A Drug-Drug Interaction Parameter Estimation Problem A two drug interaction is usually predicted by individual drug pharmacokinetic. An innovative drug-drug interaction prediction method based on a three-level hierarchical Bayesian meta-analysis model is developed that includes a Monte Carlo Markov chain pharmacokinetic parameter estimation procedure. Underlying the parameter estimation procedure is a fast integration method of the stiff pharmacokinetic equations. In this presentation, we discuss briefly the drug-drug interaction parameter estimation problem and report results of a fast integration method and its comparison with standard stiff solvers.