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

The osmotic-controlled release oral delivery system (OROS) is characterized by its use of a semi-permeable membrane, which is essential for the controlled release of the drug contained within. This system works by allowing water from the gastrointestinal tract to enter the delivery device through the semi-permeable membrane. As water enters, the pressure builds up inside the system, leading to the controlled release of the drug at a predetermined rate.

This mechanism is advantageous because it can provide a consistent and controlled release of medication, ensuring that therapeutic levels are maintained over an extended period. The semi-permeable nature of the membrane is crucial, as it only permits the controlled ingress of water while preventing the loss of the drug until it is released through an orifice.

Other options do not correctly describe the fundamental attributes of the OROS system. For instance, the first choice regarding enzymatic reaction is not a characteristic of OROS, as it does not depend on biochemical processes for drug release. The requirement for heating does not apply to OROS, and the statement about dissolving fully in the bloodstream contradicts the system's design, which is meant to release the drug over time rather than immediately dissolve. Thus, the semi-permeable membrane feature is the defining aspect