Effects of lisdexamfetamine in a rat model of binge-eating.

Binge-eating disorder is a common psychiatric disorder affecting ~2% of adults. Binge-eating was initiated in freely-fed, lean, adult, female rats by giving unpredictable, intermittent access to ground, milk chocolate over four weeks. The rats avidly consumed chocolate during 2 hr binge sessions, with compensatory reductions of normal chow intake in these sessions and the days thereafter. Bodyweights of binge-eating rats were normal. The model's predictive validity was explored using nalmefene (0.1-1.0mg/kg), R-baclofen (1.0-10mg/kg) and SB-334867 (3.0-30 mg/kg) (orexin-1 antagonist), which all selectively decreased chocolate bingeing without reducing chow intake. Sibutramine (0.3-5.0mg/kg) non-selectively reduced chocolate and chow consumption. Olanzapine (0.3-3.0mg/kg) was without effect and rolipram (1.0-10mg/kg) abolished all ingestive behaviour. The pro-drug, lisdexamfetamine (LDX; 0.1-1.5mg/kg), dose-dependently reduced chocolate bingeing by ⩽ 71% without significantly decreasing normal chow intake. Its metabolite, D-amphetamine (0.1-1.0mg/kg), dose-dependently and preferentially decreased chocolate bingeing ⩽ 56%. Using selective antagonists to characterize LDX's actions revealed the reduction of chocolate bingeing was partially blocked by prazosin (α1-adrenoceptor; 0.3 and 1.0mg/kg) and possibly by SCH-23390 (D1; 0.1mg/kg). RX821002 (α2-adrenoceptor; 0.1 and 0.3mg/kg) and raclopride (D2; 0.3 and 0.5mg/kg) were without effect. The results indicate that LDX, via its metabolite, d-amphetamine, reduces chocolate bingeing, partly by indirect activation of α1-adrenoceptors and perhaps D1 receptors.

Differences in the neurochemical and behavioural profiles of lisdexamfetamine methylphenidate and modafinil revealed by simultaneous dual-probe microdialysis and locomotor activity measurements in freely-moving rats.

Lisdexamfetamine dimesylate is a novel prodrug approved in North America, Europe and Brazil for treating attention deficit hyperactivity disorder (ADHD). It undergoes rate-limited hydrolysis by red blood cells to yield d-amphetamine. Following our previous work comparing lisdexamfetamine with d-amphetamine, the neurochemical and behavioural profiles of lisdexamfetamine, methylphenidate and modafinil were compared by dual-probe microdialysis in the prefrontal cortex (PFC) and striatum of conscious rats with simultaneous locomotor activity measurement. We employed pharmacologically equivalent doses of all compounds and those that spanned the therapeutically relevant and psychostimulant range. Lisdexamfetamine (0.5, 1.5, 4.5 mg/kg d-amphetamine base, per os (po)), methylphenidate (3, 10, 30 mg/kg base, po) and modafinil (100, 300, 600 mg/kg base, po) increased efflux of dopamine and noradrenaline in PFC, and dopamine in striatum. Only lisdexamfetamine increased 5-hydroxytryptamine (5-HT) efflux in PFC and striatum. Lisdexamfetamine had larger and more sustained effects on catecholaminergic neurotransmission than methylphenidate or modafinil. Linear correlations were observed between striatal dopamine efflux and locomotor activity for lisdexamfetamine and methylphenidate, but not modafinil. Regression slopes revealed greater increases in extracellular dopamine could be elicited without producing locomotor activation by lisdexamfetamine than methylphenidate. These results are consistent with clinical findings showing that lisdexamfetamine is an effective ADHD medication with prolonged duration of action and good separation between its therapeutic actions and stimulant side-effects.

A preclinical evaluation of the discriminative and reinforcing properties of lisdexamfetamine in comparison to D-amfetamine, methylphenidate and modafinil.

Lisdexamfetamine dimesylate, which consists of L-lysine covalently bound to D-amfetamine, is the first prodrug for treating ADHD. Its metabolic conversion to yield D-amfetamine by rate-limited, enzymatic hydrolysis is unusual because it is performed by peptidases associated with red blood cells. Other stimulants shown to be effective in managing ADHD include D-amfetamine, methylphenidate and modafinil. All have the potential for misuse or recreational abuse. The discriminative and reinforcing effects of these compounds were determined in rats using a 2-choice, D-amfetamine (0.5 mg/kg, i.p.)-cued drug-discrimination test, and by substitution for intravenous cocaine in self-administration. Lisdexamfetamine (0.5-1.5 mg/kg [D-amfetamine base], p.o.) generalised to saline when tested 15 min post-dosing, but dose-dependently generalised to d-amfetamine at 60 min. At 120 min, its D-amfetamine-like effects were substantially diminished. At 15 min, methylphenidate (3.0-10 mg/kg, p.o.) and D-amfetamine (0.1-1.5 mg/kg, p.o.) dose-dependently generalised to the intraperitoneal D-amfetamine cue. Switching to the intraperitoneal route reduced the interval required for lisdexamfetamine to be recognised as D-amfetamine-like, but did not alter its potency. Switching to intraperitoneal injection increased the potency of methylphenidate and D-amfetamine by 3.4× and 2.2×, respectively. Modafinil (50-200 mg/kg, i.p.) generalised partially, but not fully, to d-amfetamine. Methylphenidate (0.1, 0.3, 1.0 mg/kg/injection, i.v.) maintained robust self-administration at the 2 highest doses. Neither lisdexamfetamine (0.05, 0.15 or 0.5 mg/kg/injection [D-amfetamine base], i.v.) nor modafinil (0.166, 0.498 or 1.66 mg/kg/injection, i.v.) served as reinforcers. The results reveal important differences between the profiles of these stimulants. Lisdexamfetamine did not serve as a positive reinforcer in cocaine-trained rats, and although it generalised fully to D-amfetamine, its discriminative effects were markedly influenced by its unusual pharmacokinetics.

Diagnostic classification of the instantaneous wave-free ratio is equivalent to fractional flow reserve and is not improved with adenosine administration. Results of CLARIFY (Classification Accuracy of Pressure-Only Ratios Against Indices Using Flow Study).

OBJECTIVES: This study sought to determine if adenosine administration is required for the pressure-only assessment of coronary stenoses. BACKGROUND: The instantaneous wave-free ratio (iFR) is a vasodilator-free pressure-only measure of the hemodynamic severity of a coronary stenosis comparable to fractional flow reserve (FFR) in diagnostic categorization. In this study, we used hyperemic stenosis resistance (HSR), a combined pressure-and-flow index, as an arbiter to determine when iFR and FFR disagree which index is most representative of the hemodynamic significance of the stenosis. We then test whether administering adenosine significantly improves diagnostic performance of iFR. METHODS: In 51 vessels, intracoronary pressure and flow velocity was measured distal to the stenosis at rest and during adenosine-mediated hyperemia. The iFR (at rest and during adenosine administration [iFRa]), FFR, HSR, baseline, and hyperemic microvascular resistance were calculated using automated algorithms. RESULTS: When iFR and FFR disagreed (4 cases, or 7.7% of the study population), HSR agreed with iFR in 50% of cases and with FFR in 50% of cases. Differences in magnitude of microvascular resistance did not influence diagnostic categorization; iFR, iFRa, and FFR had equally good diagnostic agreement with HSR (receiver-operating characteristic area under the curve 0.93 iFR vs. 0.94 iFRa and 0.96 FFR, p = 0.48). CONCLUSIONS: iFR and FFR had equivalent agreement with classification of coronary stenosis severity by HSR. Further reduction in resistance by the administration of adenosine did not improve diagnostic categorization, indicating that iFR can be used as an adenosine-free alternative to FFR.

Adult congenital heart disease interventions: recommendations from a joint working group of the British Congenital Cardiac Association, British Cardiovascular Intervention Society, and the British Cardiovascular Society.

In order to optimise care of the adult patients with complex congenital heart disease, there is a need to develop recommendations for interventions. This document is the work of representatives of the three relevant societies and provides recommendations for institutions and operators performing cardiac interventions in these patients.

Development and validation of a new adenosine-independent index of stenosis severity from coronary wave-intensity analysis: results of the ADVISE (ADenosine Vasodilator Independent Stenosis Evaluation) study.

OBJECTIVES: The purpose of this study was to develop an adenosine-independent, pressure-derived index of coronary stenosis severity. BACKGROUND: Assessment of stenosis severity with fractional flow reserve (FFR) requires that coronary resistance is stable and minimized. This is usually achieved by administration of pharmacological agents such as adenosine. In this 2-part study, we determine whether there is a time when resistance is naturally minimized at rest and assess the diagnostic efficiency, compared with FFR, of a new pressure-derived adenosine-free index of stenosis severity over that time. METHODS: A total of 157 stenoses were assessed. In part 1 (39 stenoses), intracoronary pressure and flow velocity were measured distal to the stenosis; in part 2 (118 stenoses), intracoronary pressure alone was measured. Measurements were made at baseline and under pharmacologic vasodilation with adenosine. RESULTS: Wave-intensity analysis identified a wave-free period in which intracoronary resistance at rest is similar in variability and magnitude (coefficient of variation: 0.08 ± 0.06 and 284 ± 147 mm Hg s/m) to those during FFR (coefficient of variation: 0.08 ± 0.06 and 302 ± 315 mm Hg s/m; p = NS for both). The resting distal-to-proximal pressure ratio during this period, the instantaneous wave-free ratio (iFR), correlated closely with FFR (r = 0.9, p < 0.001) with excellent diagnostic efficiency (receiver-operating characteristic area under the curve of 93%, at FFR <0.8), specificity, sensitivity, negative and positive predictive values of 91%, 85%, 85%, and 91%, respectively. CONCLUSIONS: Intracoronary resistance is naturally constant and minimized during the wave-free period. The instantaneous wave-free ratio calculated over this period produces a drug-free index of stenosis severity comparable to FFR. (Vasodilator Free Measure of Fractional Flow Reserve [ADVISE]; NCT01118481).

Estimation of symptom-free days in generalized anxiety disorder.

OBJECTIVE: The efficacy of treatments for generalized anxiety disorder has usually been measured in terms of response or remission of symptoms. These endpoints, however, may not adequately capture the transient periods of symptom abatement and relapse characteristic of chronic psychiatric disorders. Here, we evaluate the measurement of treatment effectiveness in terms of the number of symptom-free days (SFDs). RESEARCH DESIGN AND METHODS: A pooled analysis was performed of data from five manufacturer-initiated trials of venlafaxine extended-release (XR) in patients with generalized anxiety disorder without co-morbid major depressive disorder. The trials were randomized, double-blind, placebo-controlled and of 8 weeks duration (total intent-to-treat population 1295 venlafaxine XR, 544 placebo). Two of the studies had extensions up to 6 months (intent-to-treat population 514 venlafaxine XR, 253 placebo). The patients were >or= 18 years of age with a Hamilton Rating Scale for Anxiety (HAM-A) score of >or= 18. MAIN OUTCOME MEASURES: SFDs were estimated using weekly scores on the HAM-A. Values of 7 and 0 SFDs, respectively, were assigned to each week the patient had a HAM-A score of or= 18 (the minimum threshold for anxiety). Fractional SFD values were assigned proportionately to weekly HAM-A scores between 7 and 18. RESULTS: The median (inter-quartile range) SFDs were 19 (2-36) for venlafaxine XR and 10 (0-27) for placebo in the 8-week studies (p < 0.0001). In the 6-month extension studies the SFDs were 102 (27-139) for venlafaxine XR and 36 (0-94) for placebo (p < 0.0001). CONCLUSIONS: SFDs differentiate between active treatment and placebo in clinical trials and may be an appropriate measure of treatment effectiveness.

Impact of gastrointestinal symptom severity on response to venlafaxine extended-release in patients with generalized anxiety disorder.

BACKGROUND: This retrospective analysis evaluated the prevalence and severity of pre-treatment gastrointestinal (GI) symptoms in patients with generalized anxiety disorder (GAD), the impact of these GI symptoms on the efficacy and tolerability of venlafaxine extended-release (XR), and the effect of treatment on prestudy GI symptoms. METHOD: Data from 1932 nondepressed GAD patients were pooled from 5 randomized, double-blind, placebo-controlled studies of venlafaxine XR clinically conducted between May 1995 and December 1997. The GI symptom severity at baseline was estimated from item 11 on the Hamilton Rating Scale for Anxiety (HAM-A). Patients with a GI symptom severity score < or = 2 (moderate or less) and those with a GI symptom severity score > 2 (severe/very severe) were compared for baseline characteristics and short-term (8-week) and long-term (24-week) outcomes. RESULTS: At baseline, for all randomized patients with a HAM-A item 11 score, GI symptoms were rated moderate or lower in 82.8% of patients (GI-low) and severe/very severe in 17.2% (GI-high). The GI-high subgroup was statistically significantly (p < .05) younger, had a longer duration of GAD, and had higher mean HAM-A total scores than the GI-low subgroup. Compared with placebo, venlafaxine XR significantly reduced HAM-A total and psychic anxiety factor scores, regardless of baseline GI symptom severity. The incidence of adverse events, particularly nausea, was higher for the GI-high versus GI-low subgroup. CONCLUSION: Baseline severity of GI symptoms correlated with overall severity of GAD but had no impact on treatment outcome with venlafaxine XR. These data do not support the hypothesis that high baseline GI symptom severity has a negative effect on treatment with venlafaxine XR in GAD patients.

Social adjustment in generalised anxiety disorder: a long-term placebo-controlled study of venlafaxine extended release.

The objective of this analysis was to evaluate the short- (8 weeks) and long-term (24 weeks) efficacy of three fixed doses of venlafaxine extended release (ER) and placebo on the social adjustment of patients with generalised anxiety disorder (GAD). We analysed data from 544 outpatients who participated in a 24-week, double-blind, multicentre, parallel-group, placebo-controlled study conducted at 55 centres in five countries. All patients meet the DSM-IV criteria for GAD and were randomly assigned to receive venlafaxine ER 37.5, 75, and 150 mg or matched placebo administered orally once daily. Social adjustment was measured using the Social Adjustment Scale-Self Report, which explores social adaptation in the areas of work, social and leisure, extended family, primary relationship (marital), parental, and family unit. At baseline, the GAD patients had a high level of social dysfunction. Venlafaxine ER showed a dose-related improvement in social impairment during short-term treatment and in sustaining this improvement over the long-term. In the most severely socially impaired subgroup, placebo remission rates on the HAM-A were low, and the magnitude of the venlafaxine-placebo difference on the mean HAM-A total score was high, reaching more than 7 points. The benefits of venlafaxine ER treatment of GAD extend beyond that of improvement of anxiety symptoms to a significant improvement in the impairment of functioning that is associated with the illness.

Venlafaxine versus placebo in the preventive treatment of recurrent major depression.

BACKGROUND: Major depression is often chronic and recurrent, yet most long-term therapeutic trials are not adequately designed to assess antidepressant efficacy in recurrence prevention. Long-term efficacy and safety of prophylactic venlafaxine treatment were evaluated in outpatients with recurrent major depression. METHOD: Patients with a history of recurrent DSM-III-R major depression received open-label treatment with venlafaxine, 100 to 200 mg/day, for 6 months. Those who responded to treatment (Hamilton Rating Scale for Depression [HAM-D(21)] score < or = 12, day 56) and remained relapse-free (no more than 2 HAM-D(21) scores > 10 and no Clinical Global Impressions-Severity of Illness [CGI-S] score > or = 4, months 2-6) either continued taking venlafaxine, 100 to 200 mg/day, or were switched in a double-blind fashion to placebo for 12 months. The primary efficacy outcome was the number of patients experiencing a recurrence of major depression (CGI-S score > or = 4). The cumulative probability of recurrence was calculated using the Kaplan-Meier method of survival analysis. Data were collected from November 1992 through December 1995. RESULTS: Of the 235 patients who enrolled in the recurrence-prevention period, 225 (N = 109, venlafaxine; N = 116, placebo) provided efficacy data. Survival analysis determined a 22% cumulative probability of recurrence in venlafaxine-treated patients after 12 months compared with 55% for the placebo group (p <.001). More than twice as many placebo-treated patients (48%) as venlafaxine-treated patients (21%) discontinued treatment because of lack of efficacy (p <.001). CONCLUSION: Twelve-month maintenance venlafaxine treatment was significantly more efficacious than placebo in preventing major depression recurrence in patients who had been successfully treated with venlafaxine for 6 months.

Pooled analysis of venlafaxine XR efficacy on somatic and psychic symptoms of anxiety in patients with generalized anxiety disorder.

We evaluated the relative efficacy of venlafaxine XR on the psychic versus somatic symptoms of anxiety in patients with generalized anxiety disorder as determined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Data were pooled and analyzed from 1,841 patients with generalized anxiety disorder who participated in five short-term (8-week) double-blind, multicenter, placebo-controlled studies, two of which had long-term (6-month) extensions. Somatic and psychic anxieties were studied using the Hamilton rating scale for anxiety (HAM-A) factor scores. We examined response rates (> or =50% improvement over baseline severity score) in the overall population and in patients with mainly somatic symptomatology at baseline (somatizers). Venlafaxine XR significantly reduced factor scores for both psychic and somatic HAM-A factors compared with placebo, from the first and second weeks of treatment, respectively. Patients treated with venlafaxine XR had significantly higher rates of response than patients receiving placebo on the psychic (58% vs. 38%, P<.001 at week 8; 66% vs. 35% at week 24, P<.001) and somatic (56% vs. 43%, P<.001 at week 8; 67% vs. 47% at week 24, P<.001) factors of the HAM-A. There was a TreatmentxFactor interaction (P<.027) in response rates: Patients treated with venlafaxine showed similar somatic and psychic anxiety response rates, whereas placebo-treated patients showed higher somatic compared with psychic response rates. Somatizers showed similar rates of response to the total population for the somatic factor of the HAM-A in either treatment group. Patients with generalized anxiety disorder treated with venlafaxine XR showed similar absolute rates of response on somatic and psychic symptoms, but relative to patients treated with placebo, more improvement in psychic than somatic symptoms.

Predictors of outcome following venlafaxine extended-release treatment of DSM-IV generalized anxiety disorder: a pooled analysis of short- and long-term studies.

This pooled analysis evaluated potential predictive abilities of baseline demographic factors, psychiatric history, and DSM-IV diagnostic criteria for short- and long-term outcome after treatment with venlafaxine extended release (XR) or placebo in patients with generalized anxiety disorder (GAD). Pooled data from 1,839 patients in five placebo-controlled studies of venlafaxine XR for GAD were analyzed by logistic regression. Odds ratios (ORs) were used to quantify pretreatment factors' abilities to predict response (50% reduction, baseline Hamilton Rating Scale for Anxiety [HAM-A] severity) and remission (total HAM-A score

A method for controlling for a high placebo response rate in a comparison of venlafaxine XR and diazepam in the short-term treatment of patients with generalised anxiety disorder.

This randomised, double-blind, placebo-controlled study compared the efficacy of venlafaxine XR (75 or 150 mg/d) with diazepam (15 mg/d) over an 8-week treatment period in 540 non-depressed outpatients with generalised anxiety disorder (GAD). At week 8, significant improvements from baseline were observed in the venlafaxine XR, diazepam and placebo groups. Although these improvements were higher in the first two groups than in the placebo group for each of the primary efficacy variables (Hamilton Rating Scale for Anxiety (HAM-A) total, HAM-A psychic anxiety factor, Hospital Anxiety and Depression Scale (HAD) anxiety sub-scale and Clinical Global Impression (CGI) improvement), there were no statistically significant differences between groups. These non-positive results were thought to be due to the very high placebo response observed in some centres. To understand the variability of the study, a secondary preplanned analysis was performed. This involved sub-dividing the study centres according to their ability to detect a two-point mean difference between diazepam and placebo at week 8 on the HAM-A total score. Centres able to show such a difference were termed verum-sensitive. Improvements from baseline to week 8 in venlafaxine XR-treated patients from verum-sensitive centres were significantly greater than in placebo on each of the primary efficacy measures (P

Effectiveness of venlafaxine, extended release formulation, in the short-term and long-term treatment of generalized anxiety disorder: results of a survival analysis.

A survival analysis of data from two placebo-controlled, randomized, long-term (6-month) studies was used to examine the effectiveness of venlafaxine, extended release (XR) formulation, in patients with generalized anxiety disorder (GAD). Patients in a placebo-controlled, flexible-dose study received 75 to 225 mg/day venlafaxine XR, while patients in a placebo-controlled, fixed-dose study received once-daily venlafaxine XR doses of 37.5 mg, 75 mg, or 150 mg. The survival analysis was based on the clinician's decision to discontinue treatment in a placebo-controlled study and incorporated data from all patients who were randomized. In each study, placebo-treated patients discontinued treatment due to lack of efficacy more frequently and earlier than those receiving venlafaxine XR (p < 0.001, log-rank test). A dose-response relationship was apparent, with the lowest rate of withdrawal seen at the highest venlafaxine XR dose. Survival curves for discontinuations due to adverse events did not differ significantly in either study. These results were consistent with the conventional intent-to-treat efficacy assessments of changes in anxiety severity, highlighting the superiority of venlafaxine XR over placebo in the long-term treatment of GAD. Overall, these results demonstrate the clinical effectiveness of venlafaxine XR in the short-term and long-term treatment of GAD.

Achieving remission with venlafaxine and fluoxetine in major depression: its relationship to anxiety symptoms.

Venlafaxine, a serotonin and norepinephrine reuptake inhibitor (SNRI), produces significantly higher remission rates in depressed patients than do the selective serotonin reuptake inhibitors (SSRIs). In this analysis of pooled data, we explored the relationship between differences in treatment efficacy, early improvement of symptoms, and severity of baseline anxiety in depressed patients treated with either venlafaxine or fluoxetine. A pooled analysis was performed on data from 1,454 outpatients with major depression from five double-blind, randomized studies comparing the 6-week efficacy of venlafaxine (542 patients) with fluoxetine (555 patients). The Hamilton rating scale for depression (HAM-D) total and item scores were analyzed at different treatment times up to 6 weeks. Venlafaxine and fluoxetine both produced statistically significant higher response and remission rates compared with placebo starting from week 2 for response and weeks 3 to 4 for remission. Venlafaxine was statistically significantly superior to fluoxetine from week 3 until week 6 in respect of response rate, and from week 2 until week 6 for remission rate. After 1 week of treatment, greater improvement in individual symptoms was observed in the depressed mood, suicide, and psychic anxiety items of the HAM-D scale for both venlafaxine- and fluoxetine-treated patients compared with placebo. Improvement in psychic anxiety was statistically significantly greater with venlafaxine than with fluoxetine. The presence of baseline psychic anxiety correlated significantly to treatment outcome when analyzing the remission rates. In depressed patients with moderate anxiety (HAM-D psychic anxiety score < or = 2), venlafaxine statistically significantly increased remission rates compared with placebo from week 4 until week 6, while a significant effect of fluoxetine on remission rates was observed starting at week 6. Remission rates in the severely anxious depressed patients (score > 2) were statistically significantly higher with venlafaxine than placebo starting from week 3 until the end of the study period, but no difference could be observed between fluoxetine and placebo. Baseline severity of psychic anxiety had a significant impact on remission rates after treatment of patients diagnosed with depression. Venlafaxine's superior remission rates in the more severely anxious patients and its ability to improve psychic anxiety as early as week 1 compared with fluoxetine suggest that venlafaxine's early efficacy on anxiety symptoms may be the basis for its superior efficacy in depression.