1. Name Of The Medicinal Product
Tambocor™ 50mg Tablets
2. Qualitative And Quantitative Composition
Each tablet contains flecainide acetate 50mg
3. Pharmaceutical Form
Tablet
4. Clinical Particulars
Tambocor is a potent sodium channel blocking agent for the treatment of the conditions listed below:
The effect on the JT interval is insignificant at therapeutic levels.
4.1 Therapeutic Indications
Tambocor tablets are indicated for:
a) AV nodal reciprocating tachycardia; arrhythmias associated with Wolff-Parkinson-White Syndrome and similar conditions with accessory pathways.
b) Paroxysmal atrial fibrillation in patients with disabling symptoms when treatment need has been established and in the absence of left ventricular dysfunction (see 4.4, Special warnings and special precautions for use). Arrhythmias of recent onset will respond more readily.
c) Symptomatic sustained ventricular tachycardia.
d) Premature ventricular contractions and/or non-sustained ventricular tachycardia which are causing disabling symptoms, where these are resistant to other therapy or when other treatment has not been tolerated.
Tambocor tablets can be used for the maintenance of normal rhythm following conversion by other means.
Tambocor tablets are for oral administration.
4.2 Posology And Method Of Administration
Adults: Supraventricular arrhythmias: The recommended starting dosage is 50mg twice daily and most patients will be controlled at this dose. If required the dose may be increased to a maximum of 300mg daily.
Ventricular arrhythmias: The recommended starting dosage is 100mg twice daily. The maximum daily dose is 400mg and this is normally reserved for patients of large build or where rapid control of the arrhythmia is required.
After 3-5 days it is recommended that the dosage be progressively adjusted to the lowest level which maintains control of the arrhythmia. It may be possible to reduce dosage during long-term treatment.
Children: Tambocor is not recommended in children under 12, as there is insufficient evidence of its use in this age group.
Elderly Patients: The rate of flecainide elimination from plasma may be reduced in elderly people. This should be taken into consideration when making dose adjustments.
Plasma levels: Based on PVC suppression, it appears that plasma levels of 200-1000 ng/ml may be needed to obtain the maximum therapeutic effect. Plasma levels above 700-1000 ng/ml are associated with increased likelihood of adverse experiences.
Dosage in impaired renal function: In patients with significant renal impairment (creatinine clearance of 35ml/min/1.73 sq.m. or less) the maximum initial dosage should be 100mg daily (or 50mg twice daily).
When used in such patients, frequent plasma level monitoring is strongly recommended.
It is recommended that intravenous treatment with Tambocor should be administered in hospitals.
Treatment with oral Tambocor should be under direct hospital or specialist supervision for patients with:
a) AV nodal reciprocating tachycardia; arrhythmias associated with Wolff-Parkinson-White Syndrome and similar conditions with accessory pathways
b) Paroxysmal atrial fibrillation in patients with disabling symptoms.
Treatment for patients with other indications should continue to be initiated in hospital.
4.3 Contraindications
Tambocor is contra-indicated in cardiac failure and in patients with a history of myocardial infarction who have either asymptomatic ventricular ectopics or asymptomatic non-sustained ventricular tachycardia.
It is also contra-indicated in patients with long standing atrial fibrillation in whom there has been no attempt to convert to sinus rhythm, and in patients with haemodynamically significant valvular heart disease.
Unless pacing rescue is available, Tambocor should not be given to patients with sinus node dysfunction, atrial conduction defects, second degree or greater atrio-ventricular block, bundle branch block or distal block.
4.4 Special Warnings And Precautions For Use
Electrolyte disturbances should be corrected before using Tambocor.
Since flecainide elimination from the plasma can be markedly slower in patients with significant hepatic impairment, flecainide should not be used in such patients unless the potential benefits clearly outweigh the risks. Plasma level monitoring is strongly recommended in these circumstances.
Tambocor is known to increase endocardial pacing thresholds - ie to decrease endocardial pacing sensitivity. This effect is reversible and is more marked on the acute pacing threshold than on the chronic. Tambocor should thus be used with caution in all patients with permanent pacemakers or temporary pacing electrodes, and should not be administered to patients with existing poor thresholds or non-programmable pacemakers unless suitable pacing rescue is available.
Generally, a doubling of either pulse width or voltage is sufficient to regain capture, but it may be difficult to obtain ventricular thresholds less than 1 Volt at initial implantation in the presence of Tambocor.
The minor negative inotropic effect of flecainide may assume importance in patients predisposed to cardiac failure. Difficulty has been experienced in defibrillating some patients. Most of the cases reported had pre-existing heart disease with cardiac enlargement, a history of myocardial infarction, arterio-sclerotic heart disease and cardiac failure.
Tambocor should be avoided in patients with structural organic heart disease or abnormal left ventricular function.
Tambocor should be used with caution in patients with acute onset of atrial fibrillation following cardiac surgery.
In a large scale, placebo-controlled clinical trial in post-myocardial infarction patients with asymptomatic ventricular arrhythmia, oral flecainide was associated with a 2.2 fold higher incidence of mortality or non-fatal cardiac arrest as compared with its matching placebo. In that same study, an even higher incidence of mortality was observed in flecainide-treated patients with more than one myocardial infarction. Comparable placebo-controlled clinical trials have not been done to determine if flecainide is associated with higher risk of mortality in other patient groups.
4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction
Flecainide is a class I anti-arrhythmic and interactions are possible with other anti-arrhythmic drugs where additive effects may occur or where drugs interfere with the metabolism of flecainide. The following known categories of drugs may intereact with flecainide:
Cardiac glycosides; Flecainide can cause the plasma digoxin level to rise by about 15%, which is unlikely to be of clinical significance for patients with plasma levels in the therapeutic range. It is recommended that the digoxin plasma level in digitalised patients should be measured not less than six hours after any digoxin dose, before or after administration of flecainide.
Class II anti-arrhythmics; the possibility of additive negative inotropic effects of beta-blockers, and other cardiac depressants such as verapamil, with flecainide should be recognised.
Class III anti-arrhythmics; when flecainide is given in the presence of amiodarone, the usual flecainide dosage should be reduced by 50% and the patient monitored closely for adverse effects. Plasma level monitoring is strongly recommended in these circumstances
Class IV anti-arrhythmics; use of flecainide with other sodium channel blockers is not recommended.
Anti-depressants; fluoxetine increases plasma flecainide concentration; increased risk of arrhythmias with tricyclics; manufacturer of reboxetine advises caution.
Anti-epileptics; limited data in patients receiving known enzyme inducers (phenytoin, phenobarbital, carbamazepine) indicate only a 30% increase in the rate of flecainide elimination.
Anti-psychotics: clozapine– increased risk of arrhythmias
Anti-histamines; increased risk of ventricular arrhythmias with mizolastine and terfenadine (avoid concomitant use)
Anti-malarials: quinine increases plasma concentration of flecainide.
Antivirals: plasma concentration increased by ritonavir, lopinavar and indinavir (increased risk of ventricular arrhythmias (avoid concomitant use)
Diuretics: Class effect due to hypokalaemia giving rise to cardiac toxicity.
Ulcer healing drugs: cimetidine inhibits metabolism of flecainide. In healthy subjects receiving cimetidine (1g daily) for one week, plasma flecainide levels increased by about 30% and the half-life increased by about 10%.
Anti-smoking aids: Co-administration of bupropion with drugs that are metabolized by CYP2D6 isoenzyme including flecainide, should be approached with caution and should be initiated at the lower end of the dose range of the concomitant medication. If bupropion is added to the treatment regimen of a patient already receiving flecainide, the need to decrease the dose of the original medication should be considered.
Treatment with Tambocor is compatible with use of oral anti-coagulants.
4.6 Pregnancy And Lactation
There is no evidence as to drug safety in human pregnancy. In New Zealand White rabbits high doses of flecainide caused some foetal abnormalities, but these effects were not seen in Dutch Belted rabbits or rats. The relevance of these findings to humans has not been established. Data have shown that flecainide crosses the placenta to the foetus in patients taking flecainide during pregnancy.
Flecainide is excreted in human milk and appears in concentrations which reflect those in maternal blood. The risk of adverse effects to the nursing infant is very small.
4.7 Effects On Ability To Drive And Use Machines
No effect.
4.8 Undesirable Effects
Body as a Whole: Asthenia, fatigue, fever,oedema.
Cardiovascular: Pro-arrhythmic effects occur but are most likely in patients with structural heart disease and/or significant left ventricular impairment.
In patients with atrial flutter the use of Tambocor has been associated with
1:1 AV conduction following initial atrial slowing with resultant ventricular acceleration. This has been seen most commonly following the use of the injection for acute conversion. This effect is usually short lived and abates quickly following cessation of therapy.
The following adverse effects have also been reported.
AV block-second-degree and third degree, bradycardia, cardiac failure/congestive cardiac failure, chest pain, hypotension, myocardial infarction, palpitation, sinus pause or arrest and tachycardia (AT or VT).
Skin and Appendages: A range of allergic skin reactions have been reported including rashes, alopecia and rare but serious reports of urticaria. There have also been isolated cases of photosensitivity and rash.
Immune System: A small number of cases of increases in anti-nuclear antibodies have been reported, with and without systemic inflammatory involvement.
Haematological: Reductions in red blood cells, white blood cells and platelets have been occasionally reported. These changes are usually mild.
Psychiatric: Rarely, hallucinations, depression, confusion, amnesia, anxiety and insomnia have been reported.
Gastrointestinal: Occasionally nausea and vomiting. The following have also been reported: abdominal pain, anorexia, constipation, diarrhoea, dyspepsia and flatulence (bloating)
Liver and Bilary System: A number of cases of elevated liver enzymes and jaundice have been reported in association with Tambocor treatment. So far this has always been reversible on stopping treatment. Hepatic dysfunction has also been reported.
Neurological: Most commonly giddiness, dizziness and lightheadedness which are usually transient. Rare instances of dyskinesia have been reported, which have improved on withdrawal of flecainide therapy. Rare instances of convulsions, and during long term therapy a few cases of peripheral neuropathy, paraesthesia and ataxia have been reported.There also have been reports of flushing, headache, hypoaesthesia, increased sweating, somnolence, syncope, tinnitus, tremor and vertigo.
Ophthalmological: Visual disturbances, such as double vision and blurring of vision may occur but these are usually transient and disappear upon continuing or reducing the dosage.
Extremely rare cases of corneal deposits have also been reported.
Respiratory: Dyspnoea and rare cases of pneumonitis have been reported.
4.9 Overdose
Overdosage with flecainide is a potentially life threatening medical emergency. No specific antidote is known. There is no known way of rapidly removing flecainide from the system, but forced acid diuresis may theoretically be helpful. Neither dialysis nor haemoperfusion is helpful and injections of anticholinergics are not recommended.
Treatment may include therapy with an inotropic agent, intravenous calcium, giving circulatory assistance (eg balloon pumping), mechanically assisting respiration, or temporarily inserting a transvenous pacemaker if there are severe conduction disturbances or the patient's left ventricular function is otherwise compromised.
5. Pharmacological Properties
5.1 Pharmacodynamic Properties
Tambocor is a Class 1 anti-arrhythmic (local anaesthetic) agent.
Tambocor slows conduction through the heart, having its greatest effect on His Bundle conduction. It also acts selectively to increase anterograde and particularly retrograde accessory pathway refractoriness. Its actions may be reflected in the ECG by prolongation of the PR interval and widening of the QRS complex. The effect on the JT interval is insignificant.
5.2 Pharmacokinetic Properties
Oral administration of flecainide results in extensive absorption, with bioavailability approaching 90 to 95%. Flecainide does not appear to undergo significant hepatic first-pass metabolism. In patients, 200 to 600 mg flecainide daily produced plasma concentrations within the therapeutic range of 200-1000 µg/L. Protein binding of flecainide is within the range 32 to 58%.
Recovery of unchanged flecainide in urine of healthy subjects was approximately 42% of a 200mg oral dose, whilst the two major metabolites (Meta-O-Dealkylated and Dealkylated Lactam Metabolites) accounted for a further 14% each. The elimination half-life was 12 to 27 hours.
5.3 Preclinical Safety Data
Not applicable
6. Pharmaceutical Particulars
6.1 List Of Excipients
Pregelatinised Starch, USNF
Croscarmellose Sodium, USNF
Microcrystalline Cellulose, Ph Eur
Hydrogenated Vegetable Oil, USNF
Magnesium Stearate, Ph Eur
6.2 Incompatibilities
None known
6.3 Shelf Life
5 years
6.4 Special Precautions For Storage
Do not store above 30°C. Keep container in the outer carton.
6.5 Nature And Contents Of Container
UPVC/PVDC blister packs containing 60 tablets
6.6 Special Precautions For Disposal And Other Handling
Not applicable
7. Marketing Authorisation Holder
Meda Pharmaceuticals Ltd
Skyway House
Parsonage Road
Takeley
Bishop's Stortford
CM22 6PU
United Kingdom
8. Marketing Authorisation Number(S)
PL 15142/0078
9. Date Of First Authorisation/Renewal Of The Authorisation
22 May 1997/ 16 March 2001
10. Date Of Revision Of The Text
13th July 2010
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