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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: AIMS, METHODS AND RESULTS. Meshes: Administration, Oral, Adrenergic beta-Antagonists, Adult, Anti-Arrhythmia Agents, Austria, Blood Pressure, Cross-Over Studies, Double-Blind Method, Drug Monitoring, Exercise, Exercise Test, Healthy Volunteers, Heart Rate, Humans, Male, Molecular Structure, Propafenone, Recovery of Function, Structure-Activity Relationship, Young Adult.
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Does propafenone show class Ic and class II antiarrhythmic effects? Context: Propafenone is a well-known Class Ic antiarrhythmic agent. It has the typical chemical structure of a beta-blocker, but human studies on its beta-blocking effects revealed conflicting results. Twelve healthy males received single oral doses of 600 mg propafenone and placebo according to a randomized, double-blind, placebo-controlled, cross-over protocol. Four hours following drug intake, heart rate and blood pressure were measured, and plasma concentrations of propafenone were determined at rest, during exercise and after recovery. At exercise, propafenone significantly decreased heart rate (-6%, P < 0.05), systolic blood pressure (-6%, P < 0.05), and the rate-pressure product (-11%, P < 0.05). Plasma concentrations of propafenone increased during exercise (+23%, P < 0.05) and decreased during recovery (-33%, P < 0.05).
assistant
Both effects on heart rate and blood pressure as well as the changes of plasma concentrations of propafenone during exercise represent two particular features of beta-blockers. Therefore, we conclude that propafenone is both a Class Ic and a Class II antiarrhythmic agent, and 600 mg propafenone, i.e. the dose recommended in current guidelines for cardioversion of paroxysmal atrial fibrillation, cause clinically significant beta-blockade. Thus, single oral doses of 600 mg propafenone appear also suitable for cardioversion of paroxysmal atrial fibrillation in patients with structural heart disease since beta-blockers are explicitly indicated in the treatment of both coronary artery disease and heart failure. Final Decision: yes