Pharmacokinetic analyses with RUGFIT: an interactive pharmacokinetic computer program.

Area of Science:

• Pharmacokinetics
• Computational Biology
• Biopharmaceutics

Background:

• Accurate modeling of experimental data is crucial in pharmacokinetics.
• Existing software often requires initial parameter estimates and can converge to local minima.
• Complex biological processes may require flexible modeling approaches.

Purpose of the Study:

• Introduce RUGFIT, an interactive computer program for fitting polyexponential equations.
• Evaluate RUGFIT's performance in modeling various pharmacokinetic profiles.
• Compare RUGFIT with existing nonlinear regression programs.

Main Methods:

• Iterative stripping method to minimize sum of squared residuals.
• Fitting polyexponential equations without prior assumptions on the number of terms or initial estimates.
• Comparison with Boxenbaum et al. test and other software (CFT3, NONLIN, NONLINEAR).

Main Results:

• RUGFIT successfully fits polyexponential equations to diverse experimental data, including plasma decay and entero-hepatic recirculation curves.
• The program avoids local minima, yielding results comparable to established methods.
• Inadequate model selection with RUGFIT can lead to significant errors in area under the curve and bioavailability estimations.

Conclusions:

• RUGFIT provides a robust and flexible tool for pharmacokinetic data analysis.
• The program's ability to avoid local minima enhances the reliability of parameter estimation.
• Careful model selection is essential for accurate pharmacokinetic interpretation and decision-making.