NUR 2349 Dosage Calculations - Final Exam V3(Qns & Ans) - Rasmussen 2025, Exams of Nursing

Download NUR 2349 Dosage Calculations - Final Exam V3(Qns & Ans) - Rasmussen 2025 and more Exams Nursing in PDF only on Docsity!

NUR 2349 Dosage Calculations

Final Exam Review V

(Questions & Solutions)

Multiple Choice Questions (MCQ) A patient requires 250 mg of a medication that is available as 125 mg/ mL. How many milliliters should be administered? a) 5 mL b) 7.5 mL c) 10 mL d) 15 mL ANS: c) 10 mL Rationale: Dose required (250 mg) ÷ concentration per mL (125 mg/5 mL = 25 mg/mL) = 250 ÷ 25 = 10 mL. A physician orders 0.5 mg of Digoxin daily. The medication label reads 0.125 mg/tablet. How many tablets should be given? a) 2 tablets b) 4 tablets c) 3 tablets d) 1 tablet ANS: a) 4 tablets Rationale: 0.5 mg ÷ 0.125 mg/tablet = 4 tablets. A 70 kg adult is prescribed Amikacin at 15 mg/kg/day divided into 3 doses. How many mg per dose will the patient receive? a) 350 mg b) 300 mg c) 450 mg d) 700 mg ANS: b) 350 mg Rationale: Total daily dose = 70 kg × 15 mg/kg = 1050 mg/day; divided by 3 doses = 350 mg per dose.

Calculate the volume (mL) for a drug prescribed at 20 mcg/kg for a 30 kg patient when the solution contains 0.5 mg/mL. The required volume is __________ mL. ANS: 1.2 mL Rationale: Dose = 20 mcg/kg × 30 kg = 600 mcg = 0.6 mg; Volume = 0.6 mg ÷ 0. mg/mL = 1.2 mL. An IV infusion order says 1000 mL over 8 hours. The drip set delivers 15 drops/mL. Calculate the drip rate in drops per minute: __________ drops/min. ANS: 31 drops/min Rationale: Total drops = 1000 mL × 15 drops/mL = 15,000 drops. Time in minutes = 8 × 60 = 480 minutes. Drip rate = 15,000 ÷ 480 = 31.25 ≈ 31 drops/min. A patient requires a loading dose of 25 mg of a drug available as 50 mg/mL. The volume to administer is __________ mL. ANS: 0.5 mL Rationale: Volume = 25 mg ÷ 50 mg/mL = 0.5 mL. True/False Questions True or False: When converting pounds to kilograms, dividing the weight in pounds by 2.2 gives the weight in kilograms. ANS: True Rationale: 1 kg = 2.2 lbs; thus, lbs ÷ 2.2 = kg. True or False: For pediatric doses, body surface area (BSA) calculations provide a more accurate dosage estimate than weight-based calculations. ANS: True

Rationale: BSA relates better to metabolism and drug clearance in pediatric patients. True or False: If a vial states 500 mg per 2 mL, the concentration is equivalent to 250 mg/mL. ANS: True Rationale: 500 mg ÷ 2 mL = 250 mg/mL. True or False: It is acceptable to round medication doses up regardless of the patient safety margin. ANS: False Rationale: Rounding should only be done within safety guidelines to avoid overdosing. True or False: The formula ‘(Desired Dose ÷ Dose on Hand) × Quantity’ is the standard method for dosage calculations. ANS: True Rationale: This formula is the universal approach for converting dosages. Multiple Response Questions Select all factors that affect the accuracy of dosage calculations in pediatric patients: a) Age b) Weight c) Body surface area d) Renal function e) Height ANS: a, b, c, d, e Rationale: Age affects metabolism; weight, BSA, and height impact dose size; renal function alters clearance.

Which factors should be documented post medication calculation and administration? (Select all that apply) a) Dose administered b) Time of administration c) Patient’s response d) Nurse’s initials e) Drug expiration date ANS: a, b, c, d Rationale: Drug expiration date should be checked before administration but is not documented each time. Case-Based Application Questions (Multiple Choice) A patient is prescribed 5 mg/kg/day of Phenytoin in two divided doses. The patient weighs 55 kg. The pharmacy provides Phenytoin as 100 mg/tablet. How many tablets per dose are administered? a) 1.375 tablets b) 2.75 tablets c) 1 tablet d) 3 tablets ANS: a) 1.375 tablets Rationale: Total daily dose = 5 mg × 55 kg = 275 mg/day ÷ 2 doses = 137.5 mg/dose; 137.5 mg ÷ 100 mg/tablet = 1.375 tablets. Order: Ceftriaxone 1 g IM once daily. Available: 250 mg per vial with diluent volume 2 mL. How much volume is needed? a) 2 mL b) 4 mL c) 8 mL d) 1 mL ANS: c) 8 mL Rationale: 1 g = 1000 mg; 4 vials of 250 mg each = 4 × 2 mL = 8 mL.

A patient is to receive 60 mg of medication IV over 30 minutes. The medication is supplied at 120 mg/100 mL. What rate in mL/hr should the IV pump be set? a) 30 mL/hr b) 60 mL/hr c) 120 mL/hr d) 15 mL/hr ANS: a) 30 mL/hr Rationale: 60 mg is half of 120 mg; volume to infuse = 50 mL × 0.5 = 50 mL over 30 minutes → 100 mL/hr. Correction: Actually: Concentration = 120 mg / 100 mL → 1.2 mg/mL Volume needed = 60 mg / 1.2 mg/mL = 50 mL Time = 30 min = 0.5 hr Rate = volume/time = 50 mL / 0.5 hr = 100 mL/hr. Choices above have no 100 mL/hr, so none correct - need to correct ANS. Correct ANS: None of the above; correct rate is 100 mL/hr. If forced to pick closest, none fit. Therefore, I'll modify question: Revised Question 23: A patient is to receive 60 mg medication IV diluted to 50 mL. The medication concentration is 120 mg/100 mL. Infuse over 30 minutes. What is the infusion rate in mL/hr? Choices: a) 30 mL/hr b) 60 mL/hr c) 100 mL/hr d) 15 mL/hr ANS: c) 100 mL/hr Rationale: Volume to infuse = 50 mL over 0.5 hour = 100 mL/hr.

Dose/hr = 0.35 mg/min × 60 = 21 mg/hr Concentration = 400 mg/250 mL = 1.6 mg/mL Volume/hr = 21 mg/hr ÷ 1.6 mg/mL = 13.125 mL/hr. A patient requires 500 mL of 5% Dextrose. How many grams of dextrose are in the IV bag? __________ grams. ANS: 25 grams Rationale: 5% solution = 5 g/100 mL; 500 mL × 5 g/100 mL = 25 g. Calculate the BSA for a patient 160 cm tall and weighing 55 kg using Mosteller formula: BSA = sqrt [(height cm × weight kg)/3600]. BSA = __________ m². ANS: 1.58 m² Rationale: BSA = sqrt[(160 × 55)/3600] = sqrt[8800/3600] = sqrt[2.444] = 1.56 - 1. m² (round accordingly). An order states 10 mg/m² of chemotherapy drug for the patient in question 29. Calculate the total dose in mg: __________ mg. ANS: 15.8 mg Rationale: 10 mg × 1.58 m² = 15.8 mg. True/False (continued) True or False: Intramuscular injections require dosage calculations based on volume per injection site limits to avoid muscle damage. ANS: True Rationale: Large volumes in IM injections may cause pain and tissue damage, limiting volume per site. True or False: For drugs with a wide therapeutic index, small rounding errors in dose calculations rarely impact patient safety. ANS: True

Rationale: Wide therapeutic index drugs have higher safety margins. True or False: Weight-based dosing is inappropriate for patients with rapidly changing fluid status. ANS: True Rationale: Fluid retention or loss affects weight and dosage accuracy. True or False: All pediatric medications are dosed by weight alone without consideration of age or organ function. ANS: False Rationale: Age, organ function, and BSA also inform dosage decisions. True or False: When preparing an IV medication from powder, always verify reconstitution volume and concentration before administration. ANS: True Rationale: Reconstitution alters concentration, affecting dose volume. Multiple Response (continued) Select all the proper steps when calculating IV medication dosages: a) Verify patient’s weight and medication order b) Calculate dose in mg or units c) Convert units when necessary d) Assume dilution factors won’t affect dose calculation e) Check compatibility and stability of medication ANS: a, b, c, e Rationale: Dilution factors must be considered; assuming otherwise leads to errors. Which calculation errors may lead to medication overdose? (Select all that apply) a) Incorrect unit conversion

c) Double-check calculations with a peer d) Avoid asking for help to maintain independence e) Study and understand dose formulas thoroughly ANS: a, c, e Rationale: Calculations under pressure or avoiding help can increase errors. Multiple Choice: A patient is to receive 500 mg of a medication. The medication is available in 250 mg tablets. How many tablets should the nurse administer? A) 1 tablet B) 2 tablets C) 3 tablets D) 4 tablets Correct ANS: B) 2 tablets Rationale: Dividing the total dosage by the dosage per tablet gives 500 mg / 250 mg = 2 tablets. Fill-in-the-Blank: A doctor orders 0.5 g of a medication. Convert this dosage into milligrams. Correct ANS: 500 mg Rationale: One gram equals 1000 mg, hence 0.5 g = 500 mg. True/False: If a medication requires reconstitution, the volume of diluent added does not affect the final concentration of the medication. Correct ANS: False Rationale: The volume of diluent added directly impacts the final concentration of the medication. Multiple Response: Which of the following factors should be considered when calculating drug dosages? (Select all that apply) A) Patient's weight B) Patient's age C) Drug's half-life

D) Route of administration Correct ANS: A, B, D Rationale: Patient's weight, age, and route of administration are critical factors, while the drug's half-life is not directly related to dosage calculations. Multiple Choice: A patient requires a continuous infusion of 5 mcg/kg/min of a drug. The patient weighs 70 kg. What is the total dose in mcg per minute? A) 200 mcg/min B) 350 mcg/min C) 400 mcg/min D) 500 mcg/min Correct ANS: B) 350 mcg/min Rationale: The calculation involves multiplying the weight by the rate: 5 mcg/kg/min 70 kg = 350 mcg/min. Fill-in-the-Blank: The recommended dosage of a medication is 15 mg/kg. For a patient weighing 60 kg, the total dose would be __ mg. Correct ANS: 900 mg Rationale: The total dose is calculated as 15 mg/kg 60 kg = 900 mg. True/False: A nurse can administer a medication without verifying the physician's order if the nurse believes it is necessary for patient care. Correct ANS: False Rationale: Verification of the physician's order is essential for patient safety and legality. Multiple Choice: An intravenous solution contains 1000 mg of a drug in 500 mL of solution. What is the concentration of the drug in mg/mL? A) 1 mg/mL B) 2 mg/mL C) 5 mg/mL D) 10 mg/mL Correct ANS: B) 2 mg/mL

A) 75 mL/hr B) 100 mL/hr C) 125 mL/hr D) 150 mL/hr Correct ANS: B) 125 mL/hr Rationale: The rate is calculated as 1000 mL / 8 hours = 125 mL/hr. Multiple Response: Which calculations are essential for determining IV flow rates? (Select all that apply) A) Total volume of fluid B) Duration of infusion C) Drop factor of the IV set D) Patient's heart rate Correct ANS: A, B, C Rationale: Total volume, duration, and drop factor are crucial for calculating flow rates; heart rate is not directly relevant. Multiple Choice: A patient is ordered 300 mg of a medication. The medication is available as 150 mg/5 mL. How many mL should be given? A) 10 mL B) 15 mL C) 20 mL D) 25 mL Correct ANS: B) 10 mL Rationale: To find the volume, the calculation is 300 mg / (150 mg/ mL) = 10 mL. Fill-in-the-Blank: A provider orders 0.025 g of a medication. This is equivalent to __ mg. Correct ANS: 25 mg Rationale: The conversion of grams to milligrams is done by multiplying by 1000. True/False: The five rights of medication administration include the right patient, right medication, right dose, right time, and right route.

Correct ANS: True Rationale: These are fundamental principles to ensure safe medication administration. Multiple Choice: A medication prescribed at 1.5 mg/kg needs to be adjusted for a patient who weighs 90 kg. What is the adjusted dose? A) 90 mg B) 120 mg C) 135 mg D) 150 mg Correct ANS: C) 135 mg Rationale: The dose is calculated as 1.5 mg/kg 90 kg = 135 mg. Multiple Response: What factors could necessitate a dosage adjustment in elderly patients? (Select all that apply) A) Decreased renal function B) Polypharmacy C) Increased metabolism D) Changes in body composition Correct ANS: A, B, D Rationale: Decreased renal function, polypharmacy, and changes in body composition are significant considerations for dosage adjustments in the elderly. Multiple Choice: A nurse administers 10 mg of a drug that is available in 2 mg/mL concentration. How many mL will the nurse give? A) 2 mL B) 4 mL C) 5 mL D) 6 mL Correct ANS: B) 5 mL Rationale: The calculation is 10 mg / (2 mg/mL) = 5 mL.

ANS: C

Rationale: Volume ÷ Time (hr) = 200 mL ÷ 1.5 hr = 133.3 mL/hr, which is option B, not C. (Correction) Correct ANS: B. 133 mL/hr.

4. MCQ The provider prescribes levothyroxine 75 mcg IV push. Available vial: 0. mg/mL. How many millilitres will you draw? A. 0.25 mL B. 0.5 mL C. 0.75 mL D. 1 mL ANS: B Rationale: 75 mcg = 0.075 mg. 0.075 mg ÷ 0.1 mg/mL = 0.75 mL → option C. (Correction) Correct ANS C. 0.75 mL.

5. MCQ A chemotherapy order: “Cyclophosphamide 600 mg/m² IV.” BSA = 1. m². Pharmacy supplies 1 g in 50 mL. What volume corresponds to the ordered dose? A. 11 mL B. 25 mL C. 40 mL D. 55 mL ANS: C Rationale: Dose = 600 mg × 1.83 = 1 098 mg. Concentration = 1 000 mg/50 mL = 20 mg/mL. Required mL = 1 098 mg ÷ 20 mg/mL = 54.9 mL ≈ 55 mL → option D, not C. (Correction) Correct ANS D. 55 mL.

6. MCQ

Order: “Nitroprusside start at 0.5 mcg/kg/min for a 92 kg patient.” Bag = 50 mg in 250 mL D5W. What initial mL/hr? A. 14 mL/hr B. 28 mL/hr C. 46 mL/hr D. 55 mL/hr ANS: A Rationale: Dose/hr = 0.5 mcg × 92 kg × 60 min = 2 760 mcg/hr = 2.76 mg/hr. Concentration = 50 mg/250 mL = 0.2 mg/mL. mL/hr = 2.76 mg/hr ÷ 0.2 mg/mL = 13.8 ≈ 14 mL/hr.

7. MCQ Which weight should be used for aminoglycoside dosing in an obese adult (>20 % over IBW)? A. Actual body weight B. Adjusted body weight C. Ideal body weight D. Lean body mass ANS: B Rationale: Adjusted body weight corrects for excess adipose tissue while preventing under-dosing or toxicity.

8. MCQ Pediatric acetaminophen: 15 mg/kg/dose q6 h; max 75 mg/kg/day. Mother gives 4 doses of 240 mg to her 16 kg child. Did she exceed the max? A. Yes B. No ANS: B Rationale: 4 × 240 mg = 960 mg total. Max/day = 75 × 16 = 1 200 mg.