Wellbutrin Pharmacology 4

Wellbutrin Pharmacology

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Pharmacology Page 4

MAO Inhibitors: The concurrent administration of bupropion and MAO inhibitor is contraindicated. At least 14 days should elapse between discontinuation of an MAO inhibitor and initiation of treatment with bupropion. Treatment with a MAO inhibitor should not be started until 2 weeks after discontinuation of bupropion treatment.
Bupropion is contraindicated in patients with known hypersensitivity to bupropion or to any of the components of the formulation.
Manufacturers' Warnings In Clinical States: Patients should be made aware that Wellbutrin SR contains the same active ingredient (bupropion HCl) as Zyban. Wellbutrin SR should not be administered to patients already receiving a product containing bupropion (see Contraindications).

Agitation and Insomnia: In placebo-controlled trials, patients receiving bupropion tablets experienced an increased incidence of agitation, anxiety, and insomnia relative to those receiving placebo (see Adverse Effects). These symptoms were sometimes of sufficient magnitude to require discontinuation of bupropion, or concurrent treatment with sedative/hypnotic drugs.
Psychosis, Confusion, and Other Neuropsychiatric Phenomena: Patients treated with bupropion have been reported to show a variety of neuropsychiatric signs and symptoms including delusions, hallucinations, psychosis, concentration disturbance, paranoia and confusion. In some cases these abated upon dose reduction and/or withdrawal of treatment.

Seizures: Data for bupropion tablets revealed a seizure incidence of approximately 0.1% (3 of 3 100 patients followed prospectively) in patients treated at the recommended dose range of 100 to 300 mg/day. The incidence of seizures increased to 0.4% (4/1 000), above the recommended dose, at 400 mg/day. Data for the immediate-release buproprion revealed a seizure incidence of approximately 0.4% (13 of 3 200 patients followed prospectively) in patients treated at doses of 300 to 450 mg/day. Additional data accumulated for the immediate-release formulation of buproprion suggests that the estimated seizure incidence increases almost 10-fold between 450 and 600 mg/day. Given the wide variability among individuals and their capacity to metabolize and eliminate drugs, the disproportionate increase in seizure incidence with dose incrementation calls for caution in dosing. The risk of seizure occurring with bupropion use appears to be associated with the presence of predisposing risk factors. Therefore caution should be used when treating patients with predisposing factors which increase the risk of seizures, including: history of head trauma or prior seizure; CNS tumor; excessive use of alcohol; abrupt withdrawal from alcohol, benzodiazepines or other sedatives; addiction to opiates, cocaine, or stimulants; use of concomitant medications that lower seizure threshold (e.g., antipsychotics, antidepressants, lithium, theophylline or systemic steroids); use of over-the-counter stimulants or anorectics; diabetes treated with oral hypoglycemics or insulin.
The risk of seizure may be minimized if the total daily dose of bupropion does not exceed 300 mg (the maximum recommended dose), and no single dose of bupropion exceeds 150 mg, in order to avoid high peak concentrations of buproprion and/or its metabolites.
Precautions: Suicide: The possibility of a suicide attempt in seriously depressed patients is inherent to the illness and may persist until significant remission occurs. Close supervision of high risk patients should accompany initial drug therapy, and consideration should be given to the need for hospitalization. In order to reduce the risk of overdose, prescriptions for bupropion should be written for the smallest number of tablets consistent with good patient management.

Allergic Reactions: Anaphylactoid reactions characterized by symptoms such as pruritus, urticaria, angioedema, and dyspnea requiring medical treatment have been reported in clinical trials with bupropion at a rate of 1 to 3 per thousand. In addition, there have been rare spontaneous postmarketing reports of erythema multiforme, Stevens-Johnson syndrome, and anaphylactic shock associated with bupropion.
In uncontrolled and controlled clinical trials, skin disorders, primarily rashes, pruritus and urticaria, led to discontinuation of 1.5% and 1.9 %, respectively of bupropion-treated subjects.

Activation of Psychosis and/or Mania: Antidepressants can precipitate manic episodes in bipolar patients during the depressed phase of their illness and may activate latent psychosis in other susceptible patients. Bupropion is expected to pose similar risks.
Altered Appetite and Weight: In clinical trials bupropion was associated with dose-related weight loss. In 8-week controlled trials mean weight loss for trial completers was 0.1 kg for placebo, 0.8 kg for bupropion 100 mg/day, 1.4 kg at 150 mg/day, and 2.3 kg at 300 mg/day. If weight loss is a major presenting sign of a patient's depressive illness, the potential anoretic and/or weight reducing effect of bupropion should be considered.