The thermogenic and hypophagic effects of sibutramine's metabolite (metabolite 2), a 5-hydroxytryptamine (5-HT) and noradrenaline reuptake inhibitor, were investigated in rats and compared with duloxetine and Bupropion ( Wellbutrin SR ). Metabolite 2 increased colonic temperature for 2.5-4.5 h. Duloxetine was also thermogenic but was less effective than metabolite 2. Bupropion ( Wellbutrin SR ) similarly increased colonic temperature and was as efficacious, but less potent, than metabolite 2. At -8 degrees C, metabolite 2, duloxetine and Bupropion ( Wellbutrin SR ) all decreased response to heat reinforcement and reduced colonic temperature. Metabolite 2 produced a sustained increase in oxygen consumption (VO(2)) at 29 degrees C from 90 to 240 min, whereas duloxetine was far less effective. Bupropion ( Wellbutrin SR ) rapidly enhanced VO(2), but its effect was less prolonged than that of metabolite 2. Metabolite 2 markedly reduced 24-h food intake. Duloxetine decreased feeding although its effect was shorter-lived, but Bupropion ( Wellbutrin SR ) was without effect. Thus, sibutramine's antiobesity action is probably attributable to effects on energy intake and expenditure. Duloxetine shares these properties, but is generally less efficacious. Any potential weight-reducing effect of Bupropion ( Wellbutrin SR ) is probably due to thermogenesis.

The effect of H2-antagonists on the absorption of Bupropion ( Wellbutrin SR ) in rats.

Bupropion ( Wellbutrin SR ) absorption was investigated by oral administration of Bupropion ( Wellbutrin SR ) 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 ( Wellbutrin SR ) administration. The assay of Bupropion ( Wellbutrin SR ) in plasma was carried out by an HPLC method. Cimetidine or ranitidine did not significantly affect the plasma Bupropion ( Wellbutrin SR ) 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 ( Wellbutrin SR ) among the three groups. These results indicate that neither cimetidine nor ranitidine significantly affects the rate or the extent of Bupropion ( Wellbutrin SR ) absorption in rats.

Prescribing trends of antidepressants in bipolar depression.

BACKGROUND: This study utilizing pharmacoepidemiologic methods was undertaken to determine the prescribing patterns of antidepressants particularly in bipolar depression. METHOD: From pharmacy records of the McLean Hospital, the number of patients receiving antidepressants and given electroconvulsive therapy (ECT) from June 1, 1987, to May 8, 1993, was determined. We later linked these data bases with patients who were diagnosed with DSM-III-R bipolar depression (296.5) during the same period of time. RESULTS: During the 6-year period, it was determined that 3829 inpatients had received tricyclic antidepressants (TCAs), 2981 Fluoxetine ( Prozac ), 2603 trazodone, 809 Bupropion ( Wellbutrin SR ), 743 monoamine oxidase inhibitors (MAOIs), 592 stimulants, 588 Sertraline HCL ( Zoloft ), 48 Paroxetine ( Paxil ), and 894 ECT. There were significant increases over time in prescriptions of MAOIs compared with Fluoxetine ( Prozac ) (chi 2 = 14.36, p = .006), and Bupropion ( Wellbutrin SR ) compared with TCAs (chi 2 = 6.45, p = .04). There was a trend for Bupropion ( Wellbutrin SR ) to be prescribed more over time compared with Fluoxetine ( Prozac ) (chi 2 = 5.09, p = .08). There were no significant changes in the prescribing of other antidepressants or in the use of ECT. CONCLUSION: At our center, prescribing of Bupropion ( Wellbutrin SR ) and MAOIs in bipolar depression has increased significantly. This may be related to the reports in the literature of the low switch rates to mania with the use of these drugs.

Central effects of repeated treatment with Bupropion ( Wellbutrin SR ).

The effect of Bupropion ( Wellbutrin SR ), a new clinically active antidepressant drug, administered repeatedly to rats and mice, was compared with that of imipramine. The drugs were given orally twice a day for 14 days, Bupropion ( Wellbutrin SR ) in a dose of 20 mg/kg, imipramine--10 mg/kg. The action of Bupropion ( Wellbutrin SR ) was studied in the following tests: clonidine-induced aggression in mice, open field in rats, amphetamine-induced hypermotility in rats, clenbuterol-induced hyperthermia in rats kept at high ambient temperature. Moreover, the effect of Bupropion ( Wellbutrin SR ) on 3H-prazosin binding to membranes from the cerebral cortex was measured. On the basis of the results obtained it may be concluded that in some tests chronically administered Bupropion ( Wellbutrin SR ) acts like imipramine; as both drugs potentiate the amphetamine-enhanced locomotor activity, attenuate the hyperthermic response to clenbuterol and increase the number of 3H-prazosin binding sites in the cerebral cortex.