[Medical Q&A] What is the difference between sustained-release tablets and controlled-release tablets?

Planner: Chinese Medical Association

Reviewer: Zhao Jie, Chief Pharmacist Professor of the First Affiliated Hospital of Zhengzhou University

When you buy medicines at a pharmacy, you may find that the same medicine has sustained-release and controlled-release versions. For example, the antihypertensive drug nifedipine has both nifedipine sustained-release tablets and nifedipine controlled-release tablets. Since the names of the medicines are different, there is a difference between the two.

The surface of sustained-release tablets is usually wrapped with a semipermeable membrane of special material. Gastric juice can enter the tablet through this semipermeable membrane to dissolve part of the drug, and promote the drug to slowly seep out through the micropores on the semipermeable membrane within a certain period of time, so that the drug concentration can maintain a stable level for a long period of time. This technology prevents sustained-release tablets from dissolving directly like ordinary tablets, but slowly releases the drug through the film, thereby avoiding large fluctuations in drug concentration in a short period of time. Controlled-release tablets use more complex technology and processes to place the drug in a synthetic high-quality inert polymer so that the drug can be slowly released at a constant rate or a near-constant rate. In other words, this technology can more accurately control the release rate and time of the drug, making the blood concentration of the drug in the body more stable. It should be noted that whether it is a sustained-release tablet or a controlled-release tablet, it should be swallowed whole and cannot be broken or chewed for consumption. Otherwise, the drug cannot be released slowly, which not only affects the efficacy, but also may cause adverse reactions. Both sustained-release tablets and controlled-release tablets can prolong the release time of the drug in the body. The specific choice of which one needs to follow the doctor's advice.