The major classifications of antidepressants are MAOI (monamine oxidase inhibitor), TCA (tricyclic), SSRI (selective serotonin reuptake inhibitor) and SNRI (serotonin-norepinephrine reuptake inhibitor). As researchers try to develop more selective antidepressants and to eliminate as many side effects as possible, new drugs and new antidepressant classifications are appearing. We will briefly discuss some of the new types of antidepressants here.
Buproprion: Buproprion is a unique antidepressant. It inhibits dopamine and norepinephrine reuptake and is a nicotine antagonist. Buproprion is less sedating than other antidepressants and does not cause weight gain or sexual side effects. It is an effective aid for treating tobacco addiction and may be helpful in other addictions, too. On the negative side, buproprion is more likely to cause seizures than other antidepressants.
NSRI: Norepinephrine-serotonin reuptake inhibitors have a greater effect on norepinephrine than on serotonin. Milnacipram (Ixel) is the only currently available NSRI. Milnacipram has been available in Europe for several years; US FDA approval is pending. NOTE: Not everybody agrees with some of the new antidepressant classifications; some people would classify milnacipram as an SNRI.
NARI: Selective Nor-Adrenaline Reuptake inhibitors work specifically to increase nor-adrenaline (norepinephrine). Reboxetine is the only NARI available. It is effective in treating depression, and also seems to improve motivation, energy level and social functioning.
NaSSA: Mirtazapine (Remeron) is the only Nor-adrenaline and Specific Serotonin Antidepressant. It is also the only tetracyclic antidepressant. It has few side effects other than sleepiness and weight gain and is often used as a second medication to treat resistant depression.
Nefazadone: Nefazadone is another unique antidepressant. It works mostly by blocking specific serotonin receptors. It inhibits serotonin and norepinephrine reuptake to a small extent, and is a potent alpha1 adrenergic antagonist. Alpha antagonist medications have specific effects on the heart and blood vessels, as well as other organs.
As research continues in the quest to find the perfect antidepressant, more types of antidepressants are likely to emerge.