- 藉由可逆或是不可逆抑制Monoamine oxidase or its cofactor covallently 而抑制生物胺的代謝而增加濃度
- MAO is fully inhibited after several days of treatment, the antidepressant action of the MAO inhibitors, like that of the SSRls and TCAs, is delayed several weeks. Phenelzine and tranylcypromine have a mild, amphetamine-like stimulant effect.
- nonselective MAOI:抑制MAO-A and MAO-B 譬如: phenelzine和tranylcypromine
- selective MAOI
- Use of MAO inhibitors is now limited due to the complicated dietary restrictions required of patients taking MAO inhibitors. Two MAO inhibitors are currently available for treatment of depression: phenelzine and tranylcypromine.
- These drugs inhibit not only MAO in the brain but also peripheral oxidases that catalyze oxidative deamination of drugs and potentially toxic substances, such as tyramine, which is found in certain foods(aged cheeses, chicken liver, beer, and red wines, is normally inactivated by MAO in the gut. ) .
- Individuals receiving an MAO inhibitor are unable to degrade tyramine obtained from the diet. Tyramine causes the release of large amounts of stored catecholamines from nerve terminals, resulting in headache, tachycardia, nausea, hypertension, cardiac arrhythmias, and stroke.因此有自殺傾向的患者可能會用來自殺
- Phentolamine or prazosin are helpful in the management of tyramine-induced hypertension.
- Other possible side effects include drowsiness, orthostatic hypotension, blurred vision, dry mouth, dysuria, and constipation.
- MAO inhibitors and SSRls should not be coadministered due to the risk of life-threatening ‘serotonin syndrome’ Both types of drugs require wash-out periods of six weeks before the other type is administered.
- MAO inhibitors are indicated for depressed patients who are unresponsive or allergic to TCAs, or who experience strong anxiety.
- atypical depression
- phobic states
- selective MAO-B I: selegiline
- These drugs are well absorbed on oral administration, but antidepressant effects require two to four weeks of treatment. Enzyme regeneration, varies, after termination of the drug. Thus, when switching antidepressant agents, a minimum of two weeks of delay must be allowed after termination of MAO inhibitor therapy.
- MAOI can not be used together with non-stimulant drug for attention deficit hyperactivity disorder: Atomoxetine
- MAOI和能增加NE、dopamine的物質不能並用Ex. 安非他命