Wellbutrin scientific update |
|
 |
|
PMID: 16949560 [PubMed - indexed for MEDLINE]
Vann RE, Rosecrans JA, James JR, Philibin SD, Robinson SE.
Neurochemical and behavioral effects of bupropion and mecamylamine in the presence of nicotine.
A report on the neurochemical and behavioral efficacy of bupropion and mecamylamine in the presence of nicotine. Bupropion exhibits both nAChR agonist- and antagonistic-like effects. Bupropion elicits unique pharmacological differences when administered in the presence of nicotine.
The primary mechanism of action of bupropion, a smoking cessation drug, is commonly believed to involve the dopaminergic system although evidence exists that bupropion also has effects at nicotinic acetylcholine receptors (nAChRs). This study evaluated the disruptive effects of nicotine on response rates in the presence of bupropion and the nAChR antagonist, mecamylamine, as well as the ability of these drugs to alter nicotine-stimulated nAChR function in various brain areas. Rats were trained to respond on a single lever under a variable interval 15 (VI15) schedule for food reinforcement. Initially, dose effect curves were generated for nicotine, bupropion and mecamylamine. Upon determining the dose of nicotine (1.2 mg/kg) effective in completely disrupting rates of responding, it was established that both mecamylamine and bupropion block nicotine's rate-reducing effects. This result suggests that bupropion shares behavioral effects with mecamylamine when administered in the presence of nicotine. To explore this relationship further, the effect of in vivo administration of bupropion or mecamylamine on nicotine-stimulated (86)Rb(+) efflux was studied in synaptosomes prepared from the frontal cortex, hippocampus, striatum and thalamus. Nicotine-stimulated (86)Rb(+) efflux from all brain regions was significantly reduced in rats administered 3.0 mg/kg mecamylamine (s.c.) 15 min prior to dissection compared to control rats. In contrast, a significant increase in nicotine-stimulated (86)Rb(+) efflux was observed in all brain regions from rats administered 30.0 mg/kg bupropion (s.c.) 15 min prior to dissection compared to control rats. Taken together these results demonstrate that when administered in the presence of nicotine, bupropion elicits unique pharmacological differences such that it exhibits both nAChR agonist- and antagonistic-like effects.
Pharmacol Biochem Behav. 2005 May;81(1):65-70.
Kawakami Y, Kitamura Y, Araki H, Kitagawa K, Suemaru K, Shibata K, Gomita Y.
Department of Hospital Pharmacy, Okayama University Medical School, 2-5-1, Shikata-cho, Okayama, 700-8558, Japan.
Effects of monoamine reuptake inhibitors on wet-dog shakes mediated by 5-HT(2A) receptors in ACTH-treated rats.
The efficacy of monoamine reuptake inhibitors on wet-dog shakes which is mediated by 5-HT(2A) receptors in ACTH-treated rats. The influence of imipramine was examined during the study. Constant intake of imipramine, desipramine and mazindol reduced the volume of wet-dog shakes in naive rats.
We examined the influence of imipramine, a serotonin (5-HT) and noradrenaline (NA) reuptake inhibitor, desipramine, a NA reuptake inhibitor, bupropion, a dopamine reuptake inhibitor, fluvoxamine, a selective 5-HT reuptake inhibitor, and mazindol, a catecholamine reuptake inhibitor, on a 5-HT(2A) receptor-mediated behavior, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced wet-dog shakes, in naive and adrenocorticotropic hormone (ACTH)-treated rats. Chronic administration of imipramine, desipramine and mazindol suppressed the number of wet-dog shakes in naive rats. Chronic ACTH (100 mug/rat, s.c.) treatment increased the number. Chronic administration of imipramine did not decrease the number of wet-dog shakes in ACTH-treated rats. On the other hand, desipramine and mazindol inhibited the increase in wet-dog shakes in ACTH-treated rats. Fluvoxamine and bupropion did not have any effect on the (+/-)-DOI-induced response in naive and ACTH-treated rats. NA reuptake inhibitors may improve the hyperfunction of 5-HT(2A) receptors induced by chronic ACTH treatment.
J Clin Psychiatry. 2005 May;66(5):603-10.
Zimmerman M, Posternak MA, Attiullah N, Friedman M, Boland RJ, Baymiller S, Berlowitz SL, Rahman S, Uy KK, Singer S, Chelminski I.
From the Department of Psychiatry and Human Behavior, Brown University School of Medicine, Rhode Island Hospital, Providence.
Why Isn't Bupropion the Most Frequently Prescribed Antidepressant?
A review on the effectiveness of the Bupropion as the most frequently prescribed antidepressant. Bupropion does not help to cause weight gain and sexual dysfunction like other antidepressants. It is better to avoid prescribing bupropion for depressed patients with high anxiety.
OBJECTIVE: Reviews of antidepressant medication efficacy suggest that all antidepressants are equally effective. Bupropion is less likely than other antidepressants to cause weight gain and sexual dysfunction, the 2 side effects that are of greatest concern to patients and that have the greatest impact on long-term compliance. If bupropion is as effective as other antidepressants, and it does not cause the side effects that are the most frequent causes of long-term noncompliance, then why isn't it the most frequently prescribed antidepressant medication? To understand psychiatrists' decision making at the time an antidepressant is chosen, we conducted the Rhode Island Factors Associated With Antidepressant Choice Survey (FAACS). METHOD: For 1137 DSM-IV-diagnosed depressed patients initiated on an antidepressant, the treating psychiatrist completed a 43-item questionnaire listing factors that might have influenced the choice of medication. The questionnaire was filled out immediately after the antidepressant was prescribed to treat a depressive disorder. This study was conducted from August 2001 to February 2002. RESULTS: Because the reasons for choosing a medication to augment an existing regimen might be different from those used in monotherapy, augmentation trials were excluded from the analysis, leaving a sample of 965 patients. Bupropion was rarely prescribed when the presence of comorbid anxiety disorders or symptoms reflecting central nervous system activation influenced antidepressant selection. When the desire to avoid side effects, especially sexual dysfunction and weight gain, were the basis of selection, then bupropion was significantly more often prescribed than other antidepressants (p < .001). CONCLUSIONS: Although there is little evidence that patient factors predict differential medication response, psychiatrists are strongly inclined to base antidepressant selection on clinical profiles and avoid prescribing bupropion for depressed patients with high anxiety. Possible reasons for the discrepancy between psychiatrists' prescribing habits and the results of empirical study are discussed.
Wellbutrin description...
|
|
Drug category:Antidepressants
 Wellbutrin scientific update
|
|
My Basket