Monoamine oxidase inhibitors (MAOIs) were among the earliest treatments for depression. The MAOIs block an enzyme, monoamine oxidase. Examples are phenelzine (Nardil), tranylcypromine (Parnate) , isocarboxazid (Marplan), and transdermal selegiline (the EMSAMskin patch). Although MAOIs work well, they're not prescribed very often because of the risk of serious interactions with some other medications and certain foods. Foods that can negatively react with the MAOIs include aged cheese and aged meats.
Mirtazapine (Remeron) is also a unique antidepressant that is thought to affect mainly serotonin and norepinephrine through different brain receptors than other medicines. It is usually taken at bedtime because it often causes drowsiness. Side effects are usually mild and include sleepiness, weight gain, elevated triglycerides, and dizziness.