Question

Determine the dosage in the following problems. Round dosages to the nearest tenth as indicated. The recommended dose for Oncovin (vincristine) is \(2 \mathrm{mg}\) per \(\mathrm{m}^{2}\). The child has a BSA of \(0.8 \mathrm{~m}^{2}\)

Short answer

The dosage is 1.6 mg.

Step-by-step solution

Understanding the Dosage Formula

The dosage formula is given by \( \text{Dosage} = \text{Dose Per Square Meter} \times \text{Body Surface Area (BSA)} \). The dose per square meter provided is \(2 \text{ mg/m}^2\).

Plug in the Values

Substitute the given values into the dosage formula: \( \text{Dosage} = 2 \text{ mg/m}^2 \times 0.8 \text{ m}^2 \).

Calculate the Dosage

Perform the multiplication: \( \text{Dosage} = 2 \times 0.8 = 1.6 \text{ mg} \).

Round the Dosage

Since the problem asks to round to the nearest tenth, the calculated dosage of \(1.6\) mg is already at the nearest tenth.

Key concepts

Pharmacy Calculations

Pharmacy calculations are an essential skill for ensuring correct medication dosing, especially in healthcare settings. These calculations help pharmacists and healthcare professionals determine the right amount of medication for patients, based on various factors.
Understanding pharmacy calculations involves a few key concepts:

• Dosage Formulas: Dosages are often calculated using specific formulas. These formulas can be based on weight, body surface area, age, or other relevant factors.
• Units of Measurement: Pharmaceutical calculations typically use metric system units such as milligrams (mg), micrograms (mcg), or grams (g). Being familiar with these units and knowing how to convert between them is crucial.
• Rounding: Healthcare professionals often need to round dosage calculations to prevent dosing errors. This is typically done to the nearest whole number or decimal point, depending on the requirements.

Pharmacy calculations are pivotal in ensuring patient safety, as incorrect dosing can lead to adverse effects or reduce therapeutic effectiveness. Therefore, a systematic approach to calculating dosages, like the one used in Oncovin's dose calculation, ensures precision and safety.

Body Surface Area

Body Surface Area (BSA) is an important measurement used in medicine to assess the dose of medication that a patient needs. It considers the relationship between height and weight to provide a more accurate measurement of body size than weight alone.
BSA is particularly important in calculating chemotherapy dosages, as it helps tailor medication doses to an individual's metabolic rate. The formula to calculate BSA is often called the Mosteller formula, which is:\[\text{BSA} = \sqrt{\left(\frac{\text{height (cm)} \times \text{weight (kg)}}{3600}\right)}\]

• Why Use BSA?: BSA is thought to provide a more accurate estimation of metabolic mass than body weight. This is particularly useful for medications with a narrow therapeutic index, such as chemotherapeutics.
• Pediatric Considerations: In children, BSA is frequently used because of the significant differences in body size and composition as compared to adults. Using BSA helps in precisely adjusting the medication dose according to their physiological needs.
• Application: As seen in the Oncovin example, knowing the BSA allows for calculating the accurate dose by multiplying it with the recommended dose per square meter, ensuring safe and effective treatment.

Pediatric Dosage

Pediatric dosage calculation is a careful and essential aspect of administering medications to children. Children's bodies process drugs differently from adults, making it necessary to adjust doses appropriately.

• Importance of Accurate Dosing: Given the variations in children’s age, weight, and body surface area, precise dosing helps in preventing underdosing or overdosing.
• Common Methods: Pediatric doses can be calculated using weight-based (mg/kg), age-based, or body surface area-based formulas. The BSA method, as demonstrated in the Oncovin example, is particularly beneficial for oncology medications.
• Safety Considerations: Attention to detail in calculating pediatric doses is critical. Rounding and verifying calculations can prevent harmful dosage errors. It's also important to consult pediatric dosing references and guidelines.

An understanding of pediatric dosage calculations allows for adjustments that reflect the needs and safety considerations of younger patients. This ensures that medical interventions are both effective and appropriate for their developmental stage.