Writing for pharmacology researchers and practitioners in medicine or pharmacology, Vergnaud (materials and chemical engineering, U. de Saint-Etienne, France) and Rosca (polymer Chemistry and technology, Polytechnic U., Bucharest, Romania) explain mathematical modeling to correlate in-vitro and in-vivo controlled-release drug dosage forms. They present methods for calculating the profiles of plasma levels obtained with controlled-release dosage forms, and provide examples and case studies to illustrate the techniques. The master curves they present use dimensionless numbers in repeated doses, either for the time or for the plasma drug concentration, and so can be applied to any drug with a linear pharmacokinetics.