- A 70-year-old female needs a non-sterile oral suspension of gabapentin 50 mg/mL, total volume 180 mL, to be stored refrigerated in an amber bottle. You have gabapentin 300 mg capsules and will QS with a suitable vehicle. Using a mortar/pestle and graduated cylinder, how many grams of gabapentin are needed for the entire batch?
Answer: 9 g
This question assesses total active ingredient needs for oral suspensions from capsule contents. The key calculation is 50 mg/mL × 180 mL = 9,000 mg = 9 g of gabapentin. The correct answer, 9 g, accounts for the full batch volume accurately. Choice A (0.9 g) underestimates by a factor of 10; choice C (90 g) overestimates similarly; choice D (18 g) doubles the amount. Formula: concentration in mg/mL × volume in mL = total mg, then convert to grams if needed. Refrigerated storage enhances suspension stability.
- A 30-year-old female is prescribed a compounded oral solution of potassium chloride at 10 mEq/15 mL. Prepare a total of 480 mL using purified water and a suitable sweetener q.s. ad 480 mL; the prescriber requests dye-free. If potassium chloride provides 1 mEq per 74.5 mg, using a balance and graduated cylinder, how many grams of potassium chloride are needed for the total batch?
Answer: 23.84 g
This question tests calculation involving milliequivalents (mEq) and unit conversions for electrolyte solutions. First, determine total mEq needed: (10 mEq/15 mL) × 480 mL = 320 mEq. Then convert to mass using the given conversion factor: 320 mEq × 74.5 mg/mEq = 23,840 mg = 23.84 g. The correct answer C (23.84 g) accurately represents this calculation. Option A (1.19 g) appears to calculate for 16 mEq instead of 320, option B (11.92 g) uses half the required amount, and option D (0.119 g) divides by 200. When working with mEq calculations, first determine total mEq needed, then use the substance-specific conversion factor. Always verify unit conversions and decimal placement in multi-step calculations.
- A 47-year-old male needs compounded capsules: baclofen 7.5 mg per capsule, quantity 120 capsules, because 7.5 mg strength is unavailable. You will use baclofen powder with a capsule-filling machine. How many grams of baclofen are required for the batch (ignore overage)?
Answer: 0.9 g
This question evaluates capsule batch for unavailable doses. The key calculation is 7.5 mg/capsule × 120 = 900 mg = 0.9 g of baclofen. The correct answer, 0.9 g, ignores overage. Choice A (0.09 g) under by 10; choice C (9 g) over by 10; choice D (90 g) by 100. Total = dose × quantity. Machines ensure uniformity.
- A 26-year-old female requests a compounded lidocaine oral rinse at 2% w/v for short-term mucosal pain relief. Prepare a total of 250 mL using purified water and a suitable flavoring agent; the prescriber requests alcohol-free formulation. Using a balance and graduated cylinder, how many grams of lidocaine HCl are required to prepare 250 mL of a 2% w/v solution?
Answer: 5 g
This question assesses understanding of weight/volume (w/v) percentage calculations for oral liquid preparations. The w/v percentage means grams of solute per 100 mL of solution, so 2% w/v requires 2 g per 100 mL. For 250 mL: (2 g/100 mL) × 250 mL = 5 g. The correct answer C (5 g) represents this accurate calculation. Option A (0.5 g) incorrectly calculates for 25 mL instead of 250 mL, option B (2.5 g) uses half the required amount, and option D (50 g) multiplies by 10 suggesting confusion with mg units. When preparing w/v solutions, remember the percentage represents grams per 100 mL of final solution. Use proportion calculations to scale up or down from the 100 mL basis to your required volume.
- A 38-year-old female requires a compounded mouthwash: diphenhydramine 0.5% (w/v), total volume 300 mL, sugar-free. You will prepare from diphenhydramine HCl powder and purified water using a balance and graduated cylinder. How many grams of diphenhydramine HCl are needed?
Answer: 1.5 g
This question tests w/v for mouthwashes. The key factor is 0.5% w/v for 300 mL: (0.5/100) × 300 = 1.5 g of diphenhydramine HCl. The correct answer, 1.5 g, is sugar-free. Choice A (0.15 g) under by 10; choice C (15 g) over by 10; choice D (0.5 g) ignores volume. Grams = (percentage/100) × mL. Sugar-free aids diabetics.
- A 40-year-old male with a known peanut allergy needs a compounded hydrocortisone ointment at 1% w/w, and the prescriber specifies a peanut-oil-free ointment base. Compound a total of 60 g, using white petrolatum q.s. ad 60 g. Using an electronic balance and ointment slab/spatula, what quantity of hydrocortisone (in grams) is needed for this formulation?
Answer: 0.6 g
This question evaluates calculation of API quantity for a weight/weight (w/w) percentage ointment preparation. For a 1% w/w preparation, the API comprises 1 g per 100 g of total product. Calculating for 60 g total: (1 g/100 g) × 60 g = 0.6 g. The correct answer B (0.6 g) accurately represents this calculation. Option A (0.06 g) divides by an additional factor of 10, option C (6 g) multiplies by 10 suggesting a 10% preparation, and option D (1.2 g) doubles the correct amount suggesting 2% strength. When compounding w/w ointments, the percentage always refers to the weight of API per 100 parts total weight. Ensure proper decimal placement when scaling percentages to different batch sizes.
- A 52-year-old female needs a compounded topical ointment: mupirocin 2% (w/w), total 22 g, in a polyethylene glycol (PEG) base. Using an electronic balance and ointment slab, how many grams of mupirocin are required?
Answer: 0.44 g
This question tests w/w for ointments. The key calculation is 2% of 22 g: (2/100) × 22 = 0.44 g of mupirocin. The correct answer, 0.44 g, uses PEG base. Choice A (0.22 g) halves; choice C (2.2 g) multiplies by 10; choice D (4.4 g) by 20. Active = (percentage/100) × total. Slabs aid mixing.
- A 50-year-old female requires compounded suppositories: hydrocortisone 25 mg per suppository, quantity 12. You will use hydrocortisone powder and a suppository mold; each suppository will have a final weight of 2 g. How many grams of hydrocortisone are needed for the entire batch (ignore overage)?
Answer: 0.3 g
This question evaluates suppository batch calculations. The key calculation is 25 mg/suppository × 12 = 300 mg = 0.3 g of hydrocortisone. The correct answer, 0.3 g, ignores overage as specified. Choice A (0.03 g) under by 10; choice C (3 g) over by 10; choice D (0.25 g) miscalculates dose. Total = dose × quantity, convert units. Molds ensure uniform suppositories.
- A 58-year-old male is prescribed compounded gabapentin capsules, 225 mg per capsule, because this strength is not commercially available. The prescription is for 90 capsules; each capsule will be filled with gabapentin powder and lactose monohydrate as the diluent. Using a capsule-filling machine and balance, how many grams of gabapentin are required for the batch (do not include any overage)?
Answer: 20.25 g
This question tests batch calculation for solid dosage form compounding, specifically capsules with a non-standard strength. The calculation involves multiplying the per-capsule dose by the total number of capsules: 225 mg × 90 capsules = 20,250 mg = 20.25 g. The correct answer B (20.25 g) accurately reflects this calculation. Option A (2.025 g) represents a decimal placement error (divided by 10), option C (202.5 g) multiplies by 10 suggesting a unit conversion error, and option D (0.2025 g) divides by 100. When compounding batches of capsules, calculate the total API needed by multiplying individual dose by quantity, then convert to appropriate weighing units. Always verify decimal placement when converting between mg and g to ensure accurate compounding.
- A 19-year-old male needs a topical solution for acne: clindamycin 1% (w/v), total volume 120 mL, in an alcohol-free aqueous base. Using a balance and graduated cylinder, how many grams of clindamycin are required?
Answer: 1.2 g
This question tests w/v for topical solutions. The key factor is 1% w/v for 120 mL: (1/100) × 120 = 1.2 g of clindamycin. The correct answer, 1.2 g, fits the alcohol-free base. Choice A (0.12 g) under by 10; choice C (12 g) over by 10; choice D (2.4 g) doubles. Grams = (percentage/100) × mL. Aqueous bases reduce irritation.
- A pediatric patient (2-year-old female, 12 kg) needs an oral suspension of metronidazole 25 mg/mL, total volume 100 mL. You have metronidazole benzoate powder available and will QS with a flavored vehicle. Using a balance and graduated cylinder, how many grams of metronidazole are needed?
Answer: 2.5 g
This question evaluates concentration calculations for pediatric oral suspensions. The key calculation is 25 mg/mL × 100 mL = 2,500 mg = 2.5 g of metronidazole. The correct answer, 2.5 g, matches the direct computation for the flavored vehicle. Choice A (0.25 g) underestimates by 10; choice C (25 g) overestimates by 10; choice D (250 g) by 100. Formula: total active = concentration × volume. Note potential need for equivalent adjustments if using salts like benzoate.
- A 7-year-old female (25 kg) needs an oral suspension of fluconazole 10 mg/mL, total volume 90 mL, to be dispensed in an amber bottle. You have fluconazole powder available and will QS with a vehicle. How many milligrams of fluconazole are required?
Answer: 900 mg
This question assesses suspension totals. The key factor is 10 mg/mL × 90 mL = 900 mg of fluconazole. The correct answer, 900 mg, fits amber bottle. Choice A (90 mg) under by 10; choice C (9,000 mg) over by 10; choice D (450 mg) halves. Total mg = concentration × volume. Amber protects from light.
- A dermatologist prescribes a topical cream for a 16-year-old female: clindamycin phosphate 1% (w/w) cream, total 45 g, in an oil-in-water base. You will weigh ingredients on an electronic balance. How many grams of clindamycin phosphate are required?
Answer: 0.45 g
This question tests w/w concentration for topical creams. The key factor is 1% w/w of 45 g: (1/100) × 45 g = 0.45 g of clindamycin phosphate. The correct answer, 0.45 g, ensures precise formulation in the oil-in-water base. Choice A (0.045 g) is too low by a factor of 10; choice C (4.5 g) too high by 10; choice D (45 g) assumes 100%. Use: (percentage/100) × total weight = grams active. Uniform mixing is key for topical efficacy.
- A prescriber orders a non-sterile oral suspension for a 9-year-old female (30 kg): spironolactone 5 mg/mL, total volume 240 mL, to be stored at room temperature. You have spironolactone powder available and will QS with a suspending vehicle. How many grams of spironolactone are needed?
Answer: 1.2 g
This question examines suspension quantities. The key factor is 5 mg/mL × 240 mL = 1,200 mg = 1.2 g of spironolactone. The correct answer, 1.2 g, suits room temperature storage. Choice A (0.12 g) under by 10; choice C (12 g) over by 10; choice D (2.4 g) doubles. Total = concentration × volume. Vehicles ensure suspension homogeneity.
- A 33-year-old female needs a compounded topical gel: diclofenac sodium 1.5% (w/w), total 80 g, using a carbomer gel base. Using an electronic balance, what total grams of diclofenac sodium are required?
Answer: 1.2 g
This question assesses w/w percentages for topical gels. The key calculation is 1.5% of 80 g: (1.5/100) × 80 = 1.2 g of diclofenac sodium. The correct answer, 1.2 g, ensures proper gel base incorporation. Choice A (0.8 g) uses 1% incorrectly; choice C (12 g) multiplies by 10; choice D (1.5 g) ignores total weight. Use: active weight = (percentage/100) × total. Carbomer bases aid in gel stability.
- How many grams of 10% ointment are needed to make 100 g of 8% using 2% and 10%?
Answer: 75 g
Use alligation: 10% and 2% must be mixed in a ratio of (8-2) to (10-8), or 6 to 2, which simplifies to 3 to 1. That means 3 parts of the total 4 parts come from the 10% ointment. For 100 g total, you need 75 g of 10% ointment. The tempting wrong answer is 25 g, but that is the amount of 2% ointment you would need, not the 10%.
- How many mL of a 1:2000 w/v solution contain 5 mg of drug?
Answer: 10 mL
A 1:2000 w/v solution has 1 g (1000 mg) in 2000 mL, or 0.5 mg/mL. To get 5 mg, divide 5 mg by 0.5 mg/mL, giving 10 mL. The tempting 2.5 mL comes from misreading the ratio as 2 mg/mL rather than 0.5 mg/mL.
- A 45-year-old female requests a compounded topical cream: ketoconazole 2% (w/w) in a fragrance-free cream base. Prepare a total of 60 g and avoid propylene glycol due to sensitivity. Using an electronic balance and ointment slab, how many grams of ketoconazole are required to achieve the desired concentration?
Answer: 1.2 g
This question tests the concept of weight-in-weight (w/w) concentration in pharmaceutical compounding for topical creams. The key calculation involves determining the amount of active ingredient needed for a 2% w/w ketoconazole cream in a total of 60 g. The correct answer, 1.2 g, is calculated using the formula: (percentage/100) × total weight = (2/100) × 60 g = 1.2 g, ensuring the desired concentration is achieved accurately. Choice A (0.6 g) underestimates by using half the percentage or miscalculating the proportion, while choice C (12 g) overestimates by treating it as 20% instead of 2%; choice D (2.4 g) likely doubles the correct amount erroneously. A transferable tip is to always confirm units: percentage w/w means grams of solute per 100 grams of total mixture. In compounding, precise weighing on an electronic balance is crucial to maintain therapeutic efficacy and patient safety.
- A 28-year-old male with a peanut allergy needs a compounded topical ointment: salicylic acid 5% (w/w) in a peanut-free petrolatum base. Prepare 30 g total using an electronic balance and ointment slab. How many grams of salicylic acid are required?
Answer: 1.5 g
This question examines w/w percentage calculations for topical ointments with allergen considerations. The key calculation is 5% w/w of 30 g total: (5/100) × 30 g = 1.5 g of salicylic acid. The correct answer, 1.5 g, provides the exact amount for the peanut-free base, ensuring therapeutic concentration. Choice A (0.15 g) is a decimal error underestimation; choice C (3.0 g) doubles it incorrectly; choice D (15 g) treats it as 50% erroneously. Always apply: grams active = (percentage/100) × total weight. Selecting appropriate bases avoids sensitivities in compounding.
- A 40-year-old male requires a compounded oral rinse: lidocaine 2% (w/v) solution, total volume 200 mL, alcohol-free. You will prepare from lidocaine HCl powder and purified water using a balance and graduated cylinder. How many grams of lidocaine HCl are needed?
Answer: 4 g
This question examines w/v calculations for oral rinses. The key factor is 2% w/v for 200 mL: (2/100) × 200 = 4 g of lidocaine HCl. The correct answer, 4 g, provides the alcohol-free solution accurately. Choice A (0.4 g) undercalculates by 10; choice B (2 g) halves the volume; choice D (20 g) overestimates by 5. Formula: grams = (percentage/100) × volume in mL. Alcohol-free bases improve patient tolerance.
