The integrated in vitro--in silico--in vivo approach has emerged into a biopharmaceutical toolkit that could accelerate drug development and improve drug product clinical performance in patients. In the present study, the influence of physiologically based media and dynamic dissolution testing on drug release from two metformin hydrochloride immediate release products with proven bioequivalence was tested. Metformin-specific physiologically based pharmacokinetic (PBPK) model was developed based on a range of literature or in silico predicted data using gastrointestinal simulation technology implemented in the Simcyp software package. Various approaches were employed in order to estimate the human effective permeability which was used as input for metformin plasma profile simulation. Influence of the rate and extent of metformin dissolution on drug absorption was evaluated. Both convolution and deconvolution approaches were used in order to establish a correlation between the in vitro and in vivo data. The results obtained indicate that physiologically based dissolution media and glass bead dissolution device exhibit certain advantages over the compendial dissolution apparatus and simple buffers which tended to be over-discriminative. Gastrointestinal simulation technology implemented in the Simcyp Simulator was successfully used in developing drug-specific PBPK model for metformin. Simulations indicate that in vitro dissolution kinetics has no significant effect on metformin absorption, if more than 65% of drug is released in 1 hour. Level A in vitro-in vivo correlation was obtained using both convolution and deconvolution approaches.