Venlafaxine occupation at the noradrenaline reuptake site: in-vivo determination in healthy volunteers

Venlafaxine vs. fluoxetine in postmenopausal women with major depressive disorder: an 8-week, randomized, single-blind, active-controlled study

BACKGROUND

In the population of postmenopausal patients with major depressive disorder (MDD), the superiority of serotonin-norepinephrine reuptake inhibitors (SNRIs) over selective serotonin reuptake inhibitors (SSRIs) has not yet been definitively proven. Consequently, a direct comparison of the efficacy of SSRIs and SNRIs in the treatment of postmenopausal depression could provide relevant data. The aim of this study was to compare the efficacy and safety of venlafaxine vs. fluoxetine in the treatment of postmenopausal MDD.

METHODS

This was an 8-week, multicenter, randomized, single-blind, active-controlled trial conducted at a psychiatric hospital (Beijing Anding Hospital) and a general hospital (Beijing Chaoyang Hospital) between April 2013 and September 2017. The primary outcome measure was improving depressive symptoms (Hamilton Depression Rating Scale (HAMD-24) score). The secondary outcomes included the change of HAMD-24 anxiety/somatization factor score and Clinical Global Impressions-Improvement (CGI-I) response rate. Safety was assessed by treatment-emergent adverse events (TEAEs) and laboratory tests. Efficacy was analyzed by using the full analysis set (FAS) following the modified intention-to-treat (mITT) principle. The primary endpoint measurements were analyzed using a mixed-effect model for repeated measures (MMRM) model with patients as a random-effect factor, treatment group as the independent variable, time as a repeated measure, and baseline covariates, using a first-order ante dependence covariance matrix.

RESULTS

A total of 184 women were randomized. The full analysis set (FAS) included 172 patients (venlafaxine, n = 82; fluoxetine, n = 90). Over the 8-week study period, the reduction in HAMD-24 scores was significant (P < 0.001) in both groups, while a significantly greater decline from baseline was observed in the venlafaxine group compared with the fluoxetine group (least-squares mean difference [95% CI]: - 2.22 [- 7.08, - 0.41]), P = 0.001). The baseline-to-week-8 least-squares mean change of the anxiety/somatization factor scores, CGI-I response rate were greater in the venlafaxine group than in the fluoxetine group (all P < 0.05). The most frequent TEAEs (≥5%) in both groups were nausea, somnolence, dizziness, headache, and dry mouth. There was no significant difference in the incidence of adverse events between the two groups.

CONCLUSION

Venlafaxine was well tolerated and compared to fluoxetine, it led to a greater improvement in the treatment of postmenopausal MDD.

TRIAL REGISTRATION

Clinical Trials. gov #NCT01824433 . The trial was registered on April 4, 2013.

Changes in cardiovascular function after venlafaxine but not pregabalin in healthy volunteers: a double-blind, placebo-controlled study of orthostatic challenge, blood pressure and heart rate

It is generally thought that venlafaxine raises blood pressure at higher doses; however, some studies have found no effect or a decrease in blood pressure. The aim of this study was to evaluate the cardiovascular (CV) effects of 3 weeks of dosing with venlafaxine, pregabalin and placebo on young healthy adults. Fifty-four participants, of mean age 23.1 years (sd 4.68), 29 male, were randomised into three parallel groups. Each group received one of the three drugs, dosed incrementally over a 3-week period to reach daily doses of 150 mg/day venlafaxine and 200 mg/day pregabalin. Blood pressure sphygmomanometer measurements, heart rate measurements, and orthostatic challenges recorded continuously beat-to-beat were performed weekly over this period and 5 days after treatment cessation. Results showed resting systolic blood pressure (SBP) and resting and standing diastolic blood pressure (DBP) and heart rate (HR) were significantly raised by venlafaxine compared with the pregabalin and placebo groups. SBP drop on standing was larger, the resulting overshoot was smaller, and recovery was slower on venlafaxine. HR recovery was significantly impaired by venlafaxine. CV changes were observed after only 1 week of dosing at 112.5 mg/day. These effects of venlafaxine are likely to be due to its action of noradrenergic reuptake inhibition.

Noradrenergic function in generalized anxiety disorder: impact of treatment with venlafaxine on the physiological and psychological responses to clonidine challenge

Serotonin and noradrenaline reuptake inhibitor (SNRI) antidepressants have evidence of efficacy in the treatment of generalized anxiety disorder (GAD); however, it is not clear whether there is an advantage over selective serotonin reuptake inhibitor (SSRI) medicines and there is limited evidence for noradrenergic dysfunction in GAD. We tested whether a dysfunctional alpha-2 adrenoceptor system is present in patients with GAD and the effects of SNRI treatment on this system. The method used was an infusion of clonidine (a selective alpha-2 adrenergic receptor agonist) on psychological and physiological outcomes in three subject groups: 10 untreated GAD patients, five SNRI-treated GAD patients and seven normal controls. The clonidine challenge elicited sedation, a rise in growth hormone, decrease in blood pressure, decline in saccadic eye movement (SEM) variables, and improvement in verbal fluency as anticipated in the 22 subjects examined. Lower cortisol levels were found in controls and higher blood pressure readings in GAD-treated subjects, as well as evidence that GAD-treated subjects had SEMs that were intermediate between control and GAD subjects' scores and have less clonidine-induced sedation. The implications of these findings with reference to the study hypothesis in this small study are discussed.

Effects of acute tryptophan depletion in serotonin reuptake inhibitor-remitted patients with generalized anxiety disorder

BACKGROUND

Serotonergic antidepressants [selective serotonin reuptake inhibitor (SSRI)] are first-line treatments for generalised anxiety disorder (GAD); however, it is not known if synaptic serotonin (5-HT) availability is important for SSRI efficacy. The present study tested the hypothesis that temporary reduction in central 5-HT transmission, through acute tryptophan depletion (ATD), would reverse the therapeutic effect of the SSRIs in GAD patients.

METHODS

Twelve patients (six males) with GAD, who showed sustained clinical improvement with SSRI treatment, underwent ATD in a double-blind, placebo-controlled, within-subjects design over 2 days, 1 week apart. At the peak time of depletion, the participants inhaled 7.5% CO2 and air in random order for at least 12 min each. Psychological responses were measured using the Spielberger State Anxiety Inventory (STAI-S) and GAD-symptom visual analogue scales (VASs; e.g., worry and tense) and Profile of Mood States.

RESULTS

Free plasma tryptophan to large neutral amino acid (LNAA) ratio decreased by 92% on the depletion day and decreased by 2% on the control day. Irrespective of depletion condition, 7.5% CO(2) inhalation significantly increased STAI-S and GAD-related VAS scores (all p < 0.05) compared with air inhalation. ATD had no effect on any of these measures despite the substantial reduction in free tryptophan/LNAA ratio.

CONCLUSIONS

Although SSRIs treat GAD effectively, the present results suggest that the mechanism of action is different to that seen in panic, social anxiety, and post-traumatic stress disorders. Successful SSRI treatment of GAD may involve long-term receptor changes or alterations in other neurotransmitter systems downstream of serotonin.

Pharmacotherapy of anxiety

The pharmacological treatment of anxiety has a long and chequered history, and recent years have seen a rich development in the options available to prescribers. Most of the currently used anxiolytic agents act via monoaminergic (chiefly serotonin) or amino acid (GABA or glutamate) neurotransmitters, and this chapter describes the pharmacology of the major drug groups. Clinical applications are discussed with respect to the five major anxiety disorders, as well as simple phobia and depression with concomitant anxiety. Prospective future developments in the field are considered.

Relative Antidepressant Efficacy of Venlafaxine and SSRIs: Sex-Age Interactions

OBJECTIVE

To investigate whether differences in antidepressant efficacy are moderated by an interaction of age and gender.

METHODS

A pooled dataset from eight randomized, controlled trials of patients with major depressive disorder (MDD) was reanalyzed to compare remission rates following therapy with venlafaxine (n = 851), one of several selective serotonin reuptake inhibitors (SSRIs) (n = 748), or placebo (n = 446). Remission was defined as a final Hamilton Rating Scale for Depression (HAM-D) score < or =7. Pairwise comparisons were conducted using stepwise multiple logistic regression models with main effect and interaction terms for treatment, sex, and age (younger: <50; older: > or =50). Among older women, the impact of hormone replacement therapy (HRT) on remission rates also was examined.

RESULTS

Remission rates on venlafaxine therapy were not affected by age, sex, or HRT use. Among women, but not men, there was a significant interaction reflecting poorer SSRI response in the older age group (Wald chi-square = 4.21, df = 1, p = 0.04); HRT appeared to eliminate this difference. Whereas the advantage in remission rates favoring venlafaxine was modest for men and younger women (6%-9%), the difference among older women not taking HRT was 23%.

CONCLUSIONS

These findings provide further evidence that age, gender, and HRT moderate response to antidepressant medications.

Overview of diagnosis and drug treatments of anxiety disorders

Anxiety disorders are common and often disabling. They fall into five main categories: panic disorder, social anxiety disorder, generalized anxiety disorder, obsessive-compulsive disorder and posttraumatic stress disorder, each of which have characteristic symptoms and cognitions. All anxiety disorders respond to drugs and psychological treatments. This review will focus on drug treatments. Recent research has emphasized the value of antidepressants especially the selective serotonin reuptake inhibitors, benzodiazepines, and related sedative-like compounds. The common co-existence of depression with all of the anxiety disorders means that the selective serotonin reuptake inhibitors are now generally considered to be the first-line treatments but the benzodiazepines have some utility especially in promoting sleep and working acutely to reduce extreme distress.

Naloxone displacement at opioid receptor sites measured in vivo in the human brain

We report the use of a sensitive non-tomographic positron detecting system to measure the dose-response curve of naloxone in human brain. [11C]Diprenorphine was administered to normal volunteers in tracer amounts and, 30 min later, various bolus doses of naloxone were given (1.5-160 microg/kg) intravenously and change in [11C]diprenorphine binding monitored over the next 30 min. We found that this method produced results consistent with existing data. It was observed that approximately 13 microg/kg of naloxone ( approximately 1 mg in an 80 kg man) was required to produce an estimated 50% receptor occupation. This is consistent with the clinical dose of naloxone used to reverse opiate overdose (0.4 mg-1.2 mg).

Venlafaxine: a new class of antidepressant

Venlafaxine represents a new class of antidepressant, the serotonin and noradrenaline re-uptake inhibitor (or SNRI). This article discusses its evolution, pharmacological properties and role in the treatment of depression and related disorders, beginning with an outline of the biology of depression.

Venlafaxine extended release (ER) in the treatment of generalised anxiety disorder: twenty-four-week placebo-controlled dose-ranging study

BACKGROUND

Generalised anxiety disorder (GAD) has received less study than other anxiety disorders, particularly its long-term treatment.

AIMS

To assess the efficacy and safety of venlafaxine extended release (ER) in patients with GAD.

METHOD

A total of 541 out-patients, 18-86 years old, were recruited to this 24-week, placebo-controlled, double-blind study of three fixed doses (37.5, 75 and 150 mg/day) of venlafaxine ER.

RESULTS

All doses of venlafaxine ER showed efficacy superior to placebo, apparent from week 2, that was sustained throughout the 24-week study for the two higher doses. The discontinuation rate did not differ significantly among the treatment groups.

CONCLUSIONS

Venlafaxine ER is an effective and safe treatment for GAD for up to 6 months.