From the Guidelines
Verapamil ER (extended-release) and SR (sustained-release) formulations differ primarily in their release mechanisms and dosing schedules, with ER allowing for once-daily dosing and SR requiring twice-daily dosing, as indicated in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
Key Differences
- Verapamil ER releases the medication more slowly over a longer period, allowing for once-daily dosing, usually taken every 24 hours.
- Verapamil SR releases the medication at a somewhat faster rate than ER formulations and generally requires twice-daily dosing, usually taken every 12 hours.
Clinical Implications
- The difference in release rate affects how the drug concentration is maintained in the bloodstream throughout the day, with ER formulations providing more consistent blood levels and potentially fewer side effects for some patients.
- When switching between these formulations, it's crucial to maintain the same total daily dose but adjust the frequency according to the specific formulation, as advised in the guideline 1.
Administration Guidelines
- Both Verapamil ER and SR formulations should be swallowed whole and not crushed or chewed, as this would destroy the release mechanism and potentially cause too much medication to be released at once, increasing the risk of side effects like low blood pressure, headache, or constipation.
- The choice between Verapamil ER and SR should be based on individual patient needs and preferences, considering factors such as dosing convenience, side effect profiles, and specific clinical conditions, in line with the recommendations from the American College of Cardiology/American Heart Association task force on clinical practice guidelines 1.
From the FDA Drug Label
In multiple-dose studies under fasting conditions, the bioavailability, measured by AUC, of verapamil hydrochloride extended-release was similar to verapamil hydrochloride (immediate release); rates of absorption were of course different The tablets are designed for sustained release of the drug in the gastrointestinal tract; sustained-release characteristics are not altered when the tablet is divided in half.
The main difference between Verapamil (Calcium Channel Blocker) Extended Release (ER) and Sustained Release (SR) formulations is:
- Rate of absorption: ER and SR have different rates of absorption.
- Design: SR tablets are designed to release the drug in a sustained manner in the gastrointestinal tract, and this characteristic is maintained even when the tablet is divided in half. However, the provided drug labels do not contain direct information that explicitly compares ER and SR formulations in terms of their differences. 2 2
From the Research
Difference between Verapamil Extended Release (ER) and Sustained Release (SR) formulations
- The main difference between Verapamil Extended Release (ER) and Sustained Release (SR) formulations lies in their drug delivery systems and the duration of action 3.
- Sustained Release (SR) formulations of Verapamil are designed to provide a steady release of the medication over a longer period, typically 12-24 hours, allowing for once-daily dosing 4, 5.
- Extended Release (ER) formulations, on the other hand, are designed to release the medication more slowly over a longer period, typically 24 hours or more, also allowing for once-daily dosing 3.
- The SR formulation of Verapamil has been shown to be effective in lowering blood pressure in patients with mild to moderate hypertension, with a significant reduction in both systolic and diastolic blood pressure 5.
- The ER formulation of Verapamil, such as the pellet-filled capsule formulation (Verelan), provides controlled absorption, 24-hour blood pressure control, and improved peak-to-trough plasma levels, allowing for once-daily dosing regardless of dosage size 3.
- Both SR and ER formulations of Verapamil have been shown to be effective in reducing blood pressure and are generally well-tolerated, with similar adverse event profiles 4, 5, 3, 6.
Key Characteristics of Verapamil SR and ER Formulations
- Sustained Release (SR) formulation:
- Provides a steady release of the medication over 12-24 hours
- Allows for once-daily dosing
- Effective in lowering blood pressure in patients with mild to moderate hypertension
- Extended Release (ER) formulation:
- Releases the medication more slowly over 24 hours or more
- Allows for once-daily dosing
- Provides controlled absorption and 24-hour blood pressure control
- Improves peak-to-trough plasma levels