Encainide Brand Name– Enkaid
What is Encainide
NOTE: This drug is discontinued in the US; however, it is available for compassionate use in patients previously receiving encainide.
Encainide is an orally administered class IC antiarrhythmic agent previously used in the treatment of documented life-threatening arrhythmias, nonsustained ventricular tachycardia, and frequent PVCs. It is similar to flecainide and moricizine.
The results of the Cardiac Arrhythmia Suppression Trial (CAST) indicate that the rates of nonfatal cardiac arrest and total mortality in patients with recent myocardial infarction, asymptomatic or symptomatic ventricular arrhythmias, and mild to moderate left ventricular dysfunction were significantly increased in patients who received encainide.
These implications led to the withdrawal of encainide from the U.S. market in 1991, although the manufacturer continued to make the drug available (compassionate use program) to those patients previously receiving encainide.
Encainide was originally approved by the FDA in December 1986.
Indications
- premature ventricular contractions (PVCs)
- ventricular tachycardia
For the treatment of premature ventricular contractions (PVCs), nonsustained ventricular tachycardia, or other life-threatening ventricular arrhythmias
What is the dosage?
- Encainide is administered at a dose of 50 mg/day. After oral administration, encainide is rapidly absorbed and reaches a peak plasma concentration of 511 nM. Encainide inhibited Kv channels with an IC50 value of 8.9 ± 1.75 μM, which was higher than the peak plasma concentration.
- However, application of 300 nM encainide effectively inhibited the Kv current. Considering that arterial smooth muscle cells have high input resistance, small alterations in ionic conductance alter the vascular tone.
- Furthermore, inadvertent drug use may increase the blood concentration of encainide. Therefore, the dose of encainide should be carefully selected, particularly for patients with multiple cardiovascular diseases.
Side Effects
- arrhythmia exacerbation
- dizziness
- dyspnea
- headache
- heart failure
- hyperglycemia
- insomnia
- nausea
- tinnitus
- ventricular fibrillation
- ventricular tachycardia
- visual impairment
- vomiting
Monitoring Parameters
- blood glucose
- ECG
- serum creatinine/BUN
- serum potassium
Contraindications
- AV block
- breast-feeding
- bundle-branch block
- cardiogenic shock
- cardiomyopathy
- diabetes mellitus
- geriatric
- heart failure
- hepatic disease
- hyperkalemia
- hypokalemia
- myocardial infarction
- pregnancy
- renal disease
- renal failure
- renal impairment
- sick sinus syndrome
- ventricular dysfunction
Interactions
- Acebutolol
- Acetaminophen; Propoxyphene
- Amiodarone
- Amlodipine; Celecoxib
- Artemether; Lumefantrine
- Atazanavir; Cobicistat
- Atenolol
- Atenolol; Chlorthalidone
- Bendroflumethiazide; Nadolol
- Betaxolol
- Bisoprolol
- Bisoprolol; Hydrochlorothiazide, HCTZ
- Brimonidine; Timolol
- Bupropion
- Bupropion; Naltrexone
- Carteolol
- Carvedilol
- Celecoxib
- Chlorpromazine
- Cimetidine
- Cinacalcet
- Citalopram
- Clozapine
- Cobicistat
- Colesevelam
- Darunavir; Cobicistat
- Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide
- Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir
- Delavirdine
- Diltiazem
- Dofetilide
- Dorzolamide; Timolol
- Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide
- Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate
- Escitalopram
- Esmolol
- Fluoxetine
- Fluoxetine; Olanzapine
- Ginger, Zingiber officinale
- Haloperidol
- Hydrochlorothiazide, HCTZ; Metoprolol
- Hydrochlorothiazide, HCTZ; Propranolol
- Imatinib
- Labetalol
- Lacosamide
- Lopinavir; Ritonavir
- Metoprolol
- Mirabegron
- Nadolol
- Nebivolol
- Nebivolol; Valsartan
- Ombitasvir; Paritaprevir; Ritonavir
- Oritavancin
- Paroxetine
- Peginterferon Alfa-2b
- Penbutolol
- Perphenazine
- Perphenazine; Amitriptyline
- Pindolol
- Propoxyphene
- Propranolol
- Quinine
- Ranolazine
- Risperidone
- Ritonavir
- Rolapitant
- Sertraline
- Sotalol
- Terbinafine
- Tetracaine
- Thioridazine
- Timolol
- Vemurafenib
What research says about encainide?
- The results of a study suggest that encainide inhibits Kv channels by shifting the steady-state activation curve in a dose-dependent and use (state)-independent manner. It was found in this study that encainide inhibits Kv channels on vascular smooth muscle regardless of its anti-arrhythmic effect.
- First, the response time of encainide on inhibition of Kv current is very short (within 1 min), suggesting direct inhibition of Kv channels by encainide.
- Second, encainide effectively shifted the steady-state activation curve toward a more positive potential, suggesting that encainide inhibited Kv channels by direct interaction with voltage sensors, inducing changes in channel structure.
- Third, vascular smooth muscle cells, which are non-excitable cells, do not express Na+ channels.
- Although the main target of the anti-arrhythmic effect of encainide is the Na+ channel, the inhibitory effect of encainide on Kv channels is independent of Na+ channels.
- Therefore, the inhibitory effect of encainide on Kv currents was not related to Na+ channel inhibition and was attributed to direct interaction with Kv channels.
Sources
- Li H, Zhou Y, Yang Y, Zha Y, Ye B, Mun SY, Zhuang W, Liang J, Park WS. Encainide, a class Ic anti-arrhythmic agent, blocks voltage-dependent potassium channels in coronary artery smooth muscle cells. Korean J Physiol Pharmacol. 2023 Jul 1;27(4):399-406. doi: 10.4196/kjpp.2023.27.4.399. PMID: 37386837; PMCID: PMC10316191.https://pmc.ncbi.nlm.nih.gov/articles/PMC10316191/
