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Pronunciation | /bjuːˈproʊpiɒn/ bew-PROH-pee-on am-fa-BEW-teh-moan |
Trade names | Wellbutrin, Zyban, others |
Other names | Amfebutamone; 3-Chloro-N-tert-butyl-β-keto-α-methylphenethylamine; 3-Chloro-N-tert-butyl-β-ketoamphetamine; 3-Chloro-N-tert-butylcathinone |
AHFS/Drugs.com | Monograph |
MedlinePlus | a695033 |
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Routes of administration | Oral (swallowed by mouth) [2] [3] |
Drug class | NDRI antidepressants |
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Bioavailability | Unknown [2] |
Protein binding | Bupropion: 84% [14] Hydroxybupropion: 77% [14] Threohydrobupropion: 42% [14] |
Metabolism | Liver, intestines (CYP2B6, others) [2] |
Metabolites | • Hydroxybupropion • Threohydrobupropion • Erythrohydrobupropion • Others |
Elimination half-life | Bupropion: alpha: 0.5–1.04 beta: 11 h [15] [2] Hydroxybupropion: 20 h [2] Threohydrobupropion: 37 h [2] Erythrohydrobupropion: 33 h [2] |
Excretion | Urine: 87% (0.5% unchanged) [2] Feces: 10% [2] |
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Formula | C13H18ClNO |
Molar mass | 239.74 g·mol−1 |
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Bupropion, formerly called amfebutamone, [16] and sold under the brand name Wellbutrin among others, is an atypical antidepressant that is US FDA-approved to treat major depressive disorder, seasonal affective disorder and to support smoking cessation. [17] [18] It is also popular as an add-on medication in the cases of "incomplete response" to the first-line selective serotonin reuptake inhibitor (SSRI) antidepressant. [18] [19] Bupropion has several features that distinguish it from other antidepressants: it does not usually cause sexual dysfunction, [18] it is not associated with weight gain [18] and sleepiness, [20] and it is more effective than SSRIs at improving symptoms of hypersomnia and fatigue. [21] Bupropion, particularly the immediate-release formulation, carries a higher risk of seizure than many other antidepressants, hence caution is recommended in patients with a history of seizure disorder. [22] The medication is taken by mouth. [2] [3]
Common adverse effects of bupropion with the greatest difference from placebo are dry mouth, nausea, constipation, insomnia, anxiety, tremor, and excessive sweating. [10] [11] Raised blood pressure is notable. [23] Rare but serious side effects include seizures, [10] [11] liver toxicity, [24] psychosis, [25] and risk of overdose. [26] Bupropion use during pregnancy may be associated with increased likelihood of congenital heart defects. [27]
Bupropion acts as a norepinephrine–dopamine reuptake inhibitor (NDRI) and a nicotinic receptor antagonist. [2] However, its effects on dopamine are weak and clinical significance is contentious. [28] [29] [30] [31] [32] Chemically, bupropion is an aminoketone that belongs to the class of substituted cathinones and more generally that of substituted amphetamines and substituted phenethylamines. [33] [34]
Bupropion was invented by Nariman Mehta, who worked at Burroughs Wellcome, in 1969. [35] It was first approved for medical use in the United States in 1985. [36] Bupropion was originally called by the generic name amfebutamone, before being renamed in 2000. [16] In 2022, it was the 21st most commonly prescribed medication in the United States, with more than 25 million prescriptions. [37] [38] It is on the World Health Organization's List of Essential Medicines. [39] In 2022, the US Food and Drug Administration (FDA) approved the combination dextromethorphan/bupropion to serve as a rapid-acting antidepressant in patients with major depressive disorder. [40]
The evidence overall supports the effectiveness of bupropion over placebo for the treatment of depression. [41] [18] [42] Some peer-reviewed studies suggest the quality of evidence is low. [42] [18] Some meta-analyses report that bupropion has an at-most small effect size for depression. [43] [44] [42] [45] One meta-analysis reported a large effect size. [18] However, there were methodological limitations with this meta-analysis, including using a subset of only five trials for the effect size calculation, substantial variability in effect sizes between the selected trials—which led the authors to state that their findings in this area should be interpreted with "extreme caution"—and general lack of inclusion of unpublished trials in the meta-analysis. [18] Unpublished trials are more likely to be negative in findings, [46] [47] and other meta-analyses have included unpublished trials. [43] [44] [42] [45] Evidence suggests that the effectiveness of bupropion for depression is similar to that of other antidepressants. [43] [44] [18]
Over the autumn and winter months, bupropion prevents the development of depression in those who have recurring seasonal affective disorder: 15% of participants on bupropion experienced a major depressive episode vs. 27% of those on placebo. [48] Bupropion also improves depression in bipolar disorder, with the efficacy and risk of an affective switch being similar to other antidepressants. [49]
Bupropion has several features that distinguish it from other antidepressants: for instance, unlike the majority of antidepressants, it does not usually cause sexual dysfunction, and the occurrence of sexual side effects is not different from placebo. [18] [50] Bupropion treatment is not associated with weight gain; on the contrary, the majority of studies observed significant weight loss in bupropion-treated participants. [18] Bupropion treatment also is not associated with the sleepiness that may be produced by other antidepressants. [20] Bupropion is more effective than selective serotonin reuptake inhibitors (SSRIs) at improving symptoms of hypersomnia and fatigue in depressed patients. [21] Bupropion is effective in the treatment of anxious depression and, contrary to common belief, does not exacerbate anxiety in this context. [51] [52] The effectiveness of bupropion for anxious depression is equivalent to that of SSRIs in the case of depression with low or moderate anxiety, whereas SSRIs show a modest effectiveness advantage in terms of response rates for depression with high anxiety. [51]
The addition of bupropion to a prescribed SSRI is a common strategy when people do not respond to the SSRI, [19] and it is supported by clinical trials; [18] however, it appears to be inferior to the addition of atypical antipsychotic aripiprazole. [53] [ further explanation needed ]
Prescribed as an aid for smoking cessation, bupropion reduces the severity of craving for nicotine and withdrawal symptoms [54] [55] [56] such as depressed mood, irritability, difficulty concentrating, and increased appetite. [57] Initially, bupropion slows the weight gain that often occurs in the first weeks after quitting smoking. With time, however, this effect becomes negligible. [57]
The bupropion treatment course lasts for seven to twelve weeks, with the patient halting the use of tobacco about ten days into the course. [57] [10] After the course, the effectiveness of bupropion for maintaining abstinence from smoking declines over time, from 37% of tobacco abstinence at 3 months to 20% at one year. [58] It is unclear whether extending bupropion treatment helps to prevent relapse of smoking. [59]
Overall, six months after the therapy, bupropion increases the likelihood of quitting smoking by approximately 1.6-fold as compared to placebo. In this respect, bupropion is as effective as nicotine replacement therapy but inferior to varenicline. Combining bupropion and nicotine replacement therapy does not improve the quitting rate. [60]
In children and adolescents, the use of bupropion for smoking cessation does not appear to offer any significant benefits. [61] The evidence for its use to aid smoking cessation in pregnant women is insufficient. [62]
In the United States, the treatment of attention deficit hyperactivity disorder (ADHD) is not an approved indication of bupropion, and it is not mentioned in the 2019 guideline on ADHD treatment from the American Academy of Pediatrics. [63] Systematic reviews of bupropion for the treatment of ADHD in both adults and children note that bupropion may be effective for ADHD but warn that this conclusion has to be interpreted with caution, because clinical trials were of low quality due to small sizes and risk of bias. [30] [64] [65] [66] Similarly to atomoxetine, bupropion has a delayed onset of action for ADHD, and several weeks of treatment are required for therapeutic effects. [30] [67] This is in contrast to stimulants, such as amphetamine and methylphenidate, which have an immediate onset of effect in the condition. [67]
Bupropion is less likely than other antidepressants to cause sexual dysfunction. [68] A range of studies indicate that bupropion not only produces fewer sexual side effects than other antidepressants but can actually help to alleviate sexual dysfunction [69] including sexual dysfunction induced by SSRI antidepressants. [70] There have also been small studies suggesting that bupropion or a bupropion/trazodone combination may improve some measures of sexual function in women who have hypoactive sexual desire disorder (HSDD) and are not depressed. [71] According to an expert consensus recommendation from the International Society for the Study of Women's Sexual Health, bupropion can be considered as an off-label treatment for HSDD despite limited safety and efficacy data. [72] Likewise, a 2022 systematic review and meta-analysis of bupropion for sexual desire disorder in women reported that although data were limited, bupropion appeared to be dose-dependently effective for the condition. [73]
Bupropion, when used for treating long-term weight gain over six to twelve months, results in an average weight loss of 2.7 kilograms (6.0 lb) over placebo. [74] This is not much different from the weight loss produced by several other weight-loss medications such as sibutramine or orlistat. [74] The combination drug naltrexone/bupropion has been approved by the US Food and Drug Administration (FDA) for the treatment of obesity. [75] [76]
Bupropion is not effective in the treatment of cocaine dependence, [77] but it is showing promise in reducing drug use in treating amphetamine-type stimulant use and cravings. [78] [79] Based on studies indicating that bupropion lowers the level of the inflammatory mediator TNF-alpha, there have been suggestions that it might be useful in treating inflammatory bowel disease, psoriasis, and other autoimmune conditions, but very little clinical evidence is available. [80] [81] [82] Bupropion is not effective in treating chronic low back pain. [83] The drug may be useful in the treatment of excessive daytime sleepiness (EDS) and narcolepsy. [84] [85] [86] [87]
Bupropion has been used to treat disorders of diminished motivation, like apathy, abulia, and akinetic mutism. [88] [89] Accordingly, the drug has been found to increase effort expenditure and improve motivational deficits in animal models. [88] However, only limited benefits of bupropion in the treatment of apathy have been observed in clinical trials in various conditions. [88]
Bupropion has been used in the treatment of postural orthostatic tachycardia syndrome (POTS). [90] [91]
Bupropion is available as an oral tablet in several different formulations. [10] [11] It is mainly formulated as the hydrochloride salt [10] [11] but also as the hydrobromide salt. [12] In addition to single-drug formulations, bupropion is formulated in combinations including naltrexone/bupropion (Contrave) for obesity and dextromethorphan/bupropion (Auvelity) for depression. [92] [93]
The US Food and Drug Administration (FDA) prescription label advises that bupropion should not be prescribed to individuals with epilepsy or other conditions that lower the seizure threshold, such as anorexia nervosa, bulimia nervosa, or benzodiazepine or alcohol withdrawal. It should be avoided in individuals who are taking monoamine oxidase inhibitors (MAOIs). The label recommends that caution should be exercised when treating people with liver damage, severe kidney disease, and severe hypertension, and in children, adolescents, and young adults due to the increased risk of suicidal ideation. [10]
The common adverse effects of bupropion with the greatest difference from placebo are dry mouth, nausea, constipation, insomnia, anxiety, tremor, and excessive sweating. [10] [11] Bupropion has the highest incidence of insomnia of all second-generation antidepressants, apart from desvenlafaxine. [94] It is also associated with about 20% increased risk of headache. [95]
Bupropion raises blood pressure in some people. One study showed an average rise of 6 mm Hg in systolic blood pressure in 10% of patients. [23] The prescribing information notes that hypertension, sometimes severe, is observed in some people taking bupropion, both with and without pre-existing hypertension. [10] [11] The safety of bupropion in people with cardiovascular conditions and its general cardiovascular safety profile remains unclear due to the lack of data. [96] [97]
Seizure is a rare but serious adverse effect of bupropion. It is strongly dose-dependent: for the immediate release preparation, the seizure incidence is 0.4% at the dose 300–450 mg per day; the incidence climbs almost ten-fold for the higher than recommended dose of 600 mg. [10] [11] For comparison, the incidence of unprovoked seizure in the general population is 0.07–0.09%, and the risk of seizure for a variety of other antidepressants is generally 0–0.5% at the recommended doses. [98]
Cases of liver toxicity leading to death or liver transplantation have been reported for bupropion. It is considered to be one of several antidepressants with a greater risk of hepatotoxicity. [24]
The prescribing information warns about bupropion triggering an angle-closure glaucoma attack. [10] On the other hand, bupropion may decrease the risk of development of open angle glaucoma. [99]
Bupropion use by mothers in the first trimester of pregnancy is associated with a 23% increase in the odds of congenital heart defects in their children. [27]
Bupropion has rarely been associated with instances of Stevens–Johnson syndrome. [100] [101]
Bupropion has not been associated with QT prolongation at therapeutic doses but has been associated with QT prolongation in overdose. [102] [103] [104]
The US Food and Drug Administration (FDA) requires all antidepressants, including bupropion, to carry a boxed warning stating that antidepressants may increase the risk of suicide in people younger than 25. This warning is based on a statistical analysis conducted by the FDA which found a 2-fold increase in suicidal thought and behavior in children and adolescents, and a 1.5-fold increase in the 18–24 age group. [105] For this analysis the FDA combined the results of 295 trials of 11 antidepressants to obtain statistically significant results. Considered in isolation, bupropion was not statistically different from placebo. [105]
Bupropion prescribed for smoking cessation results in a 25% increase in the risk of psychiatric side effects, in particular, anxiety (about 40% increase) and insomnia (about 80% increase). The evidence is insufficient to determine whether bupropion is associated with suicides or suicidal behavior. [55]
In rare cases, bupropion-induced psychosis may develop. It is associated with higher doses of bupropion; many cases described are at higher than recommended doses. Concurrent antipsychotic medication appears to be protective. [25] In most cases the psychotic symptoms are eliminated by reducing the dose, ceasing treatment or adding antipsychotic medication. [10] [25]
Although studies are lacking, a handful of case reports suggest that abrupt discontinuation of bupropion may cause antidepressant discontinuation syndrome. [106]
Bupropion is considered moderately dangerous in overdose. [107] [108] According to an analysis of US National Poison Data System, adjusted for the number of prescriptions, bupropion and venlafaxine are the two new generation antidepressants (that is excluding tricyclic antidepressants) that result in the highest mortality and morbidity. [26] For significant overdoses, seizures have been reported in about a third of all cases; other serious effects include hallucinations, loss of consciousness, and abnormal heart rhythms. When bupropion was one of several kinds of pills taken in an overdose, fever, muscle rigidity, muscle damage, hypertension or hypotension, stupor, coma, and respiratory failure have been reported. While most people recover, some people have died, having had multiple uncontrolled seizures and myocardial infarction. [10]
Since bupropion is metabolized to hydroxybupropion by the enzyme CYP2B6, drug interactions with CYP2B6 inhibitors are possible: this includes such medications as paroxetine, sertraline, norfluoxetine (active metabolite of fluoxetine), diazepam, clopidogrel, and orphenadrine. The expected result is an increase of bupropion and a decrease in hydroxybupropion blood concentration. The reverse effect (decrease of bupropion and increase of hydroxybupropion) can be expected with CYP2B6 inducers such as carbamazepine, clotrimazole, rifampicin, ritonavir, St John's wort, and phenobarbital. [109] Indeed, carbamazepine decreases exposure to bupropion by 90% and increases exposure to hydroxybupropion by 94%. [110] Ritonavir, lopinavir/ritonavir, and efavirenz have been shown to decrease levels of bupropion and/or its metabolites. [111] Ticlopidine and clopidogrel, both potent CYP2B6 inhibitors, have been found to considerably increase bupropion levels as well as decrease levels of its metabolite hydroxybupropion. [111]
Bupropion and its metabolites are inhibitors of CYP2D6, with hydroxybupropion responsible for most of the inhibition. Additionally, bupropion and its metabolites may decrease the expression of CYP2D6 in the liver. The end effect is a significant slowing of the clearance of other drugs metabolized by this enzyme. [2] For instance, bupropion has been found to increase area-under-the-curve of desipramine, a CYP2D6 substrate, by 5-fold. [111] Bupropion has also been found to increase levels of atomoxetine by 5.1-fold, while decreasing the exposure to its main metabolite by 1.5-fold. [112] As another example, the ratio of dextromethorphan (a drug that is mainly metabolized by CYP2D6) to its major metabolite dextrorphan increased approximately 35-fold when it was administered to people being treated with 300 mg/day bupropion. [109] When people on bupropion are given MDMA, about 30% increase of exposure to both drugs is observed, with enhanced mood but decreased heart rate effects of MDMA. [113] [114] Interactions with other CYP2D6 substrates, such as metoprolol, imipramine, nortriptyline, [114] venlafaxine, [109] and nebivolol [2] have also been reported. However, in a notable exception, bupropion does not seem to affect the concentrations of CYP2D6 substrates fluoxetine and paroxetine. [109] [115]
Bupropion lowers the seizure threshold, and therefore can potentially interact with other medications that also lower it, such as antipsychotics, tricyclic antidepressants, theophylline, and systemic corticosteroids. [10] The prescribing information recommends minimizing the use of alcohol, since in rare cases bupropion reduces alcohol tolerance. [10]
Caution should be observed when combining bupropion with a monoamine oxidase inhibitor (MAOI), as it may result in hypertensive crisis. [116]
Site | Value (nM) | Type | Species | |
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DAT | 173–1,800 372–2,780 330–2,900 550–2,170 | Ki Ki IC50 IC50 | Human Rat Human Rat | |
NET | 3,640–52,000 940–1,900 443–3,240 1,400–1,900 | Ki Ki IC50 IC50 | Human Rat Human Rat | |
SERT | 9,100–>100,000 1,000–>10,000 47,000–>100,000 15,600 | Ki Ki IC50 IC50 | Human Rat Human Rat | |
α1/1A-AdR | 4,200–16,000 | Ki | Human | |
α2/2A-AdR | >10,000–81,000 | Ki | Human | |
H1 | 6,600–>10,000 | Ki | Human | |
σ1 | 580–2,100 | IC50 | Rodent | |
α1-nACh | 7,600–28,000 | IC50 | Human | |
α3β2-nACh | 1,000 | IC50 | Human | |
α3β4-nACh | 1,800 | IC50 | Human | |
α4β2-nACh | 12,000 | IC50 | Human | |
α4β4-nACh | 12,000–14,000 | IC50 | Human | |
α7-nACh | 7,900–50,000 | IC50 | Human | |
α/β/δ/γ-nACh | 7,900 | IC50 | Human | |
hERG | 34,000–69,000 | IC50 | Human | |
Notes: (1) Values are in nanomolar (nM) units. The smaller the value, the more avidly the drug binds to or affects the site. (2) Affinities (Ki) were >10,000 nM at a variety of other sites (5-HT1, 5-HT2, β-adrenergic, D1, D2, mACh, nACh, GABAA). More: [120] [121] [122] [123] [124] [125] |
The mechanism of action of bupropion in the treatment of depression and for other indications is unclear. [2] However, it is thought to be related to the fact that bupropion is a norepinephrine–dopamine reuptake inhibitor (NDRI) and negative allosteric modulator of several nicotinic acetylcholine receptors. [2] Bupropion does not act as a norepinephrine–dopamine releasing agent. [126] Pharmacological actions of bupropion, to a substantial degree, are due to its active metabolites hydroxybupropion, threo-hydrobupropion, and erythro-hydrobupropion that are present in the blood plasma at comparable or much higher levels. [2] In fact, bupropion could accurately be conceptualized as a prodrug of these metabolites. [2] Overall action of these metabolites, and particularly one enantiomer S,S-hydroxybupropion, is also characterized by inhibition of norepinephrine and dopamine reuptake and nicotinic inhibition (see the chart on the right). [2] Bupropion has no meaningful direct activity at a variety of receptors, including α- and β-adrenergic, dopamine, serotonin, histamine, and muscarinic acetylcholine receptors. [20]
The occupancy of dopamine transporter (DAT) by bupropion (300 mg/day) and its metabolites in the human brain as measured by several positron emission tomography (PET) studies is approximately 20%, with a mean occupancy range of about 14 to 26%. [127] [28] [29] [30] For comparison, the NDRI methylphenidate at therapeutic doses is thought to occupy greater than 50% of DAT sites. [30] In accordance with its low DAT occupancy, no measurable dopamine release in the human brain was detected with bupropion (one 150 mg dose) in a PET study. [127] [28] [29] [128] Bupropion has also been shown to increase striatal VMAT2, though it is unknown if this effect is more pronounced than other DRIs. [129] These findings raise questions about the role of dopamine reuptake inhibition in the pharmacology of bupropion, and suggest that other actions may be responsible for its therapeutic effects. [127] [28] [30] [29] No data are available on occupancy of the norepinephrine transporter (NET) by bupropion and its metabolites. [127] [28] However, due to the increased exposure of hydroxybupropion over bupropion itself, which has higher affinity for the NET than the DAT, [130] bupropion's overall pharmacological profile in humans may end up making it effectively more of a norepinephrine reuptake inhibitor than a dopamine reuptake inhibitor. [31] [32] Accordingly, the clinical effects of bupropion are more consistent with noradrenergic activity than with dopaminergic actions. [31] [32]
Bupropion has been claimed to be a sigma σ1 receptor agonist. [131] [132] Its antidepressant-like effects in rodents depend on σ1 receptor activation. [131] [132] [133] They are enhanced and inhibited by σ1 receptor agonists and antagonists, respectively. [131] [132] [133] However, no data on the binding or functional effects of bupropion at the human sigma receptors seem to be available. [117] [118] [119] In any case, bupropion has been reported to bind to rodent σ1 receptors with IC50 values of 580 to 2,100 nM. [134] In contrast to many other phenethylamines and amphetamines, [135] bupropion is not an agonist of the trace amine-associated receptor 1 (TAAR1). [136] [137] [138] [139]
Bupropion has been found to have a mixture of anti-inflammatory and pro-inflammatory activity through modulation of the immune system. [140] [141] [142] [143] [144] [145] [146] One such mechanism underlying these effects may be reduced levels of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα). [140] [146] [147] The catecholaminergic actions of bupropion may be involved in its immunomodulatory effects. [147]
Bupropion | R,R- Hydroxy bupropion | S,S- Hydroxy bupropion | Threo- hydro bupropion | Erythro- hydro bupropion | |
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Exposure and half-life | |||||
AUC relative to bupropion [148] [149] | 1 | 23.8 | 0.6 | 11.2 | 2.5 |
Half-life [15] | 1.04 h | 19 h | 15 h | 31 h | 22 h |
Inhibition IC50 (μM) in human cells, unless noted otherwise (Lesser values indicate greater potency.) | |||||
DAT, uptake [130] | 0.66 | inactive | 0.63 | 47 (rat) [150] | no data |
NET, uptake [130] | 1.85 | 9.9 | 0.24 | 16 (rat) [150] | no data |
SERT, uptake [130] | inactive | inactive | inactive | 67 (rat) [150] | no data |
α3β4 nicotinic [130] | 1.8 | 6.5 | 11 | 14 (rat) [151] | no data |
α4β2 nicotinic [152] | 12 | 31 | 3.3 | no data | no data |
α1β1γδ nicotinic [152] | 7.9 | 7.6 | 28 | no data | no data |
5-HT3A [153] [154] | 87 (mouse) | 113 | no data | no data | no data |
After oral administration, bupropion is rapidly and completely absorbed reaching the peak blood plasma concentration after 1.5 hours (tmax). Sustained-release (SR) and extended-release (XL) formulations have been designed to slow down absorption resulting in tmax of 3 hours and 5 hours, respectively. [109] Absolute bioavailability of bupropion is unknown but is presumed to be low, at 5–20%, due to the first-pass metabolism. As for the relative bioavailability of the formulations, XL formulation has lower bioavailability (68%) compared to SR formulation and immediate release bupropion. [2]
Bupropion is metabolized in the body by a variety of pathways. The oxidative pathways are by cytochrome P450 isoenzymes CYP2B6 leading to R,R- and S,S-hydroxybupropion and, to a lesser degree, CYP2C19 leading to 4'-hydroxybupropion. The reductive pathways are by 11β-hydroxysteroid dehydrogenase type 1 in the liver and AKR7A2/AKR7A3 in the intestine leading to threo-hydrobupropion and by yet unknown enzyme leading to erythro-hydrobupropion. [2]
The metabolism of bupropion is highly variable: the effective doses of bupropion received by persons who ingest the same amount of the drug may differ by as much as 5.5 times (with a half-life of 12–30 hours), while the effective doses of hydroxybupropion may differ by as much as 7.5 times (with a half-life of 15–25 hours). [10] [155] [156] Based on this, some researchers have advocated monitoring of the blood level of bupropion and hydroxybupropion. [157]
The metabolism of bupropion also seems to follow biphasic pharmacokinetics: the redistribution alpha phase with half-life of about 1 hour [158] precedes the metabolism beta phase of about 12-30 hours. This might explain why abuse is unfeasible due to a short "high", as well as support the use of extended-release formulas to maintain a consistent concentration of bupropion.
The metabolism of bupropion is highly species-dependent. [159] [160] [161] As an example, oral bupropion results in hydroxybupropion levels that are 16-fold higher than those of bupropion itself in humans, whereas in rats, oral bupropion results in levels of bupropion that are 3.4-fold higher than those of hydroxybupropion. [159] The species-dependent metabolism of bupropion is thought to be involved in species differences in its pharmacodynamic effects. [159] [160] [161] For example, bupropion produces psychostimulant-like and reinforcing effects in rodents, whereas oral bupropion at therapeutic doses seems to have much less or no potential for such effects in humans. [162]
Bupropion is an aminoketone that belongs to the class of substituted cathinones and the more general class of substituted phenethylamines. [33] [34] It is also known structurally as 3-chloro-N-tert-butyl-β-keto-α-methylphenethylamine, 3-chloro-N-tert-butyl-β-ketoamphetamine, or 3-chloro-N-tert-butylcathinone. The clinically used bupropion is racemic, which is a mixture of two enantiomers: S-bupropion and R-bupropion. Although the optical isomers on bupropion can be separated, they rapidly racemize under physiological conditions. [2] [163]
Bupropion is a small-molecule compound with the molecular formula C13H18ClNO and a molecular weight of 239.74 g/mol. [164] [165] It is a highly lipophilic compound, [2] with an experimental log P of 3.6. [164] [165] Pharmaceutically, bupropion is used mainly as the hydrochloride salt but also to a lesser extent as the hydrobromide salt. [10] [11] [166]
A number of analogues of bupropion exist, such as hydroxybupropion, radafaxine, and manifaxine, among others. [159]
There have been reported cases of false-positive urine amphetamine tests in persons taking bupropion. [167] [168] [169]
It is synthesized in two chemical steps starting from 3'-chloro-propiophenone. The alpha position adjacent to the ketone is first brominated followed by nucleophilic displacement of the resulting alpha-bromoketone with t-butylamine and treated with hydrochloric acid to give bupropion as the hydrochloride salt in 75–85% overall yield. [35] [170]
This diagram shows the synthesis of bupropion via 3'-chloro-propiophenone. |
Bupropion was invented by Nariman Mehta of Burroughs Wellcome (now GlaxoSmithKline) in 1969, and the US patent for it was granted in 1974. [35] It was approved by the US Food and Drug Administration (FDA) as an antidepressant on 30 December 1985, and marketed under the name Wellbutrin. [36] [171] However, a significant incidence of seizures at the originally recommended dosage (400–600 mg/day) caused the withdrawal of the drug in 1986. Subsequently, the risk of seizures was found to be highly dose-dependent, and bupropion was re-introduced to the market in 1989 with a lower maximum recommended daily dose of 450 mg/day. [172]
In 1996, the US Food and Drug Administration (FDA) approved a sustained-release formulation of alcohol-resistant bupropion called Wellbutrin SR, intended to be taken twice a day (as compared with three times a day for immediate-release Wellbutrin). [173] In 2003, the FDA approved another sustained-release formulation called Wellbutrin XL, intended for once-daily dosing. [174] Wellbutrin SR and XL are available in generic form in the United States and Canada. In 1997, bupropion was approved by the FDA for use as a smoking cessation aid under the name Zyban. [175] [173] In 2006, Wellbutrin XL was similarly approved as a treatment for seasonal affective disorder. [176] [177]
In October 2007, two providers of consumer information on nutritional products and supplements, ConsumerLab.com and The People's Pharmacy, released the results of comparative tests of different brands of bupropion. [178] The People's Pharmacy received multiple reports of increased side effects and decreased efficacy of generic bupropion, which prompted it to ask ConsumerLab.com to test the products in question. The tests showed that "one of a few generic versions of Wellbutrin XL 300 mg, sold as Budeprion XL 300 mg, didn't perform the same as the brand-name pill in the lab." [179] The FDA investigated these complaints and concluded that Budeprion XL is equivalent to Wellbutrin XL in regard to bioavailability of bupropion and its main active metabolite hydroxybupropion. The FDA also said that coincidental natural mood variation is the most likely explanation for the apparent worsening of depression after the switch from Wellbutrin XL to Budeprion XL. [180] On 3 October 2012, however, the FDA reversed this opinion, announcing that "Budeprion XL 300 mg fails to demonstrate therapeutic equivalence to Wellbutrin XL 300 mg." [181] The FDA did not test the bioequivalence of any of the other generic versions of Wellbutrin XL 300 mg, but requested that the four manufacturers submit data on this question to the FDA by March 2013. [181] As of October 2013 [update] the FDA has made determinations on the formulations from some manufacturers not being bioequivalent. [181]
In April 2008, the FDA approved a formulation of bupropion as a hydrobromide salt instead of a hydrochloride salt, to be sold under the name Aplenzin by Sanofi-Aventis. [12] [182] [183]
In 2009, the FDA issued a health advisory warning that the prescription of bupropion for smoking cessation has been associated with reports of unusual behavior changes, agitation, and hostility. Some people, according to the advisory, have become depressed or have had their depression worsen, have had thoughts about suicide or dying, or have attempted suicide. [184] This advisory was based on a review of anti-smoking products that identified 75 reports of "suicidal adverse events" for bupropion over ten years. [185] Based on the results of follow-up trials this warning was removed in 2016. [186]
In 2012, the US Justice Department announced that GlaxoSmithKline had agreed to plead guilty and pay a $3 billion fine, in part for promoting the unapproved use of Wellbutrin for weight loss and sexual dysfunction. [187]
In 2017, the European Medicines Agency (EMA) recommended suspending a number of nationally approved medicines due to misrepresentation of bioequivalence study data by Micro Therapeutic Research Labs in India. [188] The products recommended for suspension included several 300 mg modified-release bupropion tablets. [189]
Following EMA's call for an industry-wide review of medicines for the possible presence of nitrosamines, [190] GlaxoSmithKline paused batch release and distribution of bupropion 150 mg tablets in November 2022. In July 2023, EMA raised the acceptable daily intake of nitrosamine impurities, leading GlaxoSmithKline to announce that distribution of bupropion 150 mg tablets would resume "across the EU and Europe" by the end of 2023. [191]
While bupropion demonstrates some potential for misuse, this potential is less than of other commonly used stimulants, being limited by features of its pharmacology. [192] Case reports describe the misuse of bupropion as producing a "high" similar to cocaine or amphetamine usage but with less intensity. Bupropion misuse is uncommon. [192] There have been some anecdotal and case-study reports of bupropion abuse, but the bulk of evidence indicates that the subjective effects of bupropion when taken orally are markedly different from those of addictive stimulants such as cocaine or amphetamine. [193] However, bupropion, by non-conventional routes of administration like injection or insufflation, has been reported to be misused in the United States and Canada, notably in prisons. [194] [195] [196] [197]
In Russia bupropion is banned as a narcotic drug, due to it being a derivative of methcathinone. [198] In Australia, France, and the UK, smoking cessation is the only licensed use of bupropion, and no generics are marketed. [199] [200] [201]
Brand names include Wellbutrin, [10] [11] Aplenzin, [12] Budeprion, Buproban, buprapan, Forfivo, Voxra, Zyban, [7] Bupron, Bupisure, Bupep, Smoquite, Elontril, Oribion and Buxon.[ citation needed ]
Bupropion has been studied limitedly in the treatment of social anxiety disorder. [202] [203] [204]
Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction.
Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants. TCAs were discovered in the early 1950s and were marketed later in the decade. They are named after their chemical structure, which contains three rings of atoms. Tetracyclic antidepressants (TeCAs), which contain four rings of atoms, are a closely related group of antidepressant compounds.
Sertraline, sold under the brand name Zoloft among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. The effectiveness of sertraline for depression is similar to that of other antidepressants such as Fluoxetine or Paroxetine. Sertraline is better tolerated than the older tricyclic antidepressants. Sertraline is effective for panic disorder, social anxiety disorder, generalized anxiety disorder, and obsessive–compulsive disorder (OCD). Although approved for post-traumatic stress disorder (PTSD), findings have shown sertraline leads to only modest improvements in symptoms. Sertraline also alleviates the symptoms of premenstrual dysphoric disorder and can be used in sub-therapeutic doses or intermittently for its treatment.
Fluvoxamine, sold under the brand name Luvox among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is primarily used to treat major depressive disorder and, perhaps more-especially, obsessive–compulsive disorder (OCD), but is also used to treat anxiety disorders such as panic disorder, social anxiety disorder, and post-traumatic stress disorder.
Venlafaxine, sold under the brand name Effexor among others, is an antidepressant medication of the serotonin–norepinephrine reuptake inhibitor (SNRI) class. It is used to treat major depressive disorder, generalized anxiety disorder, panic disorder, and social anxiety disorder. Studies have shown that venlafaxine improves post-traumatic stress disorder (PTSD). It may also be used for chronic neuropathic pain. It is taken orally. It is also available as the salt venlafaxine besylate in an extended-release formulation.
Duloxetine, sold under the brand name Cymbalta among others, is a medication used to treat major depressive disorder, generalized anxiety disorder, obsessive-compulsive disorder, fibromyalgia, neuropathic pain and central sensitization. It is taken by mouth.
Serotonin–norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant medications used to treat major depressive disorder (MDD), anxiety disorders, social phobia, chronic neuropathic pain, fibromyalgia syndrome (FMS), and menopausal symptoms. Off-label uses include treatments for attention-deficit hyperactivity disorder (ADHD), and obsessive–compulsive disorder (OCD). SNRIs are monoamine reuptake inhibitors; specifically, they inhibit the reuptake of serotonin and norepinephrine. These neurotransmitters are thought to play an important role in mood regulation. SNRIs can be contrasted with the selective serotonin reuptake inhibitors (SSRIs) and norepinephrine reuptake inhibitors (NRIs), which act upon single neurotransmitters.
Atomoxetine, sold under the brand name Strattera among others, is a selective norepinephrine reuptake inhibitor (sNRI) medication used to treat attention deficit hyperactivity disorder (ADHD) and, to a lesser extent, cognitive disengagement syndrome (CDS). It may be used alone or along with stimulant medication. It enhances the executive functions of self-motivation, sustained attention, inhibition, working memory, reaction time, and emotional self-regulation. Use of atomoxetine is only recommended for those who are at least six years old. It is taken orally. The effectiveness of atomoxetine is comparable to the commonly prescribed stimulant medication methylphenidate.
Nortriptyline, sold under the brand name Aventyl, among others, is a tricyclic antidepressant. This medicine is also sometimes used for neuropathic pain, attention deficit hyperactivity disorder (ADHD), smoking cessation and anxiety. Its use for young people with depression and other psychiatric disorders may be limited due to increased suicidality in the 18–24 population initiating treatment. Nortriptyline is not a preferred treatment for attention deficit hyperactivity disorder or smoking cessation. It is taken by mouth.
Trazodone, sold under many brand names, is an antidepressant medication, used to treat major depressive disorder, anxiety disorders, and insomnia. It is a phenylpiperazine compound of the serotonin antagonist and reuptake inhibitor (SARI) class. The medication is taken orally.
Radafaxine (developmental code GW-353,162; also known as (2S,3S)-hydroxybupropion or (S,S)-hydroxybupropion) is a norepinephrine–dopamine reuptake inhibitor (NDRI) which was under development by GlaxoSmithKline in the 2000s for a variety of different indications but was never marketed. These uses included treatment of restless legs syndrome, major depressive disorder, bipolar disorder, neuropathic pain, fibromyalgia, and obesity. Regulatory filing was planned for 2007, but development was discontinued in 2006 due to "poor test results".
Fluoxetine, sold under the brand name Prozac, among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is used for the treatment of major depressive disorder, obsessive–compulsive disorder (OCD), anxiety, bulimia nervosa, panic disorder, and premenstrual dysphoric disorder. It is also approved for treatment of major depressive disorder in adolescents and children 8 years of age and over. It has also been used to treat premature ejaculation. Fluoxetine is taken by mouth.
Vortioxetine, sold under the brand name Trintellix and Brintellix among others, is an antidepressant of the serotonin modulator and stimulator (SMS) class. Its effectiveness is viewed as similar to that of other antidepressants. It is taken orally.
Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions.
Hydroxybupropion, or 6-hydroxybupropion, is the major active metabolite of the antidepressant and smoking cessation drug bupropion. It is formed from bupropion by the liver enzyme CYP2B6 during first-pass metabolism. With oral bupropion treatment, hydroxybupropion is present in plasma at area under the curve concentrations that are as many as 16 to 20 times greater than those of bupropion itself, demonstrating extensive conversion of bupropion into hydroxybupropion in humans. As such, hydroxybupropion is likely to play a very important role in the effects of oral bupropion, which could accurately be thought of as functioning largely as a prodrug to hydroxybupropion.
Dextromethorphan/bupropion (DXM/BUP), sold under the brand name Auvelity, is a combination medication for the treatment of major depressive disorder (MDD). Its active components are dextromethorphan (DXM) and bupropion. Patients who stayed on the medication had an average of 11% greater reduction in depressive symptoms than placebo in an FDA approval trial. It is taken as a tablet by mouth.
Erythrohydrobupropion is a substituted amphetamine derivative—specifically a β-hydroxyamphetamine—and a minor active metabolite of the antidepressant drug bupropion (Wellbutrin). Bupropion is a norepinephrine–dopamine reuptake inhibitor and nicotinic acetylcholine receptor negative allosteric modulator, with its metabolites contributing substantially to its activities. Erythrohydrobupropion exists as a racemic mixture of two stereoisomers, (1R,2S)-erythrohydrobupropion and (1S,2R)-erythrohydrobupropion. Other metabolites of bupropion include hydroxybupropion and threohydrobupropion.
Threohydrobupropion is a substituted amphetamine derivative—specifically a β-hydroxyamphetamine—and a major active metabolite of the antidepressant drug bupropion (Wellbutrin). Bupropion is a norepinephrine–dopamine reuptake inhibitor and nicotinic acetylcholine receptor negative allosteric modulator, with its metabolites contributing substantially to its activities.
(2R,3R)-Hydroxybupropion, or simply (R,R)-hydroxybupropion, is the major metabolite of the antidepressant, smoking cessation, and appetite suppressant medication bupropion. It is the (2R,3R)-enantiomer of hydroxybupropion, which in humans occurs as a mixture of (2R,3R)-hydroxybupropion and (2S,3S)-hydroxybupropion (radafaxine). Hydroxybupropion is formed from bupropion mainly by the cytochrome P450 enzyme CYP2B6. Levels of (2R,3R)-hydroxybupropion are dramatically higher than those of bupropion and its other metabolites during bupropion therapy.
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: CS1 maint: DOI inactive as of November 2024 (link)Bupropion also acts as a dopamine reuptake inhibitor (Dwoskin et al. 2006), and has been used as a treatment for depression as well as a smoking cessation aid (Stahl et al. 2004). Bupropion has been shown to produce a dose-dependent increase in PR breakpoints (Bruijnzeel & Markou 2003). Furthermore, systemic administration of bupropion increases the selection of the high-effort, high-reward option in a PR-choice task in rats (Randall, Lee, Podurgiel, et al. 2014). Bupropion is also effective at rescuing motivational impairments in rodents. Administration of bupropion can rescue deficits in effort-related decision-making induced by pre-treatment with tetrabenazine (Randall, Lee, Nunes, et al. 2014; Nunes, Randall, Hart, et al. 2013) and the proinflammatory cytokine interleukin-6 (Yohn, Arif, et al. 2016). Bupropion has been reported to improve symptoms of apathy in cases of acquired brain injury, major depression (Corcoran et al. 2004), and frontotemporal dementia (Lin et al. 2016). However, several larger placebo-controlled studies suggest only limited effects of bupropion. In a study of 40 patients with schizophrenia, bupropion was found to have no significant effect on apathy or negative symptoms as a whole (Yassini et al. 2014). Furthermore, in a recent RCT of bupropion in HD, apathy was not significantly affected by the drug (Gelderblom et al. 2017). It is not clear whether bupropion lacks clinical efficacy, whether bupropion as a whole is not effective at treating motivational impairments, or simply not effective in the clinical populations tested.
AXS-05 is a combination of dextromethorphan and bupropion and has been shown to have a rapid (within one week) positive effect in patients with depression. Dextromethorphan, as described above as part of Nuedexta, is a σ-1R agonist, an NMDA antagonist, and has an affinity for the serotonin reuptake transporter. Whereas, bupropion is a moderately effective antidepressant when taken alone, thought to act by preventing dopamine and noradrenaline reuptake [230]. Studies in mice have shown that the antidepressant-like effects of bupropion are potentiated by σ-1R agonists, and inhibited by σ-1R antagonists [231]. These findings suggest that the combination of a σ-1R agonist and the dopamine/ noradrenaline reuptake inhibitor will be more effective than either treatment alone.
Many stimulants have potency at the rat TAAR1 in the micromolar range but tend to be about 5 to 10 times less potent at the human TAAR1, but bupropion was found to be inactive.87,88
In vitro functional studies showed agonist activity of solriamfetol at human, mouse, and rat TAAR1 receptors. hTAAR1 EC50 values (10–16 μM) were within the clinically observed therapeutic solriamfetol plasma concentration range and overlapped with the observed DAT/NET inhibitory potencies of solriamfetol in vitro. TAAR1 agonist activity was unique to solriamfetol; neither the WPA modafinil nor the DAT/NET inhibitor bupropion had TAAR1 agonist activity.
Эфедрон (меткатинон) и его производные, за исключением производных, включенных в качестве самостоятельных позиций в перечень