Final answer:
MAOIs are a class of antidepressants that work by inhibiting the monoamine oxidase enzyme to prevent the breakdown of certain neurotransmitters. While effective, their use is limited due to serious side effects and interactions, leading to a preference for tricyclic antidepressants and SSRIs for treating depression.
Step-by-step explanation:
Monoamine Oxidase Inhibitors (MAOIs)
Monoamine oxidase inhibitors, or MAOIs, are a class of antidepressants that were the first to be used effectively for treating depression. These drugs function by inhibiting the monoamine oxidase enzyme, which is responsible for the breakdown of neurotransmitters such as serotonin, norepinephrine, and dopamine. By inhibiting this enzyme, MAOIs increase the levels of these neurotransmitters in the brain, which can help alleviate symptoms of depression.
Examples of MAOIs include phenelzine (Nardil), and selegiline (Emsam). Despite their effectiveness, MAOIs are seldom used now due to their potential for serious side effects, including toxicity and potentially lethal food and drug interactions. Tricyclic antidepressants, which inhibit the reuptake of neurotransmitters serotonin and norepinephrine, are often preferred due to their relatively milder side effects and lower toxicity, despite MAOIs sometimes showing favorable responses especially in certain neurotic illnesses with depressive features.
Some MAOIs, such as selegiline, have been used at lower doses to treat Parkinson's disease due to their neuroprotective effects. However, the use of these medications requires careful dietary and medicinal management to avoid hypertensive crises, known as 'cheese reactions,' due to interactions with tyramine-rich foods.