): 10 mg × (1 tablet / 20 mg) Raw calculation: 10 ÷ 20 = 0.5 Rounding: Nearest half tablet = 0.5 tablet. Final answer: 0.5 tablet (one-half of a 20 mg scored tablet) Rationale: 10 mg is half of 20 mg, and the tablet is scored, so a half tablet accurately provides the dose. Clinical pearl: A scored tablet may be split along the score line; a tablet without a score should not be assumed splittable.
Question 55. Scenario: A nurse transcribes a new anticoagulant order and notices the dose is written without a leading zero. Order (as written): Warfarin .5 mg PO daily. Available: Warfarin 0.5 mg tablets. Question: What error does this order contain, what risk does it pose, and how should the dose be correctly written?
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Correct answer: Missing leading zero; the dose should be written "0.5 mg" Setup (dimensional analysis): N/A (order-writing error) Raw calculation: N/A Rounding: N/A Final answer: Rewrite as "Warfarin 0.5 mg PO daily" Rationale: ".5 mg" lacks a leading zero. If the decimal point is missed, the dose can be misread as 5 mg — a tenfold overdose. A leading zero ("0.5 mg") makes the decimal unmistakable. This is on The Joint Commission "Do Not Use" list. Clinical pearl: Always use a leading zero before a decimal fraction (0.5, not .5) and never use a trailing zero after a whole number (5.0).
Question 56. Scenario: A patient with a community-acquired pneumonia is started on a macrolide antibiotic. Order: Azithromycin 500 mg PO once on day 1. Available: Azithromycin 250 mg tablets. Question: How many tablets will the nurse administer for the day-1 dose? A. 0.5 tablet B. 1 tablet C. 2 tablets D. 4 tablets
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Correct answer: C — 2 tablets Setup (dimensional analysis): 500 mg × (1 tablet / 250 mg) Raw calculation: 500 ÷ 250 = 2.0 Rounding: Whole tablet; no rounding needed. Final answer: 2 tablets Rationale: Two 250 mg tablets supply the 500 mg day-1 dose. Distractors 0.5 and 1 tablet under-dose; 4 tablets double-dose. Clinical pearl: For a loading or day-1 dose, confirm the total is given as a single administration, not split across the day.
Question 57. Scenario: A patient with hepatic encephalopathy is prescribed lactulose; the caregiver asks for a household measure. Order: Lactulose 30 mL PO three times daily. Available: Lactulose syrup, household measuring cup. Question: How many fluid ounces is one 30 mL dose? (Use the conventionally rounded conversion 1 fl oz ≈ 30 mL.)
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Correct answer: 1 fluid ounce (approximately) Setup (dimensional analysis): 30 mL × (1 fl oz / 30 mL) Raw calculation: 30 ÷ 30 = 1.0 Rounding: Conventionally rounded conversion (1 fl oz ≈ 30 mL). Final answer: ≈ 1 fl oz Rationale: Using the nursing convention 1 fl oz ≈ 30 mL, a 30 mL dose is approximately 1 fluid ounce. Clinical pearl: 1 fl oz ≈ 30 mL is a teaching convention; the precise value is about 29.57 mL, so the "≈" matters for exact dosing.
Question 58. Scenario: A child with fever weighs 20 kg. Order: Acetaminophen 15 mg/kg/dose PO every 4 hours PRN (hypothetical educational range 10–15 mg/kg/dose). Available: Acetaminophen liquid (any concentration). Question: How many mg should be given per dose? Round to the nearest whole mg.
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Correct answer: 300 mg Setup (dimensional analysis): 15 mg/kg × 20 kg Raw calculation: 15 × 20 = 300.0 Rounding: Whole mg; no rounding needed. Final answer: 300 mg Rationale: At 15 mg/kg/dose, a 20 kg child receives 300 mg, which is within the hypothetical educational range of 10–15 mg/kg/dose. Clinical pearl: Multiply dose-per-kg by weight in kg; if the weight is given in pounds, convert to kg (÷ 2.2) first.
Question 59. Scenario: A 25 kg child with a sprained ankle needs an anti-inflammatory. Order: Ibuprofen 10 mg/kg/dose PO every 6 hours PRN. Available: Ibuprofen oral suspension 100 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth.
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Correct answer: 12.5 mL Setup (dimensional analysis): Step 1: 10 mg/kg × 25 kg = 250 mg. Step 2: 250 mg × (5 mL / 100 mg) Raw calculation: 10 × 25 = 250 mg; 250 × 5 = 1250; 1250 ÷ 100 = 12.5 Rounding: Nearest tenth; 12.5 is already a tenth. Final answer: 12.5 mL Rationale: The 25 kg child needs 250 mg; at 100 mg/5 mL, that is 12.5 mL. Clinical pearl: Chain the steps without intermediate rounding — keep the full value until the final rounding step.
Question 60. Scenario: A nurse reads the label on an amoxicillin bottle before measuring a dose. Order: Amoxicillin 600 mg PO every 12 hours. Available: Amoxicillin oral suspension labeled 400 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth.
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Correct answer: 7.5 mL Setup (dimensional analysis): 600 mg × (5 mL / 400 mg) Raw calculation: 600 × 5 = 3000; 3000 ÷ 400 = 7.5 Rounding: Nearest tenth; 7.5 is already a tenth. Final answer: 7.5 mL Rationale: The label gives 400 mg per 5 mL, so 600 mg requires 7.5 mL. Clinical pearl: Read the actual concentration on the label rather than assuming a "standard" amoxicillin strength.
Question 61. Scenario: A patient with oral candidiasis is prescribed an antifungal suspension measured in units. Order: Nystatin oral suspension 200,000 units swish and swallow four times daily. Available: Nystatin oral suspension 100,000 units/mL. Question: First calculate the volume per dose, then state which device — an oral syringe or a medicine cup — is most appropriate to measure it and why.
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Correct answer: 2 mL; use an oral syringe Setup (dimensional analysis): 200,000 units × (1 mL / 100,000 units) Raw calculation: 200,000 ÷ 100,000 = 2.0 Rounding: Whole number; no rounding needed. Final answer: 2 mL, measured with an oral syringe Rationale: The suspension is 100,000 units/mL, so 200,000 units equals 2 mL. This small volume is best measured with an oral syringe; a medicine cup cannot measure 2 mL accurately. Clinical pearl: Nystatin is "swish and swallow" for oral candidiasis — instruct the patient to hold it in the mouth before swallowing.
Question 62. Scenario: An adult with hypertension requires a dose that falls between available tablet strengths. Order: Metoprolol tartrate 75 mg PO twice daily. Available: Metoprolol tartrate 50 mg scored tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole or half tablet as appropriate.
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Correct answer: 1.5 tablets Setup (dimensional analysis): 75 mg × (1 tablet / 50 mg) Raw calculation: 75 ÷ 50 = 1.5 Rounding: Nearest half tablet = 1.5 tablets. Final answer: 1.5 tablets (one and one-half 50 mg scored tablets) Rationale: 75 mg = 50 mg + 25 mg, so one full tablet plus one half of a scored 50 mg tablet delivers the dose accurately. Clinical pearl: When a dose requires a whole plus a half, verify the tablet is scored so the half can be split accurately.
Question 63. Scenario: A nurse checks the dose delivered by a previously measured volume of antibiotic. Order: Amoxicillin 300 mg PO every 8 hours. Available: Amoxicillin oral suspension 250 mg/5 mL. Question: The nurse has drawn up 6 mL. How many mg will the patient receive? Round to the nearest whole mg.
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Correct answer: 300 mg Setup (dimensional analysis): 6 mL × (250 mg / 5 mL) Raw calculation: 250 ÷ 5 = 50 mg/mL; 50 × 6 = 300.0 Rounding: Whole mg; no rounding needed. Final answer: 300 mg Rationale: At 50 mg/mL, a 6 mL volume delivers exactly 300 mg, matching the order. Clinical pearl: Reverse-checking a drawn volume against the order is a fast way to catch measuring errors.
Question 64. Scenario: A patient with constipation needs a larger evening laxative dose measured at home. Order: Milk of magnesia 45 mL PO at bedtime. Available: Milk of magnesia liquid, dosing cup (1 tbsp = 15 mL). Question: How many tablespoons should be given? (Use the exact conversion 1 tbsp = 15 mL.)
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Correct answer: 3 tablespoons Setup (dimensional analysis): 45 mL × (1 tbsp / 15 mL) Raw calculation: 45 ÷ 15 = 3.0 Rounding: Exact conversion; no rounding needed. Final answer: 3 tablespoons Rationale: Because 1 tbsp = 15 mL exactly, 45 mL equals 3 tablespoons. Clinical pearl: For larger liquid doses, a calibrated dosing cup is appropriate; a table spoon is not a reliable substitute for a "tablespoon" measure.
Question 65. Scenario: A patient with chemotherapy-induced nausea is prescribed an antiemetic solution. Order: Ondansetron 4 mg PO every 8 hours PRN nausea. Available: Ondansetron oral solution 4 mg/5 mL. Question: How many mL will the nurse administer per dose? A. 1 mL B. 2.5 mL C. 5 mL D. 10 mL
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Correct answer: C — 5 mL Setup (dimensional analysis): 4 mg × (5 mL / 4 mg) Raw calculation: 4 × 5 = 20; 20 ÷ 4 = 5.0 Rounding: Whole number; no rounding needed. Final answer: 5 mL Rationale: The solution is 4 mg/5 mL, so a 4 mg dose equals exactly 5 mL. The distractors misapply the ratio (1 mL, 2.5 mL) or double it (10 mL). Clinical pearl: Ondansetron ODT (orally disintegrating tablets) do not require water; know which formulation is ordered.
Question 66. Scenario: A nurse reviews a new medication order and flags a trailing zero. Order (as written): Levothyroxine 50.0 mcg PO daily. Available: Levothyroxine 50 mcg tablets. Question: What error does this order contain, what risk does it pose, and how should the dose be correctly written?
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Correct answer: Trailing zero; the dose should be written "50 mcg" Setup (dimensional analysis): N/A (order-writing error) Raw calculation: N/A Rounding: N/A Final answer: Rewrite as "Levothyroxine 50 mcg PO daily" Rationale: "50.0 mcg" contains a trailing zero. If the decimal point is missed, 50.0 can be misread as 500 mcg — a tenfold overdose. Trailing zeros are on The Joint Commission "Do Not Use" list. Clinical pearl: Write whole-number doses without a trailing zero (50, not 50.0) and decimal doses with a leading zero (0.5, not .5).
Question 67. Scenario: A nurse transcribes an order that uses a dangerous abbreviation for frequency. Order (as written): Digoxin 0.125 mg q.d. Available: Digoxin 0.125 mg tablets. Question: What abbreviation error does this order contain, and how should the frequency be written to comply with The Joint Commission "Do Not Use" list?
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Correct answer: "q.d." is prohibited; write "daily" Setup (dimensional analysis): N/A (order-writing error) Raw calculation: N/A Rounding: N/A Final answer: Rewrite as "Digoxin 0.125 mg PO daily" Rationale: "q.d." (and Q.D./qd) is on The Joint Commission "Do Not Use" list because the period can be misread as an "i," turning it into "q.i.d." (four times daily) — a quadruple overdose. "Daily" is unambiguous. Clinical pearl: Spell out "daily" and "every other day" instead of using q.d. or QOD abbreviations.
Question 68. Scenario: A nurse notices a prohibited abbreviation in a diuretic order. Order (as written): Furosemide 40 mg QOD. Available: Furosemide 40 mg tablets. Question: What abbreviation error does this order contain, what is its specific danger, and how should it be rewritten?
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Correct answer: "QOD" is prohibited; write "every other day" Setup (dimensional analysis): N/A (order-writing error) Raw calculation: N/A Rounding: N/A Final answer: Rewrite as "Furosemide 40 mg PO every other day" Rationale: "QOD" (and q.o.d./qod) is on The Joint Commission "Do Not Use" list; it is easily misread as "QD" (daily) or "QID" (four times daily). For a diuretic, giving every other day versus daily changes the dose frequency substantially. Clinical pearl: Never use QOD; write out "every other day" to prevent frequency errors.
Question 69. Scenario: A nurse reads the label on a metformin bottle: "Metformin 500 mg tablets, scored." Order: Metformin 250 mg PO twice daily. Available: Metformin 500 mg scored tablets (per label). Question: How many tablets will the nurse administer per dose, and is splitting the tablet appropriate based on the label?
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Correct answer: 0.5 tablet; splitting is appropriate Setup (dimensional analysis): 250 mg × (1 tablet / 500 mg) Raw calculation: 250 ÷ 500 = 0.5 Rounding: Nearest half tablet = 0.5 tablet. Final answer: 0.5 tablet (half of a 500 mg scored tablet) Rationale: The label confirms the tablet is scored, so it may be split accurately in half to deliver 250 mg. Clinical pearl: A "scored" label indicates the manufacturer intended the tablet to be divided; an unscored tablet should not be assumed safe to split.
Question 70. Scenario: A 30 kg child is prescribed amoxicillin divided into three doses daily. Order: Amoxicillin 40 mg/kg/day PO divided every 8 hours. Available: Amoxicillin oral suspension (any concentration). Question: How many mg should the child receive per dose? Round to the nearest whole mg.
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Correct answer: 400 mg per dose Setup (dimensional analysis): Step 1: 40 mg/kg/day × 30 kg = 1200 mg/day. Step 2: 1200 mg/day ÷ 3 doses/day = 400 mg/dose Raw calculation: 40 × 30 = 1200; 1200 ÷ 3 = 400.0 Rounding: Whole mg; no rounding needed. Final answer: 400 mg per dose Rationale: The total daily dose is 1200 mg, divided into three equal every-8-hour doses of 400 mg each. Clinical pearl: For "mg/kg/day divided," always compute the total daily dose first, then divide by the number of doses per day.
Question 71. Scenario: A caregiver measures a stool softener using a household teaspoon. Order: Docusate sodium 100 mg PO twice daily. Available: Docusate sodium syrup 50 mg/5 mL. Question: How many mL — and how many teaspoons — should be given per dose? (1 tsp = 5 mL.)
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Correct answer: 10 mL = 2 teaspoons Setup (dimensional analysis): 100 mg × (5 mL / 50 mg) = 10 mL; 10 mL × (1 tsp / 5 mL) = 2 tsp Raw calculation: 100 × 5 = 500; 500 ÷ 50 = 10 mL = 2 tsp Rounding: Exact conversion; no rounding needed. Final answer: 10 mL (2 teaspoons) Rationale: At 50 mg/5 mL, a 100 mg dose is 10 mL, which equals 2 teaspoons. Clinical pearl: Convert to mL first, then to household units, to avoid compounding a measuring error.
Question 72. Scenario: A parent reports giving "three teaspoons" of a fever-reducer and the nurse checks the delivered dose. Order: Acetaminophen 480 mg PO every 4 hours PRN. Available: Acetaminophen liquid 160 mg/5 mL. Question: The parent gave 3 teaspoons (15 mL). How many mg did the child receive? Round to the nearest whole mg.
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Correct answer: 480 mg Setup (dimensional analysis): 3 tsp × (5 mL / 1 tsp) = 15 mL; 15 mL × (160 mg / 5 mL) Raw calculation: 3 × 5 = 15 mL; 160 ÷ 5 = 32 mg/mL; 32 × 15 = 480.0 Rounding: Whole mg; no rounding needed. Final answer: 480 mg Rationale: Three teaspoons equal 15 mL; at 32 mg/mL, that delivers 480 mg — matching the order. Clinical pearl: When a caregiver reports a household measure, convert to mL before computing the mg to verify the dose.
Question 73. Scenario: A patient with a toxic ingestion receives a large-volume adsorbent suspension. Order: Activated charcoal 50 g PO once now. Available: Activated charcoal suspension 50 g/240 mL. Question: First calculate the volume to administer, then state which device — an oral syringe or a calibrated medicine cup — is appropriate to measure this volume and why.
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Correct answer: 240 mL; use a calibrated medicine cup Setup (dimensional analysis): 50 g × (240 mL / 50 g) Raw calculation: 50 × 240 = 12000; 12000 ÷ 50 = 240.0 Rounding: Whole number; no rounding needed. Final answer: 240 mL, measured with a calibrated medicine cup Rationale: The suspension is 50 g/240 mL, so 50 g equals 240 mL. This large volume is impractical for an oral syringe; a calibrated medicine cup (or graduated container) is the appropriate device. Clinical pearl: Match the device to the volume — syringes for small/precise volumes, medicine cups for larger volumes.
Question 74. Scenario: A patient with iron-deficiency anemia is prescribed a liquid iron supplement. Order: Ferrous sulfate 440 mg PO daily. Available: Ferrous sulfate elixir 220 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth if needed.
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Correct answer: 10 mL Setup (dimensional analysis): 440 mg × (5 mL / 220 mg) Raw calculation: 440 × 5 = 2200; 2200 ÷ 220 = 10.0 Rounding: Whole number; no rounding needed. Final answer: 10 mL Rationale: The elixir is 220 mg/5 mL, so 440 mg (double) equals 10 mL. Clinical pearl: Liquid iron can stain teeth — give through a straw or dilute, and rinse afterward.
Question 75. Scenario: A child who weighs 40 lb has a fever. Order: Acetaminophen 15 mg/kg/dose PO every 4 hours PRN. Available: Acetaminophen liquid (any concentration). Question: Convert the weight to kg (1 kg = 2.2 lb; round kg to the nearest tenth), then calculate the mg dose. A. 270 mg B. 273 mg C. 280 mg D. 600 mg
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Correct answer: B — 273 mg Setup (dimensional analysis): Step 1: 40 lb × (1 kg / 2.2 lb) = 18.18 kg → 18.2 kg. Step 2: 15 mg/kg × 18.2 kg Raw calculation: 40 ÷ 2.2 = 18.18 kg (rounded to 18.2 kg); 15 × 18.2 = 273.0 Rounding: Weight rounded to the nearest tenth (18.2 kg); dose to nearest whole mg (273 mg). Final answer: 273 mg Rationale: Converting 40 lb to kg gives about 18.2 kg; at 15 mg/kg the dose is 273 mg. Distractor 600 mg results from failing to convert pounds to kilograms (15 × 40). Clinical pearl: Always convert pounds to kilograms before applying a mg/kg dose — the most common pediatric dosing error is skipping this step.
Question 76. Scenario: An adult with heart failure is prescribed a non-standard carvedilol dose. Order: Carvedilol 18.75 mg PO twice daily. Available: Carvedilol 6.25 mg tablets. Question: How many tablets will the nurse administer per dose? Round to the nearest whole tablet.
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Correct answer: 3 tablets Setup (dimensional analysis): 18.75 mg × (1 tablet / 6.25 mg) Raw calculation: 18.75 ÷ 6.25 = 3.0 Rounding: Whole tablet; no rounding needed. Final answer: 3 tablets Rationale: Three 6.25 mg tablets supply exactly 18.75 mg. Clinical pearl: For non-standard doses, confirm the number of tablets with the pharmacy rather than estimating fractions.
Question 77. Scenario: A 14 kg child with fever is prescribed ibuprofen; the nurse verifies the dose against a weight-based range. Order: Ibuprofen 150 mg PO every 6 hours PRN. Available: Ibuprofen oral suspension 100 mg/5 mL. Hypothetical educational safe range: 5–10 mg/kg/dose. Question: Is the ordered dose SAFE or UNSAFE? Show the converted weight, the minimum and maximum safe dose, the ordered dose, and your comparison.
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Correct answer: UNSAFE Converted weight: 14 kg (given) Minimum safe dose: 5 mg/kg × 14 kg = 70 mg/dose Maximum safe dose: 10 mg/kg × 14 kg = 140 mg/dose Ordered dose: 150 mg per dose Comparison: 150 mg > 140 mg (maximum) Conclusion: UNSAFE — the ordered dose exceeds the maximum safe dose; hold the dose and clarify with the prescriber. Rationale: The safe per-dose range for this 14 kg child is 70–140 mg. The ordered 150 mg exceeds the maximum by 10 mg. Clinical pearl: Compare the ordered dose to the calculated safe range before administering any weight-based pediatric medication.
Question 78. Scenario: A nurse confirms the milligram dose in a drawn-up volume of antibiotic. Order: Amoxicillin 200 mg PO every 8 hours. Available: Amoxicillin oral suspension 125 mg/5 mL. Question: The nurse measures 8 mL. How many mg will the patient receive? Round to the nearest whole mg.
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Correct answer: 200 mg Setup (dimensional analysis): 8 mL × (125 mg / 5 mL) Raw calculation: 125 ÷ 5 = 25 mg/mL; 25 × 8 = 200.0 Rounding: Whole mg; no rounding needed. Final answer: 200 mg Rationale: At 25 mg/mL, an 8 mL volume delivers exactly 200 mg, matching the order. Clinical pearl: Verify the concentration on the label before reverse-calculating a dose, since suspensions vary in strength.
Question 79. Scenario: A patient is prescribed azithromycin suspension on day 1 of therapy. Order: Azithromycin 250 mg PO once on day 1. Available: Azithromycin oral suspension 200 mg/5 mL. Question: How many mL will the nurse administer? Round to the nearest hundredth. A. 5 mL B. 6.25 mL C. 6.5 mL D. 7 mL
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Correct answer: B — 6.25 mL Setup (dimensional analysis): 250 mg × (5 mL / 200 mg) Raw calculation: 250 × 5 = 1250; 1250 ÷ 200 = 6.25 Rounding: Nearest hundredth; 6.25 is already to the hundredth. Final answer: 6.25 mL Rationale: At 200 mg/5 mL (40 mg/mL), 250 mg requires 6.25 mL. Distractors 5 mL and 7 mL misapply the ratio; 6.5 mL is an incorrect (over-rounded) result. Clinical pearl: Azithromycin day-1 doses are larger than subsequent daily doses — confirm which day of therapy you are dosing.
Question 80. Scenario: A caregiver must give a partial teaspoon of antibiotic to an infant. Order: Amoxicillin 125 mg PO every 8 hours. Available: Amoxicillin oral suspension 250 mg/5 mL. Question: How many mL — and how many teaspoons — should be given per dose? (1 tsp = 5 mL.)
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Correct answer: 2.5 mL = ½ teaspoon Setup (dimensional analysis): 125 mg × (5 mL / 250 mg) = 2.5 mL; 2.5 mL × (1 tsp / 5 mL) = 0.5 tsp Raw calculation: 125 × 5 = 625; 625 ÷ 250 = 2.5 mL = 0.5 tsp Rounding: Nearest tenth; 2.5 is already a tenth. Final answer: 2.5 mL (½ teaspoon) Rationale: The suspension is 250 mg/5 mL, so 125 mg is 2.5 mL, or half a teaspoon. Clinical pearl: For partial-teaspoon infant doses, use a 5 mL oral syringe rather than trying to measure a half teaspoon with household spoons.
Question 81. Scenario: A patient with hepatic encephalopathy has a larger lactulose order; the caregiver asks for a household measure. Order: Lactulose 60 mL PO once daily. Available: Lactulose syrup, household measuring cup. Question: How many fluid ounces is one 60 mL dose? (Use the conventionally rounded conversion 1 fl oz ≈ 30 mL.)
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Correct answer: 2 fluid ounces (approximately) Setup (dimensional analysis): 60 mL × (1 fl oz / 30 mL) Raw calculation: 60 ÷ 30 = 2.0 Rounding: Conventionally rounded conversion (1 fl oz ≈ 30 mL). Final answer: ≈ 2 fl oz Rationale: Using the nursing convention 1 fl oz ≈ 30 mL, a 60 mL dose is approximately 2 fluid ounces. Clinical pearl: For lactulose, document the volume in mL in the MAR; use household measures only for patient teaching.
Question 82. Scenario: A patient is prescribed a warfarin dose that the pharmacy fills using two tablet strengths. Order: Warfarin 7.5 mg PO daily. Available: Warfarin 5 mg tablets and 2.5 mg tablets. Question: How many tablets, and of which strength(s), will the nurse administer to deliver the ordered 7.5 mg?
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Correct answer: One 5 mg tablet plus one 2.5 mg tablet (2 tablets total) Setup (dimensional analysis): 7.5 mg = 5 mg + 2.5 mg Raw calculation: 5 + 2.5 = 7.5 Rounding: Whole-tablet combinations; no fractional tablet needed. Final answer: 1 × 5 mg tablet + 1 × 2.5 mg tablet = 7.5 mg Rationale: Combining one 5 mg and one 2.5 mg tablet delivers exactly 7.5 mg without splitting any tablet. Clinical pearl: When a dose falls between available strengths, prefer a combination of whole tablets over splitting a higher-strength tablet.
Question 83. Scenario: A patient's usual levothyroxine 137 mcg is out of stock, and the pharmacy currently has only 88 mcg tablets. Order: Levothyroxine 137 mcg PO daily. Available: Levothyroxine 88 mcg tablets (only strength available today). Question: How many tablets would be required to deliver 137 mcg, and is this a practical (accurately measurable) tablet dose? What should the nurse do?
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Correct answer: ≈ 1.56 tablets — impractical; clarify/obtain the correct strength Setup (dimensional analysis): 137 mcg × (1 tablet / 88 mcg) Raw calculation: 137 ÷ 88 = 1.5568 Rounding: N/A (impractical fractional tablet) Final answer: 1.56 tablets is NOT practical — do not administer; contact the pharmacy/prescriber Rationale: 137 mcg would require about 1.56 of the 88 mcg tablets. Cutting a tablet into 0.56 of its strength is not accurately measurable. The nurse should request the correct 137 mcg strength or an alternative combination and clarify before administering. Clinical pearl: If a calculated tablet dose is not a practical whole (or clean half) of the available strength, stop and clarify — never guess a fraction.
Question 84. Scenario: A patient with a new NG tube needs daily aspirin for cardiovascular protection but cannot swallow tablets. Order: Aspirin 81 mg enteric-coated PO daily. Available: Aspirin 81 mg enteric-coated tablets. Question: The nurse is asked whether the enteric-coated tablet can be crushed and given through the NG tube. Should it be crushed? Explain the safety concern and the correct action.
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Correct answer: Do NOT crush — the enteric coating protects the stomach; use an alternative form Setup (dimensional analysis): N/A (safety judgment) Raw calculation: N/A Rounding: N/A Final answer: Do not crush the enteric-coated tablet; contact the prescriber for an alternative (e.g., non-enteric aspirin or another antiplatelet formulation) Rationale: Enteric coating is designed to dissolve in the intestine, not the stomach. Crushing destroys the coating, releasing aspirin in the stomach where it can cause irritation/ulceration and alters absorption. Crushing an enteric-coated product is unsafe. Clinical pearl: Enteric-coated and delayed-release products must never be crushed, chewed, or dissolved — check the label before any medication is altered for tube administration.
Question 85. Scenario: A patient who cannot swallow whole tablets takes a long-acting beta-blocker. Order: Metoprolol succinate extended-release 50 mg PO daily. Available: Metoprolol succinate extended-release 50 mg tablets. Question: Can this extended-release tablet be crushed or chewed to ease administration? Explain the specific danger and the correct action.
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Correct answer: Do NOT crush or chew — extended-release crushing causes "dose dumping"; use an alternative Setup (dimensional analysis): N/A (safety judgment) Raw calculation: N/A Rounding: N/A Final answer: Do not crush or chew; contact the prescriber to switch to an immediate-release form (e.g., metoprolol tartrate) or another formulation Rationale: Crushing an extended-release tablet destroys the release mechanism and can release the entire dose at once ("dose dumping"), producing a dangerous rapid effect and possible toxicity. The patient needs an immediate-release alternative or a liquid. Clinical pearl: Never crush extended-release (XR/ER/CR/SR) products; "succinate ER" signals extended release.
Question 86. Scenario: A 12 kg child with otitis media is prescribed a high-dose amoxicillin regimen. Order: Amoxicillin 90 mg/kg/day PO divided every 12 hours. Available: Amoxicillin oral suspension 400 mg/5 mL. Question: How many mL will the nurse administer per dose? Round to the nearest tenth.
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Correct answer: 6.8 mL Setup (dimensional analysis): Step 1: 90 mg/kg/day × 12 kg = 1080 mg/day. Step 2: 1080 mg/day ÷ 2 doses/day = 540 mg/dose. Step 3: 540 mg × (5 mL / 400 mg) Raw calculation: 90 × 12 = 1080; 1080 ÷ 2 = 540; 540 × 5 = 2700; 2700 ÷ 400 = 6.75 Rounding: Nearest tenth: 6.75 → 6.8 mL. Final answer: 6.8 mL per dose Rationale: The total daily dose is 1080 mg, so each of two doses is 540 mg; at 400 mg/5 mL that is 6.75 mL, rounded to 6.8 mL. Clinical pearl: High-dose amoxicillin (90 mg/kg/day) for otitis media is a recognized educational regimen — verify the range before administering.
Question 87. Scenario: A 22 kg child is prescribed amoxicillin; the nurse verifies the total daily dose against a weight-based range. Order: Amoxicillin 250 mg PO every 8 hours. Available: Amoxicillin oral suspension 250 mg/5 mL. Hypothetical educational safe range: 25–45 mg/kg/day. Question: Is the ordered total daily dose SAFE or UNSAFE? Show the converted weight, the minimum and maximum safe daily dose, the ordered daily dose, and your comparison.
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Correct answer: SAFE Converted weight: 22 kg (given) Minimum safe daily dose: 25 mg/kg/day × 22 kg = 550 mg/day Maximum safe daily dose: 45 mg/kg/day × 22 kg = 990 mg/day Ordered dose: 250 mg × 3 doses/day = 750 mg/day Comparison: 550 mg < 750 mg < 990 mg Conclusion: SAFE — the ordered daily dose falls within the safe range. Rationale: The ordered 250 mg every 8 hours totals 750 mg/day, which lies between the calculated minimum (550 mg) and maximum (990 mg). Clinical pearl: For mg/kg/day ranges, compare the total daily dose — not a single dose — to the range.
Question 88. Scenario: A 16 kg child needs an analgesic; the nurse computes both the dose and the volume. Order: Acetaminophen 15 mg/kg/dose PO every 4 hours PRN. Available: Acetaminophen liquid 160 mg/5 mL. Question: How many mg per dose, and how many mL, will the nurse administer? Round the mL to the nearest tenth.
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Correct answer: 240 mg = 7.5 mL Setup (dimensional analysis): Step 1: 15 mg/kg × 16 kg = 240 mg. Step 2: 240 mg × (5 mL / 160 mg) Raw calculation: 15 × 16 = 240; 240 × 5 = 1200; 1200 ÷ 160 = 7.5 Rounding: Nearest tenth; 7.5 is already a tenth. Final answer: 240 mg (7.5 mL) Rationale: The 16 kg child needs 240 mg per dose; at 160 mg/5 mL, that is 7.5 mL. Clinical pearl: Two-step problems (mg/kg → mg, then mg → mL) are best done in sequence without rounding until the end.
Question 89. Scenario: A patient with cellulitis is prescribed a full 7-day course of a cephalosporin suspension. Order: Cephalexin 500 mg PO every 6 hours for 7 days. Available: Cephalexin oral suspension 250 mg/5 mL, dispensed in 100 mL bottles (after reconstitution). Question: How many total mL are needed for the entire 7-day course, and how many 100 mL bottles should be dispensed?
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Correct answer: 280 mL total; 3 bottles Setup (dimensional analysis): Daily dose: 500 mg × 4 doses/day = 2000 mg/day. Daily volume: 2000 mg × (5 mL / 250 mg) = 40 mL/day. Course: 40 mL/day × 7 days = 280 mL. Bottles: 280 mL ÷ 100 mL/bottle = 2.8 → 3 bottles Raw calculation: 500 × 4 = 2000; 2000 × 5 = 10000; 10000 ÷ 250 = 40; 40 × 7 = 280; 280 ÷ 100 = 2.8 Rounding: Bottles rounded up to the next whole bottle (2.8 → 3). Final answer: 280 mL needed; dispense 3 (100 mL) bottles Rationale: The full course requires 280 mL; since bottles hold 100 mL each, 3 bottles are needed (2 would be insufficient). Clinical pearl: Always round the number of containers UP — you cannot dispense a fraction of a bottle.
Question 90. Scenario: A patient with an acute inflammatory condition is started on a tapering corticosteroid course. Order: Prednisone 40 mg PO daily for 5 days, then 20 mg PO daily for 5 days. Available: Prednisone 20 mg tablets. Question: How many 20 mg tablets are required for the entire 10-day course?
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Correct answer: 15 tablets Setup (dimensional analysis): Days 1–5: 40 mg/day × (1 tablet / 20 mg) = 2 tablets/day × 5 days = 10 tablets. Days 6–10: 20 mg/day × (1 tablet / 20 mg) = 1 tablet/day × 5 days = 5 tablets. Total = 10 + 5 Raw calculation: 2 × 5 = 10; 1 × 5 = 5; 10 + 5 = 15 Rounding: Whole tablets; no rounding needed. Final answer: 15 tablets for the 10-day course Rationale: The taper uses 2 tablets daily for the first 5 days (10 tablets) and 1 tablet daily for the last 5 days (5 tablets), totaling 15 tablets. Clinical pearl: For taper/step-down orders, lay out each phase separately before summing to avoid double-counting days.
Question 91. Scenario: A nurse must measure a very small volume of a cardiac glycoside solution precisely. Order: Digoxin 0.09 mg PO daily. Available: Digoxin oral solution 0.05 mg/mL. Question: How many mL will the nurse administer, and which oral syringe size (1 mL, 3 mL, or 5 mL) is most appropriate to measure it? Round the volume to the nearest tenth.
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Correct answer: 1.8 mL; use a 3 mL oral syringe Setup (dimensional analysis): 0.09 mg × (1 mL / 0.05 mg) Raw calculation: 0.09 ÷ 0.05 = 1.8 Rounding: Nearest tenth; 1.8 is already a tenth. Final answer: 1.8 mL, measured with a 3 mL oral syringe Rationale: 0.09 mg requires 1.8 mL. A 3 mL oral syringe measures 1.8 mL precisely; a 1 mL syringe is too small and a 5 mL syringe is less precise for this small volume. Clinical pearl: Choose the smallest syringe that will hold the volume, because smaller syringes have finer calibrations.
Question 92. Scenario: A caregiver gives "two teaspoons" of a pediatric suspension and the nurse verifies the milligram dose. Order: Amoxicillin 200 mg PO every 8 hours. Available: Amoxicillin oral suspension 100 mg/5 mL. Question: The caregiver gave 2 teaspoons (10 mL). How many mg did the child receive? Round to the nearest whole mg.
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Correct answer: 200 mg Setup (dimensional analysis): 2 tsp × (5 mL / 1 tsp) = 10 mL; 10 mL × (100 mg / 5 mL) Raw calculation: 2 × 5 = 10 mL; 100 ÷ 5 = 20 mg/mL; 20 × 10 = 200.0 Rounding: Whole mg; no rounding needed. Final answer: 200 mg Rationale: Two teaspoons equal 10 mL; at 20 mg/mL that delivers 200 mg, matching the order. Clinical pearl: Always convert household measures to mL before computing the milligram dose.
Question 93. Scenario: A patient is prescribed an unusual digoxin dose; the nurse checks whether it can be measured with available tablets. Order: Digoxin 0.1875 mg PO daily. Available: Digoxin 0.25 mg scored tablets and digoxin elixir 0.05 mg/mL. Question: How many tablets would 0.1875 mg require, and is that a practical (accurately measurable) tablet dose? What is the safer alternative?
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Correct answer: 0.75 tablet — impractical; use the elixir instead Setup (dimensional analysis): 0.1875 mg × (1 tablet / 0.25 mg) Raw calculation: 0.1875 ÷ 0.25 = 0.75 Rounding: N/A (impractical fractional tablet) Final answer: 0.75 tablet is NOT practical; administer digoxin elixir (3.75 mL of 0.05 mg/mL) or clarify Rationale: 0.75 of a 0.25 mg tablet would require cutting the tablet into quarters, which is not reliably accurate — especially for a narrow-therapeutic-index drug like digoxin. The safer alternative is the elixir (0.1875 mg ÷ 0.05 mg/mL = 3.75 mL). Clinical pearl: For narrow-therapeutic-index drugs, use a liquid formulation when the tablet dose is not a whole or clean half tablet.
Question 94. Scenario: A 12 kg child with fever is prescribed acetaminophen; the nurse verifies the dose against a weight-based range. Order: Acetaminophen 240 mg PO every 4 hours PRN. Available: Acetaminophen liquid 160 mg/5 mL. Hypothetical educational safe range: 10–15 mg/kg/dose. Question: Is the ordered dose SAFE or UNSAFE? Show the converted weight, the minimum and maximum safe dose, the ordered dose, and your comparison.
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Correct answer: UNSAFE Converted weight: 12 kg (given) Minimum safe dose: 10 mg/kg × 12 kg = 120 mg/dose Maximum safe dose: 15 mg/kg × 12 kg = 180 mg/dose Ordered dose: 240 mg per dose Comparison: 240 mg > 180 mg (maximum) Conclusion: UNSAFE — the ordered dose exceeds the maximum safe dose; hold and clarify with the prescriber. Rationale: The safe range for this 12 kg child is 120–180 mg per dose; the ordered 240 mg exceeds the maximum by 60 mg. Clinical pearl: Acetaminophen toxicity is serious; always verify mg/kg dosing against the safe range before giving a pediatric dose.
Question 95. Scenario: A nurse reconstitutes an antibiotic powder before measuring a dose. Order: Amoxicillin 187.5 mg PO every 8 hours. Available: Amoxicillin powder for oral suspension, which yields 125 mg/5 mL once reconstituted per label directions. Question: After reconstitution, how many mL will the nurse administer per dose? Round to the nearest tenth.
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Correct answer: 7.5 mL Setup (dimensional analysis): 187.5 mg × (5 mL / 125 mg) Raw calculation: 187.5 × 5 = 937.5; 937.5 ÷ 125 = 7.5 Rounding: Nearest tenth; 7.5 is already a tenth. Final answer: 7.5 mL (after reconstitution) Rationale: Once reconstituted to 125 mg/5 mL, a 187.5 mg dose requires 7.5 mL. Clinical pearl: Reconstitute exactly as directed and shake well before each dose; note the resulting concentration on the bottle.
Question 96. Scenario: A patient with hepatic encephalopathy has a daily lactulose order; the caregiver wants all equivalent household measures. Order: Lactulose 60 mL PO once daily. Available: Lactulose syrup (1 tbsp = 15 mL; 1 fl oz ≈ 30 mL). Question: Express the 60 mL dose in tablespoons and in fluid ounces.
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Correct answer: 4 tablespoons = 2 fluid ounces (≈ 60 mL) Setup (dimensional analysis): 60 mL × (1 tbsp / 15 mL) = 4 tbsp; 60 mL × (1 fl oz / 30 mL) = 2 fl oz Raw calculation: 60 ÷ 15 = 4; 60 ÷ 30 = 2 Rounding: Exact tbsp conversion; conventional fl oz conversion (1 fl oz ≈ 30 mL). Final answer: 4 tablespoons (≈ 2 fl oz) Rationale: Using 1 tbsp = 15 mL, 60 mL equals 4 tablespoons; using 1 fl oz ≈ 30 mL, it also equals about 2 fluid ounces. Clinical pearl: Give caregivers one consistent household measure rather than offering several, to reduce confusion.
Question 97. Scenario: An 18 kg child is prescribed amoxicillin; the nurse computes the dose and verifies the range. Order: Amoxicillin 45 mg/kg/day PO divided every 8 hours. Available: Amoxicillin oral suspension 250 mg/5 mL. Hypothetical educational safe range: 25–45 mg/kg/day. Question: How many mL per dose will the nurse administer, and is the total daily dose SAFE or UNSAFE? Round the per-dose volume to the nearest tenth.
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Correct answer: 5.4 mL per dose; SAFE Setup (dimensional analysis): Step 1: 45 mg/kg/day × 18 kg = 810 mg/day. Step 2: 810 ÷ 3 = 270 mg/dose. Step 3: 270 mg × (5 mL / 250 mg) = 5.4 mL Raw calculation: 45 × 18 = 810; 810 ÷ 3 = 270; 270 × 5 = 1350; 1350 ÷ 250 = 5.4 Rounding: Nearest tenth; 5.4 is already a tenth. Final answer: 5.4 mL per dose; total daily dose SAFE Safety check: Minimum = 25 × 18 = 450 mg/day; Maximum = 45 × 18 = 810 mg/day; Ordered = 810 mg/day (at the maximum) → SAFE. Rationale: The ordered 45 mg/kg/day equals the upper limit of the hypothetical safe range (810 mg/day), divided into three 270 mg doses of 5.4 mL each. Clinical pearl: When the ordered dose sits exactly at the top of a range, verify it is intentional and monitor the patient closely.
Question 98. Scenario: A child who weighs 21 lb is prescribed amoxicillin-clavulanate for a skin infection. Order: Amoxicillin-clavulanate 45 mg/kg/day of the amoxicillin component PO divided every 12 hours. Available: Amoxicillin-clavulanate suspension 600 mg/5 mL of the amoxicillin component. Hypothetical educational safe range for amoxicillin: 25–45 mg/kg/day. Question: Convert the weight to kg (1 kg = 2.2 lb; round to the nearest tenth), compute the per-dose volume (round to the nearest hundredth), and state whether the daily dose is SAFE or UNSAFE.
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Correct answer: 9.5 kg; 1.78 mL per dose; SAFE Converted weight: 21 lb × (1 kg / 2.2 lb) = 9.545 → 9.5 kg Setup (dimensional analysis): Daily: 45 mg/kg/day × 9.5 kg = 427.5 mg/day. Per dose: 427.5 ÷ 2 = 213.75 mg. Volume: 213.75 mg × (5 mL / 600 mg) Raw calculation: 21 ÷ 2.2 = 9.545 (→ 9.5); 45 × 9.5 = 427.5; 427.5 ÷ 2 = 213.75; 213.75 × 5 = 1068.75; 1068.75 ÷ 600 = 1.78125 Rounding: Weight to nearest tenth (9.5 kg); volume to nearest hundredth (1.78125 → 1.78 mL). Final answer: 1.78 mL per dose; daily dose SAFE Safety check: Minimum = 25 × 9.5 = 237.5 mg/day; Maximum = 45 × 9.5 = 427.5 mg/day; Ordered = 427.5 mg/day (at the maximum) → SAFE. Rationale: The 9.5 kg child needs 213.75 mg per dose (1.78 mL of the 600 mg/5 mL suspension). The daily dose equals the top of the hypothetical safe range, so it is safe but at the maximum. Clinical pearl: For very small volumes like 1.78 mL, an oral syringe (to the hundredth) is essential for accuracy.
Question 99. Scenario: A patient with community-acquired pneumonia is prescribed a 10-day course of amoxicillin suspension. Order: Amoxicillin 600 mg PO every 12 hours for 10 days. Available: Amoxicillin oral suspension 400 mg/5 mL, dispensed in 100 mL bottles (after reconstitution). Question: How many mL per dose, how many total mL for the course, how many 100 mL bottles are needed, and which device should measure the per-dose volume?
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Correct answer: 7.5 mL per dose; 150 mL total; 2 bottles; oral syringe Setup (dimensional analysis): Per dose: 600 mg × (5 mL / 400 mg) = 7.5 mL. Daily: 7.5 mL × 2 = 15 mL/day. Course: 15 mL/day × 10 days = 150 mL. Bottles: 150 mL ÷ 100 mL/bottle = 1.5 → 2 bottles Raw calculation: 600 × 5 = 3000; 3000 ÷ 400 = 7.5; 7.5 × 2 = 15; 15 × 10 = 150; 150 ÷ 100 = 1.5 Rounding: Bottles rounded up (1.5 → 2). Final answer: 7.5 mL per dose (oral syringe); 150 mL total; 2 (100 mL) bottles Rationale: Each 600 mg dose is 7.5 mL, measured with an oral syringe. The 10-day course needs 150 mL, requiring 2 bottles. Clinical pearl: A partial-milliliter dose (7.5 mL) calls for an oral syringe; round bottle counts up to ensure the full course is covered.
Question 100. Scenario: A patient with dysphagia and a new PEG tube needs all scheduled oral medications; the nurse reviews which can be crushed and which must be switched to another form. Order (via PEG tube): (a) Omeprazole 20 mg delayed-release capsule daily; (b) Metoprolol succinate extended-release 50 mg daily; (c) Lisinopril 10 mg tablet daily; (d) Amoxicillin 500 mg every 8 hours. Available: Omeprazole 20 mg delayed-release capsules; metoprolol succinate ER 50 mg tablets; lisinopril 10 mg tablets; amoxicillin oral suspension 250 mg/5 mL. Question: Which two orders must NOT be crushed, and why? For the amoxicillin order, how many mL will the nurse administer per dose?
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Correct answer: Do not crush omeprazole (delayed-release) or metoprolol succinate (extended-release); amoxicillin dose = 10 mL Setup (dimensional analysis): Amoxicillin: 500 mg × (5 mL / 250 mg) = 10 mL Raw calculation: 500 × 5 = 2500; 2500 ÷ 250 = 10.0 Rounding: Whole number; no rounding needed. Final answer: 10 mL amoxicillin per dose; request alternative forms for omeprazole and metoprolol succinate Rationale: (a) Omeprazole delayed-release (enteric-coated) capsules and (b) metoprolol succinate extended-release tablets must NOT be crushed — crushing destroys the enteric coating or release mechanism, causing gastric irritation or "dose dumping." They require alternative forms (e.g., omeprazole suspension or an immediate-release PPI; metoprolol tartrate or another beta-blocker). (c) Lisinopril 10 mg immediate-release tablets may generally be crushed/dispersed (verify with pharmacy). (d) Amoxicillin 500 mg is given as 10 mL of the 250 mg/5 mL suspension. Clinical pearl: Before crushing ANY medication for tube administration, check for enteric coating, extended-release design, and consult the pharmacist — many medications require a specific alternative form.
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