Drug interactions Fluvoxamine has a low potential for the drug interactions which are based on inhibition of enzyme Cytochrome P450 CYP2D6. Fluvoxamine shows the least interaction of the SSRIs, in regard to this specific enzyme.[21][22][23] Naturally the other SSRIs which are metabolized by CYP2D6 will have more CYP2D6-based interactions with TCAs, antiarrhythmics, B-blockers, phenytoin, opioids and neuroleptics.
Fluvoxamine does, however, inhibit cytochrome P450 enzyme CYP1A2, which metabolises agomelatine, caffeine, clozapine, haloperidol, phenacetin, tacrine, theophylline, and olanzapine. These substances can cause increased serum levels when administered together with fluvoxamine. Of major concern is the fact that the polycyclic aromatic hydrocarbons found in tobacco smoke are potent inducers of CYP1A2 so that smokers may require significant modification of medication dosage.[24] A recent warning has been published regarding potentially serious interaction with tizanidine, based on CYP1A2 metabolism.[25]
Fluvoxamine inhibits metabolism of diazepam and phenytoin via CYP2C19 and metabolism of aripiprazole, chlorpromazine, clozapine, haloperidol, olanzapine, perphenazine, risperidone, thioridazine and zuclopenthixol via CYP2D6 as well as of aripiprazole, clozapine, haloperidol, quetiapine and ziprasidone via CYP3A4.[26]
The plasma protein binding of fluvoxamine is about 77%. Drugs with low protein binding are less likely to displace other protein bound drugs, and therefore have a lower potential to cause protein binding-related drug interactions.
