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PubMedDate not supplied

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↗

PubMed1990

Antidepressant profile of bupropion and three metabolites in mice.

Bupropion is a novel antidepressant, distinct from tricyclic antidepressants both neurochemically and behaviorally. Bupropion forms several metabolites in both rodents and humans. Three chemically different molecules - BW 306, BW 494, and BW 287 - were selected. Comparative assessment of antidepressant activity of bupropion and its metabolites in mice, and pharmacological analysis of possible mechanisms of action of the parent drug and its metabolites (using interaction studies with pimozide, D,L-propranolol, and prazosin) were carried out. The results obtained show that: bupropion has a pharmacological spectrum in various animal models which predicts both antidepressant and stimulatory activity in man. BW 306 is the most active of the metabolites studied and, compared to bupropion, seems more "antidepressant" and less stimulant. BW 494, compared to bupropion or BW 306, has a lower degree of activity in various tests used to evaluate antidepressants. BW 287 has no effect in any of the tests used in this study. The interaction studies with pimozide, D,L-propranolol, and prazosin in the various tests have shown that: the stimulatory effect of bupropion, BW 306, and BW 494 is antagonized by both pimozide and prazosin. in the behavioral despair test, the reduction in the duration of immobility by bupropion and BW 494 is antagonized by pimozide, but not by prazosin or D,L-propranolol. the antagonism of reserpine-induced hypothermia by bupropion and BW 306 is significantly decreased by prazosin and D,L-propranolol, but not by pimozide. These data suggest that the clinical antidepressant profile (without a major stimulatory effect) observed in man after administration of bupropion is related to metabolite BW 306 and possibly to BW 494, rather than to bupropion itself.

Animals↗

PubMed1991

Cardiovascular effects of bupropion in depressed patients with heart disease.

OBJECTIVE: The cardiovascular effects of therapeutic plasma levels of tricyclic antidepressants in depressed patients with and without preexisting cardiac disease have been well characterized and include orthostatic hypotension and conduction delay. Bupropion, structurally unrelated to tricyclic antidepressants, is relatively free of cardiac side effects in depressed patients without cardiac disease. However, it is unknown whether bupropion is safe for depressed patients with preexisting heart disease, so the authors studied the cardiovascular effects of bupropion in such patients. METHOD: The subjects were 36 inpatients with DSM-III major depression and preexisting left ventricular impairment (N = 15), ventricular arrhythmias (N = 15), and/or conduction disease (N = 21). The patients continued their cardiac drug regimens and received bupropion for 3 weeks (mean +/- SD dose = 442 +/- 47 mg/day). Cardiovascular functioning was measured by pulse, blood pressure, high-speed ECG, 24-hour portable ECG, and radionuclide angiography. RESULTS: Although bupropion caused a rise in supine blood pressure, it did not cause significant conduction complications, did not exacerbate ventricular arrhythmias, had a low rate of orthostatic hypotension, and had no effect on pulse rate. However, bupropion treatment was discontinued for 14% of the patients because of adverse effects, including exacerbation of baseline hypertension in two patients. CONCLUSIONS: The cardiovascular profile of bupropion may make this drug a useful agent in the treatment of the depressed patient with preexisting cardiovascular disease. Further studies, with longer durations of bupropion treatment and more subjects, are needed to confirm these findings.

Aged↗

PubMed1992

Bupropion in the treatment of bipolar disorders: the same old story?

BACKGROUND: The treatment of bipolar disorders with mood stabilizing agents is complicated by breakthrough episodes of depression. Currently there are no consistently safe and effective medications for these episodes. The authors address the use of bupropion for this purpose. METHOD: Bupropion was added to the treatment regimens of 3 male and 8 female patients who had bipolar disorders as diagnosed by DSM-III-R criteria and were depressed and nonresponsive to current treatment. Ten of the 11 had previously cycled into manic episodes when treated with either a tricyclic antidepressant, fluoxetine, or phenelzine. RESULTS: Seven of the 11 patients had moderate-to-marked improvement after 6 weeks of treatment. A moderate-to-marked improvement continued in 4 of the 11 patients after a mean of 12 months of treatment (range, 0-20 months), justifying the continuation of bupropion. Baseline Global Assessment of Functioning scores, history of previous response to other antidepressants, treatment refractoriness, comorbid diagnoses, bipolar subtype, family history, cycle length, and demographics did not discriminate between bupropion responders and nonresponders. However, 6 of the 11 patients experienced manic or hypomanic episodes that necessitated discontinuation of bupropion. Five of the 6 patients who had manic episodes had been stabilized on lithium and carbamazepine or valproate prior to the addition of bupropion. CONCLUSION: These findings, based on consecutive cases, suggest that bupropion may pose the same risks as other antidepressants in precipitating manic episodes in depressed bipolar patients. The authors conclude that caution should be exercised when using bupropion in the treatment of bipolar disorders.

Adult↗

PubMed1991

Double-blind comparison of bupropion and fluoxetine in depressed outpatients.

BACKGROUND: This study was undertaken to compare the efficacy and safety of bupropion and fluoxetine. METHOD: Moderately to severely depressed outpatients who fulfilled the DSM-III-R criteria for nonpsychotic major depressive disorder and had a score of 20 or more on the Hamilton Rating Scale for Depression (21 item) participated in this two-center study. Following a 1-week placebo phase, patients were randomly assigned to receive either bupropion or fluoxetine for 6 weeks of double-blind treatment. Weekly efficacy assessments included Hamilton Rating Scale for Depression, Hamilton Rating Scale for Anxiety, Clinical Global Impressions-Severity, and Clinical Global Impressions-Improvement. Vital signs and adverse experiences were also assessed weekly. RESULTS: A total of 61 patients were randomly assigned to receive bupropion (225-450 mg/day) and 62 were randomly assigned to receive fluoxetine (20-80 mg/day). The mean daily dose at the end of the study was 382 mg/day for the bupropion treatment group and 38 mg/day for the fluoxetine treatment group. There were no statistically significant differences between treatments on any of the efficacy variables. On the basis of a 50% or greater reduction in the HAM-D scores, 63% (N = 37) of the bupropion-treated and 58% (N = 35) of the fluoxetine-treated patients were categorized as responders, and on the basis of CGI scores, 68% (N = 40) of the bupropion-treated and 58% (N = 35) of the fluoxetine-treated patients were rated as much or very much improved. HAM-A scores decreased by 59% for both treatment groups. The incidence of treatment-emergent adverse events was low with no statistically significant differences between treatments. Twenty-six percent (N = 16) of the bupropion-treated and 29% (N = 18) of the fluoxetine-treated patients prematurely discontinued treatment. CONCLUSION: Both bupropion and fluoxetine demonstrated similar efficacy in relieving depression and accompanying symptoms of anxiety, and both exhibited a similar, favorable safety profile.

Adult↗

PubMed1985

Characterization of the bupropion cue in the rat: lack of evidence for a dopaminergic mechanism.

Using a two-lever operant task rats were trained to discriminate 40 mg/kg IP of bupropion from saline. Despite bupropion's established dopaminergic activity in vitro and in vivo, it was found that the bupropion cue was neither mimicked by the dopaminergic drugs L-DOPA and bromocriptine nor blocked by a variety of neuroleptics (haloperidol, thioridazine, and thiothixene). In addition, bupropion was active in attenuating the behavior-suppressing effects of haloperidol, unlike amphetamine and the atypical antidepressants, nomifensine and viloxazine. The bupropion cue was not mimicked or disrupted by adrenergic or serotonergic drugs, but it did generalize to some stimulants (amphetamine, cocaine and caffeine) as well as to nomifensine and viloxazine. The generalizations were blocked by neuroleptics. These data indicate that bupropion's cue properties may not be based on its ability to modulate dopaminergic receptor activity. The possible involvement of phenylethylamine in the bupropion cue is also discussed.

Animals↗

PubMed1992

Effects of bupropion on core body temperature of mice.

The effects of bupropion on core body temperature of intact or reserpinized mice were studied. Intraperitoneal (IP) administration of bupropion to mice induced a dose-dependent hypothermia. The response of bupropion was decreased by the D-2 antagonist sulpiride or pimozide, but not by the D-1 antagonist SCH 23390, antimuscarinic drug atropine, alpha-adrenergic blocker phenoxybenzimine, beta-adrenergic antagonist propranolol or antiserotonergic methergoline. Reserpine induced hypothermia, which was reversed by bupropion administration. The reversal response of bupropion was reduced by propranolol, but not sulpiride, SCH 23390, phenoxybenzamine, atropine or methergoline. It is concluded that bupropion-induced hypothermia may be mediated through D-2 receptor activation, while the reversal of reserpine-induced hypothermia by bupropion may be exerted through beta-adrenergic stimulation.

Adrenergic alpha-Antagonists↗

PubMed1989

Acute effects of bupropion on extracellular dopamine concentrations in rat striatum and nucleus accumbens studied by in vivo microdialysis.

This study examined the acute effects of the novel antidepressant drug, bupropion, on extracellular concentrations of dopamine (DA), its metabolites, and the serotonin metabolite 5-HIAA in the striatum and nucleus accumbens using on-line microdialysis in freely moving rats. Bupropion HCl (10, 25, and 100 mg/kg intraperitoneally) increased extracellular striatal DA in a dose- and time-dependent manner; 1 mg/kg did not affect extracellular DA. The maximal response occurred within the first 20 minutes (+76%, +164%, and +443% for each dose, respectively) followed by a gradual decrease to a stable but elevated level for the next 2 hours. This neurochemical response was strongly associated with bupropion-induced stereotyped behavior during the first hour but not during the subsequent 2 hours. Bupropion decreased DOPAC concentrations, increased 5-HIAA, and had variable effects on homovanillic acid (HVA) (decreases with 10 mg/kg and increases with 25 and 100 mg/kg). The increase in extracellular DA after bupropion (25 mg/kg) was blocked by tetrodotoxin and was therefore action-potential-dependent. Bupropion produced similar neurochemical responses in the striatum and the nucleus accumbens. These results suggest that increases in DA transmission contribute to the behavioral effects of bupropion and are consistent with a role for DA in the antidepressant effects of this drug. The partial dissociation between DA release and stereotyped behavior suggests that the relationship between neurotransmitter release and behavior may be complex.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1986

Bupropion effects in attention deficit and conduct disorders.

Children with Attention Deficit and/or Conduct Disorders were treated with bupropion, a new antidepressant, to determine its clinical, cognitive, and EEG effects. Seventeen male patients (age range 7 to 13.4 years; mean 10.4) participated in an open clinical trial consisting of a baseline placebo period (4 weeks), bupropion therapy (8 weeks), and post-drug placebo (2 weeks). Evaluations included clinical assessments, parents, teachers, and self-ratings; cognitive tests and blood level measurements of bupropion. Fifteen patients received a daily maximum of 150 mg, one received 100 mg and one 50 mg. Clinical global improvement with bupropion therapy was marked in 5 patients, moderate in 7, mild in 2, and none in 3. The Children's Psychiatric Rating Scale indicated improvements of hyperactivity, withdrawal, anxiety, hostility/uncooperativeness, sleep disorder, antisocial behaviour, neuroticism, depression and eating disturbance. Parents' Questionnaires indicated significant improvements of conduct disorder, anxiety, hyperactivity, muscle tension and psychosomaticism. While no single cognitive test showed significant improvement, all nine tests changed in the positive direction. Adverse effects were infrequent, transient and mild. There were no clinically significant changes of the laboratory values and vital signs. Two weeks following bupropion discontinuation, clinical global improvement was maintained in 8 patients, 7 showed relapses, while 2 remained unimproved. Analyses of computerized EEG revealed that degree of clinical improvement was indexed by baseline EEG parameters and that there were significant bupropion effects on EEG measures. Double-blind trials of bupropion are recommended in child psychiatry disorders.

Adolescent↗

PubMed1988

The effect of H2-antagonists on the absorption of bupropion in rats.

Bupropion absorption was investigated by oral administration of bupropion alone or in combination with cimetidine or ranitidine to rats. Blood samples were collected before and at 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.5 and 6 h after bupropion administration. The assay of bupropion in plasma was carried out by an HPLC method. Cimetidine or ranitidine did not significantly affect the plasma bupropion concentrations on concurrent administration. No significant differences were observed between area under the curves (AUC)s, maximum plasma concentration, time to peak and the half-life of bupropion among the three groups. These results indicate that neither cimetidine nor ranitidine significantly affects the rate or the extent of bupropion absorption in rats.

Absorption↗

PubMed1986

Effect of plasma from patients containing bupropion and its metabolites on the uptake of norepinephrine.

The uptake of norepinephrine into cortical punches from the brain of the rat was studied in the presence of buffer and plasma from patients containing bupropion and its metabolites. Even though bupropion and its metabolite (compound II) were equipotent in inhibiting the uptake of NE in buffer, compound II was twice as active as bupropion in the presence of human plasma. When the inhibition of uptake of NE in the presence of plasma, obtained from patients on bupropion on steady-state, was correlated with levels of bupropion and its metabolites (II, III, IV) a highly significant correlation was seen in the presence of compound II. Since this compound accumulated in plasma from patients 20-100 times that of the parent compound, the mode of action of bupropion may in part be due to the effect of this compound on the uptake of NE.

Animals↗

PubMed1988

Anorectic and behavioural effects of bupropion.

1. Bupropion (12.5-75 mg kg-1) was given intraperitoneally to rats and was found to decrease the food consumption of the animals dose-dependently. While phenoxybenzamine, propranolol and methergoline failed to antagonize the anorectic effect of the drug; pimozide a dopamine receptor blocker decreased anorexia induced by bupropion. 2. Bupropion (12.5-50 mg kg-1) also caused a marked increase in locomotor activity of the rats. The increase in locomotion produced by bupropion was completely antagonized by pretreatment of the animals with pimozide and reserpine plus a-methyl-p-tyrosine, but not by pretreatment with phenoxybenzamine, propranolol or methergoline. 3. Taking into considerations the evidences of dopaminergic properties of bupropion shown by the others, it could be suggested that the anorexia and hyperactivity produced by bupropion may be induced through the indirect dopaminergic mechanism.

Animals↗

PubMed1986

A case of bupropion-induced seizure.

Bupropion is a novel new antidepressant without the undesirable anticholinergic, cardiotoxic, sedative, or sexual side effects of other available antidepressants. However, like many other antidepressants, there is a small risk that patients on bupropion may develop a seizure even at moderate doses and moderate blood levels and even in the absence of any premorbid history or other predisposing factors to epilepsy. The report presents the case of a 25-year-old woman with a 12-year history of agoraphobia and panic attacks treated with bupropion in a research protocol. She was in good physical health, with normal physical and neurological examination, and normal complete blood count, serum mineral analysis-12, and urinalysis laboratory values. She had no premorbid history of epilepsy or neurological illness, nor any other known predisposing factors to epilepsy. On day 28 of the study, immediately after her dose of bupropion was increased from 450 to 600 mg/day, she had a generalized convulsion with tonic and clonic phases, loss of consciousness, and postictal confusion that was reliably witnessed by several observers. The EEG abnormality had cleared 15 days later. Further EEGs after 4 weeks and 10 weeks were normal. Five years later she remains seizure-free, off all antiseizure medication, and without any further complications from this incident. This seizure occurred at a modest blood level of bupropion (83 ng/ml) and at a dose not considered excessive (600 mg/day). Other confounding organic and neurological illness or use of other medication was carefully and systematically ruled out, leaving the bupropion as the most likely explanation for her seizure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Effects of chronic bupropion on interstitial concentrations of dopamine in rat nucleus accumbens and striatum.

Bupropion is a novel atypical antidepressant that inhibits dopamine (DA) uptake. The present experiments investigated the effects of acute (10 mg/kg, twice daily for 2 days) and chronic (10 mg/kg, twice daily for 21 days) bupropion treatment on interstitial DA concentrations using simultaneous in vivo microdialysis in the nucleus accumbens (NAC) and striatum of awake freely moving rats. Compared to animals that had not previously been exposed to the drug, bupropion (25 mg/kg, IP) induced increases in extracellular DA were significantly enhanced in the NAC of the chronic but not the acute bupropion group. This effect was regionally selective, as it was not observed in the striatum. In accordance with previous reports, concurrent behavioral measurements indicated that the locomotor stimulant effects of bupropion were also enhanced in the chronic group. These results demonstrate that bupropion-induced behavioral sensitization is accompanied by a selective potentiation of the effects of this compound on interstitial DA concentrations in the NAC.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1990

Disposition of bupropion in healthy volunteers and subjects with alcoholic liver disease.

Bupropion hydrochloride is a new monocyclic antidepressant. In humans, its disposition results in the formation of three major metabolites: the morpholinol metabolite, the erythroamino alcohol, and the threoamino alcohol metabolite. Bupropion's disposition was monitored following a single oral 200 mg dose in eight healthy volunteers and eight age- (44.5 +/- 8.4 years) and weight- (77.4 +/- 6.7 kg) matched volunteers with alcoholic liver disease. This latter group is of interest because the incidence of depression is more frequent in alcoholics than in the general population, and the liver is the major route of elimination for cyclic antidepressants. The mean elimination half-life of the morpholinol metabolite was significantly prolonged in subjects with alcoholic liver disease (32.2 +/- 13.5 vs. 21.1 +/- 4.9 hours (p less than 0.05), while the differences in bupropion (17.3 +/- 8.6 hours vs. 16.5 +/- 10.4 hours for healthy subjects and subjects with alcoholic liver disease, respectively), erythroamino alcohol (26.1 +/- 13.3 hours vs. 29.8 +/- 6.9 hours for healthy subjects and subjects with alcoholic liver disease, respectively), and threoamino alcohol (25.5 +/- 8.6 hours vs. 23.4 +/- 10.7 hours for healthy subjects and subjects with alcoholic liver disease, respectively) were minimal. Mean area under the plasma concentration time curves for bupropion and metabolites were increased in subjects with alcoholic liver disease; however, clear differences between means of these small groups did not emerge, probably due to the increased variability of bupropion pharmacokinetics in these subjects. As a therapeutic agent for the treatment of depression in chronic alcoholics who may consume alcohol in combination with their antidepressant therapy, the lack of sedation with bupropion could be advantageous.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

A comparison of the effects of sibutramine hydrochloride, bupropion and methamphetamine on dopaminergic function: evidence that dopamine is not a pharmacological target for sibutramine.

Sibutramine hydrochloride, a novel monoamine reuptake inhibitor antidepressant, has been studied to determine whether it alters dopaminergic function in the brain. Its effects have been compared with bupropion, a dopamine reuptake inhibitor, and methamphetamine, a dopamine reuptake inhibitor and releasing agent. Sibutramine (0.1-3 mg/kg PO) and methamphetamine (0.3-30 mg/kg PO) both prevented reserpine (0.75 mg/kg IV) ptosis in rats with ED50 values of 0.6 mg/kg and 4.2 mg/kg, respectively. Bupropion (10-100 mg/kg PO) was ineffective against reserpine ptosis. The efflux of [3H]-dopamine from preloaded rat striatal slices was not altered by 10(-7)-10(-5) M concentrations of sibutramine, BTS 54,354, BTS 54,505 (secondary and primary amine metabolites, respectively) or bupropion. In contrast, methamphetamine (10(-8)-10(-4) M) caused a significant concentration-dependent increase in [3H]-dopamine release. Sibutramine (3 mg/kg IP or 6 mg/kg PO) and bupropion (10 mg/kg IP or 30 mg/kg PO) did not alter 3-methoxytyramine (3-MT) levels in rat striatum. Striatal 3-MT concentrations were, however, dose-dependently increased by methamphetamine (0.3-10 mg/kg IP or 0.42-4.2 mg/kg PO). Sibutramine (6 mg/kg PO) did not induce circling in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic neuronal tract. Bupropion (10-100 mg/kg PO) did not induce circling at the lowest dose, but caused increasing ipsilateral rotation at higher doses. Methamphetamine (0.42 or 4.2 mg/kg PO) induced ipsilateral circling with marked effects at the higher dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Bupropion treatment of fluoxetine-resistant chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) includes many symptoms of major depression. For this reason, many antidepressants have been used to treat the symptoms of this disorder. Among the more recently released antidepressants are fluoxetine and bupropion. In this open study, nine CFS patients who either could not tolerate or did not respond to fluoxetine showed significant response when administered 300 mg/day of bupropion for an 8-week period in both rating of HDRS (t = 4.80, p < 0.01) and BDI (t = 2.48, p < 0.05). Furthermore, bupropion improvement in Hamilton Depression Rating Scale correlated significantly with change in plasma homovanillic acid (HVA) (r = 0.96, p < 0.01). Plasma total methylhydroxyphenolglycol (MHPG) also increased significantly during bupropion treatment (t = 2.37, p = 0.05). Measures of T1 microsomal antibodies also decreased over treatment time; increases in natural killer cell numbers correlated inversely with change in plasma levels of free MHPG (r = -0.88, p < 0.05). Bupropion responders were more likely to have trough blood levels above 30 ng/ml (chi 2 = 3.6, p = 0.05).

Adult↗

PubMed1985

The conditioned place preference paradigm in rats: effect of bupropion.

The effect of bupropion in the conditioned place preference paradigm in rats is described. In doses between 10 and 50 mg/kg i.p. bupropion increased the time rats spent in a shuttle box compartment conditioned to this compound. This effect of bupropion was not blocked by pretreatment of the animals with 0.1 mg/kg i.p. haloperidol or 50 mg/kg i.p. sulpiride. The same doses of the neuroleptics did, however, attenuate locomotor hyperactivity induced by bupropion. Bupropion thus seems to belong to the group of CNS stimulants whose effect in the conditioned place preference paradigm is not blocked by neuroleptics.

Animals↗