Flat- Fixed Dosing vs. Body Surface Area-Based Dosing of Anticancer Drugs in Adults: Does It Make a Difference?
Explain Body-Surface-Area-based dosage
Body Surface Area-based dosing is a critical formula applicable in the calculation of drug doses in the case of two types of patient groups. These two types of patient groups include cancer patient under the aspect of chemotherapy and pediatric patients. DuBois and DuBois derived the formula in the case of 1916 in a research which nine individuals took part (DuBois & DuBois, 1916). It is ideal to note that the average or normal adults have a BSA of about 1.73 m2. It refers to the current standard of care applicable in the determination of the dose of various chemotherapy drugs in relation to the body surface area of the patients on chemotherapy drugs. It is critical to understand that BSA-based dosing is a 'one size fits all' approach in relation to calculating drug dose with reference to patients on chemotherapy drugs. The mathematical formula utilizes the height and weight of the patient in the calculation of the drug dose for chemotherapy and pediatric drugs.
It is critical to note that BSA-based dosing approach is ineffective in addressing dosage issues for chemotherapy and pediatric drugs. According to various research studies, BSA-based dosing approach is ineffective in relation to realizing the optimal or right systematic concentration of the drugs with the aim of generating best treatment results (De Jongh et al., 2001). Since its development in 1916, various research studies continue to illustrate how individuals absorb and process substances in the form of drugs and food into their systems. This is because of the number of factors influencing the rate of drug clearance. The rate of drug clearance varies from one person to another with approximately 30-fold difference. For instance, the functioning of an organ as well as the state of the disease will have massive impact on the body and its ability to process the chemotherapy drugs. In addition, it is essential to note that more advanced cancer has the ability to absorb more drugs in comparison to the smaller tumor. Moreover, other factors in the form of age, genetics, sex, drug-drug interactions, and sleeping patterns might be crucial in causing variability from one person to another (Scripture & Figg, 2006). This makes BSA-based dosing ineffective towards the achievement of the goals and objectives.
How the formula is applied
It is ideal to note that most of the pediatric dosages and oncologic dosages utilize the BSA-based dosing in relation to the calculation of the medication. This is an indication that the patient's body surface area is critical in arriving at the medication. In the calculation of the body surface area of an individual, the following formula is applicable: A= ? (W.H)/3600. In this case, A refers to the patient's body surface area (m2), W represents the weight of the patient in kg, while H. represents the height of the patient in inches. Finally, 3600 represents the conversion or the correction factor thus kg/m3. In case the weight of the patient is in pounds (lbs) and the height is in inches, it is ideal to replace the 3600 (correction factor) with 3131. The formula relates to the initial DuBois and Dubois in the case of 1916 as follows BSA= 0.007184 X Height (m) 0.725 X Weight (kg) 0.425 before the transformation in 1987 by Mosteller.
The BSA-based dosing is also applicable in the case of the calculation of the medication of children. In the case o calculating the medication for children in using the formula, it is ideal to divide the child's body surface area by 1.73 before multiplying the result by the adult dose. For instance, in the case a physician prescribes Benadryl 150 mg/m2 for an 8-year-old child weighing 75 pounds and a height of about 4 feet 2 inches tall. Considering that the normal adult dose is about 25 mg q.i.d., it is critical to determine the how many mg of Benadryl for administration four times a day for the child. In execution of this scenario, it is ideal to change the feet to inches. This is through multiplying 4 by 12 to generate 48 thus 50 inches following to the addition of the two inches. A= ? (W.H)/3131