Heterocyclic Antidepressants (HCAs)

00:01 Let's move on to heterocyclic antidepressant. They act a lot like the TCA's. They have fewer interactions in the periphery however. And so in that respect there are a little bit of an improvement of the older TCA's. There are still some other miscellanous receptors that are affected however and that's how side effects are engendered. So bupropion is a very popular heterocyclic antidepressant. It's sold as Wellbutrin for depression and interestingly enough it's also sold as Zyban in the United States for the treatment of smoking cessation. It's used in depression as an add-on to other drugs and it actually works quite well. It antagonizes central norepinephrine and dopamine reuptake and it antagonizes nicotine receptors at the same time. So your depressed smoker is an ideal patient for this particular agent. Now side effects with this drug include anxiety, agitation, once again a dry mouth like the TCA's. You can get aggravation of psychosis, you have to be aware that those patients who are at risk of getting psychosis, use this drug with caution. Once again, the heterocyclic antidepressants with this drug included increase risk of seizure at high doses. Other groups of heterocyclic antidepressants include mirtazapine also known as Remeron. This drug antagonizes norepinephrine and serotonin reuptake. It also antagonizes serotonin receptors directly. It increases release by antagonizing the pre-synaptic alpha 2 adrenoreceptors. This causes decreased feedback inhibition. So the side effects with this medication are less reflex tachycardia but more weight gain and it's more sedating.