EEG profile of litoxetine after single and repeated administration in healthy volunteers

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Clinical pharmacology of psychotropic drugs

No Abstract

Absolute bioavailability and electroencephalographic effects of conventional and extended-release formulations of venlafaxine in healthy subjects

Venlafaxine is currently marketed for treatment of depressive disorders as a conventional tablet formulation with a twice or three times daily dosage regimen. The absolute bioavailability of the conventional (CF) and extended-release (XR) formulations and their effects on electroencephalograms (EEG) and on a visual analog scale (VAS) for nausea were assessed in a randomized, double-blind, four-way crossover, placebo-controlled study of 16 healthy young men who were given either a single oral dose of 50 mg of CF venlafaxine, 75 mg of XR venlafaxine, or an intravenous dose of 10 mg of venlafaxine, or a placebo at 1-week intervals. The absolute bioavailability of venlafaxine was between 40% and 45% and was similar for both the CF and XR formulations. Venlafaxine produced central effects of a desipramine-like antidepressant. Regardless of formulation tested, the main EEG changes were an increase in fast beta (20-30 Hz) energy, which was more pronounced over the frontotemporal regions and extended within the full beta range (16-40 Hz). Maximum effect was reached at 6 hours for the CF and reached a plateau from 10 to 24 hours for the XR formulation. A dose-proportional increase in central activity, expressed as area under the effect curve (AUE) of the beta band, was observed between the CF (50 mg) and XR (75 mg) formulations. Compared with the CF tablet, the XR formulation also produced a much less intense maximum effect and a decrease of 63% in the AUE of nausea normalized by dose. The XR formulation has the same absolute bioavailability and the same central activity as assessed by EEG, but produced less intensive nausea than CF venlafaxine. The present findings suggest that a once-daily dosage regimen should be sufficient. This was confirmed by several clinical trials in depressive patients.

The psychomotor and cognitive effects of litoxetine in young and middle aged volunteers

1. The effects of a range of doses of litoxetine (twice daily for 4 days), a novel specific serotonin re-uptake inhibitor, were evaluated in young and middle aged volunteers. 2. Psychometric testing was carried out at various time points on days 1 and 4 of each treatment period. The test battery consisted of critical flicker fusion (CFF), choice reaction time (CRT), compensatory tracking (CTT), Stroop and Sternberg memory scanning tests. Subjective feelings of sleep and sedation were measured by the Leeds Sleep Evaluation Questionnaire (LSEQ) and line analogue rating scales (LARS). 3. Pharmacokinetic profiles were determined from analyses of blood samples taken after the final dose on day 5. 4. Overall, there were few changes in any of the psychometric tests and although the higher doses of litoxetine improved CFF, these effects were weak in that differences could only be detected when the results were pooled against time. 5. The pharmacokinetic profile of litoxetine was very similar in both the young and middle aged subjects, and there was no difference regarding tolerability. 6. There is little evidence from this study to suggest that litoxetine has any intrinsic sedative activity which is likely to interfere with the performance of activities of everyday life.