Drug Dosage Calculation Exam 14

Text Mode – Text version of the exam

Questions

1. Nurse Sam is preparing medications for his patients. An order for 250 mg of Clinoril comes in, and the available tablets each contain 0.5 grams of the drug. As Sam readies the medication, he asks himself, “How many of these tablets should I administer to fulfill the ordered dose?”

2. Nurse Amy reviews her patient’s chart and sees an order for 0.6 g of Motrin. The medication drawer holds Motrin tablets, each containing 600 mg. As Amy readies the medication, she thinks, “How many tablets should I give to meet the ordered dosage?”

3. Nurse Phil is preparing a morphine sulfate injection for a patient. The order specifies gr 1/8, while the available solution is labeled as gr 1/12 per mL. Phil considers, “What volume should I draw up to administer the correct dosage?”

4. Nurse Sally is dispensing medications for her shift. She comes across a physician’s order for Tylenol gr VIII. The medication tray only has Tylenol 500mg tablets. Sally wonders, “How many tablets should I administer to fulfill this order?”

5. Nurse Peter is preparing to administer medication when he reads a doctor’s order for 40mg of Phenobarbital. The pharmacy has sent up 20mg tablets. He wonders, “How many tablets do I need to administer to satisfy this order?”

6. Nurse Lisa is dispensing medications for the day. She reads a doctor’s order for Tylenol gr V. The pharmacy has provided her with Tylenol 300mg tablets. She asks herself, “How many tablets do I need to administer to fulfill this order?”

7. Nurse Jake is preparing to administer Aqueous Penicillin G to a patient. The order is for 1.2 million units, and the available concentration is 1,000,000 units/mL. He thinks, “How many milliliters should I give to meet this order?”

8. Nurse Tom is attending a postoperative patient experiencing pain. The physician has ordered Demerol 35mg for the patient. The medication supplied is in a vial labeled Demerol 50mg/mL. He thinks, “How much Demerol should I draw up from this vial to provide the ordered dose?”

9. Nurse Lily is tending to a patient experiencing moderate pain. The doctor has ordered 10mg of Demerol to be administered. The available Demerol vial is labeled 25mg/mL. She wonders, “What volume of Demerol should I extract from the vial to administer the ordered dose?”

10. Nurse Adam is attending to a patient suffering from severe nausea. The physician has ordered 20mg of Phenergan. The available Phenergan vial is labeled as 50mg/mL. Adam thinks, “How much volume of Phenergan should I extract from the vial to match the prescribed dose?”

11. Nurse Ella is preparing to administer an injection to a patient with severe allergies. The order is for Benadryl 45 mg. The available Benadryl comes in a 1mL vial labeled as 50mg/mL. She contemplates, “How many milliliters of Benadryl should I draw up in a TB syringe to match the ordered dose?”

12. Nurse Daniel is set to administer Benadryl to a patient with allergies. The physician’s order is for 25mg of Benadryl. The available vial contains 50mg/mL and is 1mL in volume. Daniel ponders, “What volume of Benadryl should I draw into the TB syringe to fulfill the ordered dose?”

13. Nurse Kate is preparing an analgesic for a patient experiencing severe pain. The physician has ordered 45mg of Toradol. The available vial contains 60mg in 2mL. Kate considers, “How much Toradol should I draw up into the 3mL syringe to match the physician’s order?”

Answers & Rationales

1. Solution:

Nurse Sam needs to convert the weights to the same unit in order to determine the number of tablets he needs to give.

Firstly, let’s clarify our units. We know that:
1 gram (g) = 1000 milligrams (mg)

The tablets that Sam has each contain 0.5 grams of the drug. So, to convert that to milligrams:

0.5 g * 1000 = 500 mg

Each tablet contains 500 mg of the drug.

Sam needs to give a total of 250 mg, so to figure out how many tablets that is, we divide the total amount needed by the amount in each tablet:

250 mg / 500 mg/tablet = 0.5 tablet

This means Sam should administer half of a tablet to fulfill the ordered dose of 250 mg. Always remember to check with a pharmacist or prescribing doctor if you are unsure about the dosage, especially when it involves administering a fraction of a pill.

2. Solution:

First, Nurse Amy needs to convert the weights to the same unit to determine the number of tablets she should administer.

We know that:
1 gram (g) = 1000 milligrams (mg)

The order is for 0.6 grams of Motrin, so we convert that to milligrams:

0.6 g * 1000 = 600 mg

So, the order is for 600 mg of Motrin.

The available Motrin tablets each contain 600 mg. To find out how many tablets Amy should administer, we divide the total milligrams needed by the milligrams contained in each tablet:

600 mg / 600 mg/tablet = 1 tablet

So, Nurse Amy should administer one tablet to meet the ordered dosage of 0.6 g.

3. Solution:

To answer this question, Nurse Phil needs to use a bit of basic algebra. Here’s how he can do it:

First, let’s identify what we know:

1. The doctor’s order specifies a dosage of gr 1/8 (which means 1/8 of a grain).
2. The available morphine sulfate solution has a concentration of gr 1/12 per mL (which means there is 1/12 of a grain in each mL).

Nurse Phil’s task is to determine how many mLs of the solution he needs to draw up to administer a dose of gr 1/8. He can set up a proportion to solve this:

Let’s say X is the volume Nurse Phil needs to draw up. So we can say that the amount of the drug in the dosage (gr 1/8) is to the amount of the drug in each mL of the solution (gr 1/12) as X mL is to 1 mL. In mathematical terms:

(gr 1/8) / (gr 1/12) = X / 1

Cross multiplying and solving for X, we get:

1 * X = (1/8) * 12

X = 1.5 mL

So, Nurse Phil should draw up 1.5 mL of the morphine sulfate solution to administer the ordered dosage of gr 1/8.

4. Solution:

First, it is important to understand the grain (gr) unit of measurement often used in medical prescriptions.

1 grain (gr) is approximately equal to 64.79891 milligrams (mg).

The prescription for Tylenol gr VIII implies 8 grains of Tylenol.

So let’s convert the grains to milligrams:
8 grains * 64.79891 mg/grain = 518.39128 mg

So, the order is for approximately 518.39 mg of Tylenol.

Given that each tablet of Tylenol contains 500 mg, to determine how many tablets are required, Sally would divide the total milligrams needed by the milligrams per tablet:

518.39 mg / 500 mg/tablet = 1.03678 tablets

As it’s not practical (or safe) to split tablets beyond halves, Nurse Sally would need to round this number to the nearest whole or half tablet.

Therefore, Nurse Sally should administer 1 tablet to the patient. This is slightly less than the ordered amount, but it’s the closest dose she can provide with the tablets available.

As always in such cases, it’s best for Sally to consult with the prescribing doctor or pharmacist to ensure that the slightly lower dosage is appropriate.

5. Solution:

First, let’s identify what we know:

1. The doctor’s order specifies a dosage of 40 mg of Phenobarbital.
2. The available Phenobarbital tablets each contain 20 mg.

Nurse Peter’s task is to determine how many tablets he needs to administer to fulfill the doctor’s order. To do this, he should divide the total milligrams needed (40 mg) by the milligrams contained in each tablet (20 mg):

40 mg / 20 mg/tablet = 2 tablets

So, Nurse Peter needs to administer 2 tablets of Phenobarbital to satisfy the doctor’s order of 40 mg.

6. Solution:

To answer Nurse Lisa’s question, we need to convert the grains to milligrams.

We know that 1 grain (gr) is approximately equal to 64.79891 milligrams (mg).

The prescription for Tylenol gr V implies 5 grains of Tylenol.

So let’s convert the grains to milligrams:

5 grains * 64.79891 mg/grain = approximately 323.995 mg

So, the order is for approximately 324 mg of Tylenol.

Now, given that each tablet of Tylenol contains 300 mg, we can find out how many tablets are needed by dividing the total milligrams needed by the milligrams in each tablet:

324 mg / 300 mg/tablet = 1.08 tablets

Since it’s impractical (and often unsafe) to split tablets beyond halves, Nurse Lisa would need to round this number to the nearest half or whole tablet.

Therefore, she should administer 1 tablet to the patient. This is slightly less than the ordered dose, but it’s the closest dosage she can provide with the tablets available. As always in these cases, it’s best for her to consult with the prescribing doctor or a pharmacist to ensure that the slightly lower dosage is appropriate.

7. Solution:

Nurse Jake needs to find the volume in milliliters (mL) of the Aqueous Penicillin G that he needs to administer to deliver 1.2 million units.

We know that:
1. The doctor’s order specifies a dosage of 1.2 million units.
2. The available Aqueous Penicillin G has a concentration of 1,000,000 units/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of units needed by the number of units per mL:

1.2 million units / 1,000,000 units/mL = 1.2 mL

So, Nurse Jake should administer 1.2 mL of the Aqueous Penicillin G to meet the ordered dosage of 1.2 million units.

8. Solution:

Nurse Tom’s task is to figure out how many milliliters (mL) of Demerol he should administer to deliver the ordered dose of 35 mg.

We know that:
1. The doctor’s order specifies a dosage of 35 mg of Demerol.
2. The available Demerol has a concentration of 50 mg/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of milligrams needed by the number of milligrams per mL:

35 mg / 50 mg/mL = 0.7 mL

So, Nurse Tom should draw up 0.7 mL of Demerol from the vial to provide the ordered dosage of 35 mg.

9. Solution:

Nurse Lily’s task is to figure out how many milliliters (mL) of Demerol she should administer to deliver the ordered dose of 10 mg.

We know that:
1. The doctor’s order specifies a dosage of 10 mg of Demerol.
2. The available Demerol has a concentration of 25 mg/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of milligrams needed by the number of milligrams per mL:

10 mg / 25 mg/mL = 0.4 mL

So, Nurse Lily should draw up 0.4 mL of Demerol from the vial to administer the ordered dosage of 10 mg.

10. Solution:

Nurse Adam needs to determine how many milliliters (mL) of Phenergan he should draw up to deliver the ordered dose of 20 mg.

We know that:
1. The doctor’s order specifies a dosage of 20 mg of Phenergan.
2. The available Phenergan has a concentration of 50 mg/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of milligrams needed by the number of milligrams per mL:

20 mg / 50 mg/mL = 0.4 mL

So, Nurse Adam should extract 0.4 mL of Phenergan from the vial to match the prescribed dosage of 20 mg.

11. Solution:

Nurse Ella needs to calculate the volume in milliliters (mL) of Benadryl she should draw up to deliver the ordered dose of 45 mg.

We know that:
1. The doctor’s order specifies a dosage of 45 mg of Benadryl.
2. The available Benadryl has a concentration of 50 mg/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of milligrams needed by the number of milligrams per mL:

45 mg / 50 mg/mL = 0.9 mL

So, Nurse Ella should draw up 0.9 mL of Benadryl in a TB syringe to match the ordered dosage of 45 mg.

12. Solution:

Nurse Daniel’s task is to determine how many milliliters (mL) of Benadryl he needs to administer to deliver the ordered dose of 25 mg.

We know that:
1. The doctor’s order specifies a dosage of 25 mg of Benadryl.
2. The available Benadryl has a concentration of 50 mg/mL.

The volume (in mL) needed to deliver the ordered dosage can be found by dividing the number of milligrams needed by the number of milligrams per mL:

25 mg / 50 mg/mL = 0.5 mL

So, Nurse Daniel should draw up 0.5 mL of Benadryl into the TB syringe to fulfill the ordered dosage of 25 mg.

13. Solution:

Nurse Kate needs to calculate the volume in milliliters (mL) of Toradol she should draw up to deliver the ordered dose of 45 mg.

We know that:
1. The doctor’s order specifies a dosage of 45 mg of Toradol.
2. The available Toradol has a concentration of 60 mg in 2 mL.

First, we need to find the concentration in terms of mg/mL. We can calculate this by dividing the total amount of Toradol (60 mg) by the total volume (2 mL):

60 mg / 2 mL = 30 mg/mL

This means there are 30 mg of Toradol in each mL.

Next, we need to find out how many mL contain 45 mg of Toradol. We do this by dividing the number of milligrams needed by the number of milligrams per mL:

45 mg / 30 mg/mL = 1.5 mL

So, Nurse Kate should draw up 1.5 mL of Toradol into the 3 mL syringe to match the physician’s order of 45 mg.