Pharmacy Curriculum Outcomes Assessment (PCOA) Practice Exam 2025 - Free Pharmacy Practice Questions and Study Guide

The therapeutic index of a drug measures the safety of a drug by comparing the median toxic dose (the dose at which 50% of patients experience severe side effects) to the median effective dose (the dose at which 50% of patients experience a therapeutic effect). This means that the therapeutic index takes into account not only the efficacy, or effectiveness, of a drug, but also its potential for harmful side effects. Option A, affordability, and option C, availability, are unrelated to the therapeutic index and can vary depending on factors such as insurance coverage and production and distribution processes. Option D mentions efficacy and side effects, which are both important factors in measuring the therapeutic index, but it does not include the comparison of median toxic dose to median effective dose, making it incorrect. Option B is the best choice because it captures the specific purpose of the therapeutic index and distinguishes it from the other options.