Tricyclic and Heterocyclic Antidepressants

Mirtazapine is associated with modest anticholinergic side effects, including dry mouth and constipation. Anticholinergic side effects and their management are discussed in the Tricyclic and Heterocyclic Antidepressants section later in this chapter. 

Fluoxetine was the first SSRI to reach general clinical use. Paroxetine and sertraline differ mainly in having shorter half-lives and different potencies as inhibitors of specific P450 isoenzymes. While the SSRIs have not been shown to be more effective overall than prior drugs, they lack many of the toxicities of the tricyclic and heterocyclic antidepressants. Thus, patient acceptance has been high despite adverse effects such as nausea, decreased libido, and even decreased sexual function. 

At about the same time, the drug imipramine was first produced. It was originally developed as a phenothiazine (antipsychotic), but was found to have antidepressant properties. Soon came amitriptyline, followed later by other "tricyclic" and "heterocyclic" antidepressants. 

Izumi X Inoue T, Kitagawa N et al. Open pergolide treatemtn of tricyclic and heterocyclic antidepressant-resistant depression, j Affect Disord 2000 61 127-132. 

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