**7.2 Monoamine oxidase inhibitors**

Among the all clinically introduced drugs, monoamine oxidase inhibitors were found to be first drugs for the treatment of depression while these are replaced by tricyclic and other types of antidepressant drugs because these having more efficacies and less side effects than the monoamine oxidase inhibitors. Phenelzine, tranylcypromine and iproniazide are the example of monoamine oxidase inhibitors. That drug irreversibly inhibits the MAO-A and MAO-B enzymes [76].
