Pharmaceutical Calculations Flashcards

A 72-year-old male weighs 80 kg and has a serum creatinine of 1.0 mg/dL. Using the Cockcroft-Gault equation [CrCl = (140 − age) × weight ÷ (72 × SCr)], what is his estimated creatinine clearance?

Answer: 75 mL/min

(140 − 72) × 80 ÷ (72 × 1.0) = 68 × 80 ÷ 72 ≈ 75.6 mL/min.

How many milliequivalents (mEq) of potassium chloride are contained in 30 mL of a 2 mEq/mL solution?

Answer: 60 mEq

2 mEq/mL × 30 mL = 60 mEq of potassium chloride.

Using the alligation method, what volumes of 70% alcohol and 30% alcohol are needed to prepare 500 mL of 50% alcohol?

Answer: 250 mL of 70% and 250 mL of 30%

Parts of 70% = 50 − 30 = 20; parts of 30% = 70 − 50 = 20; equal ratio = 250 mL each.

A pediatric patient has a body surface area (BSA) of 0.5 m². The adult dose of a medication is 200 mg. Using the BSA method (Pediatric dose = [Child BSA ÷ 1.73 m²] × Adult dose), what is the appropriate pediatric dose?

Answer: 58 mg

(0.5 ÷ 1.73) × 200 mg = 0.289 × 200 ≈ 58 mg.

An IV infusion is ordered at 30 drops/min using a 20 drops/mL administration set. What is the equivalent infusion rate in mL/hr?

Answer: 90 mL/hr

30 drops/min ÷ 20 drops/mL = 1.5 mL/min × 60 min/hr = 90 mL/hr.

A powder for reconstitution has a powder volume of 1.5 mL. The final volume after reconstitution should be 5 mL. How much diluent must be added?

Answer: 3.5 mL

Diluent volume = final volume − powder volume = 5.0 − 1.5 = 3.5 mL.

A patient is prescribed atenolol 50 mg once daily for 30 days. What quantity of 50 mg tablets should be dispensed?

Answer: 30 tablets

1 tablet/dose × 1 dose/day × 30 days = 30 tablets.