Question

Calculate the following dosages using the medication label or information provided. Label answers correctly: tabs, caps, mL. Answers expressed in milliliters should be rounded to the nearest tenth where indicated. Order: Flagyl $0.5\mathrm{g}$ p.o. b.i.d. for 1 week. Available: Flagyl tablets labeled $500\mathrm{mg}$ ________

Short answer

The patient needs 1 tablet of 500 mg Flagyl per dose.

Step-by-step solution

Understand the Prescription

The doctor's order is for 0.5 grams of Flagyl to be taken orally twice a day. 'p.o.' means 'per os', which is Latin for 'by mouth'. 'b.i.d.' means 'bis in die', which means twice daily.

Convert Units

To solve the problem, we need to convert the prescribed dose from grams to milligrams because the available tablets are in milligrams. 1 gram is equivalent to 1000 milligrams, so 0.5 grams is equivalent to: $0.5\text{ grams}\times 1000\text{ mg/gram}=500\text{ mg}$.

Match Available Dosage with Prescription

Now that we've converted 0.5 grams to 500 mg, we compare it with the available dosage. The medication provided is Flagyl in 500 mg tablets, which exactly matches the prescribed dose of 500 mg.

Calculate the Number of Tablets Per Dose

Since the available tablets are 500 mg each and the patient's dose is 500 mg, the patient will need 1 tablet per dose.

Conclusion

Based on the calculation, the patient needs 1 tablet of 500 mg per dose of Flagyl.

Key concepts

Unit Conversion

One of the most important skills in dosage calculation is unit conversion. It's common in the medical field to encounter different units of measurement. For medication dosages, you might see grams, milligrams, liters, or milliliters. Understanding how to convert between these units is crucial. Here’s a quick guide:

• 1 gram (g) = 1000 milligrams (mg)
• 1 liter (L) = 1000 milliliters (mL)

To convert from a larger unit (grams) to a smaller unit (milligrams), you multiply by 1000. Conversely, to convert from milligrams to grams, you divide by 1000. This is useful when you have a prescription in grams but your available medication is in milligrams. For example, in the original exercise, converting 0.5 grams to milligrams is necessary because the medication available is in 500 mg tablets. This kind of conversion ensures that patients receive the correct dosage.

Medication Labels

Medical labels provide essential information about medication strength and form. Understanding these labels is vital for healthcare practitioners to administer drugs safely and accurately. A typical medication label includes:

• Medication Name
• Strength (e.g., 500 mg)
• Form (e.g., tablets, capsules)
• Expiry Date

In the given exercise, the available medication is labeled as "500 mg" tablets. This tells you the strength of each tablet. Knowing the correct tablet strength helps match it accurately to the prescribed dosage. Effective interpretation of labels prevents medication errors and ensures patient safety. Always verify that the information matches the prescription before dispensing or administering medication.

Medication Dosage Instructions

Dosage instructions are critical as they inform how much medication a patient should take and how often. These instructions may include terminology like "p.o." and "b.i.d." which are common in medical prescriptions. Here's a breakdown:

• "p.o." stands for "per os" which means orally or by mouth.
• "b.i.d." means "bis in die," or "twice a day."

In the exercise, the patient needs to take 0.5 g of Flagyl orally, twice a day for one week. Converting 0.5 g to 500 mg and noting that each tablet is 500 mg means the patient should take one tablet per dose. Adhering to these instructions is crucial for treatment efficacy and avoiding overdoses or underdoses. Patients should always be informed about how to take their medications correctly to promote adherence and achieve the best possible health outcomes.