In vitro in vivo correlation (IVIVC) is a mathematical model describing the relationship between in vitro drug release and its in vivo drug absorption. The benefit of establishing this correlation is to enable the dissolution to serve as a surrogate of the in vivo drug behavior. This should minimize the number of bioavailability studies performed during the initial approval process, scale-up and postapproval change. IVIVC development may be significantly influenced by the biopharmaceutic and pharmacokinetic properties of a drug since they are the determinants of in vitro drug dissolution and the in vivo drug absorption. The objectives of this dissertation research were to: (1) investigate the influence of biopharmaceutic and pharmacokinetic properties (i.e. biopharmaceutical classification system, stereoisomerisms, first pass effect, inter- and intra-subject variability) on the IVIVC development and validation for metoprolol extended release (ER) product, (2) develop and evaluate a deconvolution-based IVIVC for a diltiazem ER product, and (3) elucidate the effect of variability associated with the pharmacokinetic of the drug products on the in vitro and in vivo release of metoprolol and diltiazem ER products. Dissolution studies were performed for metoprolol (100 mg) and diltiazem (90 mg) ER bio-batch using various dissolution testing conditions (USP Apparatus I, II, and III). Two clinical studies on both products were conducted in a randomized single dose, fasting, and crossover study design. Metoprolol studies were conducted in normal healthy extensive metabolizers, whereas subjects participating on diltiazem studies were randomly selected from the population. The study of stereoselectivity on the IVIVC development for metoprolol demonstrated an inability of using racemate data to predict R-enantiomer concentrations, while they were predictive of the active S-stereoisomer. Enantiomer specific IVIVCs were predictive of their in vivo performance. In the evaluation of first pass metabolism with metoprolol and its metabolites, the developed IVIVC was not able to directly predict the bioavailability of metoprolol, suggesting that first pass metabolism will play a role in IVIVC development. Additionally, deconvolution-based IVIVC for diltiazem was not predictive due to an extensive pharmacokinetic variation in its first pass elimination. In addition, inter- and intra-subject variability was found to minimize the predictive performance of the average and individual IVIVCs for S-metoprolol and diltiazem.