Rythmosin is indicated for the treatment of paroxysmal atrial fibrillation/flutter (PAF), paroxysmal supraventricular tachycardia (PSVT). Rythmosin is also indicated for the treatment of documented ventricular arrhythmias.
Propafenone works by slowing the influx of sodium ions into the cardiac muscle cells, causing a decrease in excitability of the cells. Propafenone is more selective for cells with a high rate, but also blocks normal cells more than class Ia or Ib. Propafenone differs from the prototypical class Ic antiarrhythmic in that it has additional activity as a beta-adrenergic blocker which can cause bradycardia and bronchospasm.
The dose of Propafenone must be individually titrated on the basis of response and tolerance. It is recommended that therapy be initiated with Propafenone 150 mg given every eight hours (450 mg/day). Dosage may be increased at a minimum of 3 to 4 day intervals to 225 mg every 8 hours (675 mg/day) and if necessary, to 300 mg every 8 hours (900 mg/day). The usefulness and safety of dosages exceeding 900 mg per day have not been established.
Adverse reactions associated with propafenone occur most frequently in the gastrointestinal, cardiovascular and central nervous systems. Change in taste, constipation, diarrhea, dizziness, drowsiness, dry mouth, gas, headache, light-headedness, nausea, tiredness etc. may happen. Severe allergic reactions also reported with propafenone.
Always consult a registered doctor before taking any medicine. This information is for general knowledge only.
Propafenone is contraindicated in the presence of uncontrolled congestive heart failure, cardiogenic shock, sinoatrial, atrioventricular and intraventricular disorders of impulse generation and/or conduction (e.g. sick sinus node syndrome, atrioventricular block) in the absence of an artificial pacemaker, bradycardia, marked hypotension, bronchospastic disorders, manifest electrolyte imbalance and known hypersensitivity to the drug.
Rythmosin is metabolized by CYP2D6 (major pathway) and CYP1A2 and CYP3A4. Drugs that inhibit CYP2D6 (such as desipramine, paroxetine, ritonavir, sertraline), CYP1A2 (such as amiodarone) and CYP3A4 (such as ketoconazole, ritonavir, saquinavir, erythromycin and grapefruit juice) can be expected to cause increased plasma levels of propafenone. In addition, propafenone is an inhibitor of CYP2D6. Coadministration of propafenone with drugs metabolized by CYP2D6 (such as desipramine, imipramine, haloperidol, venlafaxine) might lead to increase plasma concentrations of these drugs.
Hepatic Dysfunction: Rythmosin is highly metabolized by the liver and should therefore, be administered cautiously to patients with impaired hepatic function. As a result, the dose of propafenone given to patients with impaired hepatic function should be approximately 20 to 30% of the dose given to patients with normal hepatic function. Renal Dysfunction: A considerable percentage of propafenone metabolites (18.5% to 38% of the dose/48 hours) are excreted in the urine. Until further data are available, propafenone should be administered cautiously to patients with impaired renal function. Neuromuscular Dysfunction: Exacerbation of myasthenia gravis has been reported during propafenone therapy.