MCPG
Monoamine Oxidase Inhibitors (MAOIs)
Monoamine Oxidase Inhibitors (MAOIs) are a class of medications that are primarily used to treat depression. They are known for their effectiveness in treating atypical depression and are sometimes used in cases where other antidepressants have failed. MAOIs work by inhibiting the activity of monoamine oxidase, an enzyme responsible for breaking down neurotransmitters such as serotonin, norepinephrine, and dopamine in the brain.
Mechanism of Action[edit | edit source]
Monoamine oxidase (MAO) is an enzyme that exists in two forms: MAO-A and MAO-B. MAO-A preferentially degrades serotonin and norepinephrine, while MAO-B primarily breaks down phenylethylamine and certain other trace amines. Both forms metabolize dopamine. By inhibiting these enzymes, MAOIs increase the levels of these neurotransmitters in the synaptic cleft, thereby enhancing mood and alleviating depressive symptoms.
Types of MAOIs[edit | edit source]
There are several MAOIs that have been used in clinical practice, including:
- Phenelzine
- Tranylcypromine
- Isocarboxazid
- Selegiline (also used in the treatment of Parkinson's disease)
Each of these drugs has a slightly different profile in terms of selectivity and side effects.
Clinical Uses[edit | edit source]
MAOIs are primarily used to treat major depressive disorder, especially when it is resistant to other treatments. They are also used in the treatment of:
- Atypical depression
- Anxiety disorders
- Parkinson's disease (specifically selegiline)
Side Effects and Interactions[edit | edit source]
MAOIs are associated with a range of side effects, including:
- Orthostatic hypotension
- Weight gain
- Sexual dysfunction
- Insomnia
One of the most significant concerns with MAOIs is their potential to cause hypertensive crisis when taken with tyramine-rich foods or certain medications. This is due to the inhibition of MAO-A, which normally breaks down tyramine, a compound found in aged cheeses, cured meats, and some alcoholic beverages.
Dietary Restrictions[edit | edit source]
Patients taking MAOIs must adhere to dietary restrictions to avoid hypertensive crises. Foods high in tyramine should be avoided, including:
- Aged cheeses
- Fermented meats
- Certain alcoholic beverages
History[edit | edit source]
MAOIs were among the first antidepressants developed, with the first being discovered in the 1950s. They were initially used to treat tuberculosis before their antidepressant properties were recognized.
Current Research[edit | edit source]
Research into MAOIs continues, with studies focusing on their potential use in treating other psychiatric disorders and their mechanisms of action. Newer MAOIs with improved safety profiles are also being developed.
Also see[edit | edit source]
- Antidepressant
- Selective Serotonin Reuptake Inhibitor
- Tricyclic Antidepressant
- Atypical Depression
- Hypertensive Crisis
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