Paxil CR and Rythmol SR

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Using propafenone together with PARoxetine may increase the effects of propafenone. Contact your doctor if you experience tiredness, dizziness, fainting, confusion, slow heart beats, seizures, and a worsening irregular heartbeat. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

MONITOR: Coadministration with certain selective serotonin reuptake inhibitors (SSRIs) may increase the plasma concentrations of propafenone. The mechanism is SSRI inhibition of CYP450 2D6, the isoenzyme responsible for the metabolic clearance of propafenone in most people. In nine healthy 2D6-extensive metabolizers, fluoxetine pretreatment (20 mg once a day for 10 days) significantly increased the elimination half-life, peak plasma concentration (Cmax), and area under the concentration-time curve (AUC) of both the S- and R-enantiomers of propafenone (400 mg single dose). Oral clearance decreased by about 34% for both enantiomers. In vitro inhibition data suggest that fluoxetine and paroxetine have the most significant effects on 2D6 metabolism of propafenone, while fluvoxamine and sertraline have only modest effects. However, fluvoxamine also inhibits CYP450 3A4 and 1A2, which may be important metabolic pathways for propafenone in poor metabolizers of 2D6 (approximately 7% of Caucasians and less than 2% of Asians and individuals of African descent). Because the metabolites formed by these isoenzymes demonstrate antiarrhythmic activity comparable to that of the parent drug, the overall clinical significance of this interaction is unknown. Theoretically, increased noncardioselective beta-blockade may occur in some patients, since propafenone, but not the metabolites, possesses beta-sympatholytic activity.

MANAGEMENT: Caution is advised if certain SSRIs, particularly fluoxetine or paroxetine, must be used concomitantly with propafenone. Lower initial dosages of the antiarrhythmic agent may be appropriate. Patients who are already stabilized on their antiarrhythmic regimen should be monitored for altered effects on myocardial conduction following addition or discontinuation of SSRI therapy (up to 2 weeks for most SSRIs and 5 weeks for fluoxetine due to its long half-life), and the antiarrhythmic dosage adjusted if necessary. Alternatively, an antidepressant that does not interfere with CYP450 2D6 metabolism may be considered, such as citalopram, escitalopram, or venlafaxine.

Paxil CR

Generic Name: paroxetine

Brand name: Brisdelle, Paxil, Paxil CR, Pexeva

Synonyms: n.a.

What is Paxil CR?

Rythmol SR

Generic Name: propafenone

Brand name: Rythmol, Rythmol SR

Synonyms: Rythmol Extended Release

What is Rythmol SR?