(Advanced) Tape #1: Overview of definitions, issues and challenges in interactions; pharmacological mechanisms, types of interactions, clinical significance and reporting mechanisms, red flags and practitioner guidelines. ~ Tape #2: Intereactions in-depth, including a detailed review of herb pharmacokinetic and pharmacodynamic interactions including St. John?s Wort, Ginkgo and others. Data evaluation and methodological issues in the interaction literature will be discussed.