Every field of medicine has had its fair share of serendipitous scientific discovery. In fact the boom in psychiatric treatments, starting in the 1950s, was launched by the accidental discovery of our first pharmacological antidepressant: Iproniazid (Hillhouse & Porter, 2015). When looking for better treatments for tuberculosis, scientists tested the compound Iproniazid. During their experiments, patients reported uplifted mood, increased energy, and better sleep. The compound that these scientists discovered was our very first “Monoamine Oxidase Inhibitors” (MAOI) (Yeragani et al., 2011). Today we are going to break down the mechanism of MAOIs.
So what exactly is a monoamine? A monoamine is a specific type of biological compound (that gets its name from a single amine group). They are important to us, because they are often used by our nervous system as neurotransmitters (signaling molecules). Serotonin, dopamine, norepinephrine, these are all monamines that have strong implications when it comes to mental health (Australian Health Dept., 2021). MAOIs work by preventing the enzymatic breakdown of these monoamines in the nervous system. This leads to an increased amount of availability of serotonin, dopamine, and norepinephrine, as well as other lesser known neurotransmitters. This is what we believe causes the antidepressant effect of these drugs (Hillhouse & Porter, 2015; Yeragani et al., 2011).
Since the 1950s many MAOIs have been developed and used to treat depression. However, since the development of Selective-Serotonin Reuptake Inhibitors (SSRIs), MAOI use has fallen out of favor (due to its increased risk of side effects) (Hillhouse & Porter, 2015). That said, it is important not to forget how MAOIs paved the way for modern psychopharmacology!