Propafenone drug data and news

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Lifetime of meds needed for heart out of rhythm  Apr 30, 2006
The most commonly used drugs are flecainide (Tambocor), propafenone (Rythmol), sotalol (Betapace), dofetilide (Tikosyn) and amiodarone (Cordarone, Pacerone). ... - Fort Wayne Journal Gazette,

Stonefly Communications Group Named Agency of Record for Reliant's ...  Apr 17, 2006
...a unique Client Advisor model for healthcare advertising, has been named agency of record for Reliant Pharmaceuticals' Rythmol(R) SR (propafenone HCL) extended ... - PharmaLive.com (press release),

Quinidine: Small doses of quinidine completely inhibit the hydroxylation metabolic pathway, making all patients, in effect, slow metabolizers (see CLINICAL PHARMACOLOGY). There is, as yet, too little information to recommend concomitant use of propafenone and quinidine.

Local Anesthetics: Concomitant use of local anesthetics (i.e., during pacemaker implantations, surgery, or dental use) may increase the risks of central nervous system side effects.

Digitalis: RYTHMOL (propafenone hydrochloride) produces dose-related increases in serum digoxin levels ranging from about 35% at 450 mg/day to 85% at 900 mg/day of propafenone without affecting digoxin renal clearance. These elevations of digoxin levels were maintained for up to 16 months during concomitant administration. Plasma digoxin levels of patients on concomitant therapy should be measured, and digoxin dosage should ordinarily be reduced when propafenone is started, especially if a relatively large digoxin dose is used or if plasma concentrations are relatively high.

Beta-Antagonists: In a study involving healthy subjects, concomitant administration of propafenone and propranolol has resulted in substantial increases in propranolol plasma concentration and elimination half-life with no change in propafenone plasma levels from control values. Similar observations have been reported with metoprolol. Propafenone appears to inhibit the hydroxylation pathway for the two beta-antagonists (just as quinidine inhibits propafenone metabolism). Increased plasma concentrations of metoprolol could overcome its relative cardioselectivity. In propafenone clinical trials, patients who were receiving beta-blockers concurrently did not experience an increased incidence of side effects. While the therapeutic range for beta-blockers is wide, a reduction in dosage may be necessary during concomitant administration with propafenone.

Warfarin: In a study of eight healthy subjects receiving propafenone and warfarin concomitantly, mean steady-state warfarin plasma concentrations increased 39% with a corresponding increase in prothrombin times of approximately 25%. It is therefore recommended that prothrombin times be routinely monitored and the dose of warfarin be adjusted if necessary.

Cimetidine: Concomitant administration of propafenone and cimetidine in 12 healthy subjects resulted in a 20% increase in steady-state plasma concentrations of propafenone with no detectable changes in electrocardiographic parameters beyond that measured on propafenone alone.

Desipramine: Concomitant administration of propafenone and desipramine may result in elevated serum desipramine levels. Both desipramine, a tricyclic antidepressant, and propafenone are cleared by oxidative pathways of demethylation and hydroxylation carried out by the hepatic P-450 cytochrome.

Cyclosporin: Propafenone therapy may increase levels of cyclosporin.

Theophylline: Propafenone may increase theophylline concentration during concomitant therapy with the development of theophylline toxicity.

Rifampin: Rifampin may accelerate the metabolism and decrease the plasma levels and antiarrhythmic efficacy of propafenone.

Other: Limited experience with propafenone combined with calcium antagonists and diuretics has been reported without evidence of clinically significant adverse reactions.