Psychiatric Medications Q 38
A client seeks care because she feels depressed and has gained weight. To treat her atypical depression, the physician prescribes tranylcypromine sulfate (Parnate), 10 mg by mouth twice per day. When this drug is used to treat atypical depression, what is its onset of action?
A. 1 to 2 days
B. 3 to 5 days
C. 6 to 8 days
D. 10 to 14 days
Correct Answer: B. 3 to 5 days
Monoamine oxidase inhibitors, such as tranylcypromine, have an onset of action of approximately 3 to 5 days. A full clinical response may be delayed for 3 to 4 weeks. The therapeutic effects may continue for 1 to 2 weeks after discontinuation. When patients are prescribed antidepressants like MAOIs, they must be aware of the time it takes to start experiencing the therapeutic effects of the drug. Usually, the medication starts to become effective within two to three weeks.
Option A: Patients should take the antidepressant for at least six months for the maximal therapeutic benefit. Patients that take an antidepressant for less than six months are shown to have a high rate of symptomatic relapse. Monoamine oxidase inhibitors (MAOIs) were first introduced in the 1950s. They are a separate class from other antidepressants, treating different forms of depression as well as other nervous system disorders such as panic disorder, social phobia, and depression with atypical features.
Option C: Monoamine oxidase inhibitors are responsible for blocking the monoamine oxidase enzyme. The monoamine oxidase enzyme breaks down different types of neurotransmitters from the brain: norepinephrine, serotonin, dopamine, as well as tyramine. MAOIs inhibit the breakdown of these neurotransmitters thus, increasing their levels and allowing them to continue to influence the cells that have been affected by depression.
Option D: There are two types of monoamine oxidase, A and B. The MOA A are mostly distributed in the placenta, gut,, and liver, but MOA B is present in the brain, liver, and platelets. Serotonin and noradrenaline are substrates of MOA A, but phenylethylamine, methylhistamine, and tryptamine are substrates of MOA B. Dopamine and tyramine are metabolized by both MOA A and B. Selegiline and rasagiline are irreversible and selective inhibitors of MAO type B, but safinamide is a reversible and selective MAO B inhibitor.