Chemical formula: C₁₇H₂₀F₆N₂O₃ Molecular mass: 414.343 g/mol PubChem compound: 3356
Flecainide interacts in the following cases:
Life-threatening or even lethal adverse events due to interactions causing increased plasma concentrations may occur. Flecainide is metabolized by CYP2D6 to a large extent, and concurrent use of drugs inhibiting (e.g. antidepressants, neuroleptics, propranolol, ritonavir, some antihistamines) or inducing (e.g. phenytoin, phenobarbital, carbamazepine) this iso-enzyme can increase or decrease plasma concentrations of flecainide, respectively. Drugs that induce cytochrome P450 can reduce the plasma level of flecainide.
Increased risk of arrhythmias in co-administration of flecainide with tricyclics.
Flecainide should be used with caution in patients with impaired renal function (creatinine clearance ≤35 ml/min/1.73m²) and therapeutic drug monitoring is recommended.
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. Flecainide should not be administered concomitantly with other class I antiarrhythmic.
If 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.
The possibility of additive negative inotropic effects of Class II antiarrhythmics, i.e. betablockers, cardiac depressants such as verapamil, with flecainide should be recognised.
Because abiraterone causes a reduction in the hepatic metabolism of flecainide, there is a risk of an increase in the occurrence of undesirable effects.
Co-administration of bupropion (metabolised by CYP2D6) with 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.
The H2-antagonist cimetidine inhibits metabolism of flecainide. In healthy subjects receiving cimetidine (1 g daily) for 1 week, the AUC of flecainide increased by about 30% and the halflife increased by about 10%.
Increases in plasma concentrations of flecainide with a risk of overdose due to decreased hepatic metabolism by Cinacalcet.
Increased risk of arrhythmias in co-administration of flecainide with clozapine.
Darifenacin causes a reduction in hepatic metabolism of flecainide resulting in increased plasma concentrations with a risk of overdose.
Co-administration of flecainide with anticholinesterases (donepezil, rivastigmine, tacrine, pyridostigmine, neostigmine, ambentone, and galantamine) has an increased risk of bradycardia (negative inotropic activity tends to be cumulative). Clinical monitoring is necessary during treatment.
Duloxetine causes a reduction in hepatic metabolism of flecainide resulting in increased plasma concentrations with a risk of overdose.
Fluoxetine, paroxetine and other antidepressants increases plasma flecainide concentration.
Increased risk of ventricular arrhythmias in co-administration of flecainide with mizolastine, astemizole and terfenadine (avoid concomitant use).
Limited data in patients receiving known enzyme inducers (phenytoin, phenobarbital, carbamazepine) indicate only a 30% increase in the rate of flecainide elimination.
Quinine and halofantrine increases plasma concentrations of flecainide.
Plasma concentrations of flecainide are increased by ritonavir, lopinavir and indinavir (increased risk of ventricular arrhythmias) (avoid concomitant use).
Terbinafine may increase plasma concentrations of flecainide resulting from its inhibition of CYP2D6 activity.
The use of flecainide with calcium channel blockers, e.g. verapamil, is not recommended.
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 should only be used in pregnancy if the benefit outweighs the risks.
Flecainide is excreted in human milk. Plasma concentrations obtained in a nursing infant are 5-10 times lower than therapeutic drug concentrations. Although the risk of adverse effects to the nursing infant is very small, flecainide should only be used during lactation if the benefit outweighs the risks.
Flecainide has no or negligible influence on the ability to drive and use machines. However, driving ability, operation of machinery and work without a secure fit may be affected by adverse reactions such as dizziness and visual disturbances, if present.
Very common: ≥1/10, Common: ≥1/100, <1/10, Uncommon: ≥1/1,000, ≤1/100, Rare: ≥1/10,000, ≤1/1000, Very rare: ≤1/10,000, Not known: Cannot be estimated from the available data.
Uncommon: reductions in red and white blood cells and platelets, these changes are usually mild.
Rare: cases of increases in anti-nuclear antibodies, with and without systemic inflammatory involvement.
Common: depression, anxiety, insomnia.
Uncommon: hallucinations, confusion, amnesia.
Rare: nervousness.
Very common: dizziness, and light headedness which are usually transient. Giddiness, headache.
Common: paraesthesia, ataxia, dyskinesia, hypaesthesia, hyperhidrosis, syncope, tremor, vertigo, flushing, somnolence, tinnitus, increased sweating.
Uncommon: peripheral neuropathy, convulsions.
Very common: visual disturbances, such as double vision and blurring of vision these are usually transient and disappear upon continuing or reducing the dosage.
Very rare: corneal deposits.
Rare: tinnitus, vertigo.
Common: pro-arrhythmic effects are most likely in patients with structural heart disease and/or significant left ventricular impairment. These pro-arrhythmic effects include the increase of the frequency of premature ventricular contractions to more severe forms of ventricular tachycardia.
Uncommon: Patients with atrial flutter can develop a 1:1 AV conduction with increased heart rate.
Frequency not known (cannot be estimated from the available data): specific ECG changes (prolongation of PQ, QT, PR or QRS interval, increase in number or severity of arrhythmia), altered pacing threshold, incidences of bradycardia, sinus arrest or inducement or worsening of heart failure. In patients with atrial flutter the use of flecainide has been associated with 1:1 AV conduction following initial atrial slowing with resultant ventricular acceleration.
Frequency not known (cannot be estimated from the available data): AV block (II and III grades), bundle branch block or SA block, cardiac arrest, bradycardia, cardiac failure/ cardiac failure congestive, chest pain, hypotension, myocardial infarction, palpitations, sinus arrest, and tachycardia (AT or VT) has been reported. In these cases the therapy with flecainide should be discontinued. Demasking of a pre-existing Brugada syndrome.
Common: dyspnoea.
Uncommon: interstitial pneumonitis.
Rare: pneumonitis.
Frequency not known (cannot be estimated from the available data): pulmonary fibrosis, interstitial lung disease.
Common: nausea, vomiting, diarrhoea, constipation, abdominal pain.
Uncommon: dysgeusia, dry mouth, decreased appetite, dyspepsia, flatulence.
Rare: elevated liver enzymes with or without jaundice.
Frequency not known (cannot be estimated from the available data): hepatic dysfunction.
Uncommon: dermatitis allergic, including rash, alopecia.
Rare: serious urticaria.
Not known: photosensitivity, flushing, allergic skin reactions.
Very rare: arthralgia and myalgia.
Very rare: impotence.
Common: asthenia, fatigue, pyrexia, oedema.
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