Wellbutrin

Name: Wellbutrin

Wellbutrin Food Interactions

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of Wellbutrin there are no specific foods that you must exclude from your diet when receiving Wellbutrin.

Wellbutrin Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
  • Anxiety
  • dry mouth
  • hyperventilation
  • irregular heartbeats
  • irritability
  • restlessness
  • shaking
  • trouble sleeping
Less common
  • Buzzing or ringing in the ears
  • headache (severe)
  • skin rash, hives, or itching
Rare
  • Confusion
  • fainting
  • false beliefs that cannot be changed by facts
  • having extreme distrust of people
  • seeing, hearing, or feeling things that are not there
  • seizures
  • trouble concentrating
Incidence not known
  • Actions that are out of control
  • anger
  • assaulting or attacking others
  • being aggressive or impulsive
  • chest pain or discomfort
  • fast or pounding heartbeat
  • force
  • inability to sit still
  • need to keep moving
  • sweating
  • talking, feeling, or acting with excitement

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose
  • Lightheadedness, dizziness, or fainting
  • loss of consciousness
  • slow or irregular heartbeat
  • unusual tiredness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Constipation
  • decrease in appetite
  • dizziness
  • increased sweating
  • stomach pain
  • trembling
  • unusual weight loss
Less common
  • Blurred vision
  • change in sense of taste
  • drowsiness
  • frequent need to urinate
  • sore throat
  • unusual feeling of well-being

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

How is this medicine (Wellbutrin) best taken?

Use Wellbutrin as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Do not take this medicine more often than you are told. This may raise the risk of seizures. Be sure you know how far apart to take your doses.
  • Take in the morning if taking once a day.
  • Take with or without food.
  • If you are not able to sleep, do not take Wellbutrin too close to bedtime. Talk with your doctor.
  • Swallow whole. Do not chew, break, or crush.
  • To gain the most benefit, do not miss doses.
  • Keep taking this medicine as you have been told by your doctor or other health care provider, even if you feel well.
  • If you have trouble swallowing, talk with your doctor.

What do I do if I miss a dose?

  • Skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

Consumer Information Use and Disclaimer

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • This medicine comes with an extra patient fact sheet called a Medication Guide. Read it with care. Read it again each time this medicine is refilled. If you have any questions about Wellbutrin, please talk with the doctor, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about Wellbutrin. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using Wellbutrin.

Review Date: October 4, 2017

Wellbutrin Dosage and Administration

General Instructions for Use

To minimize the risk of seizure, increase the dose gradually [see Warnings and Precautions (5.3)]. Increases in dose should not exceed 100 mg per day in a 3‑day period. Wellbutrin Tablets should be swallowed whole and not crushed, divided, or chewed. Wellbutrin may be taken with or without food.

The recommended starting dose is 200 mg per day, given as 100 mg twice daily. After 3 days of dosing, the dose may be increased to 300 mg per day, given as 100 mg 3 times daily, with at least 6 hours between successive doses. Dosing above 300 mg per day may be accomplished using the 75- or 100-mg tablets.

A maximum of 450 mg per day, given in divided doses of not more than 150 mg each, may be considered for patients who show no clinical improvement after several weeks of treatment at 300 mg per day. Administer the 100‑mg tablet 4 times daily to not exceed the limit of 150 mg in a single dose.

It is generally agreed that acute episodes of depression require several months or longer of antidepressant drug treatment beyond the response in the acute episode. It is unknown whether the dose of Wellbutrin 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.

Dose Adjustment in Patients with Hepatic Impairment

In patients with moderate to severe hepatic impairment (Child-Pugh score: 7 to 15), the maximum dose of Wellbutrin is 75 mg per 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), Clinical Pharmacology (12.3)].

Dose Adjustment in Patients with Renal Impairment

Consider reducing the dose and/or frequency of Wellbutrin in patients with renal impairment (Glomerular Filtration Rate less than 90 mL per min) [see Use in Specific Populations (8.6), Clinical Pharmacology (12.3)].

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 Wellbutrin. Conversely, at least 14 days should be allowed after stopping Wellbutrin before starting an MAOI antidepressant [see Contraindications (4), Drug Interactions (7.6)].

Use of Wellbutrin with Reversible MAOIs Such as Linezolid or Methylene Blue

Do not start Wellbutrin in a patient who is being treated with a reversible MAOI such as linezolid or intravenous methylene blue. Drug interactions can increase the 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), Drug Interactions (7.6)].

In some cases, a patient already receiving therapy with Wellbutrin 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, Wellbutrin 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 Wellbutrin 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 per kg with Wellbutrin is unclear. The clinician should, nevertheless, be aware of the possibility of a drug interaction with such use [see Contraindications (4), Drug Interactions (7.6)].

Adverse Reactions

The following adverse reactions are discussed in greater detail in other sections of the labeling:

• Suicidal thoughts and behaviors in adolescents and young adults [see Boxed Warning, Warnings and Precautions (5.1)] • Neuropsychiatric symptoms and suicide risk in smoking cessation treatment [see Boxed Warning, Warnings and Precautions (5.2)] • Seizure [see Warnings and Precautions (5.3)] • Hypertension [see Warnings and Precautions (5.4)] • Activation of mania or hypomania [see Warnings and Precautions (5.5)] • Psychosis and other neuropsychiatric reactions [see Warnings and Precautions (5.6)] • Angle-closure glaucoma [see Warnings and Precautions (5.7)] • Hypersensitivity reactions [see Warnings and Precautions (5.8)]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

Adverse Reactions Leading to Discontinuation of Treatment

Adverse reactions were sufficiently troublesome to cause discontinuation of treatment with Wellbutrin in approximately 10% of the 2,400 subjects and healthy volunteers who participated in clinical trials during the product’s initial development. The more common events causing discontinuation include neuropsychiatric disturbances (3.0%), primarily agitation and abnormalities in mental status; gastrointestinal disturbances (2.1%), primarily nausea and vomiting; neurological disturbances (1.7%), primarily seizures, headaches, and sleep disturbances; and dermatologic problems (1.4%), primarily rashes. It is important to note, however, that many of these events occurred at doses that exceed the recommended daily dose.

Commonly Observed Adverse Reactions

Adverse reactions commonly encountered in subjects treated with Wellbutrin are agitation, dry mouth, insomnia, headache/migraine, nausea/vomiting, constipation, tremor, dizziness, excessive sweating, blurred vision, tachycardia, confusion, rash, hostility, cardiac arrhythmia, and auditory disturbance.

Table 2 summarizes the adverse reactions that occurred in placebo-controlled trials at an incidence of at least 1% of subjects receiving Wellbutrin and more frequently in these subjects than in the placebo group.

Table 2. Adverse Reactions Reported by at Least 1% of Subjects and at a Greater Frequency than Placebo in Controlled Clinical Trials

Adverse Reaction

Wellbutrin

(n = 323)

%

Placebo

(n = 185)

%

Cardiovascular

  Cardiac arrhythmias

5.3

4.3

  Dizziness

22.3

16.2

  Hypertension

4.3

1.6

  Hypotension

2.5

2.2

  Palpitations

3.7

2.2

  Syncope

1.2

0.5

  Tachycardia

10.8

8.6

Dermatologic

  Pruritus

2.2

0.0

  Rash

8.0

6.5

Gastrointestinal

  Appetite increase

3.7

2.2

  Constipation

26.0

17.3

  Dyspepsia

3.1

2.2

  Nausea/vomiting

22.9

18.9

Genitourinary

  Impotence

3.4

3.1

  Menstrual complaints

4.7

1.1

  Urinary frequency

2.5

2.2

Musculoskeletal

  Arthritis

3.1

2.7

Neurological

  Akathisia

1.5

1.1

  Cutaneous temperature   disturbance

1.9

1.6

  Dry mouth

27.6

18.4

  Excessive sweating

22.3

14.6

  Headache/migraine

25.7

22.2

  Impaired sleep quality

4.0

1.6

  Insomnia

18.6

15.7

  Sedation

19.8

19.5

  Sensory disturbance

4.0

3.2

  Tremor

21.1

7.6

Neuropsychiatric

  Agitation

31.9

22.2

  Anxiety

3.1

1.1

  Confusion

8.4

4.9

  Decreased libido

3.1

1.6

  Delusions

1.2

1.1

  Euphoria

1.2

0.5

  Hostility

5.6

3.8

Nonspecific

  Fever/chills

1.2

0.5

Special Senses

  Auditory disturbance

5.3

3.2

  Blurred vision

14.6

10.3

  Gustatory disturbance

3.1

1.1

Other Adverse Reactions Observed during the Clinical Development of Wellbutrin

The conditions and duration of exposure to Wellbutrin varied greatly, and a substantial proportion of the experience was gained in open and uncontrolled clinical settings. During this experience, numerous adverse events were reported; however, without appropriate controls, it is impossible to determine with certainty which events were or were not caused by Wellbutrin. The following enumeration is organized by organ system and describes events in terms of their relative frequency of reporting in the database.

The following definitions of frequency are used: Frequent adverse reactions are defined as those occurring in at least 1/100 subjects. Infrequent adverse reactions are those occurring in 1/100 to 1/1,000 subjects, while rare events are those occurring in less than 1/1,000 subjects.

Cardiovascular: Frequent was edema; infrequent were chest pain, electrocardiogram (ECG) abnormalities (premature beats and nonspecific ST‑T changes), and shortness of breath/dyspnea; rare were flushing, and myocardial infarction.

Dermatologic: Infrequent was alopecia.

Endocrine: Infrequent was gynecomastia; rare was glycosuria.

Gastrointestinal: Infrequent were dysphagia, thirst disturbance, and liver damage/jaundice; rare was intestinal perforation.

Genitourinary: Frequent was nocturia; infrequent were vaginal irritation, testicular swelling, urinary tract infection, painful erection, and retarded ejaculation; rare were enuresis, and urinary incontinence.

Neurological: Frequent were ataxia/incoordination, seizure, myoclonus, dyskinesia, and dystonia; infrequent were mydriasis, vertigo, and dysarthria; rare were electroencephalogram (EEG) abnormality, and impaired attention.

Neuropsychiatric: Frequent were mania/hypomania, increased libido, hallucinations, decrease in sexual function, and depression; infrequent were memory impairment, depersonalization, psychosis, dysphoria, mood instability, paranoia, and formal thought disorder; rare was suicidal ideation.

Oral Complaints: Frequent was stomatitis; infrequent were toothache, bruxism, gum irritation, and oral edema.

Respiratory: Infrequent were bronchitis and shortness of breath/dyspnea; rare was pulmonary embolism.

Special Senses: Infrequent was visual disturbance; rare was diplopia.

Nonspecific: Frequent were flu‑like symptoms; infrequent was nonspecific pain; rare was overdose.

Altered Appetite and Weight

A weight loss of greater than 5 lbs occurred in 28% of subjects receiving Wellbutrin. This incidence is approximately double that seen in comparable subjects treated with tricyclics or placebo. Furthermore, while 35% of subjects receiving tricyclic antidepressants gained weight, only 9.4% of subjects treated with Wellbutrin did. Consequently, if weight loss is a major presenting sign of a patient’s depressive illness, the anorectic and/or weight-reducing potential of Wellbutrin should be considered.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of Wellbutrin and are not described elsewhere in the label. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Body (General)

Arthralgia, myalgia, and fever with rash and other symptoms suggestive of delayed hypersensitivity. These symptoms may resemble serum sickness [see Warnings and Precautions (5.8)].

Cardiovascular

Hypertension (in some cases severe), orthostatic hypotension, third degree heart block.

Endocrine

Syndrome of inappropriate antidiuretic hormone secretion, hyperglycemia, hypoglycemia.

Gastrointestinal

Esophagitis, hepatitis.

Hemic and Lymphatic

Ecchymosis, leukocytosis, leukopenia, thrombocytopenia. Altered PT and/or INR, infrequently associated with hemorrhagic or thrombotic complications, were observed when bupropion was coadministered with warfarin.

Musculoskeletal

Muscle rigidity/fever/rhabdomyolysis, muscle weakness.

Nervous System

Aggression, coma, completed suicide, delirium, dream abnormalities, paranoid ideation, paresthesia, parkinsonism, restlessness, suicide attempt, unmasking of tardive dyskinesia.

Skin and Appendages

Stevens‑Johnson syndrome, angioedema, exfoliative dermatitis, urticaria.

Special Senses

Tinnitus, increased intraocular pressure.

Wellbutrin - Clinical Pharmacology

Mechanism of Action

The exact mechanism of the antidepressant action of bupropion is not known, but is presumed to be related to noradrenergic and/or dopaminergic mechanisms. Bupropion is a relatively weak inhibitor of the neuronal reuptake of norepinephrine and dopamine, and does not inhibit the reuptake of serotonin. Bupropion does not inhibit monoamine oxidase.

Pharmacokinetics

Bupropion is a racemic mixture. The pharmacological activity and pharmacokinetics of the individual enantiomers have not been studied. The mean elimination half-life (±SD) of bupropion after chronic dosing is 21 (±9) hours, and steady-state plasma concentrations of bupropion are reached within 8 days.

Absorption

The absolute bioavailability of Wellbutrin in humans has not been determined because an intravenous formulation for human use is not available. However, it appears likely that only a small proportion of any orally administered dose reaches the systemic circulation intact. In rat and dog studies, the bioavailability of bupropion ranged from 5% to 20%.

In humans, following oral administration of Wellbutrin, peak plasma bupropion concentrations are usually achieved within 2 hours. Plasma bupropion concentrations are dose‑proportional following single doses of 100 to 250 mg; however, it is not known if the proportionality between dose and plasma level is maintained in chronic use.

Distribution

In vitro tests show that bupropion is 84% bound to human plasma proteins at concentrations up to 200 mcg per mL. The extent of protein binding of the hydroxybupropion metabolite is similar to that for bupropion, whereas the extent of protein binding of the threohydrobupropion metabolite is about half that seen with bupropion.

Metabolism

Bupropion is extensively metabolized in humans. Three metabolites are active: hydroxybupropion, which is formed via hydroxylation of the tert-butyl group of bupropion, and the amino-alcohol isomers threohydrobupropion and erythrohydrobupropion, which are formed via reduction of the carbonyl group. In vitro findings suggest that CYP2B6 is the principal isoenzyme involved in the formation of hydroxybupropion, while cytochrome P450 enzymes are not involved in the formation of threohydrobupropion. Oxidation of the bupropion side chain results in the formation of a glycine conjugate of meta-chlorobenzoic acid, which is then excreted as the major urinary metabolite. The potency and toxicity of the metabolites relative to bupropion have not been fully characterized. However, it has been demonstrated in an antidepressant screening test in mice that hydroxybupropion is one‑half as potent as bupropion, while threohydrobupropion and erythrohydrobupropion are 5-fold less potent than bupropion. This may be of clinical importance because the plasma concentrations of the metabolites are as high as or higher than those of bupropion.

Following a single dose in humans, peak plasma concentrations of hydroxybupropion occur approximately 3 hours after administration of Wellbutrin and are approximately 10 times the peak level of the parent drug at steady state. The elimination half‑life of hydroxybupropion is approximately 20 (±5) hours, and its AUC at steady state is about 17 times that of bupropion. The times to peak concentrations for the erythrohydrobupropion and threohydrobupropion metabolites are similar to that of the hydroxybupropion metabolite. However, their elimination half‑lives are longer, 33 (±10) and 37 (±13) hours, respectively, and steady‑state AUCs are 1.5 and 7 times that of bupropion, respectively.

Bupropion and its metabolites exhibit linear kinetics following chronic administration of 300 to 450 mg per day.

Elimination

Following oral administration of 200 mg of 14C-bupropion in humans, 87% and 10% of the radioactive dose were recovered in the urine and feces, respectively. Only 0.5% of the oral dose was excreted as unchanged bupropion.

Population Subgroups

Factors or conditions altering metabolic capacity (e.g., liver disease, congestive heart failure [CHF], age, concomitant medications, etc.) or elimination may be expected to influence the degree and extent of accumulation of the active metabolites of bupropion. The elimination of the major metabolites of bupropion may be affected by reduced renal or hepatic function because they are moderately polar compounds and are likely to undergo further metabolism or conjugation in the liver prior to urinary excretion.

Renal Impairment: There is limited information on the pharmacokinetics of bupropion in patients with renal impairment. An inter-trial comparison between normal subjects and subjects with end-stage renal failure demonstrated that the parent drug Cmax and AUC values were comparable in the 2 groups, whereas the hydroxybupropion and threohydrobupropion metabolites had a 2.3- and 2.8-fold increase, respectively, in AUC for subjects with end-stage renal failure. A second trial, comparing normal subjects and subjects with moderate‑to‑severe renal impairment (GFR 30.9 ± 10.8 mL per min) showed that after a single 150-mg dose of sustained-release bupropion, exposure to bupropion was approximately 2-fold higher in subjects with impaired renal function, while levels of the hydroxybupropion and threo/erythrohydrobupropion (combined) metabolites were similar in the 2 groups. Bupropion is extensively metabolized in the liver to active metabolites, which are further metabolized and subsequently excreted by the kidneys. The elimination of the major metabolites of bupropion may be reduced by impaired renal function. Wellbutrin should be used with caution in patients with renal impairment and a reduced frequency and/or dose should be considered [see Use in Specific Populations (8.6)].

Hepatic Impairment: The effect of hepatic impairment on the pharmacokinetics of bupropion was characterized in 2 single-dose trials, one in subjects with alcoholic liver disease and one in subjects with mild‑to-severe cirrhosis. The first trial demonstrated that the half‑life of hydroxybupropion was significantly longer in 8 subjects with alcoholic liver disease than in 8 healthy volunteers (32 ± 14 hours versus 21 ± 5 hours, respectively). Although not statistically significant, the AUCs for bupropion and hydroxybupropion were more variable and tended to be greater (by 53% to 57%) in volunteers with alcoholic liver disease. The differences in half‑life for bupropion and the other metabolites in the 2 groups were minimal.

The second trial demonstrated no statistically significant differences in the pharmacokinetics of bupropion and its active metabolites in 9 subjects with mild-to-moderate hepatic cirrhosis compared with 8 healthy volunteers. However, more variability was observed in some of the pharmacokinetic parameters for bupropion (AUC, Cmax, and Tmax) and its active metabolites (t½) in subjects with mild-to-moderate hepatic cirrhosis. In subjects with severe hepatic cirrhosis, significant alterations in the pharmacokinetics of bupropion and its metabolites were seen (Table 3).

Table 3. Pharmacokinetics of Bupropion and Metabolites in Patients with Severe Hepatic Cirrhosis: Ratio Relative to Healthy Matched Controls

Cmax

AUC

Tmaxa

Bupropion

1.69

3.12

1.43

0.5 h

Hydroxybupropion

0.31

1.28

3.88

19 h

Threo/erythrohydrobupropion amino alcohol

0.69

2.48

1.96

20 h

  a = Difference

Left Ventricular Dysfunction: During a chronic dosing trial with bupropion in 14 depressed subjects with left ventricular dysfunction (history of CHF or an enlarged heart on x-ray), there was no apparent effect on the pharmacokinetics of bupropion or its metabolites, compared with healthy volunteers.

Age: The effects of age on the pharmacokinetics of bupropion and its metabolites have not been fully characterized, but an exploration of steady‑state bupropion concentrations from several depression efficacy trials involving subjects dosed in a range of 300 to 750 mg per day, on a 3-times-daily schedule, revealed no relationship between age (18 to 83 years) and plasma concentration of bupropion. A single‑dose pharmacokinetic trial demonstrated that the disposition of bupropion and its metabolites in elderly subjects was similar to that of younger subjects. These data suggest there is no prominent effect of age on bupropion concentration; however, another single- and multiple-dose pharmacokinetics trial suggested that the elderly are at increased risk for accumulation of bupropion and its metabolites [see Use in Specific Populations (8.5)].

Gender: Pooled analysis of bupropion pharmacokinetic data from 90 healthy male and 90 healthy female volunteers revealed no sex-related differences in the peak plasma concentrations of bupropion. The mean systemic exposure (AUC) was approximately 13% higher in male volunteers compared with female volunteers. The clinical significance of this finding is unknown.

Smokers: The effects of cigarette smoking on the pharmacokinetics of bupropion were studied in 34 healthy male and female volunteers; 17 were chronic cigarette smokers and 17 were nonsmokers. Following oral administration of a single 150-mg dose of bupropion, there were no statistically significant differences in Cmax, half-life, Tmax, AUC, or clearance of bupropion or its active metabolites between smokers and nonsmokers.

Drug Interactions

Potential for Other Drugs to Affect Wellbutrin: In vitro studies indicate that bupropion is primarily metabolized to hydroxybupropion by CYP2B6. Therefore, the potential exists for drug interactions between Wellbutrin and drugs that are inhibitors or inducers of CYP2B6. In addition, in vitro studies suggest that paroxetine, sertraline, norfluoxetine, fluvoxamine, and nelfinavir inhibit the hydroxylation of bupropion.

Inhibitors of CYP2B6: Ticlopidine, Clopidogrel: In a trial in healthy male volunteers, clopidogrel 75 mg once daily or ticlopidine 250 mg twice daily increased exposures (Cmax and AUC) of bupropion by 40% and 60% for clopidogrel, and by 38% and 85% for ticlopidine, respectively. The exposures (Cmax and AUC) of hydroxybupropion were decreased 50% and 52%, respectively, by clopidogrel, and 78% and 84%, respectively, by ticlopidine. This effect is thought to be due to the inhibition of the CYP2B6-catalyzed bupropion hydroxylation.

Prasugrel: Prasugrel is a weak inhibitor of CYP2B6. In healthy subjects, prasugrel increased bupropion Cmax and AUC values by 14% and 18%, respectively, and decreased Cmax and AUC values of hydroxybupropion, an active metabolite of bupropion, by 32% and 24%, respectively.

Cimetidine: The threohydrobupropion metabolite of bupropion does not appear to be produced by cytochrome P450 enzymes. The effects of concomitant administration of cimetidine on the pharmacokinetics of bupropion and its active metabolites were studied in 24 healthy young male volunteers. Following oral administration of bupropion 300 mg with and without cimetidine 800 mg, the pharmacokinetics of bupropion and hydroxybupropion were unaffected. However, there were 16% and 32% increases in the AUC and Cmax, respectively of the combined moieties of threohydrobupropion and erythrohydrobupropion.

Citalopram: Citalopram did not affect the pharmacokinetics of bupropion and its three metabolites.

Inducers of CYP2B6: Ritonavir and Lopinavir: In a healthy volunteer trial, ritonavir 100 mg twice daily reduced the AUC and Cmax of bupropion by 22% and 21%, respectively. The exposure of the hydroxybupropion metabolite was decreased by 23%, the threohydrobupropion decreased by 38%, and the erythrohydrobupropion decreased by 48%.

In a second healthy volunteer trial, ritonavir at a dose of 600 mg twice daily decreased the AUC and the Cmax of bupropion by 66% and 62%, respectively. The exposure of the hydroxybupropion metabolite was decreased by 78%, the threohydrobupropion decreased by 50%, and the erythrohydrobupropion decreased by 68%.

In another healthy volunteer trial, lopinavir 400 mg/ritonavir 100 mg twice daily decreased bupropion AUC and Cmax by 57%. The AUC and Cmax of hydroxybupropion were decreased by 50% and 31%, respectively.

Efavirenz: In a trial in healthy volunteers, efavirenz 600 mg once daily for 2 weeks reduced the AUC and Cmax of bupropion by approximately 55% and 34%, respectively. The AUC of hydroxybupropion was unchanged, whereas Cmax of hydroxybupropion was increased by 50%.

Carbamazepine, Phenobarbital, Phenytoin: While not systematically studied, these drugs may induce the metabolism of bupropion.

Potential for Wellbutrin to Affect Other Drugs

Animal data indicated that bupropion may be an inducer of drug-metabolizing enzymes in humans. In one trial, following chronic administration of bupropion 100 mg three times daily to 8 healthy male volunteers for 14 days, there was no evidence of induction of its own metabolism. Nevertheless, there may be potential for clinically important alterations of blood levels of co-administered drugs.

Drugs Metabolized by CYP2D6: In vitro, bupropion and its metabolites (erythrohydrobupropion, threohydrobupropion, hydroxybupropion) are CYP2D6 inhibitors. In a clinical trial of 15 male subjects (ages 19 to 35 years) who were extensive metabolizers of CYP2D6, bupropion 300 mg per day followed by a single dose of 50 mg desipramine increased the Cmax, AUC, and t1/2 of desipramine by an average of approximately 2-, 5-, and 2-fold, respectively. The effect was present for at least 7 days after the last dose of bupropion. Concomitant use of bupropion with other drugs metabolized by CYP2D6 has not been formally studied.

Citalopram: Although citalopram is not primarily metabolized by CYP2D6, in one trial bupropion increased the Cmax and AUC of citalopram by 30% and 40%, respectively.

Lamotrigine: Multiple oral doses of bupropion had no statistically significant effects on the single-dose pharmacokinetics of lamotrigine in 12 healthy volunteers.

What is Wellbutrin?

Wellbutrin (bupropion) is an antidepressant medication used to treat major depressive disorder and seasonal affective disorder.

Wellbutrin may also be used for purposes not listed in this medication guide.

Important information

You should not take Wellbutrin if you have seizures, an eating disorder, or if you have suddenly stopped using alcohol, seizure medication, or sedatives. If you take Wellbutrin for depression, do not also take Zyban to quit smoking.

Do not use bupropion if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine.

Wellbutrin may cause seizures, especially in people with certain medical conditions or when using certain drugs. Tell your doctor about all of your medical conditions and the drugs you use.

Some young people have thoughts about suicide when first taking an antidepressant. Your doctor will need to check your progress at regular visits while you are using this medicine. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.

Wellbutrin side effects

Get emergency medical help if you have any of these signs of an allergic reaction to Wellbutrin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, depression, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

  • a seizure (convulsions);

  • unusual changes in mood or behavior;

  • a manic episode - racing thoughts, increased energy, reckless behavior, feeling extremely happy or irritable, talking more than usual, severe problems with sleep;

  • blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;

  • fast heartbeats; or

  • severe skin reaction, fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common Wellbutrin side effects may include:

  • dry mouth, stuffy nose;

  • nausea, constipation;

  • sleep problems (insomnia);

  • feeling anxious;

  • dizziness; or

  • joint pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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