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15 years of clinical experience with bupropion HCl: from bupropion to bupropion SR to bupropion XL.

BACKGROUND: Bupropion has been available in the United States since 1989. Initially a thrice-daily immediate-release formulation, a twice-daily sustained-release formulation followed in 1996, and, in August 2003, a once-daily extended-release formulation was introduced. On the 15th anniversary of its introduction, we undertook a review of the background/history, mechanism of action, formulations, and clinical profile of bupropion. DATA SOURCES: Major efficacy trials and other reports were obtained and reviewed from MEDLINE searches, review of abstracts from professional meetings, and the bupropion SR manufacturer's databases. Searches of English-language articles were conducted from June 2003 through August 2004. No time limit was specified in the searches, which were conducted using the search terms bupropion, bupropion SR, and bupropion XL. DATA SYNTHESIS: Bupropion inhibits the re-uptake of norepinephrine and dopamine neurotransmission without any significant direct effects on serotonin neurotransmission. Bupropion is an effective antidepressant with efficacy comparable to selective serotonin reuptake inhibitors and other antidepressants. It is well tolerated in short-and longer-term treatment. Headache, dry mouth, nausea, insomnia, constipation, and dizziness are the most common adverse events. Seizure and allergic reactions are medically important adverse events associated with bupropion and are reported rarely. Among all the newer antidepressants in the United States, bupropion appears to have among the lowest incidence of sexual dysfunction, weight gain, and somnolence. Although not U.S. Food and Drug Administration approved for these indications, bupropion has also been used as an adjunctive treatment to reverse antidepressant-induced sexual dysfunction and to augment anti-depressant efficacy in partial responders and non-responders to other agents. CONCLUSION: Bupropion has played and will continue to play an important role as a treatment for major depressive disorder in adults, as well as for other related disorders.

Journal Article↗

Bupropion and 4-OH-bupropion pharmacokinetics in relation to genetic polymorphisms in CYP2B6.

Bupropion is applied in depression and smoking cessation. Genetic polymorphisms in cytochrome P450 2B6 (CYP2B6) may cause variability in bupropion pharmacokinetics since hydroxylation is known to be mediated by CYP2B6. Bupropion may be a probe drug for CYP2B6 activity in humans. Bupropion pharmacokinetics were studied after a single oral dose of 150 mg in 121 healthy male volunteers. The amino acid polymorphisms R22C, Q172H, S259R, K262R and R487C were analysed by polymerase chain reaction and restriction fragment length polymorphism and plasma concentrations were measured by high-performance liquid chromatography. Pharmacokinetic analysis was performed by non-parametric methods and by population pharmacokinetic modelling. A unimodal distribution of bupropion and hydroxybupropion kinetic parameters was detected with a mean (range) area under the curve (AUC) of 3.64 (0.89-8.14) micromol.h/l for bupropion and 25.5 (6.72-75.3) micromol.h/l for hydroxybupropion. Population kinetic analysis revealed that bupropion total clearance via CYP2B6 alleles *1, *2, *5 and *6 did not differ, but clearance via allele *4 was 1.66-fold higher compared to wild-type allele *1 (P=0.001). Corresponding to the high clearance of bupropion, carriers of the CYP2B6 genotype *1/*4 had significantly higher Cmax of hydroxybupropion compared to all other genotypes (P=0.03). Only a minor fraction of the variability in bupropion and hydroxybupropion kinetics could be explained by the known CYP2B6 amino acid variants, in particular by the CYP2B6*4 allele. The role of this allele should also be studied in other CYP2B6 substrates, including cyclophosphamide, halothane, mianserin, promethazine and propofol.

Adult↗

Are there gender differences in smoking cessation, with and without bupropion? Pooled- and meta-analyses of clinical trials of Bupropion SR.

AIMS: In this study, we examine gender differences in smoking cessation with and without treatment with Bupropion SR. We test whether women and men have comparable success rates quitting smoking regardless of treatment, whether Bupropion SR is effective for women, and whether Bupropion SR efficacy differs for men and women. DESIGN: A literature search was conducted to identify relevant trials. Data were analyzed with individual-level (pooled) and study-level (meta-analytical) statistics. PARTICIPANTS: Data from 4421 participants in 12 randomized smoking cessation trials of Bupropion SR 300 mg versus placebo were analyzed. FINDINGS: Results from the meta-analysis revealed that Bupropion SR was an effective aid to smoking cessation [odds ratio (OR) = 2.49, 95% confidence interval (CI) = 2.06-3.00]. Moreover, Bupropion SR proved to be an effective cessation aid for women (OR = 2.47, 95% CI = 1.92-3.17). No treatment-gender interaction was observed; women and men benefited equally from treatment with Bupropion SR (Q = 0.01, NS). Overall, women were less successful at quitting than men, regardless of treatment (OR = 0.79, 95% CI = 0.65-0.95). These results were replicated with pooled, individual-level analyses. CONCLUSIONS: Bupropion SR is an effective smoking cessation aid for women. In these trials, women have less success quitting smoking than men, whether treated with Bupropion SR or placebo. There is a need to understand more about why women are less able to quit.

Adult↗

Bupropion SR as an aid to smoking cessation in smokers treated previously with bupropion: a randomized placebo-controlled study.

BACKGROUND: Many persons who attempt to quit smoking have made previous unsuccessful attempts to quit with pharmacologic aids. An understanding of the impact of these previous attempts to quit is vital for selecting medications that may be more successful in a future attempt to quit. In particular, the effect of repeated use of bupropion SR (Zyban; INN, amfebutamone) on abstinence rates has not been studied previously. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study in 450 smokers who had previously used bupropion in a smoking cessation attempt. The study consisted of a screening phase, a 12-week treatment phase, and a follow-up at month 6. Participants made regular clinic visits throughout the treatment phase during which they received brief counseling sessions to encourage abstinence from smoking. The primary end point was continuous abstinence from smoking from weeks 4 through 7. Secondary efficacy end points were examined throughout the treatment phase and at follow-up after 6 months. RESULTS: In participants receiving bupropion SR, 27% (61 of 226) remained abstinent throughout the period from weeks 4 through 7 compared with 5% (11 of 224) of participants receiving placebo (P <.001). Significantly (P <.001) more participants who received bupropion SR during the treatment phase remained continuously abstinent from the start of week 4 through month 6 (27 of 226; 12%) compared with participants who received placebo (5 of 224; 2%). Eleven participants receiving placebo (5%) and 19 participants receiving bupropion SR (8%) stopped taking the study medication because of an adverse event. CONCLUSIONS: Bupropion SR is an effective medication for retreatment of smokers who have used bupropion SR previously.

Adult↗

Bupropion for major depressive disorder: Pharmacokinetic and formulation considerations.

BACKGROUND: Major depressive disorder (MDD) is a common psychiatric condition, with 6.6% of the adult population in the United States experiencing a major depressive episode during any given year. Depressed patients must receive adequate treatment to maximize the likelihood of clinical success. Bupropion hydrochloride, a noradrenergic/dopaminergic antidepressant, is available in 3 oral formulations: immediate release (IR) (given TID), sustained release (SR) (given BID), and extended release (XL) (given QD). Understanding the pharmacokinetic (PK) properties and formulations of bupropion can help optimize clinical use. OBJECTIVES: : The aims of this article were to provide a review of the PK properties of bupropion and identify its various formulations and clinical applications to help optimize treatment of MDD. METHODS: : In this review, data concerning PK trials/reports were collected from articles identified using a PubMed search. The search was conducted without date limitations and using the search terms bupropion, bupropion SR, bupropion XL, bupropion pharmacokinetics, bupropion metabolism, and bupropion drug interactions. Additional reports were selected from references that appeared in articles identified in the original search. In addition, data from studies summarized in product information and labeling were obtained. All available information, concentrating on studies in humans, pertinent to bupropion PK properties and/or formulations was included. RESULTS: : Bupropion is extensively metabolized by the liver (t(1/2), approximately 21 hours). Hydroxybupropion, the primary active metabolite (t(1/2), approximately 20 hours), is formed by cytochrome P450 (CYP) 2B6. At steady state, C(max) of hydroxybupropion is 4- to 7-fold higher, and the AUC is approximately 10-fold greater, compared with those of the parent drug. Threohydrobupropion and erythrohydrobupropion (mean [SD] t(1/2) values, approximately 37 [13] and approximately 33 [10] hours, respectively), the other active metabolites of bupropion, are formed via nonmicrosomal pathways. Relative to bupropion, the C(max) values are approximately 5-fold greater for threohydrobupropion and similar for erythrohydrobupropion. Based on a mouse antitetrabenazine model, hydroxybupropion is approximately 50% as active as bupropion, and threohydrobupropion and erythrohydrobupropion are approximately 20% as active as bupropion. Bupropion lowers the seizure threshold and, therefore, concurrent administration with other agents that lower the seizure threshold should be undertaken cautiously. Potential interactions with other agents that are metabolized by CYP2B6 should be considered. In addition, bupropion inhibits CYP2D6 and may reduce clearance of agents metabolized by this enzyme. Absorption of the XL formulation is prolonged compared with the IR and SR formulations (T(max), approximately 5 hours vs approximately 1.5 and approximately 3 hours, respectively). Bupropion is dosed without regard to food. CONCLUSIONS: : Understanding the PK profile and formulations of bupropion can help optimize clinical use. Bupropion is metabolized extensively, resulting in 3 active metabolites. This metabolic profile, various patient factors (eg, age, medical illnesses), and potential drug interactions should be considered when prescribing bupropion. The 3 formulations-bupropion, bupropion SR, and bupropion XL-are bioequivalent and offer options to optimize treatment for patients with MDD.

Aging↗

Bupropion: a review of its use in the management of smoking cessation.

UNLABELLED: Sustained release bupropion (amfebutamone) is a non-nicotine agent that is indicated as an aid to smoking cessation. In 2 large well designed clinical trials, sustained release bupropion 300 mg/day (the recommended dose) for 7 or 9 weeks was associated with considerably and significantly higher smoking abstinence rates (continuous abstinence and 7-day point prevalence rates) than placebo during treatment and at follow-up at 6 and 12 months. Point prevalence rates at 12 months in 2 studies were 23.1 and 30.3% with bupropion, whereas values for placebo were 12.4 and 15.6%. Continuous abstinence rates at 12 months, available from 1 trial, were 18.4% with bupropion and 5.6% with placebo. Furthermore, bupropion was associated with significantly higher quitting rates than nicotine patch in a comparative study. Combination therapy with bupropion and nicotine patch provided slightly higher abstinence rates than bupropion alone, although differences were not statistically significant. The combination was superior to nicotine patch alone. Data from a preliminary report of long term bupropion treatment (52 weeks) showed that the drug was associated with significantly higher continuous abstinence rates than placebo only to 6 months. However, point prevalence abstinence rates were significantly higher with bupropion than placebo to 18 months. Bupropion 300 mg/day recipients reported nicotine withdrawal symptoms during treatment; however, the symptoms were significantly less severe with bupropion than placebo. Patients receiving bupropion 300 mg/day or bupropion in combination with nicotine patch for smoking cessation generally gained less bodyweight than placebo recipients. The benefits of bupropion for preventing weight gain persisted after the completion of long term, but not short term therapy. Bupropion was well tolerated in clinical trials, and the only adverse events that were significantly more common with bupropion than placebo were insomnia and dry mouth. Data published so far suggest that sustained release bupropion has a low potential for inducing seizures (seizure rate approximately 0.1% in patients with depression). CONCLUSIONS: Bupropion is an effective and well tolerated smoking cessation intervention. Further studies with long term follow-up will be useful in determining whether abstinence rates are maintained with bupropion. In addition, clarification of its efficacy in comparison with other therapies used for smoking cessation would help to establish its clinical value. The reduced potential for weight gain with bupropion and the ability to use bupropion in combination with nicotine replacement therapy make the drug a useful treatment option for smoking cessation.

Antidepressive Agents, Second-Generation↗

Bupropion: a review of its mechanism of antidepressant activity.

BACKGROUND: The mechanism of action of the novel antidepressant bupropion remains unclear after many years of study. A review of the relevant biochemical, in vivo brain microdialysis, electrophysiologic, behavioral, and clinical data clarifies what is known about this unique compound and suggests possible modes of action. METHOD: A panel of 11 experts was convened for a conference to discuss bupropion's mechanism of antidepressant activity. Four of the panelists presented current research findings, followed by a discussion. RESULTS: (1) Biochemical studies suggest down-regulation of postsynaptic beta-adrenoceptors and desensitization of the norepinephrine-stimulated adenylate cyclase in the rat cortex occur only after chronic administration of very high doses of bupropion. (2) In vivo brain microdialysis studies demonstrate that, after chronic administration, there is an enhancement of bupropion-induced increases in extracellular dopamine in the nucleus accumbens. (3) Electrophysiologic data show that with acute dosing, bupropion reduces the firing rates of noradrenergic neurons in the locus ceruleus. The firing rates of dopaminergic neurons are reduced by bupropion in the A9 and A10 areas of the brain, but only at very high doses, and bupropion does not alter the firing rates of serotonergic neurons in the dorsal raphe. (4) Behavioral studies show that the most active metabolite of bupropion, hydroxybupropion (306U73), appears to be responsible for a large part of the compound's effects in animal models of antidepressant activity. (5) Clinical studies indicate that bupropion enhances noradrenergic functional activity as reflected by an increased excretion of the hydroxy metabolite of melatonin, while at the same time producing a presumably compensatory decrease in norepinephrine turnover. In one study, bupropion elevated plasma levels of the dopamine metabolite homovanillic acid in nonresponders, but not in responders. CONCLUSION: The mechanism of action of bupropion appears to have an unusual, not fully understood, noradrenergic link. The bupropion metabolite hydroxybupropion probably plays a critical role in bupropion's antidepressant activity, which appears to be predominantly associated with long-term noradrenergic effects. The mild central nervous system activating effects of bupropion appear to be due to weak dopaminergic mechanisms. There is some evidence that dopamine may contribute to bupropion's antidepressant properties. Antidepressant effects of bupropion are not serotonergically mediated.

Animals↗

Influence of fluoxetine on the ability of bupropion to modulate extracellular dopamine and norepinephrine concentrations in three mesocorticolimbic areas of rats.

The finding that serotonin (5-HT) can modulate dopamine (DA) and norepinephrine (NE) release in the brain has led us to hypothesize that fluoxetine, a selective 5-HT reuptake inhibitor, may influence the ability of bupropion, a preferential DA and NE dual reuptake inhibitor, to modulate extracellular DA and NE concentrations in some brain areas. The present study was designed to evaluate this hypothesis by assessing the effects of fluoxetine on bupropion-induced changes in extracellular monoamine concentrations by means of in vivo microdialysis. Three mesocorticolimbic areas including hypothalamus (Ht), prefrontal cortex (Pfc) and nucleus accumbens (Acb) were selected based on their relevance to depression and antidepressant actions. In the Ht of untreated rats, bupropion dose-dependently (s.c.) increased extracellular DA and NE concentrations either in single injection study or in sequential injection study. Thus, 10 mg/kg of bupropion had no effect on the DA and NE concentrations, while 30 mg/kg of bupropion induced transient but significant increases (about 240% of the baselines), and 100 mg/kg of bupropion induced marked and persistent increases (over 600% of the baselines) in the DA and NE concentrations. In the rats pre-treated with fluoxetine (10 mg/kg, s.c., 90 min interval), the threshold dose of bupropion (10 mg/kg) significantly increased the DA and NE concentrations to more than 350% of the baselines, and 30 mg/kg of bupropion markedly increased the DA and NE concentrations to more than 570% of the baselines in the Ht. The fluoxetine pre-treatment also potentiated the DA increases induced by 10 mg/kg of bupropion in the Pfc (260% for bupropion alone vs 357% for the combination) and in the Acb (224% vs 645%). The bupropion-induced NE increases were potentiated by fluoxetine mainly in the Ht. Bupropion did not significantly affect the extracellular 5-HT concentrations in all the 3 brain areas tested. In summary, the present study demonstrated that bupropion can increase extracellular DA and NE concentrations in several mesocorticolimbic areas, which may have an impact on bupropion's antidepressant actions. Furthermore, fluoxetine can potentiate the bupropion-induced DA and NE increases, which may produce more effective and rapid antidepressant actions.

Animals↗

Bupropion in breast milk: an exposure assessment for potential treatment to prevent post-partum tobacco use.

OBJECTIVES: To assess potential infant exposure to bupropion and its active metabolites in breast milk such as would occur during treatment to prevent post-partum relapse to tobacco use, and to compare the concentrations of bupropion in urine and saliva with plasma and breast milk. DESIGN AND SETTING: Cohort study, outpatient clinical research centre. SUBJECTS: Ten healthy post-partum volunteers who agreed to take bupropion for seven days, pump and discard their breast milk, and have samples of breast milk, plasma, saliva, and urine analysed. INTERVENTION: Bupropion 150 mg a day for three days and then 300 mg a day for four days. MAIN OUTCOME MEASURES: Concentrations of bupropion and its active metabolites (hydroxybupropion, erythrohydrobupropion, threohydrobupropion) in breast milk, plasma, saliva, and urine. Determination of average infant exposure. RESULTS: The calculated average dosage of bupropion in breast milk was 6.75 microg/kg/day. Therefore, the average infant exposure is 0.14% of the standard adult dose of bupropion, corrected for the difference in body weight. Considering the sum of bupropion and its active metabolites, the average infant exposure is expected to be 2% of the standard maternal dose on a molar basis. The concentration of bupropion and its active metabolites in breast milk was not associated with age, body mass index, use of oral contraceptive pills, age of infant, or the frequency of breast feeding at the time the study was initiated. The coefficient of determination (r2) between the concentration of bupropion in breast milk and in urine was 0.77 (p < 0.01). CONCLUSIONS: Bupropion and its active metabolites are present in the breast milk of lactating women. The concentrations of bupropion in breast milk and urine were highly correlated. These results indicate that the daily dose of bupropion and metabolites that would be delivered to an infant of a woman taking a therapeutic dose of bupropion is small. These results suggest that the effectiveness of bupropion to prevent post-partum relapse to tobacco use should be evaluated without excluding women who plan to breast feed.

Adult↗

Pharmacokinetics of bupropion and metabolites in plasma and brain of rats, mice, and guinea pigs.

Recent reports indicate that bupropion, a novel non-tricyclic antidepressant, is metabolized differently in certain species of animals. To further define the disposition of bupropion, a study was done involving three species, the rat, mouse, and guinea pig, as animal models to evaluate bupropion metabolism. The pharmacokinetic profiles of bupropion and its major basic metabolites, BW 306U and BW A494U, were determined following the ip administration of 40 mg/kg bupropion to these animals. Pharmacokinetic profiles of the parent drug and metabolites from plasma and brain samples were obtained using a liquid chromatographic procedure. Further investigation of the reduced bupropion metabolite BW A494U was carried out by the ip administration of this metabolite to these animals and assaying the plasma and brain samples 90 min after dosing. Analysis of the pharmacokinetic data revealed that the rat quickly metabolized bupropion, but no basic metabolites accumulated. The mouse metabolized bupropion predominantly to BW 306U, whereas the guinea pig converted bupropion to reduced bupropion (BW A494U) as well as BW 306U. Brain/plasma ratios of bupropion among these animals did not vary significantly. However, both metabolites showed dramatic differences in their brain/plasma ratios among these species. When reduced bupropion (BW A494U) was injected, almost 3% of the plasma concentration of BW A494U was determined to be bupropion in the rat. Lesser amounts were converted in the mouse and guinea pig. Therefore, we have demonstrated that distinct differences exist in the metabolism of bupropion in various species of animals. The guinea pig, when compared to the rat or mouse, appears to constitute a model that most closely resembles that of human bupropion metabolism.

Animals↗

Behavioral and biochemical effects of the antidepressant bupropion (Wellbutrin): evidence for selective blockade of dopamine uptake in vivo.

Bupropion (BW 323U; Wellbutrin), a novel compound with antidepressant effects in man, was found to reduce immobility in an "experimental helplessness" forced swimming antidepressant test in rats as did imipramine and amitriptyline. Higher doses produced elevated locomotor activity in an automated open field and produced stereotyped sniffing which was contrasted with apomorphine. When bupropion or desmethylimipramine was given before intracisternal injections of 6-hydroxydopamine, bupropion produced a dose-related selective antagonism of the destruction of dopamine neurons, while under the same conditions, desmethylimipramine produced a dose-related selective antagonism of the destruction of noradrenergic neurons. Studies in which the dose of bupropion and the dose of 6-hydroxydopamine were varied revealed that a dose-related selective antagonism of dopamine depletion by 6-hydroxydopamine occurred when doses up to and including 50 mg/kg i.p. to bupropion were administered. Some antagonism of norepinephrine depletion also occurred at 100 mg/kg of bupropion i.p. Bupropion also selectively reversed the dopamine depletion produced by alpha-methyl-m-tyrosine, a finding which is consistent with the view that bupropion is a dopamine uptake inhibitor in vivo. The importance of dopamine systems for the behavioral effects of bupropion were also studied. When the locomotor stimulant effects of bupropion were tested in rats with chronic destruction of dopamine neurons produced by 6-hydroxydopamine, bupropion failed to elevate locomotor activity. Rats treated with procedures using 6-hydroxydopamine to produce relatively selective norepinephrine depletions responded to bupropion with locomotor activity stimulation like controls. Rats with similar depletions of either dopamine or norepinephrine were also tested for the ability of low doses of bupropion to reduce immobility in the "experimental helplessness" forced swim antidepressant test. Prior destruction of dopamine neurons prevented activity of bupropion in this test. Results indicate that bupropion is a selective dopamine uptake inhibitor in vivo and that dopaminergic systems play an important role in its central nervous system pharmacology.

Animals↗

Acute doses of d-amphetamine and bupropion increase cigarette smoking.

RATIONALE: Bupropion is used clinically as a treatment for smoking cessation, but the processes by which it reduces smoking are poorly understood. Bupropion shares some neurochemical actions and behavioral effects with the psychostimulant amphetamine, and it has been shown that amphetamine increases smoking when administered acutely. The effects of single doses of bupropion on smoking have not been studied but, based on its similarities to amphetamine, we postulated that acute bupropion would also increase smoking. OBJECTIVE: To measure the effects of single doses of amphetamine and bupropion on smoking and craving for cigarettes in smokers. METHODS: Cigarette smokers who were not trying to quit participated in a three-session study in which they received placebo and a single dose of either d-amphetamine sulfate (10 and 20 mg; n=10) or bupropion hydrochloride (150 and 300 mg; n=12) after overnight abstinence. The three outcome measures were: i) subjective and behavioral effects of amphetamine and bupropion after a period of acute abstinence, ii) effects of amphetamine and bupropion on subjective responses to a single, smoked cigarette, and iii) effects of the drugs on number of cigarettes smoked during an ad libitum smoking period. RESULTS: After the acute abstinence and before smoking, both amphetamine and bupropion increased self-reported mood and euphoria, but did not change ratings of craving or withdrawal. After subjects smoked a single smoked cigarette, they reported that bupropion reduced ratings of "buzzed" and "intensity". During the period of ad libitum smoking both amphetamine and bupropion increased the number of cigarettes smoked. CONCLUSION: Acute doses of both bupropion and amphetamine increase smoking in non-treatment-seeking smokers without altering ratings of craving or withdrawal. Bupropion reduced some of the sensory responses to the smoked cigarette. It remains to be determined why bupropion increases smoking when administered acutely under controlled conditions, while it helps to reduce smoking in patients trying to quit.

Adult↗

Conversion from sustained-release to immediate-release bupropion: patient tolerability and economic impact.

STUDY OBJECTIVE: To assess patient tolerability and impact on institutional drug acquisition costs of converting patients from sustained-release bupropion to generic immediate-release bupropion. DESIGN: Retrospective medical record review. SETTING: Veterans Affairs medical center. PATIENTS: One hundred three outpatients who had been receiving sustained-release bupropion and were converted to immediate-release bupropion at equal individual doses and frequencies. MEASUREMENTS AND MAIN RESULTS: Medical records were reviewed for documentation of adverse effects thought to be associated with bupropion treatment; reports of seizure occurrence were specifically sought. Patterns of bupropion dosing were also assessed. Institutional drug acquisition costs were evaluated by comparing actual costs of bupropion for each patient before and after conversion. Adverse effects reported with immediate-release bupropion were those commonly associated with this drug (headache, agitation, chest pain, and gastrointestinal complaints) and were neither unusually frequent nor severe. No seizures were reported after the drug conversion. Mean daily doses of bupropion were not significantly different after conversion. Mean single doses of immediate-release bupropion were below 150 mg; however, six patients did receive single doses of 200 mg. After conversion, the annual institutional drug acquisition cost for bupropion decreased by approximately $48,910. CONCLUSION: Conversion from sustained-release bupropion to immediate-release bupropion appears to be safe. Single 200-mg doses of immediate-release bupropion can apparently be administered to some patients without inducing excessive adverse effects, including seizures. Marked reduction in drug acquisition costs can be achieved with this conversion.

Adult↗

Safety of intravenous methamphetamine administration during treatment with bupropion.

RATIONALE: Methamphetamine dependence is a growing problem for which no medication treatments have proven effective. OBJECTIVES: We evaluated bupropion, an antidepressant with beneficial effects for the treatment of nicotine dependence, in patients with methamphetamine dependence, to assess the safety and tolerability of methamphetamine administration during bupropion treatment. METHODS: Twenty-six participants entered the study and 20 completed the protocol. Participants received intravenous methamphetamine (0, 15, and 30 mg) before and after randomization to twice-daily bupropion (150 mg SR) or matched placebo. Dependent measures included cardiovascular effects of methamphetamine, methamphetamine and amphetamine pharmacokinetics, and peak and trough plasma concentrations of bupropion and its metabolites. RESULTS: Bupropion treatment was well tolerated, with bupropion- and placebo-treated groups reporting similar rates of adverse events. Methamphetamine administration was associated with expected stimulant cardiovascular effects, and these were not accentuated by bupropion treatment. Instead, there was a trend for bupropion to reduce methamphetamine-associated increases in blood pressure and a statistically significant reduction in methamphetamine-associated increases in heart rate. Pharmacokinetic analysis revealed that bupropion treatment reduced the plasma clearance of methamphetamine and also reduced the appearance of amphetamine in the plasma. Methamphetamine administration did not alter the peak and trough plasma concentrations of bupropion or its metabolites. CONCLUSIONS: Methamphetamine administration was well tolerated during bupropion treatment. There was no evidence of additive cardiovascular effects when the drugs were coadministered. This study provides initial evidence for the safety of prescribing bupropion for the treatment of methamphetamine abuse and dependence. The impact of bupropion treatment in patients who abuse larger doses of methamphetamine remains undetermined.

Adolescent↗

Effect of bupropion on nicotine self-administration in rats.

RATIONALE AND OBJECTIVE: The mechanisms underlying the therapeutic efficacy of bupropion as a smoking cessation agent are unknown. Bupropion inhibits monoamine uptake as well as neuronal nicotinic receptor (nAChR) function. The present study compared effects of bupropion on nicotine self-administration to those of other stimulant drugs (methamphetamine and apomorphine) that lack nAChR activity in order to determine its mechanism of action. To determine the specificity of bupropion-induced changes in nicotine self-administration, the ability of bupropion to alter sucrose-maintained responding or amphetamine self-administration was determined. METHODS: In nicotine and amphetamine self-administration and sucrose-maintained responding experiments, rats responded for nicotine (0.01 or 0.02 mg/kg per infusion, IV), amphetamine (0.2 mg/kg per infusion, IV) and sucrose pellets (45 mg), respectively, on a fixed ratio 5 schedule. Once responding stabilized, rats were pretreated 15 min before the session with bupropion (1-78 mg/kg) or vehicle. The ability of methamphetamine (0.3-3 mg/kg) or apomorphine (0.01-0.2 mg/kg) to alter responding for nicotine (0.02 mg/kg per infusion, IV) was determined. RESULTS: Bupropion produced a biphasic dose-response pattern at both nicotine infusion doses, increasing infusions at low bupropion doses and decreasing infusions at high bupropion doses. Methamphetamine produced a similar biphasic pattern, whereas apomorphine only decreased nicotine infusions at high doses. Bupropion dose-dependently decreased responding for sucrose and amphetamine. CONCLUSIONS: These results suggest that high bupropion doses decrease responding nonspecifically; whereas low bupropion doses selectively increase responding for nicotine. The increase in nicotine self-administration is likely due to inhibition of dopamine and norepinephrine transporters, combined with inhibition of nAChRs.

Animals↗