The determination of medication dosage based on body surface area, expressed in milligrams per square meter (mg/m2), is a common practice, particularly in oncology and pediatrics. This approach aims to individualize treatment by accounting for differences in patient size and metabolic rate. As an example, a chemotherapy drug might have a recommended dosage of 100 mg/m2. To calculate the appropriate dose for a patient, their body surface area (BSA) is first determined using a formula that incorporates their height and weight. This BSA value is then multiplied by the prescribed dosage to arrive at the patient-specific dose.
Using body surface area for dosage calculation offers improved accuracy over weight-based dosing alone, minimizing the risk of under- or over-treatment. This is crucial for medications with a narrow therapeutic index, where even small variations in dosage can have significant clinical consequences. Historically, this method has evolved from observations that physiological processes often correlate more closely with surface area than with total body mass. Its adoption has contributed to enhanced treatment efficacy and reduced adverse effects in vulnerable patient populations.