Single-receptors antidepressants:
Selective Serotonin Reuptake Inhibitors (SSRI) (fluoxetine, paroxetine, sertraline, fluvoxamine, citalopram) combine the effectiveness of their older counterparts with a much-improved side effect profile. They act only at serotonin receptors. They have a wide range of clinical application in the full spectrum of depressive disorders, are well tolerated, with safety in overdose and low seizurogenicity. However, some investigators have suggested that the SSRIs tend to loose efficacy overtime.
It was difficult to develope specific Selective Norepinephrin Reuptake Inhibitors (SNRI) because of cardiovascular sideeffects. Reboxetine appears to be effective and well tolerated.
Multireceptors antidepressants:
They were design to interact with more than one recepror site. Serotonin Norepinerhrin Reuptake Inhibitors (SNRIs) (venlafaxine, mirtazapine, trazodone, nefazodone) act on both serotonin and norepinephrine, but they do not interact with histaminic and cholinergic-adrenergic receptors and thus avoid trublesome advers events such as dry mouth, hypotension, and sedation. Mechanism of action of these antidepressants is different.
Venlafaxine blocks serotonin and norepinephrin receptors.
Trazodone and Nefazodone are reaptake inhibitors.
Mitazapin blocks special serotonin and adrenergic receptors.
Features of all these antidepressants are discussed.
Antidepressants effectivness in severe depression:
Antidepressants respond is affected by type of depression. In severe depression remission rates are relarively low in many of the short term clinical trails of antidepressants, but are likely fo improve with longer trials and aggressive dosing. However, aggresive dosing with the tricyclic antidepressants (TCAs) can be problematic in terms of side effects. Results from studies of the efficacy of the SSRIs in severe depression are conflicting, but, even if they are slightly less efficaious than the TCAs, their favorable side effect profile and fewer consequenses of overdose make them a useful alternative to the TCAs.
Venlafaxine/venlafaxine XR, particularly at high doses, and no anticholinergic effects may offer a greater advantage than either the TCAs or the SSRIs in severely depressed patients. Reboxitine may also have advantages in this group.
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