psychiatric disorders
Medications for Treatment of Depression
Heterocyclic Antidepressants (HCAs)
This group of medications, once the mainstay of treatment, includes tricyclic (tertiary aminesamitriptylineandimipramineand their secondary amine metabolitesnortriptylineanddesipramine), modified tricyclic, and tetracyclic antidepressants. Acutely, heterocyclic antidepressants increase the availability of primarilynorepinephrineand, to some extent, 5-HT by blocking reuptake in the synaptic cleft. Long-term use downregulates alpha-1 adrenergic receptors on the postsynaptic membrane—a possible final common pathway of their antidepressant activity. Although effective, these medications are now rarely used because overdose causes toxicity and they have more adverse effects than other antidepressants. The more common adverse effects of heterocyclics are due to their muscarinic-blocking, histamine-blocking, and alpha-1 adrenolytic actions. Many heterocyclics have strong anticholinergic properties and are thus unsuitable for older patients and those with Benign Prostatic Hyperplasia (BPH) , 