Pharmacology
This was previously featured in an exam
Cardiovascular
A patient presents with symptomatic fast atrial fibrillation. Your consultant decides to use flecainide. What is the main mechanism of action of flecainide:
Answer:
Flecainide inhibits the transmembrane influx of extracellular Na+ ions via fast channels on cardiac tissues resulting in a decrease in rate of depolarisation of the action potential, prolonging the PR and QRS intervals. At high concentrations, it exerts inhibitory effects on slow Ca2+ channels, accompanied by moderate negative inotropic effect.Flecainide
Pharmacology / Cardiovascular
Last Updated: 17th April 2019
Indications
Flecainide acetate is an orally active class Ic antiarrhythmic and may be of value for serious symptomatic ventricular arrhythmias. It may also be indicated for junctional re-entry tachycardias and for paroxysmal atrial fibrillation. However, it has a negative inotropic action and can precipitate serious arrhythmias in a small minority of patients (including those with otherwise normal hearts).
Contraindications
Flecainide is contraindicated in:
- Abnormal left ventricular function
- Atrial conduction defects (unless pacing rescue available)
- Bundle branch block (unless pacing rescue available)
- Distal block (unless pacing rescue available)
- Haemodynamically significant valvular heart disease
- Heart failure
- History of myocardial infarction and either asymptomatic ventricular ectopics or asymptomatic non-sustained ventricular tachycardia
- Long-standing atrial fibrillation where conversion to sinus rhythm not attempted
- Second-degree or greater AV block (unless pacing rescue available)
- Sinus node dysfunction (unless pacing rescue available)
Cautions
Flecainide should be used with caution in:
- Atrial fibrillation following heart surgery
- Elderly (accumulation may occur)
- Patients with pacemakers (especially those who may be pacemaker dependent because stimulation threshold may rise appreciably)
Side Effects
Common side effects of flecainide include:
- Asthenia
- Dizziness
- Dyspnoea
- Fatigue
- Fever
- Oedema
- Pro-arrhythmic effects
- Visual disturbances
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
