Question 1

A child's BSA is 0.9 m².The prescribed dose of medication is 2 mg/m².Which of the following is the calculated dosage?

Accepted Answer

Pediatric dosages are most accurately determined by using the body surface area (BSA)measurement.The reason for using the BSA is that children have a greater surface area than adults in relation to their weight.For drugs that require particularly careful dosing,charts known as nomograms are used to calculate the BSA in square meters.

Question 2

Ordered is codeine 1 gr PO;it is available in 30-mg tablets.Which of the following represents the number of tablets the patient should get?

Accepted Answer

This drug dosage calculation combines the conversion of ordered units into available units and the computation of drug dosage into one step.(Desired)10 gr × (60 mg/1 gr)× (Available)1 tablet/30 mg = 2 tablets.

Question 3

Demerol 75 mg is ordered IV push q 4 to 6 hours PRN for pain.This medication is available in 100 mg/mL.Which of the following represents the amount (in mL)that the nurse will give every 4 to 6 hours as needed?

Accepted Answer

When using a single- or multiple-dose ampule labeled with a certain volume,divide the desired dose (D)by the available dose (A): D/A = 75 mg ÷ 100 mg × 1 mL = 0.75 mL.

Question 4

A doctor has ordered a dose of Synthroid of 0.15 mg daily for a patient.The nurse learns that the pharmacy only stocks 50 mcg scored tablets.Which of the following represents the correct number of 50 mcg Synthroid tablets to give this patient?

Accepted Answer

Drug calculations are required when the drug available is in a different unit of measure than that which is ordered.First change dosages to the same unit of measurement.Next reduce to the simplest terms.Calculate the dosage using fractions,ratios,or proportions.Use common sense to check the answer.In this example,milligrams (mg)must be converted to micrograms (mcg).Since 0.15 mg equals 150 mcg,the correct answer is 3 tablets (3 × 50 mcg = 150 mcg = 0.15 mg).

Question 5

When the usual dose of a medication for a 150 lb adult is 500 mg,which of the following,according to Clark's rule,is the dose for a child weighing 65 lb?

Accepted Answer

Clark's rule: Adult weight: Adult dosage :: Child's weight : Child's dosage (x).Therefore: 150 lb : 500 mg :: 65 lb : x mg.500 × 65 = 32500.32500 ÷ 150 = 217 mg.

Question 6

The nurse prepares to administer an IV piggyback of 75 mL of medication to infuse in 30 minutes with an infusion set of 35 gtt/mL.The gtt/min should be set at which of the following rates?

Accepted Answer

The rate at which IV fluids are given is the flow rate,and this is measured in drops per minute: 35 gtt/mL × 75 mL = 88 gtt/min.

Question 7

Which of the following represents the flow rate in drops/minute for the IV order: 1000 mL of NS over 12 hours using a 60 gtt/mL infusion set?

Accepted Answer

The rate at which IV fluids are given is flow rate and is measured in drops/minute.

Question 8

An elixir is ordered for a patient as 0.6 g every 4 hours.The medicine is available as 80 mg/5 mL.Which of the following represents the amount that the nurse will give per dose?

Accepted Answer

The process and formulas used to calculate dosages of liquids are the same as those used to compute dosages of capsules or tablets.Only the unit of measure is different (0.6 g = 600 mg;600 mg/80 mg = 7.5 × 5 = 37.5 mL).

Question 9

The physician orders Demerol 50 mg IV every 2 hours PRN for pain.The medication comes in a single-dose ampule with 75 mg/mL.Which of the following represents the amount that the nurse will give the patient?

Accepted Answer

A single- or multiple-dose ampule labeled with a certain volume is a form of parenteral medication.Calculate this as: desired dose (50 mg)/available dose (75 mg)= 0.66 mL.

Question 10

Which of the following represents the flow rate in drops/minute for the IV order: 125 mL/hr of D₅W using a 15 gtt/mL infusion set?

Accepted Answer

To calculate the flow rate for IV fluid administration,two concepts must be understood: the flow rate and the drop factor.Drops/minute is the measure of flow rate.Drop factor (15 gtt/mL)× milliliters/minute (2.08 mL/min)= flow rate (drops/minute).Therefore 15 gtt/mL × 2.08 mL/min = 31 gtt/min.(Note that 125 mL/hr divided by 60 minutes per hour = 2.08 mL/min. )

Question 11

If Phenergan is available in 100 mg/2 mL ampules,which of the following represents the amount needed in milliliters to give a dose of 12.5 mg IM?

Accepted Answer

The dose desired ÷ dose available × drug form (dilution or amount of solution)= amount of solution per dose.12.5 mg/50 (mg/mL in ampules)= 0.25 mL.

Question 12

Parenteral medications come in different forms.Which of the following are considered parenteral medications? (Select all that apply. )

Accepted Answer

When medication is to be injected,it usually comes in one of three different forms: a prefilled syringe labeled with a certain dosage and volume (meperidine [Demerol],for example),a single ampule or multiple-dose vial,or a vial with powder or crystals that must be mixed or reconstituted.

Question 13

Valium 2.5 mg is ordered PO three times daily.The medication comes in 5-mg tablets.Which of the following represents the portion of the 5-mg tablet that the nurse will administer to the patient?

Accepted Answer

Tablets that are scored are easily divided to fill a smaller drug dosage order.The formula used is desired dose divided by available dose: (Desired)2.5 mg/(Available)5 mg = 0.5 mg,or 1/2 tablet.

Question 14

The order reads: Lanoxin 0.125 mg PO now.The medication is available in 0.25 mg tablets.Which of the following represents the number of tablets the nurse will give?

Accepted Answer

Drug calculations are required when the drug available is in a larger dose than that ordered.The medication desired is Lanoxin 0.125 mg,and the medication available is 0.25 mg.Divide 0.125 into 0.25 = 0.5 or 1/2 tablet.

Question 15

A nurse receives an order to administer 8 units regular insulin and 20 units NPH insulin before breakfast.Using a U-100 syringe,the nurse would prepare this dose in which of the following ways?

Accepted Answer

When the order calls for two different types of insulin,both may be given at the same time in the same syringe.Draw up the short-acting (regular)clear insulin first,then the intermediate or longer-acting cloudy type.

Question 16

The nurse observes that there is 650 mL of IV fluid remaining in the bag,and the rate is 90 mL/hr.The drop factor on the infusion set is 60 gtt/mL.Which of the following represents how long the IV will last?

Accepted Answer

Calculating the total administration time for IV fluid depends on calculating the total number of drops to be infused,using the following formula: total drops to be infused ÷ flow rate (drops/minute)× 60 (drops/hour)= total infusion time (hours and minutes).Therefore,650 mL × 60 gtt/ml = 39,000 drops to be infused.90 mL/hr × 60 gtt/mL = 5400 gtt/hr.39,000 gtt/5400 gtt/hr = 7.22 hours.Multiply 60 (min/hr)× 0.22 hr = 13 minutes.The answer is 7 hours and 13 minutes.

Question 17

Place the following steps in the correct order for performing a dosage calculation.
A)Calculate the dosage.
B)Change the dosages to the same unit of measurement.
C)Use common sense.
D)Reduce to the simplest terms.

Accepted Answer

The answer of Place the following steps in the correct...

Quiz 9: Calculating Drug Dosages