Just like reserpine, iproniazid had side effects that meant its popularity quickly declined, but its mechanism of action was a vital ingredient in the understanding of depression. In 1952, scientists found that the drug blocked an enzyme which usually breaks down the monoamines (a class of neurotransmitters including dopamine, noradrenaline, adrenaline and serotonin, amongst others), increasing levels of these chemicals in the neuron, ready for release into the synapse.
