In this review, I’ll guide you through how to solve liquid oral suspension dosage calculation problems using the desired over have formula method.
If you’d like to follow along with me and write down each step of these problems, I have a free dosage calculations worksheet here that you can download.
Check out this link for more free nursing dosage calculations reviews.
Practice Problem 1:
The order is to give 5,000 micrograms by mouth twice a day. The bottle from the pharmacy says it contains 3 milligrams per milliliter. The goal is to figure out how many milliliters per dose we should give.
To solve this, we use the desired over have formula. Here’s how it works:
- The desired dose is what the healthcare provider ordered, which is 5,000 micrograms.
- The have dose is what we have on hand, which is 3 milligrams per milliliter.
- The quantity is the volume, which is 1 milliliter.
Step 1: Convert the units
Since the units don’t match (micrograms and milligrams), we need to convert. From the metric system, we know that 1,000 micrograms equals 1 milligram. So, 5,000 micrograms is the same as 5 milligrams.
Step 2: Solve for the volume
Now, we substitute the values into the formula. We have 5 milligrams as the desired dose, and 3 milligrams per milliliter as the dose on hand. When we divide 5 by 3, we get a decimal of approximately 1.666, which means you need to give 1.7 milliliters per dose when rounded to the nearest tenth.
Practice Problem 2:
The order is to give 1,000 milligrams by mouth daily, and we are supplied with a bottle that contains 2 grams per 10 milliliters. We need to solve for teaspoons per dose.
Since we’re trying to find teaspoons, but we’re given milliliters, we’ll need to do some conversions:
- 5 milliliters equals 1 teaspoon
Step 1: Set up the problem
The desired dose is 1,000 milligrams, and the have dose is 2 grams per 10 milliliters. We can convert the milligrams into grams, knowing that 1,000 milligrams is equal to 1 gram.
Step 2: Solve for the volume
Now, we divide 1 gram by 2 grams (which gives us 0.5) and multiply by 10 milliliters, resulting in 5 milliliters per dose.
Step 3: Convert to teaspoons
Finally, we convert 5 milliliters to teaspoons. Since 5 milliliters equals 1 teaspoon, the answer is 1 teaspoon per dose.
Practice Problem 3:
The order is for 500 milligrams to be taken by mouth every 8 hours. The bottle contains 150 milligrams per 5 milliliters, and we need to solve for how many milliliters per day the patient will need.
Since the problem asks for the total per day, we need to keep in mind that the patient is getting the medication every 8 hours, and there are 24 hours in a day. This means the patient will receive 3 doses per day.
Step 1: Set up the formula
The desired dose is 500 milligrams, and the have dose is 150 milligrams per 5 milliliters.
Step 2: Solve for milliliters per dose
First, divide 500 milligrams by 150 milligrams, which gives us approximately 3.33. Then multiply that by 5 milliliters, resulting in 16.666 repeating (don’t round just yet) milliliters per dose.
Step 3: Calculate the total for the day
Since the patient is getting 3 doses per day, we multiply 16.67 milliliters by 3. This gives us a total of 50 milliliters per day.
I hope this helps you understand how to approach liquid oral suspension dosage calculations. For more practice, here are some liquid oral dosage calculation practice problems.