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 serotonin 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.