Medication administration - Oral: Nursing pharmacology

Enteral medications are administered through the GI tract, either orally, rectally, or by a nasogastric or gastrostomy tube.

Oral medications are available in tablets, capsules, and liquids, which can be either solutions or suspensions, and are the most commonly prescribed form of enteral medications for patients who are able to swallow.

As the nurse, you’ll perform medication calculations to ensure the correct dose of an enteral medication is administered.

To calculate a dosing using the Dimensional Analysis, or DA, method, the three components you need are D, for the Desired dose, or dose ordered by the health care provider; H, for Have, or the dosage you have available; and V, for Vehicle or the form and amount in which the medication comes, like tablets or liquid.

First, you’ll read the order, which is: acetaminophen 1 gram PO every 6 hours. Then, look at the medication label.

Since the medication comes in 500 mg per tablet, you’ll calculate how many tablets you should administer to achieve the desired dose.

To do this, first identify your components, Desired, Have, and Vehicle. In this case, D is 1 gram, which was obtained from the health care provider’s order.

H is 500 mg, which was obtained from the medication label. And V, is 1 tablet, which was also obtained from the label.

Next, you’ll determine if a conversion factor is required. To determine this, compare the units of D with the units of H, and see if they’re the same.

Because D and H are in different units, a conversion factor is needed. In this case, you’ll use the following conversion factor from grams to milligrams: 1 gram equals 1000 mg Now, set up your equation, where X is the dose you'll administer in tablets, written like this: X number of tablets equals Vehicle over Have multiplied by Desired multiplied by the conversion factor for grams to milligrams.

Remember, you should put the units you’re trying to convert to as the denominator so you can cancel, or cross out, “mg” and “grams.” Now, plug in the values for the components to get X tablets equals 1 tablet multiplied by 1 gram multiplied by 1000 milligrams divided by 500 milligrams multiplied by 1 gram.

Remember, you can cross out any duplicate units of measurement because they cancel out. Now you’ll multiply the numerators and then the denominators of the equation to get 1000 tablets divided by 500.

This gives you a final answer of 2 tablets, meaning you should administer 2 tablets of acetaminophen to achieve the prescribed dose of 1 gram.

Let’s look at another example. First, you’ll read the order which is: duloxetine delayed release capsule 60 mg PO every evening.

Now let’s look at the medication label. Since the medication comes in 30 mg per 1 capsule, you’ll calculate how many capsules you should administer to achieve the desired dose.

To do this, first identify your components, Desired, Have, and Vehicle. In this case, D is 60 mg, which was obtained from the health care provider’s order.

H is 30 mg, which was obtained from the medication label, and V is 1 capsule, which was also obtained from the label. Next, you’ll determine if a conversion factor is required.

To do this, compare the units of D with the units of H. Because both D and H are in milligrams, no conversion factor is needed.

Now, set up your equation, where X is the dose you’ll administer, written out like this: X number of capsules equals Vehicle over Have, multiplied by Desired Now, plug in the values for the components to get X capsules equals 1 capsule multiplied by 60 milligrams divided by 30 milligrams.

Remember, you can cross out any duplicate units of measurement because they cancel out. Now you’ll multiply the numerator to get 60 capsules divided by 30.

The answer is 2 capsules, meaning you should administer 2 capsules of duloxetine to achieve the prescribed dose of 60 mg.

Let’s look at an example with a medication that is supplied as a suspension. First, you’ll read the order which is: azithromycin oral suspension 12 mg/kg PO daily for 7 days.

You check the chart to see that the patient’s current weight is 20 kg. Then, check the medication label.

Since there are 200 mg per 5 mL oral suspension, you’ll calculate how many milliliters to administer to achieve the desired dose.

To do this, first identify your components, Desired, Have, and Vehicle. In this case, D is 12 mg/kg, which was obtained from the health care provider’s order.

H is 200 mg, which was obtained from the medication label. And V, is 5 mL, which was also obtained from the label.

Next, you’ll determine if a conversion factor is required. To do this, compare the units of D with the units of H.

Because both D and H are in milligrams no conversion factor is needed. Now, let’s set up your equation, where X is the dose in milliliters you’ll administer.

You’ll write it out like this: X milliliters equals Vehicle over Have multiplied by Desired multiplied by the patient’s weight in kilograms.

Now, plug in the values for the components to get X milliliters equals 5 milliliters multiplied by 12 milligrams multiplied by 20 kilograms divided by 200 milligrams multiplied by 1 kilogram.

Remember, cross out units of the numerator that match the units of the denominator because they cancel out. Now, you’ll multiply the numerators and then the denominators to get 1200 milliliters divided by 200.

Next, divide 1200 milliliters by 200 to solve for X. The answer is 6 mL, meaning you should administer 6 mL of azithromycin to achieve the prescribed dose of 12 mg/kg.

Let’s look at another example, for a medication administered by nasogastric tube. First, you’ll read the order, which is: potassium chloride 20 mEq via nasogastric tube once.

Then, check the medication label.Since there is 40 mEq of potassium chloride per 30 mL, you’ll calculate how many milliliters to administer to achieve the desired dose.

To do this, first identify your components, Desired, Have, and Vehicle. In this case, D is 20 mEq, which was obtained from the health care provider’s order.

H is 40 mEq, which was obtained from the medication label. And V is 30 mL, which was also obtained from the label.

Next, determine whether a conversion factor is required. To do this, compare the units of D with the units of H.

Because your D and H have the same units, no conversion factor is needed. Now, set up your equation, where X is the amount you’ll administer, written like this: X milliliters equals Vehicle over Have multiplied by Desired.

Then, plug in the values for the components to get X milliliters equals 30 milliliters multiplied by 20 milliequivalents divided by 40 milliequivalents.

Remember, you can cross out any duplicate units of measurement because they cancel out. Now you’ll multiply the numerator of the equation to get 600 mL divided by 40.

Next, divide 600 mL by 40 to solve for X. The answer is 15 mL, meaning you should administer 15 mL of potassium chloride diluted according to the instructions on the package insert to achieve the prescribed dose of 20 mEq.

Alright, as a quick recap...Enteral medications are administered via the gastrointestinal tract, and include medications given orally, rectally, or through a direct tube to the stomach or small intestine.

Oral medications are the most common route of enteral medications and come in tablets, capsules, and liquids, which can be either a solution or