Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To establish long-term efficacy and safety of encainide, 48 patients with chronic premature ventricular contractions (PVCs) underwent 6 months of therapy with encainide. Twenty-four-hour ambulatory ECGs were obtained at baseline for each daily dosage of 75 mg, 150 mg, and 225 mg of encainide during the in-hospital titration period and at the end of the first and sixth months during the follow-up period. There was a significant reduction in the median hourly total PVC rates from 480.6 at baseline to 2.0 at the end of the titration period with the highest dosage and to 22.1 at the last visit of the chronic dosing period. Nearly total suppression of PVCs was observed in 56% of patients at the end of the titration period and in 30% at the end of the 6-month follow-up period. The most common side effects were vertigo, vision disturbance, and headache. PR, QRS, and QTc intervals showed consistent significant increases from baseline during the various encainide trial periods. Encainide may have worsened ventricular arrhythmia in four patients who received more than 200 mg of encainide daily. Plasma concentrations of encainide and encainide metabolites showed wide interpatient variation, and no relationship was found between antiarrhythmic efficacy and plasma levels of encainide, O-demethyl-encainide, or 3-methoxy-O-demethyl-encainide.
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PMID:Long-term efficacy and safety of oral encainide in the treatment of chronic ventricular ectopic activity: relationship to plasma concentrations--a French multicenter trial. 241 28

Encainide is classified as a type Ic antiarrhythmic agent. Absorption is essentially complete, but bioavailability is variable because of first-pass metabolism. Two metabolic phenotypes, extensive and poor metabolizers, have been identified. O-demethyl encainide and 3-methoxy-O-demethyl encainide are active metabolites of encainide and contribute significantly to its antiarrhythmic effect. In clinical trials, encainide has been shown to be highly effective in suppressing premature ventricular contractions and ventricular tachyarrhythmias. The drug is useful in treating ventricular arrhythmias refractory to other agents. Encainide is also moderately effective in supraventricular arrhythmias involving an accessory pathway. It is highly effective in cases of Wolff-Parkinson-White syndrome, where the accessory pathway has a short refractory period. Common adverse effects of encainide are dizziness, visual disturbances, nausea, and headache. Encainide appears to be a safe and effective antiarrhythmic agent with few adverse effects and negligible hemodynamic effects. Encainide may be a useful agent for ventricular and supraventricular arrhythmias, particularly those refractory to other agents.
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PMID:Encainide: a new antiarrhythmic agent. 308 Mar 1

The chemistry, electrophysiology, pharmacokinetics, clinical use and efficacy, adverse effects, drug interactions, and dosage of encainide hydrochloride and flecainide acetate are reviewed. Encainide and flecainide are class 1c antiarrhythmic agents that slow myocardial conduction and mildly prolong the duration of repolarization. Both agents block anterograde conduction over accessory pathways and prolong the effective refractory period of the accessory pathway. Bioavailability of encainide ranges from 7% to 82%, whereas that of flecainide is 90% to 95%. Encainide is metabolized by the liver to two major active metabolites that are slowly eliminated in the urine. About 23% of flecainide's total body clearance is dependent on renal elimination, and drug excretion is slowed in patients with renal dysfunction, requiring dosage adjustments. Both agents are effective in the suppression and prevention of ventricular arrhythmias, including premature ventricular contractions and sustained and nonsustained ventricular tachycardia. These agents may also be valuable in controlling supraventricular arrhythmias. The most common adverse effects of both agents involve the central nervous system and include dizziness, blurred vision, and headache. The potential for proarrhythmic effects is a concern with these agents. The risk is greater in patients with more severe arrhythmias, poor ventricular function, or high serum concentrations of drug. The usual initial oral dosage of encainide hydrochloride is 25 mg three times a day, with a usual dosage range of 100-200 mg/day. Flecainide acetate should be initiated at 100 mg every 12 hours and may be increased up to 400 mg/day. Encainide and flecainide could become useful therapeutic options in the treatment of a variety of arrhythmias.
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PMID:Encainide hydrochloride and flecainide acetate: two class 1c antiarrhythmic agents. 311 76

The safety issues relevant to treatment with encainide in patients with supraventricular arrhythmia were reviewed based on 349 patients enrolled in clinical trials in the United States and Europe. Although 20% of patients had a history of congestive heart failure, cardiomegaly, or cardiomyopathy at entry, there was no case of new or worsened heart failure. There were 5 cases (1.4%) of proarrhythmia in adults, reflecting a worsening of the arrhythmia being treated or of a coexisting ventricular arrhythmia. The profile of drug-related adverse effects was comparable to that previously reported, causing discontinuance in 6% of patients. The effects most often seen were dizziness, visual disturbance, headache, nausea and vertigo. Only 1 patient had clinically significant abnormal laboratory values, possibly reflecting hepatocellular injury in conjunction with viral hepatitis. Most responders received a daily dose of 75 to 200 mg/day, generally given in 3 divided doses. Encainide has a very favorable safety profile for use in the treatment of supraventricular arrhythmias.
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PMID:Safety considerations and dosing guidelines for encainide in supraventricular arrhythmias. 314 70