RT Book, Section A1 Freeman, Brian S. A1 Berger, Jeffrey S. SR Print(0) ID 1204766450 T1 Drug Interactions T2 Anesthesiology Core Review: Part One: BASIC Exam, 2nd Edition YR 2024 FD 2024 PB McGraw-Hill Education PP New York, NY SN 9781264285518 LK accessanesthesiology.mhmedical.com/content.aspx?aid=1204766450 RD 2024/10/04 AB The formulation of drugs is often overlooked but may contribute to bioavailability and desired effects. For example, adding epinephrine to a local anesthetic solution gives the solution a much lower pH due to highly acidic commercial preparations of epinephrine. A more acidic solution of local anesthetic results in lower concentration of the ionized, membrane permeable form of the local anesthetic. This equilibrium change decreases tissue penetration and diminishes the desired effect.