Bupropion

7. DRUG INTERACTIONS • CYP2B6 inducers: Dose increase may be necessary if coadministered with CYP2B6 inducers (e.g., ritonavir, lopinavir, efavirenz, carbamazepine, phenobarbital, and phenytoin) based on clinical exposure, but should not exceed the maximum recommended dose. ( 7.1 ) • Drugs metabolized by CYP2D6: Bupropion inhibits CYP2D6 and can increase concentrations of: antidepressants (e.g., venlafaxine, nortriptyline, imipramine, desipramine, paroxetine, fluoxetine, sertraline), antipsychotics (e.g., haloperidol, risperidone, thioridazine), beta-blockers (e.g., metoprolol), and Type 1C antiarrhythmics (e.g., propafenone, flecainide). Consider dose reduction when using with bupropion. ( 7.2 ) • Drugs that lower seizure threshold: Dose bupropion hydrochloride extended-release tablets (XL) with caution. ( 5.3 , 7.3 ) • Dopaminergic Drugs (levodopa and amantadine): CNS toxicity can occur when used concomitantly with bupropion hydrochloride extended-release tablets (XL). ( 7.4 ) • MAOIs: Increased risk of hypertensive reactions can occur when used concomitantly with bupropion hydrochloride extended-release tablets (XL). ( 7.6 ) • Drug laboratory test interactions: Bupropion hydrochloride extended-release tablets (XL) can cause false-positive urine test results for amphetamines. ( 7.7 ) 7.1 Potential for Other Drugs to Affect Bupropion Hydrochloride Extended-Release Tablets (XL) Bupropion is primarily metabolized to hydroxybupropion by CYP2B6. Therefore, the potential exists for drug interactions between bupropion hydrochloride extended-release tablets (XL) and drugs that are inhibitors or inducers of CYP2B6. Inhibitors of CYP2B6 Ticlopidine and Clopidogrel: Concomitant treatment with these drugs can increase bupropion exposures but decrease hydroxybupropion exposure. Based on clinical response, dosage adjustment of bupropion hydrochloride extended-release tablets (XL) may be necessary when coadministered with CYP2B6 inhibitors (e.g., ticlopidine or clopidogrel) [see Clinical Pharmacology ( 12.3 ) ]. Inducers of CYP2B6 Ritonavir, Lopinavir, and Efavirenz: Concomitant treatment with these drugs can decrease bupropion and hydroxybupropion exposure. Dosage increase of bupropion hydrochloride extended-release tablets (XL) may be necessary when coadministered with ritonavir, lopinavir, or efavirenz but should not exceed the maximum recommended dose [see Clinical Pharmacology ( 12.3 ) ]. Carbamazepine, Phenobarbital, Phenytoin: While not systematically studied, these drugs may induce metabolism of bupropion and may decrease bupropion exposure [see Clinical Pharmacology ( 12.3 ) ]. If bupropion is used concomitantly with a CYP inducer, it may be necessary to increase the dose of bupropion but the maximum recommended dose should not be exceeded. 7.2 Potential for Bupropion Hydrochloride Extended-Release Tablets (XL) to Affect Other Drugs Drugs Metabolized by CYP2D6 Bupropion and its metabolites (erythohydrobupropion, threohydrobupropion, hydroxybupropion) are CYP2D6 inhibitors. Therefore, coadministration of bupropion hydrochloride extended-release tablets (XL) with drugs that are metabolized by CYP2D6 can increase the exposures of drugs that are substrates of CYP2D6. Such drugs include antidepressants (e.g., venlafaxine, nortriptyline, imipramine, desipramine, paroxetine, fluoxetine, and sertraline), antipsychotics (e.g. haloperidol, risperidone, and thioridazine), beta-blockers (e.g., metoprolol), and Type 1C antiarrhythmics (e.g. propafenone, and flecainide). When used concomitantly with bupropion hydrochloride extended-release tablets (XL), it may be necessary to decrease the dose of these CYP2D6 substrates, particularly for drugs with a narrow therapeutic index. Drugs that require metabolic activation by CYP2D6 to be effective (e.g., tamoxifen), theoretically could have reduced efficacy when administered concomitantly with inhibitors of CYP2D6 such as bupropion. Patients treated concomitantly with bupropion hydrochloride extended-release tablets (XL) and such drugs may require increased doses of the drug [see Clinical Pharmacology ( 12.3 ) ]. 7.3 Drugs that Lower Seizure Threshold Use extreme caution when coadministering bupropion hydrochloride extended-release tablets (XL) with other drugs that lower the seizure threshold (e.g., other bupropion products, antipsychotics, antidepressants, theophylline, or systemic corticosteroids). Use low initial doses of bupropion hydrochloride extended-release tablets (XL) and increase the dose gradually [see Warnings and Precautions ( 5.3 ) ]. 7.4 Dopaminergic Drugs (Levodopa and Amantadine) Bupropion, levodopa, and amantadine have dopamine agonist effects. CNS toxicity has been reported when bupropion was coadministered with levodopa or amantadine. Adverse reactions have included restlessness, agitation, tremor, ataxia, gait disturbance, vertigo, and dizziness. It is presumed that the toxicity results from cumulative dopamine agonist effects. Use caution when administering bupropion hydrochloride extended-release tablets (XL) concomitantly with these drugs. 7.5 Use with Alcohol In postmarketing experience, there have been rare reports of adverse neuropsychiatric events or reduced alcohol tolerance in patients who were drinking alcohol during treatment with bupropion hydrochloride extended-release tablets (XL). The consumption of alcohol during treatment with bupropion hydrochloride extended-release tablets (XL) should be minimized or avoided. 7.6 MAO Inhibitors Bupropion inhibits the reuptake of dopamine and norepinephrine. Concomitant use of MAOIs and bupropion is contraindicated because there is an increased risk of hypertensive reactions if bupropion is used concomitantly with MAOIs. Studies in animals demonstrate that the acute toxicity of bupropion is enhanced by the MAO inhibitor phenelzine. At least 14 days should elapse between discontinuation of an MAOI intended to treat depression and initiation of treatment with bupropion hydrochloride extended-release tablets (XL). Conversely, at least 14 days should be allowed after stopping bupropion hydrochloride extended-release tablets (XL) before starting an MAOI antidepressant [see Dosage and Administration ( 2.8 , 2.9 ) and Contraindications ( 4 ) ]. 7.7 Drug-Laboratory Test Interactions False-positive urine immunoassay screening tests for amphetamines have been reported in patients taking bupropion. This is due to lack of specificity of some screening tests. False-positive test results may result even following discontinuation of bupropion therapy. Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish bupropion from amphetamines.

Bupropion Hydrochloride Tablets are indicated for the "treatment of major depressive disorder (MDD), as defined by the Diagnostic and Statistical Manual (DSM)." The label notes that a dose increase may be considered for patients with an inadequate response after an adequate trial, and the drug should be dosed in divided doses to minimize seizure risk, with no single dose exceeding 150 mg.

2. DOSAGE AND ADMINISTRATION General: • Increase dose gradually to reduce seizure risk. ( 2.1 , 5.3 ) • Periodically reassess the dose and need for maintenance treatment. ( 2.2 ) Major Depressive Disorder: • Starting dose: 150 mg/day once daily. Usual target dose: 300 mg once daily ( 2.2 ) • After 4 days, may increase the dose to 300 mg once daily. ( 2.2 ) Seasonal Affective Disorder: • Initiative treatment in the autumn prior to onset of seasonal depressive symptoms. ( 2.3 ) • Starting dose: 150 mg once daily. Usual target dose: 300 mg once daily. ( 2.3 ) • After one week, may increase the dose to 300 mg once daily. ( 2.3 ) • Continue treatment through the winter season. ( 2.3 ) Hepatic Impairmen t: • Moderate to severe hepatic impairment: 150 mg every other day ( 2.6 ) • Mild hepatic impairment: Consider reducing the dose and/or frequency of dosing. ( 2.6 , 8.7 ) Renal Impairment: • Consider reducing the dose and/or frequency of dosing. ( 2.7 , 8.6 ) 2.1 General Instructions for Use To minimize the risk of seizure, increase the dose gradually [see Warnings and Precautions ( 5.3 ) ]. Bupropion hydrochloride extended-release tablets (XL) should be swallowed whole and not crushed, divided, or chewed. Bupropion hydrochloride extended-release tablets (XL) should be administered in the morning and may be taken with or without food. 2.2 Dosage for Major Depressive Disorder (MDD) The recommended starting dose for MDD is 150 mg once daily in the morning. After 4 days of dosing, the dose may be increased to the target dose of 300 mg once daily in the morning. It is generally agreed that acute episodes of depression require several months or longer of antidepressant treatment beyond the response in the acute episode. It is unknown whether the bupropion hydrochloride extended-release tablets (XL) dose needed for maintenance treatment is identical to the dose that provided an initial response. Periodically reassess the need for maintenance treatment and the appropriate dose for such treatment. 2.3 Dosage for Seasonal Affective Disorder (SAD) The recommended starting dose for SAD is 150 mg once daily. After 7 days of dosing, the dose may be increased to the target dose of 300 mg once daily in the morning. Doses above 300 mg of bupropion hydrochloride extended-release were not assessed in the SAD trials. For the prevention of seasonal MDD episodes associated with SAD, initiate bupropion hydrochloride extended-release tablets (XL) in the autumn, prior to the onset of depressive symptoms. Continue treatment through the winter season. Taper and discontinue bupropion hydrochloride extended-release tablets (XL) in early spring. For patients treated with 300 mg per day, decrease the dose to 150 mg once daily before discontinuing bupropion hydrochloride extended-release tablets (XL). Individualize the timing of initiation and duration of treatment should be individualized, based on the patient's historical pattern of seasonal MDD episodes. 2.4 Switching Patients from Bupropion Hydrochloride Tablets or from Bupropion Hydrochloride Sustained-Release Tablets When switching patients from bupropion hydrochloride tablets to bupropion hydrochloride extended-release tablets (XL) or from bupropion hydrochloride sustained-release tablets to bupropion hydrochloride extended-release tablets (XL), give the same total daily dose when possible. 2.5 To Discontinue Bupropion Hydrochloride Extended-Release Tablets (XL), Taper the Dose When discontinuing treatment in patients treated with bupropion hydrochloride extended-release tablets (XL) 300 mg once daily, decrease the dose to 150 mg once daily prior to discontinuation. 2.6 Dosage Adjustment in Patients with Hepatic Impairment In patients with moderate to severe hepatic impairment (Child-Pugh score: 7 to 15), the maximum dose is 150 mg every other day. In patients with mild hepatic impairment (Child-Pugh score: 5 to 6), consider reducing the dose and/or frequency of dosing [see Use in Specific Populations ( 8.7 ) and Clinical Pharmacology ( 12.3 ) ]. 2.7 Dose Adjustment in Patients with Renal Impairment Consider reducing the dose and/or frequency of bupropion hydrochloride extended-release tablets (XL) in patients with renal impairment (Glomerular Filtration Rate < 90 mL/min) [see Use in Specific Populations ( 8.6 ) and Clinical Pharmacology ( 12.3 ) ]. 2.8 Switching a Patient To or From a Monoamine Oxidase Inhibitor (MAOI) Antidepressant At least 14 days should elapse between discontinuation of an MAOI intended to treat depression and initiation of therapy with bupropion hydrochloride extended-release tablets (XL). Conversely, at least 14 days should be allowed after stopping bupropion hydrochloride extended-release tablets (XL) before starting an MAOI antidepressant [see Contraindications ( 4 ) and Drug Interactions ( 7.6 ) ]. 2.9 Use of Bupropion Hydrochloride Extended-Release Tablets (XL) with Reversible MAOIs Such as Linezolid or Methylene Blue Do not start bupropion hydrochloride extended-release tablets (XL) in a patient who is being treated with a reversible MAOI such as linezolid or intravenous methylene blue. Drug interactions can increase risk of hypertensive reactions. In a patient who requires more urgent treatment of a psychiatric condition, non-pharmacological interventions, including hospitalization, should be considered [see Contraindications ( 4 ) ]. In some cases, a patient already receiving therapy with bupropion hydrochloride extended-release tablets (XL) may require urgent treatment with linezolid or intravenous methylene blue. If acceptable alternatives to linezolid or intravenous methylene blue treatment are not available and the potential benefits of linezolid or intravenous methylene blue treatment are judged to outweigh the risks of hypertensive reactions in a particular patient, bupropion hydrochloride extended-release tablets (XL) should be stopped promptly, and linezolid or intravenous methylene blue can be administered. The patient should be monitored for 2 weeks or until 24 hours after the last dose of linezolid or intravenous methylene blue, whichever comes first. Therapy with bupropion hydrochloride extended-release tablets (XL) may be resumed 24 hours after the last dose of linezolid or intravenous methylene blue. The risk of administering methylene blue by non-intravenous routes (such as oral tablets or by local injection) or in intravenous doses much lower than 1 mg/kg with bupropion hydrochloride extended-release tablets (XL) is unclear. The clinician should, nevertheless, be aware of the possibility of a drug interaction with such use [see Contraindications ( 4 ) and Drug Interactions ( 7.6 ) ].

In placebo-controlled trials, the most common adverse reactions (occurring more frequently than placebo) were "agitation" (31.9% vs 22.2%), "dry mouth" (27.6% vs 18.4%), "constipation" (26.0% vs 17.3%), "headache/migraine" (25.7% vs 22.2%), "nausea/vomiting" (22.9% vs 18.9%), "dizziness" (22.3% vs 16.2%), "excessive sweating" (22.3% vs 14.6%), "tremor" (21.1% vs 7.6%), "insomnia" (18.6% vs 15.7%), "blurred vision" (14.6% vs 10.3%), and "tachycardia" (10.8% vs 8.6%).