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Relationships between body composition parameters and fluorouracil pharmacokinetics.
Milena Gusella1, Sivia Toso, Eros Ferrazzi
1Department of Pharmacology and Anaesthesiology, University of Padova, Padova and Oncology Division, Rovigo Hospital, Rovigo, Italy.
British Journal of Clinical Pharmacology
|September 5, 2002
Summary
Fluorouracil (FU) pharmacokinetics are better predicted by fat-free mass (FFM) and total body water (TBW) than by traditional measures, with sex influencing predictions. Bioelectrical impedance analysis (BIA) may improve FU dosing strategies.
Area of Science:
- Pharmacology
- Clinical Chemistry
- Medical Physics
Background:
- Fluorouracil (FU) is a critical chemotherapeutic agent for colorectal cancer.
- Standard dosing relies on body surface area (BSA) or body weight (BW), which may not accurately reflect individual drug disposition.
- Accurate pharmacokinetic profiling is essential for optimizing FU efficacy and minimizing toxicity.
Purpose of the Study:
- To investigate the correlation between fluorouracil (FU) clearance (CL) and volume of distribution (Vss) with body composition parameters.
- To compare the predictive power of fat-free mass (FFM), total body water (TBW), and body cell mass (BCM) against BSA and BW for FU pharmacokinetics.
- To determine if sex influences the relationship between body composition and FU pharmacokinetics.
Main Methods:
- Thirty-four colorectal cancer patients receiving FU adjuvant therapy were studied.
- Pharmacokinetic parameters (CL and Vss) were determined after intravenous FU administration.
- Body composition was assessed using non-invasive bioelectrical impedance analysis (BIA) to measure FFM, TBW, and BCM.
Main Results:
- Correlations between CL/Vss and standard anthropometric parameters, including BIA-derived measures, were initially poor (r2 range: 0.10–0.21).
- Multiple regression analysis incorporating sex, TBW, and FFM significantly improved predictive correlations for CL (r2=0.44) and Vss (r2=0.36).
- FFM-normalized CL was higher in females, suggesting more rapid FU metabolism, and Vss strongly correlated with CL (r2=0.67).
Conclusions:
- Fat-free mass (FFM) and total body water (TBW) provide better prediction of fluorouracil (FU) pharmacokinetics than standard parameters.
- Pharmacokinetic predictions are sex-dependent, highlighting the need for individualized dosing approaches.
- Bioelectrical impedance analysis (BIA) offers a promising tool for refining FU dosing strategies to improve patient outcomes.