Enkaid Side Effects
Please note - some side effects for Enkaid may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).
Enkaid Side Effects - for the Professional
Enkaid
In the National Heart Lung and Blood Institute’s Cardiac Arrhythmia Suppression Trial (CAST), the incidence of total mortality and nonfatal cardiac arrest in the Enkaid group was 40/415 (9.6%) and that in the placebo group was 15/416 (3.6%).. The most serious adverse reactions reported for Enkaid in premarketing clinical trials were the provocation or aggravation of ventricular arrhythmias. These occurred during the course of the clinical research program in about 10% of the patients who received a wide range of doses under a variety of circumstances. In some cases this resulted in the development of sustained ventricular tachycardia or ventricular fibrillation.
Only 0.4% of patients discontinued Enkaid therapy due to congestive heart failure or related causes. Second- or third-degree AV block developed in 0.5% and 0.2% of the patients, respectively. Sinus bradycardia, sinus pause or sinus arrest occurred in 1% of patients. There have been rare reports of elevated serum liver enzymes (alkaline phosphatase, serum transaminase), hepatitis, and jaundice, in which a relation to encainide is possible and there has been one instance of a rechallenge-confirmed elevation of transaminases. There have also been rare reports of elevated blood glucose levels or of increased insulin requirements in diabetic patients. Although no cause and effect relationship has been established, caution is advised in patients who develop unexplained jaundice or signs of hepatic dysfunction or hyperglycemia and consideration should be given to discontinuing therapy.
In premarketing evaluations, 2400 subjects were exposed to Enkaid, of whom more than 500 were maintained on drug for two years or longer. Adverse events were sufficiently troublesome to cause discontinuation in about 7% of the patients participating in premarketing clinical trials. The most frequently reported adverse events were dizziness, blurred or abnormal vision, and headache.
The following table lists the most common adverse events that occurred in two multi-center premarketing clinical trials, one of which compared encainide to placebo, the other to quinidine. This table lists all such adverse events reported by at least 3% of the patients and thus may include symptoms of the underlying disease, intercurrent illness or adverse reactions to drug therapy.
| Encainide/Placebo Trial | Encainide/Quinidine Trial | |||
|---|---|---|---|---|
Body System |
Encainide (N = 88) |
Placebo (N = 37) |
Encainide (N = 153) |
Quinidine (N = 154) |
| Body as a Whole | ||||
| abdominal pain | 2.3 | 0 | 1.3 | 3.9 |
| asthenia | 14.8 | 16.2 | 6.5 | 13.6 |
| chest pains | 10.2 | 8.1 | 8.5 | 8.4 |
| death | 3.4 | 0 | 1.3 | 0 |
| fever | – | – | 0 | 7.8 |
| headache | 5.7 | 5.4 | 8.5 | 15.6 |
| lower extremity pain | 5.7 | 0 | 4.6 | 5.2 |
| malaise | – | – | 0 | 3.9 |
| upper extremity pain | 4.5 | 5.4 | 2.0 | 3.9 |
| Cardiovascular | ||||
| palpitations | 12.5 | 18.9 | 7.2 | 5.8 |
| peripheral edema | 2.3 | 0 | 1.3 | 3.2 |
| proarrhythmia | 3.4 | 0 | 0.7 | 0.6 |
| Digestive | ||||
| constipation | 2.2 | 0 | 4.6 | 2.6 |
| diarrhea | 0 | 8.1 | 9.2 | 39.0 |
| dry mouth | – | – | 3.9 | 2.6 |
| dyspepsia | 5.7 | 5.4 | 4.6 | 9.7 |
| nausea | 2.3 | 2.7 | 8.5 | 10.4 |
| vomiting | 2.3 | 0 | 0.7 | 3.2 |
| Nervous | ||||
| anorexia | 1.1 | 0 | 2.0 | 3.2 |
| dizziness | 15.9 | 10.8 | 15.7 | 14.9 |
| insomnia | 3.4 | 0 | 2.0 | 1.3 |
| nervousness | 1.1 | 0 | 2.0 | 3.2 |
| somnolence | – | – | 3.9 | 1.9 |
| Respiratory | ||||
| dyspnea | 8.0 | 10.8 | 3.9 | 8.4 |
| Skin and Appendages | ||||
| rash | 1.1 | 0 | 2.0 | 4.5 |
| Special Senses | ||||
| abnormal/blurred vision | 3.4 | 2.7 | 11.1 | 5.8 |
| tinnitus | – | – | 3.9 | 3.9 |
The following table gives the incidence of the most common adverse events at selected doses of Enkaid that were used during the premarketing clinical trials which involved a total of 749 patients with ventricular arrythmias. The incidence figures in the “0 mg” column are based on events that occurred while patients were on placebo or in drug-free wash out periods.
| Daily Doses | ||||
|---|---|---|---|---|
Body System |
0 mg (N = 479) |
75 mg (N = 298) |
150 mg (N = 260) |
> 200 mg (N = 208) |
| Body as a Whole | ||||
| abdominal pain | 1 | 2 | 2 | 3 |
| asthenia | 4 | 4 | 5 | 9 |
| chest pain | 3 | 5 | 2 | 6 |
| headache | 6 | 3 | 5 | 12 |
| lower extremity pain | 3 | < 1 | 1 | 3 |
| upper extremity pain | 1 | < 1 | < 1 | 2 |
| pain | < 1 | < 1 | < 1 | < 1 |
| paresthesia | < 1 | 1 | < 1 | 2 |
| Cardiovascular | ||||
| congestive heart failure | < 1 | < 1 | 1 | 2 |
| palpitations | 5 | 4 | 3 | 8 |
| premature ventricular contraction | < 1 | < 1 | < 1 | 3 |
| QRS interval prolonged ≥ 0.20 | < 1 | < 1 | 3 | 4 |
| syncope | < 1 | < 1 | 1 | 5 |
| ventricular tachycardia | < 1 | 3 | 3 | 8 |
| Digestive | ||||
| constipation | 1 | < 1 | < 1 | 2 |
| diarrhea | 2 | < 1 | < 1 | 2 |
| dyspepsia | 1 | < 1 | < 1 | 3 |
| nausea | 2 | 2 | 2 | 6 |
| Nervous | ||||
| dizziness | 7 | 6 | 10 | 18 |
| tremor | < 1 | < 1 | < 1 | 2 |
| Respiratory | ||||
| dyspnea | 2 | 2 | 5 | 4 |
| increased cough | < 1 | < 1 | 1 | 2 |
| Skin and Appendages | ||||
| rash | 2 | < 1 | < 1 | 4 |
| Special Senses | ||||
| abnormal/blurred vision | 5 | 4 | 8 | 26 |
| taste perversion | < 1 | 1 | 2 | 1 |
Other adverse events occurring in less than 1% of the patients receiving Enkaid include: malaise, decreased or increased blood pressure, confusion, ataxia, abnormal gait, abnormal sensation, abnormal dreams, diplopia, photophobia and periorbital edema.
POSTINTRODUCTION CLINICAL EXPERIENCE
Other than the clinical experience in the CAST study described above, postmarketing experience has shown an adverse experience profile similar to that described for the premarketing clinical trials. Voluntary reports since introduction include rare reports (less than one report per 10,000 patients) of arthralgia, fever, leukopenia, positive ANA test, and thrombocytopenia. Because of the uncontrolled nature of these voluntary reports, and because most of the patients were receiving concomitant medications, any causal relationship to Enkaid treatment is difficult to establish.
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