A number of drugs are being designed that, like the SSRIs, target specific neurotransmitters that regulate depression. Most act on mechanisms that elevate both serotonin and noradrenaline and some may be more effective for severely depressed patients than are the SSRIs. Some are known as heterocyclic antidepressants. These drugs tend to have fewer adverse effects on sexual function than SSRIs, and some people have reported enhanced sexuality with some of them. Common side effects include drowsiness, nausea, dizziness, and dry mouth, but drugs vary in others effects.
Dry mouth is a particular problem with long term use of heterocyclics.
It causes less sexual dysfunction than SSRIs. Side effects include restlessness, agitation, sleeplessness, headache, rashes, stomach problems, and in rare cases, hallucinations and bizarre thinking. High doses increase the risk for seizures, particularly in those with eating disorders or those with other risk factors for seizures. In a group who required higher doses of an antidepressant in order to obtain a response, venlafaxine was slightly more effective. Venlafaxine has a variety of side effects, and high blood pressure and depressed central nervous system function can occur in high doses.