Issues in Selection of an Antidepressant

Table of Contents

1. Objectives
2. Indications
3. Antidepressant Classes
4. "Newer" Antidepressant Classes
5. Selective Serotonin Reuptake Inhibitors
6. Pharmacokinetics
7. Extra Receptor Effects
8. SSRIs in Summary
9. "New" Miscellaneous Antidepressants
10. Dual Agents
11. Special Circumstances
12. A Final Note
13. Review Questions
14. Your Feedback

Extra Receptor Effects

The SSRIs differ from each other in one other very important way, and that is by the "secondary binding profiles" or extra receptor effects. While they are all the same in terms of their mechanism of action, therapeutic profiles, and side effect profiles, it is hypothesized that the extra receptor effects may account for the reason that patients respond so differently to the different drugs. Following are some examples:

1. Fluoxetine (Prozac) has 5HT2C antagonist properties. This causes it to have a net disinhibiting effect on NE and DA. What is significant about this is most SSRIs inhibit NE and DA. So while most SSRIs can cause blunting, fluoxetine can cause activation. Some patients don't like this activation, and some love it!

2. Paroxetine (Paxil) has muscarinic cholinergic blocking effects- so it is sedating. Some people love this sedation, although it can wear out its welcome!. It also has nitric oxide synthetase inhibition. This can cause sexual dysfunction, expecially in men.

3. Sertraline (Zoloft) has mild dopamine reuptake inhibition. It is controversial whether or not this is clinically significant, although some researchers think this may contribute to activating effects. It also has sigma receptor effects which may contribute to its anxiolytic properties.