The structure of the tetracyclic antidepressant mirtazapine

A tetracyclic antidepressant is an antidepressant drug from the tetracyclic drug group.

The name tetracyclic is derived from the drug's molecular structure which consists of four ring like structures (compare tricyclic antidepressant).

Maprotiline, trade named Ludiomil®, and Mirtazapine, trade named Remeron® in the USA and Zispin® in Europe, are the only two drugs from this group widely used for the treatment of clinical depression. The tetracyclic antidepressant Mianserin was previously available internationally, however in most markets it has been phased out in favor of Mirtazepine.

Research on other tetracyclic antidepressant compounds (for example setiptiline) have been reported in the scientific literature. These other tetracyclic antidepressants are not publicly available.

There are also several chemically unrelated tetracyclic antibiotics based on Tetracycline.