Drug Dosage Calculations

A dosage schedule for a surfactant calls for 5 mL/kg of body weight. If a premature infant weighs 1200 g, how many milliliters are needed to give the appropriate dose?

6 mL (convert g to mg > 1200/1000 = 1.2, 1.2 x 5 = 6)

You have 120 mg of a drug in 30 mL of solution. How many milliliters of the solution will you use to give a 15 mg dose?

3.75 mL (120/30 x 15/? = 450/120 = 3.75) cross multiply then divide

A patient with a tidal volume of 400 milliliters has a tidal volume of how many liters? 40 4 .400 .04

.400L

You are to administer 0.075 g of a medication labeled: "25 mg per mL." How much solution (mL) needs to be taken out of the vial to administer the prescribed dosage?

.75/.25 = 3 mL

You have a 1 mg/mL vial of medication. How much of the medication solution do you need to use to give a 0.25 mg dose?

0.25 mL (1 x 0.25 = 0.25)

You have 500cc of a solution. How many liters is it?

0.5 L. (1liter = 1000 cc.) So, 500cc = 500/1000 = 1/2 or 0.5 liter.

How many mg of active ingredient are in 0.3 mL of a 5% strength solution?

15 mg (0.3 x .5 = 0.015G, 0.015 x 1000 = 15MG)

A medication is available as 80 mg/15 mL, how much is needed for a 100 mg dose?

18.75 mL 80/15 x 100/? = 1500/80 = 18.75)

What strength of drug would be administered if 6 g of active ingredient is reconstituted with sterile water to a total volume of 300 ml? 2% strength 0.5% strength 20% strength 50% strength

2% strength. 6 g of active ingredient in 300 ml represents 2 g for every 100 ml, which is a 2% solution.

A drug is available as a 20 mg/3 mL solution. What is the percent strength (percent solution)?

2.0/3 = 0.67%

A solution of drug contains 80 units/ml. How many milliliters would you need to deliver 320 units of the drug? 0.4 ml 4 ml 14 ml 40 ml

4 ml. Refer to example calculation 8 in the textbook to set up your calculation and solve for X.

A dosage of 4 mg of morphine sulfate is ordered for a patient. How many milliliters of the morphine solution needs to be taken from a vial of the medicine that contains 10 mg/ml?

4 x .10 = 0.4 mL

A rescue dosage of surfactant calls for 3 ml/kg body weight. If a premature infant weighs 1,500 g, how many milliliters are needed? 5.0 ml 9.0 ml 0.45 ml 4.5 ml

4.5 ml. You first convert the baby's weight from grams to kilograms. Then you determine how many milliliters are needed if the required dosage is 3 ml per kilogram by multiplying 3 by the weight in kg (3 ml x 1.5 kg).

Using a schedule of 0.1 mg/kg for albuterol syrup and a prepared strength mixture of 2 mg/5 mL, how much of the syrup is needed for a 20 kg child?

5 mL (0.1/1 x 2/5 = 2.0/0.5 = 4, then 20/4 = 5

A patient who weighs 55 kilograms is to receive a drug dosage of 10mg/kg. How much drug should be administered? 550 mg 250 mg 25 mg 5.5 mg

550 mg. To determine the dosage to administer, simply multiply 55 kg by 10 mg (55 kg x 10 mg = 550 mg).

A solution of medication has a prepared strength of 0.2 mg/mL. How many milliliters of solution are needed for a 1.5 mg dose?

7.5 mL (0.2/1 x 1.5/? = 1.5/0.2 = 7.5)

When calculating drug dosages based on a patient's weight in kilograms, a respiratory therapist can use the BSA nomogram to convert from pounds to kilograms. True False

False. The nomogram used to determine body surface area (BSA) combines height and weight in a single measurement to determine a patient's overall body size. If a drug dosage requires a specific number of units per patient weight in kilograms, the factor-label method should be used to convert the patient's weight from the English system to the metric system.

Normal saline in solution with albuterol is known as the solvent. True False

True. A solution contains an active drug, which is the solute dissolved in a solvent, such as sterile water or normal saline.

In a W/V solution, how much solute is there when there are 3 ml of a 1:100 solution? a. 30 mg b. 20 ml c. 10 mg d. 10 ml

a. 30 mg. The ratio becomes X = 0.03 g or 30 mg

If there are 80 units/ml, how many milliliters are needed to deliver 320 units? a. 4 ml b. 14 ml c. 40 ml d. 0.4 ml

a. 4 ml. If 1 ml contains 80 units, then 4 ml would be needed to deliver 320 units. 80 x 4 =320, or 320/80 = 4 ml

You should administer surfactant at 3 ml/kg. How many milliliters of surfactant should you give a 1.5-kg baby? a. 4.5 ml b. 0.45 ml c. 5.0 ml d. 9.0 ml

a. 4.5 ml. Multiply 1.5 kg by 3 ml/kg to get a total of 4.5 ml.

Adding 5 ml of saline instead of 2 ml of saline to 0.5 ml of a 1% drug solution will result in which of the following changes to the delivered dose of medication? a. Remain the same b. Weaken the drug c. Decrease d. Increase

a. Remain the same. The medication strength remains at 1%. By adding additional saline, you have only lengthened the time of the treatment.

What is the amount of active drug in 3 cc of a 10% drug solution? a. 0.3 mg b. 0.3 g c. 1 mg d. 1 g

b. 0.3 g. Set up the proportion 10 g/100 ml = X g/3 ml and cross-multiply. Then solve for X.

A patient weighs 88 lb. If an order is written to deliver 0.25 mg/kg, what dosage of medication would be administered to the patient? a. 22 mg b. 10 mg c. 40 mg d. 44 mg

b. 10 mg. You need to convert the weight from pounds to kilograms: 1 kg = 2.2 lbs. so 88/2.2 = 40 kg. The order reads 0.25 mg/kg of body weight. Multiply 40 kg by 0.25 to give you the answer of 10 mg to be administered.

The metric system is based upon exponential powers of: a. 100 b. 1,000 c. 10 d. 10,000

c. 10

Sterile water or normal saline is mixed with virazole, which is supplied in powder form. Which of the following represent the type of solution created? a. Liquid/solute solution b. Solid/solvent solution c. Volume/volume solution d. Weight/volume solution

d. Weight/volume solution.

There are 20 mg of cromolyn sodium in 2 ml of normal saline. What is the percentage strength of the solution? a. 10% b. 2% c. 20% d. 1%

d. 1%. When setting up the proportion, you must remember to convert your final answer to grams, because a percentage strength is reported as the amount of grams in 100 ml of solution.

What is the length of a newborn in inches if the patient is measured at 45.7 cm in length? a. 20 in. b. 19 in. c. 18 in. d. 17 in.

c. 18 in. 2.54 cm = 1 in. 45.7 cm/2.54 cm = 17.99 in. 18 in. is the closest answer.

0.3 l of a medication bag contains how many milliliters? a. 30 ml b. 3,000 ml c. 300 ml d. 3 ml

c. 300 ml. When you convert from the basic unit of liters to milliliters, you move the decimal place three times to the right. This gives you 30 ml.

What is the term for the active ingredient? a. Solvent b. Solution c. Solute d. Saline

c. Solute is the "active ingredient," or what is dissolved by a solvent to form a solution.

A patient with a tidal volume of 0.4 l, has a tidal volume of how many milliliters? a. 0.04 ml b. 0.004 ml c. 40 ml d. 400 ml

d. 400 ml is the equivalent of 0.4 l based upon converting within the metric system.

A female patient weighs 125 lb. What is her approximate weight in kilograms? a. 63 kg b. 28 kg c. 275 kg d. 57 kg

d. 57 kg. 125/2.2 = 56.81 kg, which rounds up to 57 kg.

How much active drug is in 3 ml of a 10% solution? 0.3 g 1 g 0.3 mg 1 mg

0.3 g. By definition (%solution = g). Solve: 3 x .10 = 0.3

An adult female patient weighs 125 lb. The dosage schedule for her medication calls for 5 mg/Kg body weight. How many mg of medication does this patient require?

125/2.2 = 56.81 kg x 5mg = 284 mg

A cubic centimeter (cc) is equal to:

1 mL

A drug solution contains 20 mg in 2 mL/ What is the percentage solution?

1% (2/20 = 0.1 = 1%)

If a drug order is written for 0.25 mg/kg of body weight, what dosage would be administered to a patient weighing 88 lb?

88/2.2=40, 40 x .25 = 10mg

A bottle of medication is labeled 50 mg/mL. How many milliliters of solution are needed to give a 125 mg dose?

2.5 mL (125/50 = 2.5)

A metaproterenol sulfate unit dose contains 2.5 mL of a 0.6% solution. How many milligrams of active ingredient are present in this unit dose?

2.5 x 6mg = 15 mg (convert 0.6g to 6mg)

The drug dornase alfa has been ordered for a patient with cystic fibrosis. A single 2.5 mL ampule contains a 2.5 mg dose. What is the percent solution of this medication?

2.5/2.5 = 0.1%

How many mg of active ingredient are there in 3 mL of a 0.083% solution of albuterol?

3 x .83mg = 2.49 mg (convert 0.083g to .83mg)

A medication bag contains 0.03 liters. This is equal to how many milliliters? 3 30 300 3,000

30. Refer to Table 2-2 to convert from liters to milliliters.

A 0.5% strength solution contains how many milligrams in 1 mL?

5 mg (convert g to mg > .005 x 1000 = 5)

A drug's dosage strength is available in a 1% solution. How many milliliters (mL) of drug are required to deliver a 5 mg dose to a patient?

5 x .1 = 0.5 mL

The physician order reads "Administer 5 mg metaproterenol via inhalation route with a small volume nebulizer." How many milliliters of a 1% solution should be used?

5 x .1 = 0.5 mL

A physician orders 6mL of a 20% Mucomyst solution. Your department only carries the 10% Mucomyst solution. How many mL of 10% Mucomyst must be given to equal the same dose of the 20% Mucomyst? [Hint: Find the number of mg for the 20% solution first. Then find the number of mL of the 10% solution to get that number of mg]

6 x .20 = 1.2, 1.2/.10 = 12 mL

600 g is equivalent to how many pounds? a. 1.3 lbs. b. 3.5 lbs. c. 2.7 lbs. d. 4.1 lbs.

a. 1.3 lbs. To make this a much easier task, first convert 600 g to 0.6 kg. From there you simply multiply 0.6 by 2.2 to get 1.32 lb.

Virazole is supplied in a powder form that must be mixed with normal saline or sterile water prior to nebulization. This type of solution represents a: Solid/solvent Weight/volume Liquid/solute Volume/volume

Weight/volume. A drug solution that consists of the active drug in solid (or powder) form mixed with a liquid solvent is considered a weight/volume solution.

What would the new concentration be, in percentage, of 1.5 ml of a 10% solution that has been increased with normal saline to 3.0 ml? a. 20% b. 5% c. 0.5% d. 0.05%

b. 5%. If 1.5 ml represents a 10% solution and the volume has been doubled to 3 ml, then the percentage of the solution is now half the original strength.

A patient who weighs 121 lbs. is to receive a drug dosage of 10 mg/kg. How much drug should be administered? a. 250 mg b. 550 mg c. 5.5 mg d. 25 mg

b. 550 mg. At 10 mg/kg, the given weight of 121 lbs. should be converted to 55 kg and should then be multiplied by 10, because for every kilogram of weight, 10 mg of medication should be given.

A patient is 167 cm tall. How many inches tall is the patient? a. 60 in. b. 66 in. c. 56 in. d. 86 in.

b. 66 in. There are 2.54 cm in 1 in. Divide 167 by 2.54. The answer is 65.75. Of the answer choices provided, 66 in. is the closest.

Which statement is false concerning writing numbers in health-care documentation? a. Recommendations about proper technique in writing numbers are made by the JCAHO. b. A 0 should always follow a decimal point. c. Following general guidelines when writing numbers can help prevent medication errors. d. Any decimal number should always be preceded by a 0.

b. A 0 should never follow a decimal point, because the decimal may be looked over and too high of a dose may be administered.

When a homogenous mixture of two or more substances are created, what is this phenomena called? a. A solute b. A solution c. A dissolved substance d. A solvent

b. A solution

How many milliliters of medication would be administered if only a 10 mg/ml vial of morphine sulfate were available and the physician requested the patient to receive 4 mg? a. 0.1 ml b. 1 ml c. 0.4 ml d. 4 ml

c. 0.4 ml. Each milliliter contains 10 mg. The requested dosage only asks for 4 mg. Knowing that 10 mg are in 1 ml, you can rule out choices B and D. quick solution is 4/10 = 0.4 ml.

A 70-in.-tall patient is how many centimeters tall? a. 268 cm b. 154 cm c. 178 cm d. 32 cm

c. 178 cm. There are 2.54 cm in 1 in. Multiply 70 by 2.54 to get 177.8 cm, which rounds up to 178 cm.