Propafenonedosage

The dose of propafenone hydrochloride tablets must be individually titrated on the basis of response and tolerance. Initiate therapy with propafenone hydrochloride tablets 150 mg given every 8 hours (450 mg per day). Dosage may be increased at a minimum of 3- to 4- day intervals to 225 mg every 8 hours (675 mg per day). If additional therapeutic effect is needed, the dose of propafenone hydrochloride tablets may be increased to 300 mg every 8 hours (900 mg per day). The usefulness and safety of dosages exceeding 900 mg per day have not been established. In patients with hepatic impairment or those with significant widening of the QRS complex or second- or third-degree AV block, consider reducing the dose. As with other antiarrhythmic agents, in the elderly or in ventricular arrhythmia patients with marked previous myocardial damage, the dose of propafenone hydrochloride tablets should be increased more gradually during the initial phase of treatment. The combination of cytochrome P450 3A4 (CYP3A4) inhibition and either cytochrome P450 2D6 (CYP2D6) deficiency or CYP2D6 inhibition with the simultaneous administration of propafenone may significantly increase the concentration of propafenone and thereby increase the risk of proarrhythmia and other adverse events. Therefore, avoid simultaneous use of propafenone hydrochloride tablets with both a CYP2D6 inhibitor and a CYP3A4 inhibitor. Initiate therapy with 150 mg given every 8 hours. As needed, uptitrate in 3 to 4 days to 225 to 300 mg every 8 hours. Consider reducing the dose in patients with hepatic impairment, significant widening of the QRS complex, or second- or third-degree AV block.