From the FDA Drug Label
Each propranolol hydrochloride extended-release capsule intended for oral administration contains 60 mg or 80 mg or 120 mg or 160 mg of propranolol hydrochloride. In addition, each capsule contains the following inactive ingredients: ethyl cellulose, FD&C blue #1, gelatin, hypromellose, microcrystalline cellulose and titanium dioxide The capsule is printed with black pharmaceutical ink which contains black iron oxide as a coloring agent.
The extended-release property of propranolol-er is due to the beads or more specifically the inactive ingredients such as ethyl cellulose and hypromellose that control the release of the drug, however the label does not explicitly state that, it only mentions the composition of the capsule. 1
From the Research
Propranolol-ER (extended release) is made possible by the specially designed beads inside the capsule, not the capsule itself. These beads are formulated with a polymer coating that controls the rate at which the medication is released into the body over an extended period, typically allowing for once-daily dosing instead of multiple doses throughout the day. The capsule simply serves as a container for these beads. When you take propranolol-ER, the capsule dissolves in your digestive system, releasing the beads which then gradually release the medication over time. This controlled release system maintains steady blood levels of propranolol, providing consistent beta-blocking effects for managing conditions like hypertension, angina, or anxiety with fewer fluctuations in drug concentration compared to immediate-release formulations. This technology improves patient compliance by reducing dosing frequency while minimizing peak-related side effects like fatigue or dizziness that can occur with immediate-release versions, as shown in studies such as 2 and 3. Key characteristics of these beads include their ability to release the drug in a controlled manner, with factors such as the type of polymer coating and the formulation of the beads themselves playing a crucial role in determining the release profile, as discussed in 2. Furthermore, the use of response surface methodology and multiple response optimization has been utilized to optimize the formulation of propranolol extended-release formulations, as seen in 3. Overall, the beads in propranolol-ER are the critical component that enables the extended release of the medication, and their design and formulation are essential to the drug's efficacy and safety profile.