- A 72-year-old female (weight 60 kg) with atrial fibrillation is prescribed apixaban 5 mg by mouth twice daily. Medical history: hypertension, osteoarthritis; allergies: sulfonamides (hives). Current medications: hydrochlorothiazide 25 mg daily, acetaminophen 650 mg every 6 hours as needed. Labs: SCr 1.1 mg/dL, AST/ALT within normal limits. Calculate the total quantity to be dispensed for a 30-day supply (number of 5 mg tablets).
Answer: 60 tablets
This question tests the calculation of tablet quantities for chronic medication therapy with twice-daily dosing. The key factor is the fixed dosing regimen of 5 mg twice daily, with no dose adjustments needed based on the patient's renal function (SCr 1.1 mg/dL is within acceptable range for full-dose apixaban). The correct answer (C, 60 tablets) is calculated as: 2 tablets/day × 30 days = 60 tablets. Option A (30 tablets) incorrectly calculates for once-daily dosing. Option B (90 tablets) may represent a calculation error or confusion with three-times-daily dosing. Option D (120 tablets) doubles the correct quantity, possibly confusing a 30-day supply with a 60-day supply. For chronic medications, always multiply the daily tablet count by the number of days supplied, and verify that no dose adjustments are needed based on organ function or drug interactions.
- A 28-year-old woman (weight 64 kg) is admitted for status epilepticus and is started on a continuous midazolam infusion at 0.1 mg/kg/hour. Medical history: epilepsy; current medications: levetiracetam 1500 mg twice daily. Allergies: none known. Labs: SCr 0.7 mg/dL, AST/ALT within normal limits. Midazolam concentration is 1 mg/mL. Determine the infusion rate in mL/hour.
Answer: 6.4 mL/hour
This question tests the calculation of infusion rate for a weight-based continuous midazolam infusion. The key patient-specific factor is the patient's weight of 64 kg. Option B is correct because 0.1 mg/kg/hour × 64 kg = 6.4 mg/hour, and at 1 mg/mL, the rate is 6.4 mL/hour. Option A (3.2 mL/hour) is incorrect, likely from using half the weight or rate. Options C (12.8 mL/hour) and D (0.64 mL/hour) are wrong; C doubles the rate, D might divide by 10. For continuous infusions, use: hourly dose (mg/hour) = rate (mg/kg/hour) × weight (kg), then rate (mL/hour) = hourly dose / concentration (mg/mL). This applies to similar infusions like propofol.
- A 66-year-old woman (weight 55 kg) with heart failure is prescribed furosemide 40 mg by mouth twice daily. Medical history: heart failure with reduced ejection fraction, hypertension; current medications: carvedilol 25 mg twice daily, losartan 50 mg daily, spironolactone 25 mg daily. Allergies: none known. Labs: SCr 1.1 mg/dL, potassium 4.6 mEq/L (normal ~3.5–5.0). Calculate the total quantity of furosemide 40 mg tablets to dispense for a 30-day supply.
Answer: 60 tablets
This question tests the calculation of total quantity for a 30-day supply of twice-daily furosemide. The key patient-specific factor is the fixed 40 mg twice daily dose, independent of weight. Option C is correct because 2 tablets/day × 30 days = 60 tablets. Option A (30) is incorrect, assuming once daily. Options B (45) and D (90) wrong; B might use 1.5/day, D triples. Formula: total = doses/day × days. Transferable to loop diuretics like torsemide.
- A 6-year-old boy (weight 20 kg) is diagnosed with acute otitis media and is prescribed amoxicillin 90 mg/kg/day by mouth divided every 12 hours for 10 days. Medical history: recurrent otitis media; current medications: none. Allergies: none known. Labs: not applicable. The suspension available is amoxicillin 400 mg/5 mL. What volume (mL) should be administered per dose?
Answer: 11.25 mL per dose
This question tests the calculation of volume for a weight-based pediatric dose of amoxicillin suspension. The key patient-specific factor is the child's weight of 20 kg. Option C is correct because the daily dose is 90 mg/kg/day × 20 kg = 1800 mg/day, divided every 12 hours is 900 mg/dose, and with 400 mg/5 mL, the volume is (900 mg / 400 mg) × 5 mL = 11.25 mL per dose. Option A (5.0 mL) is incorrect, likely from using half the daily dose or a lower concentration. Options B (10.0 mL) and D (22.5 mL) are wrong; B might omit dividing the daily dose, while D could double it. For pediatric suspensions, use the formula: dose (mg) = (daily rate (mg/kg/day) × weight (kg)) / doses per day, then volume (mL) = (dose (mg) / concentration (mg per unit mL)) × unit mL. This method prevents errors in similar calculations for drugs like cefdinir.
- A 10-year-old girl (weight 35 kg) with an acute asthma exacerbation is prescribed prednisolone 1 mg/kg/day by mouth for 5 days. Medical history: asthma; current medications: albuterol inhaler as needed, fluticasone inhaler 2 puffs twice daily. Allergies: none known. Labs: not applicable. Prednisolone oral solution concentration is 15 mg/5 mL. What volume (mL) should be administered per day?
Answer: 11.7 mL/day
This question tests the calculation of daily volume for weight-based prednisolone solution. The key patient-specific factor is the child's weight of 35 kg. Option C is correct because 1 mg/kg/day × 35 kg = 35 mg/day, 15 mg/5 mL, volume = (35 / 15) × 5 ≈ 11.67 mL/day. Option A (5.8) uses 2.5 kg? B (8.8) 1.5 mg/5 mL error, D (23.3) doubles. Formula: daily dose = rate × weight, volume = (dose / conc) × unit. For corticosteroids like dexamethasone.
- A 67-year-old male (weight 78 kg) is being treated for acute deep vein thrombosis and is prescribed enoxaparin 1 mg/kg subcutaneously every 12 hours for 7 days. Medical history includes hypertension and hyperlipidemia; allergies: penicillin (rash). Current medications: lisinopril 20 mg daily, atorvastatin 40 mg nightly, aspirin 81 mg daily. Labs: serum creatinine (SCr) 0.9 mg/dL, AST/ALT within normal limits. Enoxaparin is supplied as 80 mg/0.8 mL prefilled syringes. Calculate the total quantity to be dispensed for the full 7-day course (number of 80 mg/0.8 mL syringes).
Answer: 14 syringes
This question tests the calculation of total medication quantity needed for a weight-based dosing regimen over a specified treatment duration. The key patient-specific factor is the patient's weight of 78 kg, which determines the daily enoxaparin dose. The correct answer (B, 14 syringes) is calculated as follows: 78 kg × 1 mg/kg = 78 mg per dose; 78 mg × 2 doses/day × 7 days = 1,092 mg total; 1,092 mg ÷ 80 mg/syringe = 13.65 syringes, rounded up to 14 syringes. Option A (7 syringes) incorrectly calculates for once-daily dosing instead of twice-daily. Option C (28 syringes) doubles the correct answer, possibly confusing the number of doses with the number of syringes. Option D (10 syringes) underestimates the total quantity needed. When calculating quantities for weight-based medications, always multiply: weight × dose/kg × doses/day × days, then divide by the strength per unit to determine units needed, rounding up to ensure adequate supply.
- A 72-year-old man (weight 68 kg) is prescribed potassium chloride extended-release 20 mEq tablets with directions: take 1 tablet by mouth twice daily. Medical history: heart failure; current medications: furosemide 40 mg twice daily, sacubitril/valsartan 49/51 mg twice daily. Allergies: none known. Labs: potassium 3.2 mEq/L (low; normal ~3.5–5.0), SCr 1.0 mg/dL. Calculate the total quantity to be dispensed for a 30-day supply.
Answer: 60 tablets
This question tests the calculation of total quantity for a 30-day supply of twice-daily potassium chloride. The key patient-specific factor is the fixed 20 mEq twice daily dose. Option B is correct because 2 tablets/day × 30 days = 60 tablets. Option A (30) once daily, C (90) three times, D (120) double supply. Formula: total = doses/day × days. For electrolytes like magnesium.
- A 52-year-old male (weight 80 kg) is admitted for a pulmonary embolism and is ordered an unfractionated heparin continuous infusion at 18 units/kg/hour after a bolus. Medical history: obesity, hypertension; allergies: none known. Current medications: metoprolol succinate 50 mg daily. Labs: SCr 1.0 mg/dL, AST/ALT within normal limits, baseline aPTT within normal range. The heparin premix available is 25,000 units in 250 mL (concentration 100 units/mL). Determine the infusion rate for this IV medication (in mL/hour).
Answer: 14.4 mL/hour
This question tests the calculation of IV infusion rates for weight-based heparin dosing. The key patient-specific factor is the patient's weight of 80 kg, which determines the hourly heparin dose. The correct answer (C, 14.4 mL/hour) is calculated using: 18 units/kg/hour × 80 kg = 1,440 units/hour; 1,440 units/hour ÷ 100 units/mL = 14.4 mL/hour. Option A (7.2 mL/hour) represents half the correct rate. Option B (10.8 mL/hour) appears to use an incorrect weight or dose calculation. Option D (18 mL/hour) may confuse the units/kg/hour rate with the mL/hour rate. When calculating weight-based continuous infusions, use the formula: (units/kg/hour × weight in kg) ÷ concentration = mL/hour. Always double-check that the final rate seems reasonable for the clinical scenario.
- A 2-month-old male infant (weight 5 kg) is prescribed acetaminophen 15 mg/kg per dose by mouth every 6 hours as needed for fever. Medical history: none significant; current medications: none. Allergies: none known. Labs: not applicable. Acetaminophen liquid concentration is 160 mg/5 mL. What volume (mL) should be administered per dose?
Answer: 2.3 mL per dose
This question tests the calculation of volume for weight-based acetaminophen dose in infants. The key patient-specific factor is the infant's weight of 5 kg. Option B is correct because 15 mg/kg × 5 kg = 75 mg/dose, 160 mg/5 mL, volume = (75 / 160) × 5 ≈ 2.34 mL, rounded to 2.3 mL. Option A (1.2) halves, C (3.8) uses 24 mg/kg, D (4.7) doubles. Formula: dose = rate × weight, volume = (dose / conc) × unit. For antipyretics like ibuprofen.
- Albuterol 2 puffs q6h; canister contains 200 puffs; 90-day supply. How many canisters?
Answer: 4 canisters
Use 8 puffs per day (2 puffs x 4 doses daily), over 90 days = 720 puffs. One 200-puff canister lasts 25 days, so 90 days needs 3.6 canisters; round up to 4. Don't pick 3 canisters: 3 canisters provide only 600 puffs, short by 120 puffs.
- A 3-year-old girl (weight 15 kg) has nausea and vomiting and is prescribed ondansetron 0.15 mg/kg per dose by mouth every 8 hours as needed. Medical history: none significant; current medications: none. Allergies: none known. Labs: not applicable. Ondansetron oral solution concentration is 4 mg/5 mL. What volume (mL) should be administered per dose?
Answer: 2.8 mL per dose
This question tests the calculation of volume for a weight-based dose of ondansetron oral solution. The key patient-specific factor is the child's weight of 15 kg. Option B is correct because 0.15 mg/kg × 15 kg = 2.25 mg/dose, and at 4 mg/5 mL, volume = (2.25 / 4) × 5 = 2.8125 ≈ 2.8 mL. Option A (1.4 mL) is incorrect, likely from halving the dose. Options C (4.2 mL) and D (5.6 mL) are wrong; C uses 0.225 mg/kg, D doubles weight. For oral solutions, use: dose (mg) = rate (mg/kg) × weight (kg), volume (mL) = (dose / concentration mg) × unit mL. This method applies to antiemetics like promethazine.
- A 67-year-old man (weight 82 kg) is being treated for acute deep vein thrombosis and is prescribed enoxaparin 1 mg/kg subcutaneously every 12 hours for 7 days. Medical history includes hypertension and type 2 diabetes; current medications: lisinopril 20 mg daily, metformin 1000 mg twice daily, atorvastatin 40 mg nightly. Allergies: penicillin (rash). Labs: SCr 0.9 mg/dL, AST/ALT within normal limits, A1c 7.4%. Enoxaparin is supplied as 100 mg/mL in a prefilled syringe; what volume (mL) should be administered per dose?
Answer: 0.82 mL per dose
This question tests the calculation of volume for a weight-based dose of enoxaparin administered subcutaneously. The key patient-specific factor is the patient's weight of 82 kg. Option B is correct because the dose is 1 mg/kg × 82 kg = 82 mg, and with a concentration of 100 mg/mL, the volume per dose is 82 mg / 100 mg/mL = 0.82 mL. Option A (0.41 mL) is incorrect as it represents half the required dose, possibly from mistakenly using 0.5 mg/kg or dividing by 200 mg/mL. Option C (1.64 mL) and D (82 mL) are wrong; C likely doubles the dose to 2 mg/kg, while D omits dividing by the concentration. For weight-based injectable doses, use the formula: dose (mg) = dosing rate (mg/kg) × weight (kg), then volume (mL) = dose (mg) / concentration (mg/mL). This method ensures accurate administration and can be applied to other parenteral medications like heparin.
- A 50-year-old woman (weight 62 kg) is prescribed metronidazole 500 mg by mouth every 12 hours for 7 days for bacterial vaginosis. Medical history: none significant; current medications: none. Allergies: none known. Labs: AST/ALT within normal limits, SCr 0.8 mg/dL. The pharmacy has metronidazole 500 mg tablets. Calculate the total quantity to be dispensed.
Answer: 14 tablets
This question tests the calculation of total quantity for metronidazole over 7 days. The key patient-specific factor is the fixed 500 mg every 12 hours dose. Option C is correct because 2 tablets/day × 7 days = 14 tablets. Option A (7) once daily, B (10) miscalculates days, D (21) three times daily. Formula: total = doses/day × days. Applies to anaerobe coverage drugs.
- A 63-year-old male (weight 85 kg) with chronic kidney disease is prescribed gabapentin for neuropathic pain. Medical history: type 2 diabetes mellitus, CKD; allergies: none known. Current medications: insulin glargine 22 units nightly, insulin lispro with meals, losartan 50 mg daily. Labs: SCr 2.3 mg/dL (elevated; normal ~0.6–1.3 mg/dL). His estimated creatinine clearance (CrCl) is documented as 25 mL/min. The prescription is written for gabapentin 300 mg by mouth three times daily. Based on renal impairment, the recommended total daily dose for CrCl 15–29 mL/min is 200–700 mg/day given once daily. What is the correct dose adjustment for this patient with renal impairment?
Answer: Adjust to 300 mg once daily
This question tests renal dose adjustment for gabapentin based on creatinine clearance. The key patient-specific factor is the severely reduced renal function with CrCl of 25 mL/min, requiring significant dose reduction. The correct answer (B, 300 mg once daily) falls within the recommended range of 200-700 mg/day given once daily for CrCl 15-29 mL/min, representing an appropriate reduction from the original 900 mg/day (300 mg TID). Option A (continuing 300 mg TID) ignores the renal impairment and would result in drug accumulation. Option C (900 mg once daily) maintains the total daily dose but doesn't reduce it for renal impairment. Option D (300 mg BID) provides 600 mg/day, which while within range, doesn't follow the once-daily recommendation for this CrCl range. For renally-eliminated drugs like gabapentin, always consult dosing guidelines based on CrCl ranges and adjust both the dose amount and frequency as specified.
- A 32-year-old woman (weight 68 kg) is prescribed prednisone 10 mg tablets with directions: take 4 tablets daily for 3 days, then 3 tablets daily for 3 days, then 2 tablets daily for 3 days, then 1 tablet daily for 3 days, then stop. Medical history: asthma; current medications: albuterol inhaler as needed, budesonide/formoterol 2 inhalations twice daily. Allergies: none known. Labs: not applicable. What total quantity of prednisone 10 mg tablets should be dispensed?
Answer: 30 tablets
This question tests the calculation of total quantity for a tapering regimen of prednisone tablets. The key patient-specific factor is the stepwise dosing schedule over 12 days, independent of weight. Option C is correct because (4 tabs × 3 days) + (3 × 3) + (2 × 3) + (1 × 3) = 12 + 9 + 6 + 3 = 30 tablets. Option A (20 tablets) is incorrect, likely from summing only the daily tabs without multiplying by days. Options B (24 tablets) and D (40 tablets) are wrong; B might omit one step, while D could extend days per step. For tapering regimens, sum quantities as: total = Σ (daily tabs × days per step). This principle applies to steroid tapers like methylprednisolone, ensuring safe de-escalation.
- A 45-year-old female (weight 62 kg) presents with an uncomplicated urinary tract infection. Past medical history: type 2 diabetes mellitus; allergies: none known. Current medications: metformin 1000 mg twice daily, empagliflozin 10 mg daily. Labs: hemoglobin A1c 7.4%, SCr 0.8 mg/dL, AST/ALT within normal limits. She is prescribed nitrofurantoin monohydrate/macrocrystals 100 mg by mouth twice daily for 5 days. Calculate the total quantity to be dispensed for this prescription (number of capsules).
Answer: 10 capsules
This question tests the calculation of total capsules needed for a fixed-dose antibiotic regimen. The key factor is the straightforward dosing schedule of 100 mg twice daily for 5 days, with no weight-based adjustments needed. The correct answer (A, 10 capsules) is calculated by multiplying: 2 capsules/day × 5 days = 10 capsules total. Option B (14 capsules) incorrectly calculates for a 7-day course instead of 5 days. Option C (20 capsules) doubles the correct answer, possibly confusing twice-daily dosing with the total number of capsules. Option D (5 capsules) represents only one capsule per day instead of two. For fixed-dose medications, the formula is simple: doses per day × number of days = total doses needed. Always verify the duration of therapy and frequency to avoid dispensing errors.
- A 58-year-old man (weight 86 kg) is prescribed heparin for venous thromboembolism treatment: a bolus of 80 units/kg IV once, then continuous infusion at 18 units/kg/hour. Medical history: atrial fibrillation; current medications: none currently. Allergies: none known. Labs: SCr 1.0 mg/dL, AST/ALT within normal limits. The heparin premix bag concentration is 25,000 units in 250 mL. Determine the infusion rate in mL/hour.
Answer: 15.5 mL/hour
This question tests the calculation of infusion rate for weight-based heparin continuous infusion. The key patient-specific factor is the patient's weight of 86 kg. Option C is correct because 18 units/kg/hour × 86 kg = 1548 units/hour, bag is 25,000 units/250 mL = 100 units/mL, rate = 1548 / 100 = 15.48 ≈15.5 mL/hour. Option A (6.2) incorrect, perhaps quarter rate. B (12.4) uses 14 units/kg, D (18.0) ignores weight precision. Formula: hourly dose = rate × weight, rate (mL/hour) = hourly dose / concentration. Applies to anticoagulants like argatroban.
- A 9-year-old boy (weight 30 kg) is prescribed oseltamivir for influenza treatment at 75 mg by mouth twice daily for 5 days. Medical history: asthma; current medications: albuterol inhaler as needed. Allergies: none known. Labs: not applicable. Oseltamivir is available as 75 mg capsules. Calculate the total quantity to be dispensed to complete therapy.
Answer: 10 capsules
This question tests the calculation of total quantity for pediatric oseltamivir treatment. The key patient-specific factor is the weight-based dose of 75 mg twice daily for 5 days (for >23 kg). Option B is correct because 2 capsules/day × 5 days = 10 capsules. Option A (5) incorrect, half duration. C (14) adds days, D (20) doubles doses. Formula: total = doses/day × days. Transferable to antivirals like valacyclovir.
- Heparin 25,000 units/250 mL. Order 18 units/kg/hr; patient weighs 75 kg. What rate (mL/hr)?
Answer: 13.5 mL/hr
Heparin concentration is 25,000 units / 250 mL = 100 units/mL. You need 18 units/kg/hr x 75 kg = 1,350 units/hr. Divide 1,350 units/hr by 100 units/mL to get 13.5 mL/hr. The tempting 5.4 mL/hr comes from dividing by 250 mL total volume instead of the concentration, which gives the wrong units.
- A 63-year-old man (weight 72 kg) with chronic kidney disease is prescribed gabapentin 300 mg by mouth three times daily. Medical history: diabetic neuropathy, CKD; current medications: insulin lispro with meals, insulin glargine 24 units nightly. Allergies: none known. Labs: SCr 2.4 mg/dL (elevated; normal ~0.6–1.2). The prescriber requests a 30-day supply. Gabapentin is available as 300 mg capsules. Calculate the total quantity to be dispensed for 30 days.
Answer: 90 capsules
This question tests the calculation of total quantity for a 30-day supply of thrice-daily gabapentin. The key patient-specific factor is renal function, but dose is given as 300 mg TID without adjustment noted. Option C is correct because 3 capsules/day × 30 days = 90 capsules. Option A (30) assumes daily, B (60) twice daily, D (120) four times. Formula: total = doses/day × days. Essential for neuropathic pain meds like pregabalin.
