What are the differences in indications and dosing between Verapamil (Calcium Channel Blocker) Extended Release (ER) and Sustained Release (SR) formulations?

From the Guidelines

Verapamil ER and SR are different formulations of the same calcium channel blocker medication, with Verapamil ER releasing the medication more gradually over 24 hours, allowing for once-daily dosing, and Verapamil SR having a shorter duration of action, requiring twice-daily dosing. The dosing requirements for Verapamil ER and SR are as follows:

• Verapamil ER: 100-300 mg once daily, typically in the evening 1
• Verapamil SR: 120-360 mg once or twice daily 1 Both formulations are indicated for hypertension, angina, and certain arrhythmias like atrial fibrillation with rapid ventricular response. The key differences between Verapamil ER and SR are:
• Release mechanism: Verapamil ER releases the medication more gradually over 24 hours, while Verapamil SR has a shorter duration of action
• Dosing frequency: Verapamil ER is typically dosed once daily, while Verapamil SR is dosed once or twice daily
• Patient convenience and adherence: Verapamil ER offers simpler once-daily dosing, which may improve patient adherence When switching between formulations, the total daily dose remains similar, but the dosing frequency changes. Neither formulation should be crushed or chewed as this would destroy the controlled-release mechanism and potentially cause dangerous drug level spikes. Patients with hepatic or renal impairment may require lower doses of either formulation, as stated in the guidelines 1. The extended-release properties work through different polymer matrix systems that control drug dissolution rates in the gastrointestinal tract, providing more consistent blood levels throughout the dosing period. It is essential to note that the choice between Verapamil ER and SR should be based on individual patient needs and medical history, and the decision should be made in consultation with a healthcare professional. In terms of specific dosing, the guidelines recommend the following:
• Verapamil ER: 100-300 mg once daily, typically in the evening 1
• Verapamil SR: 120-360 mg once or twice daily 1 It is crucial to follow the recommended dosing guidelines and to monitor patients closely for any adverse effects or interactions. Additionally, the guidelines highlight the importance of considering drug interactions with diltiazem and verapamil, as they are both CYP3A4 major substrate and moderate inhibitor 1. Overall, Verapamil ER and SR are effective treatments for hypertension, angina, and certain arrhythmias, and the choice between formulations should be based on individual patient needs and medical history.

From the FDA Drug Label

Verapamil hydrochloride extended-release tablets are indicated for the treatment of hypertension, to lower blood pressure. Verapamil hydrochloride has a local anesthetic action that is 1. 6 times that of procaine on an equimolar basis. 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 main difference between verapamil ER and SR is the release mechanism and duration of action.

• Verapamil ER (Extended-Release): Releases the drug slowly over a longer period, providing a steady and consistent level of medication in the bloodstream.
• Verapamil SR (Sustained-Release): Releases the drug at a slower rate than immediate-release formulations, but the exact release mechanism may vary depending on the specific formulation. Indications for verapamil ER and SR may include:
• Hypertension
• Angina
• Certain types of arrhythmias Dosing may vary depending on the specific formulation, indication, and patient factors, but verapamil ER is often dosed once daily, while verapamil SR may be dosed every 8-12 hours 2 2.

From the Research

Verapamil ER and SR Formulations

• Verapamil is a calcium channel blocker available in different formulations, including extended-release (ER) and sustained-release (SR) 3, 4.
• The main difference between verapamil ER and SR formulations is the way they release the active ingredient, with ER formulations providing a more consistent release of verapamil over a longer period 3.

Indications and Dosing

• Verapamil ER and SR are indicated for the treatment of hypertension, angina pectoris, and certain types of arrhythmias 5, 3, 4.
• The dosing of verapamil ER and SR varies depending on the specific formulation and the patient's condition, with typical doses ranging from 120 to 480 mg per day 3, 4.
• Verapamil SR has been shown to be effective in reducing blood pressure and improving exercise capacity in patients with hypertension and angina pectoris 3, 4.

Pharmacokinetics and Pharmacodynamics

• The pharmacokinetics of verapamil ER and SR have been studied, with results showing that verapamil SR produces a more gradual rise and sustained elevation of plasma verapamil and norverapamil concentrations compared to verapamil IR 3.
• Verapamil ER and SR have been shown to have similar efficacy and safety profiles, with the ER formulation providing a more consistent release of verapamil over a longer period 3, 4.

Comparison with Other Calcium Channel Blockers

• Verapamil has been compared to other calcium channel blockers, such as amlodipine and diltiazem, in terms of its hemodynamic effects and efficacy in treating hypertension and angina pectoris 6, 7.
• The combination of verapamil with other calcium channel blockers, such as amlodipine, has been shown to be effective in treating patients with coronary artery disease and hypertension 6.