Question

Determine the dosage in the following problems. Round dosages to the nearest tenth as indicated. The recommended dose for bleomycin in an adult with Hodgkin disease is 10 to 20 units per \(\mathrm{m}^{2}\). The adult has a BSA of \(1.83 \mathrm{~m}^{2}\). Give the dosage range.

Short answer

The dosage range is 18.3 to 36.6 units.

Step-by-step solution

Understanding BSA and Dose Range

The problem provides a Body Surface Area (BSA) of \(1.83 \, \mathrm{m}^2\) and a dose range for bleomycin of 10 to 20 units per square meter. This means we need to calculate the dose by multiplying the BSA by the dose range per unit square meter.

Calculating Minimum Dose

To find the minimum dose, multiply the BSA \(1.83 \, \mathrm{m}^2\) by the lower end of the dose range, which is 10 units/m².\[\text{Minimum Dose} = 1.83 \, \mathrm{m}^2 \times 10 \, \text{units/m}^2 = 18.3 \, \text{units}\]

Calculating Maximum Dose

To find the maximum dose, multiply the BSA \(1.83 \, \mathrm{m}^2\) by the upper end of the dose range, which is 20 units/m².\[\text{Maximum Dose} = 1.83 \, \mathrm{m}^2 \times 20 \, \text{units/m}^2 = 36.6 \, \text{units}\]

Rounding the Dosage

Both calculated doses, 18.3 units and 36.6 units, already rounded to the nearest tenth, align with the requirement. Thus, the dosage range is 18.3 to 36.6 units.

Key concepts

Body Surface Area (BSA)

Body Surface Area (BSA) is an essential measure used to calculate drug dosages, particularly in chemotherapy treatments, due to its correlation with metabolic rate and various physiological processes. Unlike body weight, BSA offers a more accurate estimation for calculating drug dosages, as it considers both the height and weight of a person. This is especially important for drugs that have narrow therapeutic windows or high toxicity, such as bleomycin.
To calculate the BSA, various formulas can be used. The most commonly employed method is the Dubois and Dubois formula:

• \[ BSA = 0.007184 imes (height \, in \, cm)^{0.725} \times (weight \, in \, kg)^{0.425} \]

Once the BSA is determined, it can be used to calculate the precise dose of medication tailored to individual patients, ensuring both efficacy and safety. Proper dosage based on BSA helps prevent under or overdosing, which can lead to either ineffective treatment or adverse side effects.

Bleomycin Dosage

Bleomycin is a chemotherapy drug used in the treatment of various cancers, including Hodgkin disease. The dosing of bleomycin is critical due to its potential side effects, notably pulmonary toxicity. The dosage of bleomycin is commonly calculated based on BSA to ensure the treatment is as effective as possible while minimizing the risk of toxicity.
The exercise in question outlines that the recommended dose range for bleomycin is between 10 to 20 units per square meter of BSA. This means that if a patient has a BSA of 1.83 m², the dosage range can be calculated through these steps:

• Minimum Dose: Multiply the BSA by the lower limit of the dose range: \[ 1.83 \, \mathrm{m}^2 \times 10 \, \text{units/m}^2 = 18.3 \, \text{units} \]
• Maximum Dose: Multiply the BSA by the upper limit of the dose range: \[ 1.83 \, \mathrm{m}^2 \times 20 \, \text{units/m}^2 = 36.6 \, \text{units} \]

Understanding these calculations ensures that the dosage is effective and safe, tailored for each individual to manage their cancer treatment appropriately.

Therapeutic Dose Range

The therapeutic dose range is a fundamental concept in pharmacology and medicine, referring to the range of dosage levels where a drug is considered effective and safe, without causing significant adverse side effects. It's the sweet spot of medication, where the benefits outweigh the risks.
The calculation of a therapeutic dose range is particularly pertinent in chemotherapy drugs like bleomycin, where the gap between an effective dose and a toxic dose can be quite narrow. For bleomycin, defining the therapeutic dose range helps clinicians avoid pulmonary toxicity while effectively treating cancer.
In our exercise, determining the therapeutic range of bleomycin involves calculating the minimum and maximum dosages based on BSA. The range for bleomycin was determined by multiplying the patient's BSA by the dosage unit range, offering a personalized therapeutic range. Thus, for a BSA of 1.83 m², the therapeutic dose range becomes 18.3 to 36.6 units, ensuring balanced dosing that maximizes efficacy and minimizes risks.