PRONESTYL vs RYTHMOL SR

Independent side-by-side comparison.

Rated against independent regulatory sources·Last updated August 22, 2026·How we rate

Possible drug interaction. PRONESTYL and RYTHMOL SR are different prescription medicines. Combining or switching between them can cause interactions — talk to a pharmacist or prescriber before making changes. This page is not medical advice.

Attribute	PRONESTYL	RYTHMOL SR
Rating	New	70/100
Pharmacy pays	—	~$10.51 /30
Type	RX	RX
Active ingredient	PROCAINAMIDE HYDROCHLORIDE	PROPAFENONE HYDROCHLORIDE
Manufacturer	Apothecon	Glaxosmithkline
Dosage forms	Capsule, Tablet, Injectable	Capsule, extended release
Drug class	Antiarrhythmic	Antiarrhythmic
Boxed warning	None	None
Half-life	—	about 2 to 10 hours (immediate-release) in the ~90% of adults who are extensive CYP2D6 metabolizers
Treats	Atrial Fibrillation, Atrial Flutter, Supraventricular Tachycardia	Atrial Fibrillation, Supraventricular Tachycardia

pronestyl rythmol sr

Rating

New

70/100

Pharmacy pays

—

~$10.51 /30

Type

Active ingredient

PROCAINAMIDE HYDROCHLORIDE

PROPAFENONE HYDROCHLORIDE

Manufacturer

Apothecon

Glaxosmithkline

Dosage forms

Capsule, Tablet, Injectable

Capsule, extended release

Drug class

Antiarrhythmic

Boxed warning

None

Half-life

—

about 2 to 10 hours (immediate-release) in the ~90% of adults who are extensive CYP2D6 metabolizers

Treats

Atrial Fibrillation, Atrial Flutter, Supraventricular Tachycardia

Atrial Fibrillation, Supraventricular Tachycardia

Frequently asked questions

What is the difference between Pronestyl and Rythmol SR?

Pronestyl contains Procainamide Hydrochloride, while Rythmol SR contains Propafenone Hydrochloride — they have different active ingredients.

Ratings are based on FDA regulatory (recall-safety) data. This comparison is for general reference only — not medical advice. Always consult a licensed professional before choosing or switching a medication.