Antidepressants Flashcards
What are the three classifications of depression?
- Reactive (secondary): due to real stimuli (e.g., illness, grief).
- Endogenous (major): genetically determined biochemical disorder.
- Bipolar: alternating mania and depression.
What is the mechanism of action of TCAs?
Non-selectively inhibit neuronal reuptake of norepinephrine (NA) and serotonin (5-HT).
How long does it take for TCAs to show antidepressant effect?
Several weeks of continuous administration.
What receptors do TCAs block?
Serotonergic, α-adrenergic, histamine, muscarinic receptors.
What are the therapeutic uses of TCAs?
Severe major depression, panic disorder, chronic undiagnosed pain, bulimia, obsessive-compulsive disorder (SSRIs are preferred for OCD).
What is a notable adverse effect of TCAs in some patients?
Switching to hypomania or mania.
What drugs TCAs can potentiate or inhibit their effects?
Direct-acting adrenergic drugs: TCA potentiate their effects.
Indirect-acting adrenergic drugs: their effects blocked by TCAs.
What are notable drug interactions of TCAs?
With MAOIs: dangerous interaction.
Inhibit hypotensive action of guanethidine.
Displaced from plasma albumin by phenytoin & aspirin.
Interact with enzyme inducers.
Name some SSRIs.
Fluoxetine (prototype), fluvoxamine, paroxetine, sertraline.
What is a major advantage of SSRIs over TCAs?
Free from most side effects of TCAs.
What is the enzyme effect of SSRIs?
Potent CYP450 enzyme inhibitors.
What are the therapeutic uses of SSRIs?
DOC for OCD, also used in depression, bulimia, anorexia, premenstrual syndrome, diabetic neuropathy.
What is a notable side effect of SSRIs?
Weight loss.
What is a dangerous drug interaction with SSRIs?
With MAOIs.
Why is the use of MAOIs limited?
Due to significant drug and food interactions.
List some drug/food interactions with MAOIs.
Sympathomimetics, TCAs, SSRIs, morphine, L-Dopa, tyramine-rich food (e.g., fermented food).
What is the necessary washout period when switching from MAOIs to another antidepressant?
At least 2 weeks.
What is lithium used for?
Manic depression (acute attacks & prophylaxis).
What is lithium’s mechanism of action?
Depletes membrane phosphatidyl inositol (PI).
How does lithium affect ADH?
Antagonizes ADH → causes nephrogenic diabetes insipidus (responds to amiloride).
What should be avoided in lithium toxicity?
Loop diuretics.
How is lithium toxicity managed?
Sodium bicarbonate and fluids.
