Carolyn Bolden-Watson

Blockade by newly-developed antidepressants of biogenic amine uptake into rat brain synaptosomes

We determined the uptake blockade produced by eight new antidepressant drugs (etoperidone, femoxetine, lofepramine, nefazodone, paroxetine, sertraline, tomoxetine, and venlafaxine), two metabolites of newer antidepressants (desmethylsertraline and norfluoxetine), seven previously reported antidepressants, and carbamazepine. Inhibitor constants (Kis) for uptake blockade were obtained from competitive uptake studies with [3H]norepinephrine, [3H]5-hydroxytryptamine, and [3H]dopamine in rat brain synaptosomes prepared from hippocampus, frontal cortex, and striatum, respectively. Among the newer compounds, tomoxetine (Ki = 0.7 nM) and lofepramine (Ki = 1.9 nM) were potent and selective [3H]norepinephrine uptake blockers; paroxetine (Ki = 0.73 nM), sertraline (Ki = 3.4 nM), and femoxetine (Ki = 22 nM) potently and selectively inhibited [3H]5-hydroxytryptamine uptake. Although none of the drugs was potent for [3H]dopamine uptake blockade, sertraline was the most potent (Ki = 260 nM). These data are useful in predicting adverse effects and drug-drug interactions of antidepressants.

The efficacy of lamotrigine in rapid cycling and non-rapid cycling patients with bipolar disorder

BACKGROUND Patients with bipolar disorder (BD) who have rapid cycling features are often treatment refractory. Clear and conclusive evidence regarding effective treatments for this group is not available. METHODS Patients with diagnoses of refractory bipolar disorder who were currently experiencing manic, mixed, depressive, or hypomanic episodes were treated with lamotrigine as add-on therapy (60 patients) or monotherapy (15 patients). We compared the efficacy of lamotrigine in the 41 rapid cycling and 34 non-rapid cycling patients with BD. RESULTS Improvement from baseline to last visit was significant among both rapid cycling and non-rapid cycling patients for both depressive and manic symptomatology. For patients entering the study in a depressive episode, improvement in depressive symptomatology was equivalent in the two groups. Among patients entering the study in a manic, mixed, or hypomanic episode, those with rapid cycling improved less in manic symptomatology than did non-rapid cycling patients. Among rapid cycling patients with initial mild-to-moderate manic symptom severity, improvement was comparable to that in non-rapid cycling subjects; however, the subset of rapid cycling patients with severe initial manic symptomatology had little improvement in mania. Rapid cycling patients had earlier onset and more lifetime episodes of mania, depression, and mixed mania. CONCLUSIONS Lamotrigine was generally effective and well tolerated in this group of previously non-responsive, rapid cycling bipolar patients.

Bupropion sustained release (SR) for the treatment of hypoactive sexual desire disorder (HSDD) in nondepressed women.

This article describes the results of the first report of bupropion sustained release (SR) in nondepressed females with hypoactive sexual desire disorder (HSDD). Eligible females entered a 4-week, single-blind, placebo baseline phase. Subjects, all of whom did not respond to placebo, continued in a single-blind active treatment phase where they received bupropion SR for up to 8 additional weeks. We assessed HSDD by using investigator ratings of sexual desire and sexual functioning. Of the 51 evaluable subjects who entered the active treatment phase, 29% responded to treatment with bupropion SR. Bupropion SR was generally well tolerated. Pending the results of further study, bupropion SR may offer a treatment option for women with HSDD.This article describes the results of the first report of bupropion sustained release (SR) in nondepressed females with hypoactive sexual desire disorder (HSDD). Eligible females entered a 4-week, single-blind, placebo baseline phase . Subjects, all of whom did not respond to placebo, continued in a single-blind active treatment phase where they received bupropion SR for up to 8 additional weeks. We assessed HSDD by using investigator ratings of sexual desire and sexual functioning. Of the 51 evaluable subjects who entered the active treatment phase, 29% responded to treatment with bupropion SR. Bupropion SR was generally well tolerated. Pending the results of further study, bupropion SR may offer a treatment option for women with HSDD.

Naratriptan efficacy in migraineurs who respond poorly to oral sumatriptan.

Objectives.—To determine whether 347 patients would respond to a 50‐mg oral dose of sumatriptan, even though they considered themselves poor responders to this acute therapy for migraine, and to investigate whether oral naratriptan can be an effective acute therapy for migraine in the subset of patients who did not respond to sumatriptan under double‐blind, well‐controlled conditions.

Effect on body weight of bupropion sustained-release in patients with major depression treated for 52 weeks

BACKGROUND Short-term studies have demonstrated a modest weight-reducing to weight-neutral effect among patients receiving bupropion sustained-release (SR) for the treatment of depression. OBJECTIVE This study was conducted to evaluate the long-term effects of bupropion SR on body weight in patients with depression. METHODS This analysis was conducted within a long-term relapse-prevention study in patients with major depression. Those whose depression had responded to open-label treatment with bupropion SR were randomized to 44 weeks of double-blind treatment with bupropion SR 300 mg/d or placebo. Patients were categorized by body mass index (BMI) as follows: BMI < 22, BMI 22 to 26, BMI > or = 27, and BMI > or = 30. RESULTS Four hundred twenty-three patients were enrolled in the double-blind phase of the study, 210 receiving bupropion SR and 213 receiving placebo. At the end of the open-label phase, the following mean weight losses were seen in the 4 BMI groups: BMI < 22, 0.5 kg; BMI 22 to 26, 1.1 kg; and BMI > or = 27 and BMI > or = 30, 1.8 kg each. At the end of double-blind treatment, mean change-from-baseline weights were as follows: BMI < 22, -0.1 kg; BMI 22 to 26, -0.6 kg; BMI > or = 27, -1.4 kg; and BMI > or = 30, -2.4 kg. The rate of change in body weight during the double-blind phase was statistically significant compared with baseline BMI (P < 0.001, analysis of covariance). CONCLUSIONS Modest mean weight losses that increased with increasing baseline body weight were observed with long-term bupropion SR treatment. The findings of this analysis suggest that bupropion SR may be an appropriate therapeutic option in normal-weight or overweight patients with depression who are concerned about weight gain.

Antagonism of the five cloned human muscarinic cholinergic receptors expressed in CHO-K1 cells by antidepressants and antihistaminics

Based on molecular cloning studies, five different muscarinic receptor subtypes exist: m1, m2, m3, m4, and m5. We determined the affinity and selectivity of binding for sixteen antidepressants, two of their metabolites, and three antihistaminics (H1) at these subtypes. Using Chinese hamster ovary cells (CHO-K1) transfected with genes for the human muscarinic receptor subtypes, we obtained equilibrium dissociation constants (Kds) from competitive radioligand binding studies with [3H]-quinuclidinyl benzilate ([3H]QNB) and membranal preparations of these cells. QNB was the most potent compound studied (Kd 30-80 pM). Mequitazine (Kd 6-14 nM) and amitriptyline (Kd 7-16 nM) exhibited the highest affinity among the antihistaminics and antidepressants, respectively. Among the antidepressants examined were the serotonin-selective drugs sertraline and fluoxetine, both of which displayed Kd values > 1 microM. The remaining antidepressants were moderate to weak antagonists with some eliciting no radioligand competition at high concentrations. The compounds studied showed no significant selectivity among the five cloned subtypes.

Response in Relation to Baseline Anxiety Levels in Major Depressive Disorder Treated with Bupropion Sustained Release or Sertraline

Our objective was to determine if pretreatment anxiety levels were associated with preferential response to bupropion sustained release (n = 122) or sertraline (n = 126) during a 16-week randomized acute phase treatment study. Both agents had comparable antidepressant activity, and comparable anxiolytic effects using the intent-to-treat sample. Baseline anxiety levels were not related to antidepressant efficacy, and they did not differentiate responders to each agent. Time to clinically significant anxiolysis did not differentiate between treatment groups or between responders to each agent. These results contradict the commonly held, but unsubstantiated, belief that in clinically depressed anxious patients, serotonergic antidepressants are especially anxiolytic and that such patients preferentially benefit from the antidepressant or anxiolytic effects of selective serotonin reuptake inhibitors. Thus, the clinical decision to select between these two agents when treating depressed outpatients cannot rest on either levels of pretreatment anxiety or on anticipation of more rapid or more complete anxiolysis.

The Rat Neurotensin Receptor Expressed in Chinese Hamster Ovary Cells Mediates the Release of Inositol Phosphates

Abstract: To study second messenger synthesis mediated by the cloned rat neurotensin receptor, we derived a cell line stably expressing this receptor. The cDNA clone of this receptor was subcloned into the pcDNA 1 neo expression vector. This construct was then used to transfect Chinese hamster ovary (CHO)‐K1 cells. Colony clones, selected for resistance to antibiotic G‐418 sulfate, were isolated and grown separately. Nineteen individual clones were screened for total [3H]neurotensin binding as an indication of neurotensin receptor expression. The clone (CHO‐rNTR‐10) showing the highest level of specific [3H]neurotensin binding was characterized further. With intact cells, the equilibrium dissociation constant (KD) for specific [3H]neurotensin binding was 18 nM, and the maximal number of binding sites (Bmax) was 900 fmol/mg of protein or 740 fmol/106 cells (sim4.4 × 105 sites on the cellular surface). Whereas the KD was similar to that found in other cellular systems, for example, the murine neuroblastoma clone N1E‐115, the Bmax exceeded previously reported values. Incubation of intact CHO‐rNTR‐10 cells with neurotensin caused the release of inositol phosphates in a dose‐dependent manner (EC50= 3 nM), results indicating that the expressed transfected receptor was functional. Neurotensin did not inhibit cyclic AMP levels stimulated by forskolin. As with other systems, neurotensin (8‐13) was more potent than neurotensin. Neurotensin‐mediated inositol phosphate release is the first report of second messenger synthesis for this receptor expressed in a transfected cell line. These results suggest that the relation between structure and function of the neurotensin receptor can be readily studied in transfected cell lines.

Continuation phase treatment with bupropion SR effectively decreases the risk for relapse of depression

BACKGROUND This was the first controlled continuation phase study (up to 1-year total treatment) to evaluate the safety and efficacy of bupropion SR for decreasing the risk for relapse of depression in patients who responded to bupropion SR. METHODS Patients with recurrent major depression were treated with bupropion SR 300 mg/day during an 8-week open-label phase. Responders (based on Clinical Global Impressions Scale for Improvement of Illness scores) entered a randomized, double-blind phase where they received bupropion SR 300 mg/day or placebo for up to 44 weeks. After randomization, relapse was defined as the point at which the investigator intervened by withdrawing the patient from the study to treat depression. RESULTS Four hundred twenty-three patients were randomized. A statistically significant difference in favor of bupropion SR over placebo was seen in the time to treatment intervention for depression when survival curves were compared (log-rank test, p =.003). Statistically significant separation between bupropion SR and placebo began at double-blind week 12 (p <.05). Adverse events in bupropion SR-treated patients accounted for 9% and 4% of discontinuations from the open-label and double-blind phases, respectively. CONCLUSIONS Bupropion SR was shown to be effective and well tolerated in decreasing the risk for relapse of depression for up to 44 weeks.

Haloperidol but Not Clozapine Increases Neurotensin Receptor mRNA Levels in Rat Substantia Nigra

Abstract: We examined the effects of chronic (2 weeks) treatment with a typical neuroleptic, haloperidol (1 mg/kg, s.c.), and an atypical neuroleptic, clozapine (20 mg/kg, s.c.), on neurotensin receptor (NTR) mRNA levels by in situ hybridization histochemistry. Quantitative OD analysis showed haloperidol‐induced NTR mRNA levels in the substantia nigra/ventral tegmental area (SN/ VTA) 110% over control levels (significant difference from the control, p < 0.05). In contrast, the same analysis applied to the sections from clozapine‐treated animals showed no significant change in NTR mRNA levels compared with matched control sections (p > 0.05). Thus, chronic treatment with haloperidol but not clozapine resulted in elevated levels of NTR mRNA within the SN/VTA. These results suggest that the high incidence of extrapyramidal side effects of typical neuroleptics could result from changes in NTR expression in the SN/VTA.