Effect of Body Mass on Filgrastim Pharmacokinetics

Studies have shown that different percentages of body fat can alter the way drugs are distributed in the body. This study will use blood samples taken at different time points for patients taking Neupogen to determine if higher body weights affect drug exposure. The information gathered from this study will help understand if patients with higher body weights need a different dosing plan. Patients in this study will have blood draws once before they take Neupogen and 6 times after they take the Neuopen (for a total of 24 hours). These patients will be in the hospital already and will not need to make additional trips back to have blood drawn. A total of about 5-6 tablespoons of blood will be drawn for this study. 15 obese patients and 15 matched, non-obese patients will be enrolled into this study.