
Venlafaxine is structurally similar to phencyclidine and thus should not be discontinued abruptly. Patient hand-outs contain several useful warnings and physicians know that, because any psychoactive drug may impair judgment, thinking, or motor skills, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that venlafaxine does not adversely affect their ability to engage in such activities. Widely consulted drug information services, such as Medscape DrugInfo, American Hospital Formulary Service Drug Information, and First DataBank, list the following withdrawal symptoms as “serious”: agitation, anorexia, anxiety, confusion, impaired coordination, diarrhea, dizziness, dry mouth, dysphoric mood, fasciculation, fatigue, headaches, hypomania, insomnia, nausea, nervousness, nightmares, sensory disturbances (including shock-like electrical sensations), somnolence, sweating, tremor, vertigo, and vomiting. In the past 10 years, a number of clinical reports of severe venlafaxine withdrawal symptoms have been published, and for the most part these effects are duly reflected in generally available information. Its primary metabolite, O-desmethylvenlafaxine, has a half-life of 10 hours. Among the adverse effects are a number of withdrawal symptoms that form “discontinuance syndromes,” sometimes mistakenly identified with what Sternbach in 1991 proposed as the “serotonin syndrome”. Most selective serotonin-reuptake inhibitors (SSRI) and SSNRIs are reported to cause serious adverse effects in approximately 5% of patients, according to its manufacturer.

Nonlabeled uses include depressive symptom remission, obsessive-compulsive disorder, and chronic pain syndromes. It is used primarily in major depressive disorder, with labeled uses including generalized anxiety disorder and social phobia.

Venlafaxine hydrochloride ( Effexor, Dobupal) is a phenylethylamine-derivative antidepressant and anxiolytic agent that acts as a serotonin- and noradrenaline-reuptake inhibitor (SNRI).
