Drug Interaction Studies of Therapeutic Biologics: Protein and Peptide Actions and Interactions That Alter Their Pharmacokinetics, Pharmacodynamics, and Metabolism

INTRODUCTION Drug interaction can alter the pharmacokinetics and/or pharmacodynamics of a drug. In pharmacokinetic drug interactions, the concentrations of one or more drugs are altered by another drug. This change in concentration in a given drug may be due to changes in absorption, distribution, metabolism, or elimination (1). The pharmacodynamic drug interactions can be either negative (toxic effects) or positive (therapeutic benefit) and may be due to various mechanisms including receptor interaction and changes in effector mechanisms (1). For example, the combination therapy of ribavirin and interferon (IFN)-a2b in patients with chronic hepatitis C provided improved therapeutic benefit than either treatment alone, and the safety profiles of combination therapy were similar to the monotherapy treatment (2).