FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam 2025 - Free NABP Practice Questions and Study Guide

When considering the metabolism of oral morphine, it is essential to understand the concept of first-pass metabolism, which occurs when a substance is metabolized in the liver before it enters systemic circulation. Morphine undergoes significant first-pass metabolism, and research indicates that approximately 90% of oral morphine is metabolized during this process.

This high percentage of metabolism results in a considerably lower bioavailability when morphine is taken orally compared to its parenteral forms, such as intravenous administration. The liver enzymes, primarily CYP2D6 and other isoforms, convert a substantial portion of oral morphine into metabolites, which can impact both efficacy and dosing considerations in clinical practice.

Recognizing this metabolic pathway is crucial for pharmacists when making decisions about pain management and the delivery method for opioid medications. Understanding morphine’s pharmacokinetics ensures that patients receive the most effective treatment while minimizing the risk of potential side effects associated with higher doses often necessitated by this extensive first-pass effect.

Thus, indicating that approximately 90% of oral morphine is metabolized during its first pass through the liver reflects the importance of recognizing this pharmacological principle when assessing opioid administration routes and patient care strategies.