Introduction to Concepts in Pharmacotherapy By Shalini S Lynch, PharmD, University of California San Francisco School of Pharmacy Reviewed / Revised May 2022 | Modified Sep 2022 View Patient Education Drugs are selected based on characteristics of the drug (eg, efficacy, safety profile, route of administration, route of elimination, dosing frequency, cost) and of the patient (eg, age, sex, other medical problems, likelihood of pregnancy, ethnicity, and other genetic determinants).