Flecainide Verapamil

Antiarrhythmics (e.g., disopyramide, flecainide, and others) P-Blockers (e.g., propranolol, metoprolol, atenolol, and others) Calcium channel blockers (e.g., verapamil and others)... 

Drugs that may affect flecainide include amiodarone, cimetidine, cisapride, disopyramide, propranolol, ritonavir, urinary acidifiers/alkalinizers, and verapamil. Smoking may also have an effect. Drugs that may be affected by flecainide include cisapride, propranolol, and digoxin. 

FLECAINIDE CALCIUM CHANNEL BLOCKERS Risk of heart block and 1 BP when flecainide is co-administered with verapamil. A single case of asystole has been reported Additive negative inotropic and chronotropic effect Monitor PR, BP and ECG at least weekly until stable watch for heart failure... 

This occurs in otherwise healthy individuals, who possess an anomalous (accessory) atrioventricular pathway they often experience attacks of paroxj mal AV re-entrant tachycardia or atrial fibrillation. Drugs that both suppress the initiating ectopic beats and delay conduction through the accessory pathway are used to prevent attacks e.g. flecainide, sotalol or amiodarone. Verapamil and digoxin may increase conduction through the anomalous pathway and should not be used. Electrical conversion may be needed to restore sinus rhythm when the ventricular rate is very rapid. Radiofrequency ablation of aberrant pathways will almost certainly provide a cure. 

There is some anecdotal evidence that atrioventricular nodal blockade with verapamil or a beta-blocker can also be effective. However, in two cases the addition of a beta-blocker (either atenolol or metoprolol) to treatment with class I antidysrhythmic drugs (cibenzoline in one case and flecainide in the other) did not prevent the occurrence of atrial flutter with a 1 1 response (47). However, the author suggested that in these cases, although the beta-blockers had not suppressed the dysrhythmia, they had at least improved the patient s tolerance of it. In both cases the uses of class I antidysrhythmic drugs was contraindicated by virtue of structural damage, in the first case due to mitral valvular disease and in the second due to an ischemic cardiomyopathy. 

Although verapamil reduces the clearance of flecainide, this is probably not clinically important (76). However, there is also a pharmacodjmamic interaction, since both drugs increase the PR interval and have additive effects on myocardial contractihty and atrioventricular conduction (77). 

Holtzman JL, Finley D, Mottonen L, Berry DA, Ekholm BP, Kvam DC, McQuinn RL, Miller AM. The pharmacodynamic and pharmacokinetic interaction between single doses of flecainide acetate and verapamil effects on cardiac function and drug clearance. Clin Pharmacol Ther 1989 46(l) 26-32. 

Buss J, Lasserre JJ, Heene DL. Asystole and cardiogenic shock due to combined treatment with verapamil and flecainide. Lancet 1992 340(8818) 546. 

Tamargo et al gave a very recent review.139 They point out that KATP channels are inhibited by ATP and activated by Mg ADP, so that the channel activity is influenced by the ATP/ADP ratio. They also draw attention to the fact that mitochondrial KATp channel is responsible for ischemic preconditioning. They suggest that these channels are not blocked only by sulfonylureas, but also by many antiarrhythmic drugs, such as bretylium, disopyramide, flecainide and propafenone, and also by diltiazem and verapamil, but not by amiodarone or dronedarone, which will be addressed later. 

KJ.7 KCNA7 19ql3.3 None Placenta, pancreas, skeletal muscle, heart, pulmonary arteries Flecainide, quinidine, verapamil, amiodarone, 4-AP, TEA None... 

Extracted acetazolamide, amitriptyline, chlordiazepoxide, chlorpromazine, desipramine, dextromethorphan, diphenhydramine, doxepin, encainide, fentanyl, flecainide, fluoxetine, flurazepam, haloperidol, hydroxyethylflurazepam, ibuprofen, imipramine, lidocaine, ma-protiline, methadone, methaqualone, mexiletine, norchlorimipramine, nordoxepin, norfluoxetine, nordiazepam, nortriptyline, norverapamil, pentazocine, promazine, propafenone, propoxyphene, propranolol, protriptyline, quinidine, temazepam, trazodone, tri-mipramine, verapamil... 

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