Metoprolol and hydrochlorothiazide and Naltrexone and bupropion interaction

Potential for CONTRAVE to Affect Other Drugs Metabolized by CYP2D6 In a clinical study, CONTRAVE (32 mg naltrexone/360 mg bupropion) daily was coadministered with a 50 mg dose of metoprolol (a CYP2D6 substrate).

CONTRAVE increased metoprolol AUC and C max by approximately 4- and 2-fold, respectively, relative to metoprolol alone.

Drugs Metabolized by CYP2D6: Bupropion inhibits CYP2D6 and can increase concentrations of antidepressants, (e.g., selective serotonin reuptake inhibitors and many tricyclics), antipsychotics (e.g., haloperidol, risperidone and thioridazine), beta-blockers (e.g., metoprolol) and Type 1C antiarrhythmics (e.g., propafenone and flecainide).

…with drugs that are metabolized by CYP2D6 isozyme including certain antidepressants (SSRIs and many tricyclics), antipsychotics (e.g., haloperidol, risperidone and thioridazine), beta-blockers (e.g., metoprolol) and Type 1C antiarrhythmics (e.g., propafenone and flecainide), should be approached with caution and should be initiated at the lower end of the dose…

CYP2D6 inhibitors: Increased metoprolol concentration.

…catecholamine-depleting drugs (e.g., reserpine, monoamine oxidase (MAO) inhibitors) with beta adrenergic blockers may have an additive affect and increase the risk of hypotension or bradycardia CYP2D6 Inhibitors: Drugs that are strong inhibitors of CYP2D6 such as quinidine, fluoxetine, paroxetine, and propafenone were shown to double metoprolol concentrations.