A patient weighs 125 pounds.
There are 0.45 kilograms (kg) in one pound. What is the patient’s weight in kg?
A medicine is given so that 2 micrograms (ug) are given per kg of patient body weight. How many ug of this medication will be given to the patient?
The Correct Answer and Explanation is:
Answer:
Step 1: Convert weight from pounds to kilograms.
- Weight in pounds = 125 lb
- Conversion factor: 1 lb = 0.45 kg
- Weight in kg = 125 lb × 0.45 kg/lb = 56.25 kg
Step 2: Calculate medication dosage.
- Dosage = 2 micrograms per kg
- Total dosage = 2 µg/kg × 56.25 kg = 112.5 micrograms
Explanation
In medical settings, accurate dosage calculations are essential to ensure both the effectiveness and safety of treatments. This scenario involves determining the appropriate amount of medication based on the patient’s body weight, a common practice particularly for pediatric and weight-sensitive medications.
The patient’s weight is initially given in pounds (lb), which is a unit more commonly used in the United States. However, many medical dosages, especially in scientific literature and pharmaceutical calculations, are based on metric units like kilograms (kg). Therefore, the first step is to convert the patient’s weight to kilograms. Using the given conversion factor — 1 pound equals 0.45 kilograms — we calculate the patient’s weight in kilograms:
125 lb × 0.45 kg/lb = 56.25 kg.
Next, we apply the medication dosage formula. The medication must be administered at a rate of 2 micrograms (µg) per kilogram of body weight. This is a proportional dosage approach, which helps tailor the amount of drug administered to each individual, minimizing underdosing or overdosing.
To find the total dosage, we multiply the weight in kilograms by the dosage per kilogram:
56.25 kg × 2 µg/kg = 112.5 µg.
This calculated dose ensures the patient receives an amount of the medication appropriate for their size. Precision in these calculations is critical — an incorrect dose, even by a small amount, could lead to ineffective treatment or serious side effects. Therefore, healthcare professionals must always double-check unit conversions and dosage formulas. In summary, the patient will be given 112.5 micrograms of the medication.
