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: Depo-Provera \(650 \mathrm{mg} \mathrm{IM}\) once a week (on Mondays). Available: Depo-Provera labeled \(400 \mathrm{mg}\) per mL

Short answer

1.6 mL

Step-by-step solution

Identify the Required Dosage

The doctor has ordered Depo-Provera at a dosage of 650 mg to be administered once a week. Our task is to find out how many mL of the medication we need for a 650 mg dose.

Determine Concentration from the Label

From the label information provided, Depo-Provera is available at 400 mg per mL. This means for every mL of Depo-Provera, there are 400 milligrams of the drug.

Set up the Proportion

We know that 1 mL of the drug contains 400 mg. We need to find how many mL will contain 650 mg. Set up the proportion: \[ \frac{400 \, \text{mg}}{1 \, \text{mL}} = \frac{650 \, \text{mg}}{x \, \text{mL}} \]

Solve the Proportion for x

Cross-multiply to solve for \(x\): \[ 400x = 650 \times 1 \] Simplifying gives \(400x = 650\). Divide both sides by 400: \[ x = \frac{650}{400} \] which simplifies to \(x = 1.625\) mL.

Round to the Nearest Tenth

The result from the calculation is 1.625 mL. Round this to the nearest tenth, which gives 1.6 mL.

Label the Dosage Correctly

The dose of 650 mg Depo-Provera requires 1.6 mL to be administered. Always label appropriately: the answer is 1.6 mL.

Key concepts

Depo-Provera

Depo-Provera is a commonly prescribed medication with a variety of uses. It is an injectable form of birth control that contains a hormone called medroxyprogesterone acetate. This medication is often administered via intramuscular (IM) injection and is typically used for preventing pregnancy.
Additionally, it can be prescribed for other health conditions such as reducing the risk of uterine cancer or managing endometriosis symptoms. Generally, Depo-Provera is given once every three months; however, depending on the doctor's instructions or specific health needs, like in the exercise where it's prescribed weekly, the dosage frequency may vary. It's crucial to understand the concentration and dosage instructions on the medication label. These details are essential for safe and effective administration, ensuring the patient receives the correct amount for the intended therapeutic effect.

Proportions in Dosage Calculations

Proportional reasoning is a fundamental concept in dosage calculations. Understanding how to set up and solve a proportion is crucial, especially in medicine where exact dosage equals safe and effective treatment. In the exercise, we need to determine how many mL of Depo-Provera are required to administer a 650 mg dose, given that the concentration provided on the medication label is 400 mg per mL. You use proportions to solve problems of this nature by setting up a ratio that compares the known concentration to the unknown quantity you need to find:

• Known ratio: 400 mg per 1 mL
• Unknown ratio: 650 mg per x mL

By setting the two fractions equal to each other, you can then solve for the unknown variable. This method ensures consistency and accuracy in converting and calculating medication dosages.

Unit Conversions in Medicine

Unit conversion is a key component when it comes to dosage calculation in medicine. Many medications, like Depo-Provera, are measured in milligrams (mg) and must be converted to milliliters (mL) or vice versa, depending on the prescription and the form of the medication. In the exercise, you must convert milligrams to milliliters using the concentration provided. This is a common task because healthcare providers might prescribe a medication in mg (as it focuses on the active ingredient), but you usually administer it in mL or another unit based on its available pharmacy formulation.

• To maintain precision, use the concentration information from the medication label (e.g., 400 mg/mL for Depo-Provera) to facilitate accurate conversion.
• Always double-check conversions to prevent errors in dosage.

Through careful calculations, healthcare professionals can avoid underdosing or overdosing, which are critical for patient safety.

Rounding Rules in Dosage Calculation

Rounding is an important process in dosage calculations to simplify and accurately administer medication dosages. The aim is to ensure that doses are manageable and practical to measure while still being accurate. In the exercise, after solving the proportion and getting the result of 1.625 mL, you must round this to one decimal place, resulting in a rounded dosage of 1.6 mL. The general rule of rounding—round up if the next digit is 5 or more and round down if it's less than 5—applies:

• Round to the nearest tenth when dealing with mL in medication dosages unless instructed otherwise.
• Proper rounding helps minimize errors in treatment delivery, ensuring the dose is not only accurate but also easy to measure.

Always be aware of the rounding guidelines specific to the institution or medication in use, as different drugs may have specific guidelines due to their potency or pharmacokinetics.