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Oral Medications

Overview

Oral medications are the most common route of administration in nursing. They come in solid forms — tablets, capsules, and caplets — and require accurate calculation to ensure the correct dose is given.

Reading the Medication Order

Every medication order contains:

Component Example
Patient name John Smith
Medication name metoprolol
Dose 25 mg
Route orally (PO)
Frequency twice daily (BID)
Prescriber signature Dr. Jones

Reading the Stock Label

The stock label tells you what is available:

Component Example
Medication name metoprolol tartrate
Strength 25 mg per tablet
Form tablet
Total quantity 100 tablets

The Calculation

Once you have the order and stock, set up the unit cancellation chain:

\[\frac{\text{ordered dose}}{\cancel{\text{unit}}} \times \frac{\text{quantity}}{\text{stock dose}} = \text{answer}\]

Tablets and Capsules

Example 1 — Straightforward: Order: metoprolol 50 mg orally Stock: 25 mg per tablet

\[\frac{50 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{25 \cancel{\text{ mg}}} = 2 \text{ tablets}\]

Example 2 — Half tablet: Order: lisinopril 5 mg orally Stock: 10 mg per tablet

\[\frac{5 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{10 \cancel{\text{ mg}}} = 0.5 \text{ tablet}\]

Scored vs Unscored Tablets

  • Scored tablets have a line across the middle and are designed to be split — 0.5 tablet is acceptable
  • Unscored tablets should never be split
  • Enteric coated tablets should never be split or crushed
  • Capsules should never be split unless specifically formulated as sprinkle capsules

Example 3 — Unit conversion required: Order: levothyroxine 0.1 mg orally Stock: 50 mcg per tablet

\[\frac{0.1 \cancel{\text{ mg}}}{1} \times \frac{1000 \cancel{\text{ mcg}}}{1 \cancel{\text{ mg}}} \times \frac{1 \text{ tablet}}{50 \cancel{\text{ mcg}}} = 2 \text{ tablets}\]

Example 4 — Higher stock strength: Order: atorvastatin 20 mg orally Stock: 40 mg per tablet

\[\frac{20 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{40 \cancel{\text{ mg}}} = 0.5 \text{ tablet}\]

Daily and Multi-Dose Calculations

Example 5: Order: metformin 500 mg orally three times daily for 7 days Stock: 500 mg per tablet How many tablets for the full course?

Step 1 — tablets per dose: [\frac{500 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{500 \cancel{\text{ mg}}} = 1 \text{ tablet per dose}]

Step 2 — total tablets: [1 \text{ tablet} \times 3 \text{ doses/day} \times 7 \text{ days} = 21 \text{ tablets}]

Reasonableness Check

Tablet Safety Guidelines

  • Giving more than 3 tablets per dose is unusual — recheck
  • Giving less than 0.5 tablet is unusual — recheck
  • If the answer is not a multiple of 0.5, recheck your work
  • Never crush or split medications without verifying it is safe

Practice Problems

Problem 1

Order: atenolol 100 mg orally Stock: 50 mg per tablet How many tablets?

Answer
\[\frac{100 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{50 \cancel{\text{ mg}}} = 2 \text{ tablets}\]

Problem 2

Order: warfarin 2.5 mg orally Stock: 5 mg per tablet How many tablets?

Answer
\[\frac{2.5 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{5 \cancel{\text{ mg}}} = 0.5 \text{ tablet}\]

Verify tablet is scored before splitting.

Problem 3

Order: levothyroxine 0.075 mg orally Stock: 25 mcg per tablet How many tablets?

Answer
\[\frac{0.075 \cancel{\text{ mg}}}{1} \times \frac{1000 \cancel{\text{ mcg}}}{1 \cancel{\text{ mg}}} \times \frac{1 \text{ tablet}}{25 \cancel{\text{ mcg}}} = 3 \text{ tablets}\]

Problem 4

Order: prednisone 40 mg orally Stock: 20 mg per tablet How many tablets?

Answer
\[\frac{40 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{20 \cancel{\text{ mg}}} = 2 \text{ tablets}\]

Problem 5

Order: amoxicillin 500 mg orally three times daily for 10 days Stock: 250 mg per capsule How many capsules for the full course?

Answer

Step 1 — capsules per dose: [\frac{500 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ capsule}}{250 \cancel{\text{ mg}}} = 2 \text{ capsules per dose}]

Step 2 — total capsules: [2 \times 3 \times 10 = 60 \text{ capsules}]

Problem 6 — Flag This Answer

Order: digoxin 0.5 mg orally Stock: 62.5 mcg per tablet How many tablets?

Answer
\[\frac{0.5 \cancel{\text{ mg}}}{1} \times \frac{1000 \cancel{\text{ mcg}}}{1 \cancel{\text{ mg}}} \times \frac{1 \text{ tablet}}{62.5 \cancel{\text{ mcg}}} = 8 \text{ tablets}\]

Flag This

8 tablets is far outside the reasonable range. Before proceeding, verify the order, recheck the stock concentration, and consult the prescriber or pharmacist. Do not administer without clarification.

Clinical Tip

Always read the medication label three times:

  1. When retrieving the medication from storage
  2. When preparing the dose
  3. Before administering to the patient

This is not a suggestion — it is a professional standard.